Mission: Leg III of SEAMAP Summer Groundfish Survey Geographic Area of Cruise: Gulf of Mexico Date: July 16, 2019
Weather Data from the Bridge Latitude: 28.51° N Longitude: 84.40° W Wave Height: 1 foot Wind Speed: 6 knots Wind Direction: 115 Visibility: 10 nm Air Temperature: 30.8°C Barometric Pressure: 1021 mb Sky: Clear
In my previous blog, I mentioned the challenges of doing survey work on the eastern side of the Gulf near Florida. I also mentioned the use of a probe to scan the sea floor in advance of trawling for fish samples. That probe is called the EdgeTech 4125 Side Scan Sonar. Since it plays a major role in the scientific research we have completed, I wanted to focus on it a bit more in this blog. Using a scanner such as this for a groundfish survey in the Gulf by NOAA is not typical. This system was added as a precaution in advance of trawling due to the uneven nature of the Gulf floor off the Florida Coast, which is not as much of a problem the further west one goes in the Gulf. Scanners such as these have been useful on other NOAA and marine conservation research cruises especially working to map and assess reefs in the Gulf.
Having seen the side scanner used at a dozen different research stations on this cruise, I wanted to learn more about capabilities of this scientific instrument. From the manufacturer’s information, I have learned that it was designed for search and recovery and shallow water surveys. The side scanner provides higher resolution imagery. While the imagining sent to our computer monitors have been mostly sand and rock, one researcher in our crew said he has seen tanks, washing machines, and other junk clearly on the monitors during other research cruises.
This means that the side scanner provides fast survey results, but the accuracy of the results becomes the challenge. While EdgeTech praises the accuracy of its own technology, we have learned that accurate readings of data on the monitor can be more taxing. Certainly, the side scanner is great for defining large items or structures on the sea floor, but in areas where the contour of the floor is more subtle, picking out distinctions on the monitor can be harder to discern. On some scans, we have found the surface of the sea floor to be generally sandy and suitable for trawling, but then on another scan with similar data results, chunks of coral and rock have impeded our trawls and damaged the net.
Did You Know?
In 1906, American naval architect Lewis Nixon invented the first sonar-like listening device to detect icebergs. During World War I, a need to detect submarines increased interest in sonar. French physicist Paul Langévin constructed the first sonar set to detect submarines in 1915. Today, sonar has evolved into more sophisticated forms of digital imaging multibeam technology and side scan sonar (see https://oceanexplorer.noaa.gov/explorations/lewis_clark01/background/seafloormapping/seafloormapping.html for more information).
When I first arrived aboard Oregon II, the new environment was striking. I have never spent a significant amount of time on a trawling vessel or a research ship. Looking around, I took many pictures of the various features with an eye on the architectural elements of the ship. One of the most common fixtures throughout the vessel are posted signs. Lamented signs and stickers can be found all over the ship. At first, I was amused at the volume and redundancy, but then I realized that this ship is a communal space. Throughout the year, various individuals work and dwell on this vessel. The signs serve to direct and try to create consistency in the overall operation of the ship and the experience people have aboard it. Some call the ship “home” for extended periods of time such as most of the operational crew. Others, mostly those who are part of the science party, use the vessel for weeks at a time intermittently. Before I was allowed join the science party, I was required to complete an orientation. That orientation aligns with policies of NOAA and the expectation aboard Oregon II of its crew. From the training, I primarily learned that the most important policy is safety, which interestingly is emblazoned on the front of the ship just below the bridge.
The signs seem to be reflective of past experiences on the ship. Signs are not only reminders of important policies and protocols, but also remembrances of challenges confronted during past cruises. Like the additional equipment that has been added to Oregon II since its commission in 1967, the added signs illustrate the history the vessel has endured through hundreds of excursions.
Examples of that history is latent in the location and wording of signs. Posted across from me in the computer lab are three instructional signs: “Do not mark or alter hard hats,” “Keep clear of sightglass do not secure gear to sightglass” (a sightglass is an oil gauge), and “(Notice) scientist are to clear freezers out after every survey.”
Author and journalist Daniel Pink talks about the importance of signs in our daily lives. His most recent work has focused on the emotional intelligence associated with signs. Emotional intelligence refers to the way we handle interpersonal relationships judiciously and empathetically. He is all about the way signs are crafted and displayed, but signs should also be thought of in relation to how informative and symbolic they can be within the environment we exist. While the information is usually direct, the symbolism comes from the way we interpret the overall context of the signs in relation to or role they play in that environment.
You may be wondering what role technology plays in a hydrographic survey. I have already written about how modern survey operations rely on the use of multibeam sonar. What I have not described, and am still coming to understand myself, is how complex the processing of sonar data is, involving different types of hardware and software.
For example, when the sonar transducer sends out a pulse, most of the sound leaves and eventually comes back to the boat at an angle. When sound or light waves move at an angle from one substance into another, or through a substance with varying density, they bend. You have probably observed this before and not realized it. A plastic drinking straw in a glass of water will appear broken through the glass. That is because the light waves traveling from the straw to your eye bend as they travel.
The bending of a wave is called refraction. Sound waves refract, too, and this refraction can cause some issues with our survey data. Thanks to technology, there are ways to solve this problem. The sonar itself uses the sound velocity profile from our CTD casts in real time to adjust the data as we collect it. Later on during post processing, some of the data may need to be corrected again, using the CTD cast profiles most appropriate for that area at that general time. Corrections that would be difficult and time-consuming if done by hand are simplified with the use of technology.
Another interesting project in which I’ve been privileged to participate this week was setting up a base station at Shark Point in Ugak Bay. You have most likely heard of the Global Positioning System, and you may know that GPS works by identifying your location on Earth’s surface relative to the known locations of satellites in orbit. (For a great, kid-friendly explanation of GPS, I encourage students to check out this website.) But what happens if the satellites aren’t quite where we think they are? That’s where a base station, or ground station, becomes useful. Base stations, like the temporary one that we installed at Shark Point, are designed to improve the precision of positioning data, including the data used in the ship’s daily survey operations.
Setting up the Base Station involved several steps. First, a crew of six people were carried on RA-7, the ship’s small skiff, to the safest sandy area near Shark Point. It was a wet and windy trip over on the boat, but that was only the beginning! Then, we carried the gear we needed, including two tripods, two antennae (one FreeWave antenna to connect with the ship and a Trimble GPS antenna), a few flexible solar panels, two car batteries, a computer, and tools, through the brush and brambles and up as close to the benchmark as we could reasonably get. A benchmark is a physical marker (in this case, a small bronze disk) installed in a location with a known elevation above mean sea level. For more information about the different kinds of survey markers, click here.
Next we laid out a tarp, set up the antennae on their tripods, and hooked them up to their temporary power source. After ensuring that both antennae could communicate, one with the ship and the other with the satellites, we met back up with the boat to return to the ship. The base station that we set up will be retrieved in about a week, once it has served its purpose.
Career Focus – Commanding Officer (CO), NOAA Corps
Meet Ben Evans. As the Commanding Officer of NOAA Ship Rainier, he is the leader, responsible for everything that takes place on board the ship as well as on the survey launches. Evans’ first responsibility is to the safety of the ship and its crew, ensuring that people are taking the appropriate steps to reduce the risks associated with working at sea. He also spends a good deal of his time teaching younger members of the crew, strategizing with the other officers the technical details of the mission, and interpreting survey data for presentation to the regional office.
Evans grew up in upstate New York on Lake Ontario. He knew that he wanted to work with water, but was unsure of what direction that might take him. At Williams College he majored in Physics and then continued his education at Woods Hole Oceanographic Institution, completing their 3-year Engineering Degree Program. While at WHOI, he learned about the NOAA Commissioned Officers Corps, and decided to apply. After four months of training, he received his first assignment as a Junior Officer aboard NOAA Ship Rude surveying the waters of the Northeast and Mid-Atlantic. Nearly two decades later, he is the Commanding Officer of his own ship in the fleet.
When asked what his favorite part of the job is, Evans smiled to himself and took a moment to reply. He then described the fulfillment that comes with knowing that he is a small piece of an extensive, ongoing project–a hydrographic tradition that began back in 1807 with the United States Survey of the Coast. He enjoys working with the young crew members of the ship, sharing in their successes and watching them grow so that together they may carry that tradition on into the future.
For my last post, I would like to talk about some of the amazing marine life that I have seen on this trip. Seals, sea lions, and sea otters have shown themselves, sometimes in surprising places like the shipyard back in Seward. Humpback whales escorted us almost daily on the way to and from our small boat survey near Ugak Bay. One day, bald eagles held a meeting on the beach of Ugak Island, four of them standing in a circle on the sand, as two others flew overhead, perhaps flying out for coffee. Even the kelp, as dull as it might seem to some of my readers, undulated mysteriously at the surface of the water, reminding me of alien trees in a science fiction story.
Stepping up onto dry land beneath Shark Point, we were dreading (yet also hoping for) an encounter with the great Kodiak brown bear. Instead of bears, we saw a surprising number of spring flowers, dotting the slopes in clumps of blue, purple, and pink. I am sensitive to the smells of a new place, and the heady aroma of green things mixed with the salty ocean spray made our cold, wet trek a pleasure for me.
Word of the Day
Davit – a crane-like device used to move boats and other equipment on a ship
Speaking of Refraction…
Thank you to NOAA Ship Rainier, the Teacher at Sea Program, and all of the other people who made this adventure possible. This was an experience that I will never forget, and I cannot wait to share it with my students back in Georgia!
Geographic Area of Cruise: U.S. Southeastern Continental Margin, Blake Plateau
Date: June 5, 2019
Latitude: 29°01.5’ N
Longitude: 079°16.0’ W
Wave Height: 2 feet
Wind Speed: 10 knots
Wind Direction: 128
Visibility: 10 nm
Air Temperature: 27.7°C
Barometric Pressure: 1021.3
Science and Technology Log
What is sonar?
Sonar is the use of sound to describe the marine environment. Sonar can be compared to satellites that use light to provide information about Earth, but instead of light, sound is used. It is used to develop nautical charts, detect hazards under the water, find shipwrecks, learn about characteristics of the water column such as biomass, and map the ocean floor. There are two types of sonar, active and passive. Active sonar is sonar that sends out its own sound wave. The sonar sends a sound wave (ping) out into the water and then waits for the sound to return. The return sound signal is called an echo. By assessing the time, angle, and strength of the return sound wave or echo one can learn many details about the marine environment. Passive sonar does not actively send out a sound ping, but rather listens for the sound from other objects or organisms in the water. These objects may be other vessels and these organisms may be whales or marine ecosystems such as coral reefs.
Sound waves move through the water at different speeds. These speeds are known as frequencies and the unit of measurement for sound is a hertz (Hz). Lower frequencies (example 18 kHz) are able to go farther down because they move slower and have more power behind them. It is like when a car goes down your street, pumping the bass (always seems to happen when I am trying to sleep) and you can hear it for a long time. That is because it is a low frequency and has longer wave lengths. Higher frequencies (example 200 kHz) move faster, but have less power. The sound waves should reach the bottom, an object, or biomass in the water column, but there may be no return or echo. High frequency sound waves are closer together. High frequencies give you a good image of what is happening near the surface of the water column and low frequencies give you a good idea of what is happening near, on, or under the ocean floor.
Type of Sonar on Okeanos Explorer
There are many types of sonar and other equipment aboard Okeanos Explorer for use during mapping operations. All have different capabilities and purposes. Together they provide a complete sound image of what is happening below us.
Kongsberg EM302 Multibeam Sonar
Multibeam sonar sends sound out into the water in a fan pattern below the hull (bottom) of the ship. It is able to map broad areas of the water column and seafloor from depths of 10 meters to 7,000 meters. Only the deepest trenches are out of its reach. It is the most appropriate sonar system to map seafloor features such as canyons and seamounts. The fan like beam it emits is 3-5.5x the water depth with a max swath range of 8 km. However, when you get to its depths below 5,000 meters the quality of the sound return is poor so scientists keep the swath range narrower to provide a higher quality of data return. The widest swath area scientists can use while maintaining quality is a depth of 3,300-5,000 meters. The user interface uses a color gradient to show you seafloor features (red=shallow and purple=deep).
Backscatter uses the same pings from the multibeam. People use backscatter to model or predict physical or biological properties and composition of the sea floor. The coloring typically is in grayscale. A stronger echo looks brighter in the image. A weaker echo looks darker in the image. It gives you a birds-eye view of seafloor characteristics such as substrate density and seafloor features.
An Expendable Bathy-Thermograph (XBT) provides you with information on the temperature gradients within the water. When the temperature profile is applied to a salinity profile (taken from World Ocean Atlas) you are able to determine sound velocity or the rate at which the sound waves can travel through the water. When sound moves through water it does not move in a straight line. Its path is affected by density which is determined by water type (freshwater or saltwater) and temperature. Freshwater is less dense than saltwater and cold water is denser than warm water. The XBT information accounts for sound refraction (bending) through various water densities. When near shore XBTs are launched more frequently because the freshwater inputs from land alter density of the water and temperatures in the water column are more varied. XBTs are launched less frequently when farther from shore since freshwater inputs are reduced or nonexistent and the water column temperature is more stable. However, ocean currents such as the Gulf Stream (affecting us on this cruise) can affect density as well. The Gulf Stream brings warm water from the Gulf of Mexico around the tip of Florida and along the eastern coast of the United States. Therefore, one must also take into account which ocean currents are present in the region when determining the launch schedule of XBTs.
Simrad EK60 and EK80 Split-beam Sonar
Split-beam sonar sends out sound in single beam of sound (not a fan like the multibeam). Each transducer sends out its own frequency (example 18 kHz, 38 kHz, 70 KHz, 120 kHz, and 200 kHz). Some frequencies are run at the same time during mapping operations. Mapping operations typically do not use the 38 kHz frequency since it interferes with the multibeam sonar. Data collected with the use of the EK60 or EK80 provides information about the water column such as gaseous seeps, schools of fish, and other types of dense organism communities such as zooplankton. If you remember my “did you know” from the second blog, I discussed how sonar can be used to show the vertical diurnal migration of organisms. Well the EK60 or EK80 is the equipment that allows us to see these biological water column communities and their movements.
Knudsen 3260 Sub-bottom Profiler
The purpose of using a sub-bottom profiler is to learn more about the layers (up to 80 meters) below the ocean floor. It works in conjunction with the sonar mapping the ocean floor to provide more information about the bottom substrate, such as sediment type and topography features. Sub-bottom data is used by geologists to better understand the top layers of the ocean floor. A very low frequency is used (3.5 kHz) because it needs to penetrate the ocean sediment. It will give you a cross section of the sea floor so floor features can be detected.
Telepresence aboard the ship allows the science team to get mapping products and raw data to land on a daily basis. The science team can also live feed data collection to shore in real time. By allowing a land based shore team to see the data in real time you are adding another system of checks and balances. It is one more set of eyes to make sure the data being collected looks correct and there are no issues. It also allows a more collaborative approach to mapping, since you are able to involve a worldwide audience in the mission. Public viewers can tune in as well. Support for the technology needed to allow telepresence capabilities comes in partnership with the Global Foundation of Ocean Exploration (GFOE). With GFOE’s help, the protocols, high-speed satellite networks, Internet services, web and social media interfaces, and many other tools are accessible when out to sea. The NOAA Office of Exploration and Research (OER) provides the experts needed to develop, maintain, and operate the telepresence systems while at sea, but also at shore through the Exploration Command Centers (ECCs) and the University of Rhode Island’s Inner Space Center.
All in all, the equipment aboard Okeanos Explorer is impressive in its abilities to provide the science team with a high quality and accurate depiction of the ocean floor and water column. The science team aboard is able to interpret the data, clean out unwanted data points, store massive data files on computers, and send it back to land daily, all while rocking away at sea. Very impressive and very cool!
I learned all about memes today. Apparently they are very popular on the ship. So popular, we are even in the middle of a meme contest. For those of you unfamiliar to memes like I was, a meme is a funny picture with a clever caption that makes you laugh or relates to something in your life. After my tutorial in meme making, we had a great time out on the bow of the ship playing corn hole and hanging out. The night was beautiful. The humidity subsided and there was a great breeze. After the sun set, I watched the stars come out and then went inside to learn more about the mapping process. I am starting to get a better understanding of what the science team is doing. You know the how and the why of it all. After I couldn’t keep my eyes open any longer, I made my nightly venture out onto the bow to look from some bioluminescence, the glittering of zooplankton in the night. A magical site. I will leave you wondering how the ocean glitters until one of my future blogs when I describe the process of bioluminescence.
Did You Know?
The SOFAR (Sound Fixing and Ranging) channel occurs in the world’s oceans between depths of 800 to 1000 meters in the water column. Because of the density and pressure around this channel, sound waves travel for an extended distance. It is thought that fin whales travel to this channel to communicate with other fin whales many kilometers away.
Today we depart Key West. The days in port have been spent readying equipment, training mission crew, and exploring the beauty that is Key West. We say our final goodbyes to terra firma and head out to sea.
If you visit OER’s website, you will see in their mission that they are the “only federal organization dedicated to ocean exploration. By using unique capabilities in terms of personnel, technology, infrastructure, and exploration missions, OER is reducing unknowns in deep-ocean areas and providing high-value environmental intelligence needed by NOAA and the nation to address both current and emerging science and management needs.” The purpose of OER is to explore the ocean, collect data, and make this data publicly available for research, education, ocean management, resource management, and decision-making purposes.
One of OER’s priorities is to map the US Exclusive Economic Zone (EEZ) at depths of 200 meters or greater. This is some deep stuff. The EEZ distance from shore is dependent on a variety of factors such as proximity to territorial waters of other countries and the continental shelf. If you want to learn more about how EEZs are established visit the United Nations Oceans and the Law of the Sea Website https://www.un.org/en/sections/issues-depth/oceans-and-law-sea/. Within the EEZ a country has exclusive rights to various activities such as fishing, drilling, ocean exploration, conservation, and resource management.
We are currently en route to our mapping area so we can map previously unmapped areas. The mapping that will occur on this mission will be used to help inform dive locations for the ROV (Remotely Operated Vehicle) mission that will take place after our mission. Mapping allows us to understand sea floor characteristics and learn more about deep sea ecosystems that can be later explored with an ROV. An ecosystem of interest for this mapping mission is deep sea coral habitat. The area where we will be mapping is thought to be the largest deep sea coral habitat in US waters and it is largely unmapped. As data is collected, it is cleaned (more on this at a later time) of noise (unwanted data points). Products such as multi-beam geospatial layers are made available to end users on land roughly 24 hours after data is collected. End users could include other researchers, educators, ocean policy and management decision-makers, and more specifically those who will be joining the ROV mission happening in two weeks.
We have just left port. The dolphins are jumping, the sea is the most perfect turquoise blue, and the wind blows on our sun-kissed faces. I have left port many times on my various trips, but today was magical. I think what makes this departure from port so magical is the journey that lies ahead. I am nervous and excited all at the same time. It is slowly settling in that I am able to participate in this once in a lifetime experience. Never in my wildest dreams did I think I would be aboard an ocean exploration vessel. Wow! Just Wow!
So far everything is good. Dabbled pretty hard in the seasickness world today. I tried to get on my computer too early and it went down swell from there. However, some wind on my face, ginger soup, and bubbly water made everything better. Many people have told me it is important to embark on a task to get my mind off feeling unwell. I have taken this to heart and have been meeting all the wonderful people on the ship, learning more about them and their role on the ship. In the coming two weeks, I plan on learning about every facet that it takes to operate an exploration mission. From what makes the ship move forward to the detailed intricacies of mapping the sea floor to those who make it all possible.
I hope I will be able to share my experience with you so it feels like you are with me on the ship. Using words and pictures I will try to make you feel as if you are aboard with all of us. I will do my best to show you the blue hues we encountered today and explain what it is like to be out to sea with land many miles away. But I still encourage you all to try it for yourself. Words and images will only give you half the story. You need to feel the rest firsthand.
Sunset is upon the horizon so I leave you for now. Stay tuned for more about our grand adventure.
Did You Know?
You can use sonar to learn more about the organisms living in the water column. For example, sonar has the ability to show you the migration of zooplankton and their predators to the surface at night and back down when the sun rises. This phenomenon is called vertical diurnal migration.
Different terms are used to describe items, locations, or parts of the ship. As I learn new words I would like to share my new vocabulary with all of you. If there is a ship term you want to know more about let me know and I will find out!
Mission: Hydrographic Survey – Approaches to Houston
Geographic Area of Cruise: Gulf of Mexico
Date: July 24th, 2018
Weather Data from the Bridge
Visibility: 5 Nautical Miles
Sky Condition: 8/8
Wind: Direction: 70.1°, Speed: 13.3 knots
Air: Dry bulb:26.9°C Wet bulb: 24.7°C
Science and Technology Log
Coming to NOAA Ship Thomas Jefferson, I was eager to learn all I could about sonar. I am amazed that we have the ability to explore the ocean floor using sound.
Over the course of my previous blog entries, I have described the tools and processes used to survey using sonar. This time, I am going to try to frame the sounds that the sonars are using in a musical context, in the hope that doing so will help students (and myself) better understand the underlying concepts.
Note – many aspects of music are not standardized. For the purpose of this blog post, all musical tuning will be in equal temperament, at A=440. When I reference the range of a piano, I will be referencing a standard 88-key instrument. Many of the sonar frequencies do not correspond exactly to an in-tune pitch, so they have been written to the nearest pitch, with a comment regarding if the true frequency is higher or lower than the one written.
In sonar and in music, when considering soundwaves it is important to know their frequency, a measure of how many waves occur over the course of a set period of time. Frequency is measured in a unit called Hertz (abbreviated as Hz), which measures how many soundwaves occur in one second. One Hertz is equal to one soundwave per second. For example, if you heard a sound with a frequency of 100Hz, your ears would be detecting 100 soundwaves every second. Musicians also are concerned with frequency, but will use another name for it: pitch. These words are synonymous – sounds that are higher in pitch are higher in frequency, and sounds that are lower in pitch are lower in frequency.
Below are the eight octaves of the note A that are found on a piano, each labeled with their frequency. The notes’ frequencies have an exponential relationship – as you move from low to high by octave, each note has a frequency that is double that of its predecessor.
The highest note on a piano, C, has a frequency of 4186.01Hz
Average, healthy young humans hear sounds ranging from 20Hz to 20,000Hz. All sounds outside of that range are inaudible to people, but otherwise no different from sounds that fall within the human range of hearing. The highest note we would be able to hear would be an E♭, at a frequency of 19,912.16Hz (a frequency of exactly 20,000Hz would fall in between E♭ and E♮, though would be closer to E♭). If put on a musical staff, it would look like this:
The hull of NOAA Ship Thomas Jefferson is equipped with several sonar transmitters and receivers, which can operate at a wide variety of frequencies.
Higher frequencies provide higher resolution returns for the sonar, but they dissipate more quickly as they travel through water than lower frequencies do. Surveyors assess the depth of the water they are surveying, and choose the frequency that will give them the best return based on their conditions. Most of the sonar frequencies are too high for humans to hear. The ship’s multi-beam echo sounder has a variable frequency range of 200,000Hz-400,000Hz, though as I’ve been on board they’ve been scanning with it at 300,000Hz. Likewise, the multi-beam sonars on the launches have also been running at 300,000Hz. The ship has a sub-bottom profiler, which is a sonar used for surveying beneath the seafloor. It operates at a frequency of 12,000Hz, and has the distinction of being the only sonar on the ship that is audible to humans, however, we have not had a need to use it during my time aboard the Thomas Jefferson.
The ship’s side scan towfish (which I described in my previous blog entry) operates at 455,000Hz.
Here, we can see what those frequencies would look like if they were to be put on a musical staff.
Altering the frequency isn’t the only way to affect the quality of the reading which the sonar is getting. Surveyors can also change the pulse of the sonar. The pulse is the duration of the ping. To think about it in musical terms, changing the pulse would be akin to switching from playing quarter notes to playing half notes, while keeping the tempo and pitch the same. Different sonar pulses yield different readings. Shorter pulses provide higher resolution, but like higher frequency pings, dissipate faster in water, whereas longer pulses provide lower resolution, but can reach greater depths.
Mariners have a reputation for being a rather superstitious bunch, so I decided to ask around to see if that held true for the crew of the Thomas Jefferson. Overall, I found that most didn’t strictly adhere to any, but they were happy to share some of their favorites.
Everyone I spoke to told me that it is considered bad luck to leave port on a Friday, though the Commanding Officer, CDR Chris van Westendorp, assured me that you could counteract that bad luck by making three 360° turns to the left as soon as the ship is able. Many on the crew are also avid fishermen, and told me that bringing bananas aboard would lead to a bad catch, and one went so far as to be mistrustful of yellow lighters as well.
Certain tattoos are said to bring good luck – I was told that sailors often have a chicken and a pig tattooed on their feet. According to custom, those animals were often stored in wooden crates that would float if a ship went down, and having them tattooed onto you would afford you the same benefit. When asked if he was superstitious one of our helmsmen Jim proudly showed me a tattoo he has of a dolphin. He explained that having a sea creature tattooed on your body would prevent drowning. “It works!” he said with a grin, “I’ve never drowned!”
Several maritime superstitions deal with foul weather. Umbrellas are said to cause bad weather, as is split pea soup. Whistling while on the bridge is said to “whistle in the winds.” While not a superstition per se, many crew members told me variations of the same meteorological mantra: Red sky at night, sailor’s delight. Red sky in the morning, sailors take warning.
One of the NOAA Corps Officers aboard, ENS Garrison Grant, knew several old superstitions related to shipbuilding. When laying the keel (the first piece of the ship to be put into place), shipbuilders would scatter evergreen boughs and tie red ribbons around it to ward off witches. Historically, having women aboard was considered bad luck, though, conversely it was said that if they showed their bare breasts to a storm, it would subside. This is why several ancient ships had topless women carved into the masthead. Legend has it that in order to assure that a ship would float, when it was ready to be launched for the first time, virgins would be tied to the rails that guided the ship from the ship yard into the water. The weight of the ship would crush them, and their blood would act as a lubricant, allowing the ship to slide into the water for the first time. Yikes! Thankfully, as society became more civilized, this practice evolved into the custom of breaking a bottle of champagne against a ship’s bow!
Did you know? Musical instruments play an important role in ship safety! In accordance with maritime law, ships will use auditory cues to make other vessels aware of their presence in heavy fog. For large ships, this includes the ringing of a gong at regular intervals.
Latest Highlight: During this week’s fire drill, I got to try the fire hose. It was very powerful and a lot of fun!
Mission: Hydrographic Survey – Approaches to Houston
Geographic Area of Cruise: Gulf of Mexico
Date: July 15th, 2018
Weather Data from the Bridge
Latitude: 28° 49.4115’N
Longitude: 93° 37.4893’W
Visibility: 10+ Nautical Miles
Sky Condition: 4/8
Wind: Direction: 240°, Speed: 7 knots
Air: Dry bulb:31.5°C Wet bulb: 27.5°C
Science and Technology Log
NOAA Ship Thomas Jefferson is well underway in its mission of surveying the seafloor. The primary tool that the ship (as well as its 2 Hydrographic Survey Launches) is using to accomplish this task is sonar. Sonar was originally an acronym for SOund Navigation And Ranging. If you are familiar with echolocation – the system that some animals (such as bats and dolphins) use to navigate their surroundings – then you already have a basic understanding of how sonar works. The sonar transmits a short sound (called a ping) that will travel down, away from the ship, until it hits the seafloor. At this point, it will reflect off of the sea floor, and echo back up to the ship, where it is detected by the sonar’s receiver. The crew aboard are then able to calculate the depth of the water.
To make the necessary calculations, there are 3 variables at play: the time that it takes for the ping to travel; the distance that the ping travels; and the velocity, or the speed, at which the ping moves through the water. If we know two of those variables, it is easy to calculate the third.
When using sonar to determine the depth of the water, distance is the unknown variable – that’s what we’re ultimately trying to figure out. To do so, we need to know the other two variables. Time is an easy variable for the sonar to measure. The sonar has a transmitter, which generates the ping, and a receiver, which hears it. These two components communicate with one another to give us an accurate measure of time. The third variable, velocity, is a bit trickier.
In saltwater, sound travels approximately 1500 meters per second. However, that rate can vary slightly based on water conditions such as temperature and salinity (how salty the water is). In order for sonar to get as accurate a reading as possible, it needs to calculate the precise speed of sound for the particular water it is in at the moment. The sonar is able to do that by using a component called a sound velocity sensor, known colloquially as a singaround.
A singaround looks like a bar with a nub on each end. One nub is a projector, and the other is a reflector. The projector broadcasts a ping that travels parallel to the hull of the ship, bounces off of the reflector, and returns to the projector. We use that information to calculate velocity. The calculation uses the same 3 variables as above (time, distance, and velocity), but this time, distance isn’t the unknown variable anymore – we know exactly how far the ping has traveled, because we know how far the projector and reflector are from one another. The singaround electronically measures how long it takes for the ping to travel, and since we now know two of the variables (distance and time) we can calculate the third (velocity) for our particular water conditions at the face of the sonar.
Sound travels roughly 4 times faster in water than it does in air (this is because water is denser than air). To ensure that the sonar gets an accurate reading, it is important that air bubbles don’t get in the way. The boat’s hull (bottom) has a triangular metal plate directly in front of the sonar, which routes air bubbles around to the side of the sonar.
Each day, the ship’s CO (Commanding Officer) publishes a POD, or Plan Of the Day. This is full of important information – it tells us what the ship will be doing; if/when we will deploy the launch boats, and who will be on them; what time meals will be; and the expected weather conditions. Below is an example from Friday, July 13th.
On Friday, I had the opportunity to go out on one of the Hydrographic Survey Launches. Because of their smaller size, the launch boats are great for surveying difficult to maneuver areas. For instance, we spent most of the day surveying an area near an oil rig, and were able to get much closer than the Thomas Jefferson could.
I’ve been very impressed by how multi-talented everyone on the ship seems to be. In addition to analyzing data, the ship’s survey techs can also be found handling lines as the survey boats are launched and recovered, and do a lot of troubleshooting of the hardware and software they’re using. The coxswains (people who drive small boats) double as engineers, fixing issues on the launch vessels when away from the ship. I’m surrounded by some very gifted people!
Did you know?: As president, Thomas Jefferson ordered the first survey of the coastline of the United States. Because of this, NOAA Ship Thomas Jefferson is named for him.
Latest Highlight: While surveying, we spotted a water spout in the distance. A water spout is a tornado that forms over water. Luckily, we were a safe distance away. It was an amazing sight to see!
Mission: Hydrographic Survey- Approaches to Houston
Geographic Area of Cruise: Gulf of Mexico
Date: July 1, 2018
Weather Data from the Bridge
Latitude: 29° 10.1’ N
Longitude: 093° 54.5’ W
Visibility: 10+ NM
Sky Condition: 3/8
Wind: 16 kts
Sea Water: 29.4° C
Air: 27° C
Science and Technology Log
At this point I have been able to understand more of the sonar technology taking place during the survey aboard the Thomas Jefferson. The ship uses two types of sonar: multibeam and side scan. Both work together transmitting and receiving sound pulses to and from the ocean floor. This provides a multispectral analysis.
Multibeam sonar is located underneath the hull of the ship. Multibeam is used to detect bathymetry (the depth of the ocean floor). Multibeam backscatter (reflected wave energy) gives a reading of the surface intensity. For example, a strong signal would mean a harder surface like rock or pipeline. With multibeam sonar, you can also adjust the sound wave frequency. For example, high frequency (primarily used during this survey in the Gulf of Mexico) is used for shallower waters allowing for higher resolution images. Images from multibeam have a color gradient to allow for clear vision of contours and depth differences. One way surveyors aboard the TJ may use backscatter images is to determine areas where bottom sampling might be applicable.
The side scan sonar is used alongside multibeam to provide black and white scans of images. Like multibeam backscatter, side scan measures the intensity of the sound returning from the sea floor. For example, a side scan return with high intensity could indicate a difference in material like pipeline or a wreck. A low intensity value could mean that the side scan sonar waves have reached a muddy substrate. Julia used the analogy of a tennis ball being bounced against a wall of different materials. For example, the tennis ball hitting a concrete wall would bounce back with higher intensity than one being bounced against a soft wall. Side scan sonar is very effective at detecting features that protrude off the sea floor, and for shallow water surveys, typically can see farther and cover a greater area the sea floor than multibeam echosounders alone.
The side scan sonar sensor is located on a torpedo-shaped “towfish” and pulled behind the boat. When viewing side scan images, surveyors typically look for the acoustic shadow cast by a feature protruding off the sea floor. By measuring the length of the acoustic shadow, hydrographers can determine whether the feature requires additional investigation. For example, the outline of a shipwreck, bicycle, or pipeline. However, it can also detect mammals like dolphins or schools of fish.
While this is happening, surveyors are also towing a MVP or Moving Vessel Profiler to capture information about the water column. This is important because multiple factors in the water column need to be corrected in order for accurate sonar calculations. For example, the speed of sound in salt water is roughly 1500 m/s but may change while the ship is traveling over different parts of the sea floor or passing through a thermocline (steep temperature gradient) or halocline (steep salinity gradient). The MVP is similar to the CTD used on the launch boat (see previous post), but the MVP allows the ship to continue moving at about 10 knots (average survey speed), while the CTD must be cast when the ship is stationary.
For more information on multispectral analysis and sonar, see these resources:
One of my goals in the classroom is to teach students to be comfortable making and learning from mistakes. Making mistakes in math and science is common and welcome because they lead to great discussion and future change. Often, my sixth graders get discouraged or so caught up in failure that they become paralyzed in making further attempts. While aboard the Thomas Jefferson, I have witnessed several aspects not go according to plan. I think these experiences are important to share because they provide real-life examples of professionals coming together, learning from mistakes, and moving forward.
Around 4:00 am, the towfish side scan sonar became entangled with the MVP. This was a horrendous disaster. The crew spent about 16 hours contemplating the issue and collecting data using the multibeam only, which is less than ideal. One of XO LCDR McGovern’s many roles aboard the ship is to serve as the investigator. She reviewed tapes of the early morning, talked with the crew, and later held a debrief with all involved. When something like this happens, the ship must write a clear incident report to send to shore. There were many questions about why and how this happened as well how to best proceed. In the end, the towfish and MVP were untangled with no damage present to the sensor. Within the same day, both were cast out and back in use.
I find this to be an astounding example of perseverance and teamwork. Despite being disappointed and upset that a critical tool for collecting accurate data was in dire shape, the crew came up with a plan of action and executed. Part of the engineering and scientific processes include evaluation and redesign. Elements of the sea and a center drift of the side scan lead to a documented new plan and refiguring the process so that this is unlikely to happen again.
+Saw a tuna eat a flying fish
+There is a large sense of purpose on the ship. Despite complex sleep schedules to enable 24 hour operations with a smaller crew, people are generally happy and working hard.
+ There seems to be an unlimited supply of ice cream in the ice cream freezer. Junior Officer, ENS Garrison Grant introduced me to a new desert- vanilla ice cream, a scoop of crunchy peanut butter, and chocolate syrup. I also found the rainbow sprinkles.
Mission: Pelagic Juvenile Rockfish Recruitment and Ecosystem Assessment Survey
Geographic Area of Cruise: Pacific Ocean off the California Coast
Date: June 8, 2017
TAS David Amidon with a tray of sorted catch
Different Rockfish species caught 6/8/17
Science and Technology Log
The main scientific research being completed on the Reuben Lasker during this voyage is the Pelagic Juvenile Rockfish Recruitment and Ecosystem Assessment Survey and it drives the overall research on the ship during this voyage. Rockfish are an important commercial fishery for the West Coast. Maintaining healthy populations are critical to maintaining the fish as a sustainable resource. The samples harvested by the crew play an important role in establishing fishery regulations. However, there is more happening than simply counting rockfish here on the ship.
How does it work? Let me try to explain it a bit.
First, the ship will transfer to a specific location at sea they call a “Station.”
For a half hour prior to arrival, a science crew member will have been observing for Marine Mammals from the bridge area. When the station is reached, a new observer from the science crew will take over the watch outside on the deck. The fishermen on the boat crew will then unwind the net and launch it behind the boat. It must be monitored from the deck in order to ensure it is located 30 m below the surface. Once everything is set, then the ship trawls with the net at approximately 2 knots. Everything must be consistent from station to station, year to year in order to follow the standardized methods and allow the data recorded to be comparable. After the 15 minutes, then the crew pulls the net in and collects the sample from the net. This process is potentially dangerous, so safety is a priority. Science crew members can not go on the deck as they have not received the proper training.
Timelapse video of the fishermen bringing in a catch. 6/7/17 (No sound)
Once the sample is hauled in, the science personnel decide which method will be used to establish a representative sample. They pull out a sample that would most likely represent the whole catch in a smaller volume. Then we sort the catch by species. After completing the representative samples, they will eventually stop taking counts of the more abundant organisms, like krill. They will measure the volume of those creatures collected and extrapolate the total population collected by counting a smaller representative sample. Finally, we counted out all of the less abundant organisms, such as squid, lanternfish and, of course, rockfish. After the sample is collected and separated, Chief Scientist Sakuma collects all of the rockfish and prepares them for future investigations on shore.
A selection of species caught off the coast of San Clemente. These include Market Squid, Anchovies, Red Crab, King-of-Salmon (the long ribbonfish), and Butterfish, among others.
NOAA has used this platform as an opportunity. Having a ship like the Reuben Lasker, and the David Starr Jordan before that, collecting the samples as it does, creates a resource for furtAher investigations. During the trawls we have catalogued many other species. Some of the species we analyzed include Sanddab, Salp, Pyrosoma, Market Squid, Pacific Hake, Octopus, Blue Lanternfish, California Headlightfish and Blacktip Squid, among others. By plotting the biodiversity and comparing the levels we recorded with the historic values from the stations, we gain information about the overall health of the ecosystem.
What happens to the organisms we collect? Not all of the catch is dumped overboard. Often, we are placing select organisms in bags as specimens that will be delivered to various labs up and down the coast.
This is a tremendous resource for researchers, as there is really no way for many of these groups to retrieve samples on their own. Rachel Zuercher joined the crew during this survey in part to collect samples to aid in her research for her PhD.
Along with the general species analysis, the team specifically analyzes the abundance of specific krill species. Krill forms the base of the marine ecosystems in the pelagic zone. They are a major food source for many species, from fish to whales. However, different krill species are favored by different consumers. Therefore, an extension of the Ecosystem Assessment involves determining the abundance of specific krill species. Thomas Adams has been responsible for further analyzing the krill collected. He counts out the representative sample and use microscopes to identify the species collected based on their physical characteristics.
Additionally, at most stations a Conductivity, Temperature and Depth cast (CTD) is conducted. Basically, bottles are sent overboard and are opened at a specified depth.
Then they are collected and the contents are analyzed. Often these happen during the day prior to the Night Shift taking over, with final analysis taking place after the cruise is complete. This data is then connected with the catch numbers to further the analysis. Ken Baltz, an oceanographer on the ship, uses this information to determine the production of the phytoplankton based on the amounts of chlorophyll detected at depth. This is an important part of the food web and by adding in this component, it makes the picture below the surface clearer.
Finally, there are two more scientific investigations running as we cruise the open seas during the daylight hours. Michael Pierce is a birdwatcher from the Farallon Institute for Advanced Ecosystem Research who is conducting a transect survey of Seabirds and Marine Mammals. He is based on the Flying Bridge and catalogs any birds or marine mammals that pass within 300 meters of the ship’s bow. Although difficult, this study attempts to create a standardized method for data collection of this nature. As he explained, birds are more perceptive than we are – what looks like open ocean really varies in terms of temperature, salinity and diversity below the surface. Therefore, birds tend to favor certain areas over others. These are also important components of the food web as they represent upper level predators that are not collected in the trawl net. Also, on the bottom of the ship transducers are installed that are able to gather information through the EK60 Echosounder. This sonar can accurately identify krill populations and schools of fish underwater. Again, adding the data collected from these surveys help create a much more complete understanding of the food web we are analyzing out on the open sea.
Sunday, June 4
The waves were very active all day. Boy am I glad I’m wearing the patch. There was so much wind and the waves were so high, there was a question if we were even going to send the net out. High wind and waves obviously add an element of concern, especially for the safety of the boat crew working the net.
I spent some of the day up on the Bridge- the section of the boat with all of the navigation equipment. The Executive Officer (XO) gave me an impromptu lesson about using the map for navigation. They have state-of-the-art navigation equipment, but they also run a backup completed by hand and using a compass and straightedge just like you would in math class. Of note – the Dungeness Crab season is wrapping up and many fishermen leave traps in the water to catch them. When the boat is passing through one of these areas, someone will act like a spotter so the boat can avoid getting tangled up. When I was looking with him, we saw some whale plumes in the distance.
We did launch the net twice Sunday night, collecting a TON of krill each time. In the first batch, we also caught some squid and other small prey species. The second trawl was very surprising. Despite cutting it down to a 5 minute trawl, we caught about the same amount of krill. We also caught more squid and a lot of young salmon who were probably feeding on the krill.
Monday, June 5
I am getting used to the hours now – and do not feel as guilty sleeping past 2PM considering we are up past 6 in the morning. It will make for a tricky transition back to “the real world” when I go home to NY!
During the day, spent some time just talking with the science folks and learning about the various tasks being completed. I also spent some time up on the Flying Bridge as they said they had seen some Mola, or Giant Ocean Sunfish (although I did not see them). I did have a chance to make a few videos to send to my son Aiden’s 3rd grade teacher back in NY. It did not work out as well as I had hoped, but considering we are out in the middle of the ocean, I really can’t complain about spotty wi-fi.
Once we started the night shift, we really had a good night. We completed work at 5 stations – which takes a lot of time. We saw a LOT of biodiversity last night – easily doubling if not tripling our juvenile rockfish count. We also saw a huge variety of other juvenile fish and invertebrates over the course of the night. We finally wrapped up at 6:30 AM, what a night!
Tuesday, June 6th
We found out today that we will need to dock the ship prematurely. There is a mechanical issue that needs attention. We are en route straight through to San Diego, so no fishing tonight. However, our timing will not allow us to reach port during the day, so we will get a chance to sample the southernmost stations Wednesday night. Thus is life at sea. The science crew is staying on schedule as we, hopefully, will be back on the water this weekend.
Wednesday, June 7th
After a day travelling to San Diego, we stopped at the stations near San Clemente to collect samples. Being much farther south than before, we saw some new species – red crabs, sardines and A LOT of anchovies. Closer to shore, these counts dropped significantly and krill showed up in numbers not seen in the deeper trawl. Again, I am amazed by the differences we see in only a short distance.
More from our anchovy haul- the bucket contains the entire catch from our second trawl, the tray shows how we analyzed a subset. Also on the tray you find Red Crab, Salps, Mexican Lanternfish and Krill.
I am on the day schedule which is from noon to midnight. Between stations tonight is a long steam so I took the opportunity with this down time to visit the bridge where the ship is commanded. The NOAA Corps officers supplied a brief history of the corp and showed me several of the instrument panels which showed the mapping of the ocean floor.
“The National Oceanic and Atmospheric Administration Commissioned Officer Corps, known informally as the NOAA Corps, is one of seven federal uniformed services of the United States, and operates under the National Oceanic and Atmospheric Administration, a scientific agency within the Office of Commerce.
“The NOAA Corps is part of NOAA’s Office of Marine and Aviation Operations (OMAO) and traces its roots to the former U.S. Coast and Geodetic Survey, which dates back to 1807 and President Thomas Jefferson.”(1)
During the Civil War, many surveyors of the US Coast and Geodetic Survey stayed on as surveyors to either join with the Union Army where they were enlisted into the Army, or with the Union Navy, where they remained as civilians, in which case they could be executed as spies if captured. With the approach of World War I, President Woodrow Wilson, to avoid the situation where surveyors working with the armed forces might be captured as spies, established the U.S. Coast and Geodetic Survey Corps.
During WWI and World War II, the Corps abandoned their peacetime activities to support the war effort with their technical skills. In 1965 the Survey Corps was transferred to the United States Environmental Science Services Administration and in 1979, (ESSA) and in 1970 the ESSA was redesignated as the National Oceanic and Atmospheric Administration and so became the NOAA Corps.
“Corps officers operate NOAA’s ships, fly aircraft, manage research projects, conduct diving operations, and serve in staff positions throughout NOAA.” (1)
“The combination of commissioned service with scientific and operational expertise allows the NOAA Corps to provide a unique and indispensable service to the nation. NOAA Corps officers enable NOAA to fulfill mission requirements, meet changing environmental concerns, take advantage of emerging technologies, and serve as environmental first responders.” (1)
There are presently 321 officers, 16 ships, and 10 aircraft.
We are steaming on a course that has been previously mapped which should allow us to drop the net in a safe area when we reach the next station.
What can you do ?
When I asked “What can I tell my students who have an interest in NOAA ?”
If you have an interest in climate, weather, oceans, and coasts you might begin with investigating a Cooperative Observer Program, NOAA’s National Weather Service.
“More than 8,700 volunteers take observations on farms, in urban and suburban areas, National Parks, seashores, and mountaintops. The data are truly representative of where people live, work and play”.(2)
Did you know:
The NOAA Corps celebrates it 100 Year Anniversary this May 22, 2017!
Research vessels do not just work during the day. It is a 24/7 operation. Tonight I checked in with the night shift to learn more about the sonar mapping that has been done in the dark ever since I boarded NOAA Ship Pisces.
The first thing I noticed entering the dry lab was a pad of paper with math all over it. Todd, the survey technician I interviewed earlier, had noticed the the picture the ship’s sonar was producing had a curved mustache-like error in the image. Details like temperature need to be taken into account because water has different properties in different conditions that affect how sound waves and light waves move through it. He used the SOH-CAH-TOA law to find the speed of sound where the face of the transducer head was orientated. He found a six meter difference between the laser angle and what the computer was calculating. Simple trigonometry on a pad of paper was able to check what an advanced computer system was not.
NOAA Ship Pisces is also equipped with an advanced multibeam sonar. (Sonar stands for SOund NAvigation and Ranging.) In fact, there are only eight like it in the world. One of Todd’s goals before he retires from NOAA is to tweak it and write about it so other people know more about operating it. Since they are so few and you need to go to them, there are fewer publications about it.
Another mapping device is the side scan sonar. It is towed behind the vessel and creates a 300 meter picture with a 50 meter blind spot in the center, which is what is underneath the device. Hydrographic vessels have more sonars to compensate for this blind spot. The purpose of the mapping is to identify new habitat areas, therefore expanding the sampling universe of the SEAMAP Reef Fish Surveys.
Up on the bridge looks much different. The lights are off and monitors are covered with red film to not ruin the crew’s night vision. Everything is black or red, with a little green coming from the radar displays. This is to see boats trying to cross too close in front of NOAA Ship Pisces or boats with their lights off.Lieutenant Noblitt and Ensign Brendel are manning the ship.
Ensign Brendel noted to me that, “We have all of this fancy equipment, but the most important equipment are these here binoculars.” They are always keeping a lookout. The technology on board is built for redundancy. There are two of most everything and the ship’s location is also marked on paper charts in case the modern equipment has problems.
There are international rules on the water, just like the rules of the road. The difference is there are no signs out here and it is even less likely you know who is following them. Each boat or ship has a series of lights that color codes who they are or what they are doing. Since NOAA Ship Pisces is restricted in maneuverability at night due to mapping, they have the right of way in most cases. It is also true that it takes longer for larger vessels to get out of the way of a smaller vessel, especially in those instances that the smaller one tries to pass a little too close. This did happen the night before. It reminds me of lifeguarding. It is mostly watching, punctuated with moments of serious activity where training on how to remain calm, collected, and smart is key.
It has been a privilege seeing and touching many species I have not witnessed before. Adding to the list of caught species is bonito (Sarda sarda) and red porgy (Pagrus pagrus). I always think it is funny when the genus and species is the same name. We have also seen Atlantic spotted dolphins (Stenella frontalis) jumping around. There are 21 species of marine mammals indigenous to the Gulf of Mexico, most in deep water off of the continental shelf. I also learned that there are no seals down here.
One of the neatest experiences this trip was interacting with a sharksucker (Echeneis naucrates). It has a pad that looks like a shoe’s sole that grips to create a suction that sticks them to their species of choice. The one we caught prefers hosts like sharks, turtles…and sometimes science teachers.
Did You Know?
Fishing boats use colored lights to indicate what kind of fishing they are doing, as the old proverb goes red over white fishing at night, green over white trawling tonight. Vessels also use international maritime signal flags for communication during the day.
Mission: Spring Coastal Pelagic Species (Anchovy/Sardine) Survey
Geographic Area of Cruise: Pacific Ocean
Date: April 21, 2017
Weather Data from the Bridge:
Lat: 38o 2.4’N Long: 123o 6.2’W
Air Temperature: 13.9oC (57oF)
Water Temperature: 12.9oC (55oF)
Wind speed: 12 knots (13.8 mph)
Barometer: 1014.97 mbar
Conditions: Clear skies and the seas are pretty smooth
Scientific and Technology Log:
Today, I decided to learn more about the other key research part of the Coastal Pelagic Survey. As the trawling is happening at night and the egg and larval collections during the day, acousticians are listening to what is below us. Using this information, research scientists can assess the population of coastal pelagic species (CPS). The acoustics room is full of stacks of computers, servers, monitors and organized wires. NOAA researchers collect enormous amounts of data as we move down the 80 mile transects across the Pacific Ocean. On this leg, we have not found many large schools of sardines or anchovies, but the data from acoustic-sampling did lead us to some jack mackerel. I am going to try to explain some of the technology they use on the Reuben Lasker.
Simrad EK60 and EK80: These are two sonar systems that use multiple frequencies to listen to the ocean right below the ship. In the diagram, it is seen in green. The EK80 is newer and is being tested on the Reuben Lasker. It collects enormous amounts of data and acousticians are looking at how best to use that data.
Simrad ME70: This multibeam sonar (seen in orange in the diagram) listens to the water below and around the ship. It would almost look like a fan. This does not only tell us what is below, but what is beside the ship as well.
Simrad SX90: This is a long-range sonar (shown in gray) that looks at the surface for a good distance around the ship. When I was there, they were analyzing 450 meter radius around the ship. This is where the UAS would come in to use. If a school of sardines or anchovies are seen on this sonar, they could possibly deploy the drone to fly over the school and take photographs. Researchers could then analyze those photographs and collect appropriate data. Researchers can also potentially use this system to see how the ship moving through the water effects the behavior of the school.
Simrad MS70: The MS70 is a multibeam sonar that also analyzes the water off the side of the ship. It almost fills in the imaging gap left by the ME70.
All of these sonars are linked together by a program called K-SYNC. This program makes sure that the sonars don’t “ping” at the same time and cause interference with all of the systems. The Reuben Lasker also a very quiet propulsion system to limit the interference of the sound of the ship moving through the water. The ship also has 3 hydrophones that can be used to listen to marine mammals.
Together these five sonar systems give the Reuben Lasker an incredible view of what is in the water under and around the ship. This informs the trawls at night and together gives a good picture of the CPS in the waters of coastal California.
So what do we do during the time we are not working? The ship is full of movies, an exercise room, and snacks are available all day. I have been able to read a couple books, watch a few movies with the science team, work on my blog and talk to crewmembers, and even watch some TV (including seeing the Penguins play a couple hockey games). When you are on shift, there will be some downtime and then a bunch of activity as the net is pulled in. I have also tried to soak in the clean ocean air and take moments just to enjoy the experience. My Teacher At Sea voyage has been enjoyable, but I am looking forward to arriving back in San Francisco on April 22nd and flying home that night to be with my family.
Did you know?
Sonar, an acronym for SOund Navigation And Ranging, is a technique that uses sound to navigate, communicate, or detect objects on or under the surface of the water. American naval architect, Lewis Nixon, invented the first sonar-like device in 1906. Because of the demands of WWI, Paul Langevin constructed the first sonar set to detect submarines in 1915.
NOAA Teacher at Sea
Aboard NOAA Ship Pisces (In Port)
May 04, 2016 – May 17, 2016
Mission: SEAMAP Reef Fish Survey
Geographical Area of Cruise: Gulf of Mexico
Date: Saturday, May 7, 2016
Tenacity helps NOAA manage our seafood supply.
Tenacity, otherwise known as perseverance or stamina, is a required skill at the National Oceanic and Atmospheric Administration (NOAA). Aboard NOAA Ship Pisces, we are all anxious to head out to collect data about the type and abundance of reef fish along the continental shelf and shelf edge of the Gulf of Mexico. However, things don’t always go as planned. Much like the animals we study, scientists must rapidly adapt to their changing circumstances. Instead of waiting for a problem to be solved, fisheries biologists of all ages and experience work in the lab, using the newest, most sophisticated technology in the world to meet our demand for seafood.
As I ate dinner tonight in the mess (the area where the crew eats), I stared at the Pisces’ motto on the tablecloth, “patience and tenacity.”
The Pisces is a “quiet” ship; it uses generators to supply power to an electric motor that turns the ship’s propeller. The ship’s motor (or a mysteriously related part) is not working properly, and without a motor, we will not sail. This change of plans provides other opportunities for me, and you, to learn about many fascinating projects developing in the lab. Sound science begins right here at the Southeast Fisheries Science Center Laboratory in Pascagoula, Mississippi.
Kevin Rademacher, a fishery biologist in the Reef Fish Unit, meets me at the lab where he works when he isn’t at sea. As he introduces me to other biologists working in the protected species, plankton, and long line units, I begin to appreciate the great biodiversity of species in the Gulf of Mexico. I get a glimpse of the methods biologists use to conduct research in the field, and in the lab.
While it looks like a regular old office building on the outside, the center of the building is filled with labs where fish are taken to be discovered. Mark Grace, a fisheries biologist in the lab, made one such discovery of a rare species of pocket shark on a survey in the gulf. The only other specimen of a pocket shark was found coast of Peru in 1979. Mark’s discovery raises more questions in my mind than answers.
When I met Mark, he explained that capability of technology to gather data has outpaced our ability to process it. “Twenty years ago, we used a pencil and a clipboard. Think about the 1980s when they started computerizing data points compared to the present time… maybe in the future when scientists look back on the use of computers in science, it will be considered to be as important as Galileo looking at the stars” he said. It’s important because as Mark also explains, “This correspondence is a good example. We can send text, website links, images, etc…and now its a matter of digital records that will carry in to the future.”
How do fishery biologists find fish?
Earth has one big connected ocean that covers the many features beneath it. Looking below the surface to the ocean floor, we find a fascinating combination of continental shelves, canyons, reefs, and even tiny bumps that make unique homes for all of the living creatures that live there. Brandi Noble, one of 30-40 fishery biologists in the lab, uses very complicated sonar (sound) equipment to find “fish hot spots,” the kinds of places fish like to go for food, shelter and safety from predators. Fisheries sonar sends pulses of sound, or pings, into the water. Fishery biologists are looking for a varied echo sound that indicates they’ve found rocky bottoms, ledges, and reefs that snapper and grouper inhabit.
The sonar can also survey fish in a non-invasive way. Most fish have a swim bladder, or a gas filled chamber, which reflects sonar’s sound waves. A bigger fish will create a returning echo of greater strength. This way, fisheries biologists can identify and count fish without hurting them.
Ship Pisces uses a scientific methods to survey, determining relative abundance and types of fish in each area. They establish blocks of habitat along the continental shelf to survey and then randomly sample sites that they will survey with video cameras, CTD (measures temperature, salinity, and dissolved oxygen in the water), and fishing. Back in the lab, they spend hours, weeks, and years, analyzing the data they collect at sea. During the 2012 SEAMAP Reef Fish Survey, the most common reef fish caught were 179 red snapper (Lutjanus campechanus), 22 vermillion snapper (Rhomboplites aurorubens), and 10 red porgy (Pagrus pagrus). Comparing the 2012 data with survey results from 2016 and other years will help policy makers develop fishing regulations to protect the stock of these and other tasty fish.
How do fishery biologists manage all the information they collect during a survey?
Scientists migrate between offices and labs, supporting each other as they identify fish and marine mammals from previous research expeditions.
Our mission, the SEAMAP Reef Fish Survey has been broken into four parts or legs. The goal is to survey some of the most popular commercially harvested fish in the Gulf of Mexico. Kevin Rademacher is the Field Party Chief for Leg 1 and Leg 3 of the survey.
Last week, he showed me collections of frozen fish, beetle infested fish, and fish on video. At one point the telephone rang, it was Andrew Paul Felts, another biologist down the hall. “Is it staying in one spot?” Kevin asks. “I bet it’s Chromis. They hang over a spot all the time.”
We head a couple doors down and enter a dark room. Behind the blue glow of the screen sits Paul, working in the dark, like the deep water inhabitants of the video he watches. Paul observes the physical characteristics of a fish: size, shape, fins, color. He also watches its behavior. Does it swim in a school or alone? Does it stay in one spot or move around a lot? He looks at its habitat, such as a rocky or sandy bottom, and its range, or place on the map.
As you watch the video below, observe how each fish looks, its habitat, and its behavior.
To learn about fisheries, biologists use the same strategies students at South Prairie Elementary use. Paul is using his “eagle eyes,” or practiced skills of observation, as he identifies and counts fish on the screen. All the scientists read, re-read and then “read the book a third time” like a “trying lion” to make sense out of their observations. Finally, Paul calls Kevin, the “wise owl,” to make sure he isn’t making a mistake when he identifies a questionable fish.
Using Latin terminology such as “Chromis” or “Homo” allows scientists to use the same names for organisms. This makes it easier for scientists worldwide, who speak different languages, to communicate clearly with each other as they classify the living things they study.
I appreciate how each member of the NOAA staff, on land and at sea, look at each situation as a springboard to more challenging inquiry. They share with each other and with us what they have learned about the diversity of life in the ocean, and how humans are linked to the ocean. With the knowledge we gain from their hard work and tenacity, we can make better choices to protect our food supply and support the diversity of life on Earth.
Crew members tell me that every day at sea is a Monday. In port, they are able to spend time with family and their communities. I have been able to learn a bit about Pascagoula, kayak with locals, and see many new birds like the least tern, swallow tailed kite, eastern bluebird and clapper rail. Can you guess what I ate for dinner last night?
Mission: Mapping CINMS Geographical area of cruise: Channel Islands, California Date: May 8, 2016 Weather Data from the Bridge:
Science and Technology Log
In previous posts, I’ve discussed the ME70 multibeam sonar on board Shimada. You’d think that I’ve told you all there is to know about the wondrous data this piece of equipment provides, but oh, no, dear readers, I’ve merely scraped the surface of that proverbial iceberg. In this post, I will explain how the raw data from the ME70 is used to create important seafloor maps. Heck, I’ll even throw in a shipwreck! Everyone loves shipwrecks.
Back to the multibeam. As you may remember, the ME70 uses many beams of sonar to capture a 60 degree image of the water column. It collects A LOT of data, one survey line at a time. Lots of data are good, right? Well, if you want to map the bottom of the ocean, you don’t need ALL the data collected by the ME70, you just need some of it. Take, for example, fish. You don’t want big balls of fish obscuring your view of the seafloor, you just want the seafloor! Leave the schools of fish for Fabio.
The person you need to make your seafloor map is Kayla Johnson. First, she sends the raw data to a program called MatLab. This nifty software separates the bottom data from all the other stuff in the water column and packages it in something called a .gsf file. Next, this .gsf file goes to this huge processing program called CARIS HIPS, where it is converted into an something called HDCS data.
You’d think that all you’d need to make an accurate seafloor map would be data from the multibeam, but it is actually much more complicated than that (of course you knew that! just look at how long this blog post is). Think about it: while you’re running your survey lines and collecting data, the ocean and, therefore, the ship are MOVING. The ship is heaving, rolling, and pitching, it’s travelling in different directions depending on the survey line, the tides are coming in and out, the temperature and salinity of the water varies, etc. etc. All of these variables affect the data collected by the ME70 and, hence, must be accounted for in the CARIS software. Remember how I said it was HUGE? This is why.
Everyone still with me? Ok, let’s continue processing this data so that Kayla can make our beautiful map. Next up, she’s going to have to load data into CARIS from the POS. POSMV (POSition of Marine Vehicles) is a software interface used on the ship that collects real-time data on where we are in relation to the water (heave, pitch, and roll). She’s also going to load into CARIS the local tide information, since the ship will be closer to the seafloor at low tide than at high. Not including tidal change is a good way to get a messed-up map! Once the POSMV and tide files are loaded into CARIS, they are applied to the survey line.
Next, Kayla has to compute the TPU (Total Propagated Uncertainty). I could spend the next four paragraphs explaining what it is and how it’s computed, but I really don’t feel like writing it and you probably wouldn’t want to read it. Let’s just say that nothing in life is 100% certain, so the TPU accounts for those little uncertainties.
Since the data was collected using multiple beams at a wide angle, there will be beams returning bad data, especially at the edges of the collection zone. Sometime a bad data point could be a fish, but most often bad data happens when there is an abrupt change in seafloor elevation and the beams can’t find the bottom. So, Kayla will need to manually clean out these bad data points in order to get a clean picture of the seafloor.
These data need a haircut!
Almost done! Last, Kayla makes the surface. All the data points are gridded to a certain resolution based on depth (lots of explanation skipped here…you’re welcome), with the end result being a pretty, pretty picture of the bottom of the seafloor. Phew, we made it! These seafloor maps are incredibly important and have numerous applications, including fisheries management, nautical charting, and searching for missing airplanes and shipwrecks (see! I told you there would be a shipwreck!). I’ll be getting into the importance of this mapping cruise to the Channel Islands Marine Sanctuary in my final post, so stay tuned.
Shipwreck in Buzzard’s Bay, MA image courtesy of NOAA Ship Thomas Jefferson
U-boat image courtesy of NOAA Ship Thomas Jefferson
Endnote: A word about XBTs
Before all your data are processed, you need to know how fast the sound waves are travelling through the water. When sound is moving through water, changes in temperature and salinity can bend the wave, altering your data. An XBT is an expendable bathythermograph that is sent overboard every four hours. It transmits temperature and salinity readings throughout its quick trip to the ocean bottom, allowing the computer to make data adjustments, as needed.
Did You Know?
Hey, you’ve made it to the bottom of this post! If you are interested in seafloor mapping, have I got an institute of higher learning for you. The College of Charleston has a program called BEAMS, which trains future ocean surveyors and includes a course called Bathymetric Mappings. Three of the hip young scientists on board have taken this course and it seems to be pretty amazing. If you love sailing the high seas AND data processing, you might want to check it out.
NOAA Teacher at Sea Emily Whalen Aboard NOAA Ship Henry B. Bigelow April 27 – May 10, 2015
Mission: Spring Bottom Trawl Survey, Leg IV
Geographical Area of Cruise: Gulf of Maine Date: May 1, 2015
Weather Data from the Bridge: Winds: Light and variable
Air Temperature: 6.2○ C
Water Temperature: 5.8○ C
Science and Technology Log:
Earlier today I had planned to write about all of the safety features on board the Bigelowand explain how safe they make me feel while I am on board. However, that was before our first sampling station turned out to be a monster haul! For most stations I have done so far, it takes about an hour from the time that the net comes back on board to the time that we are cleaning up the wetlab. At station 381, it took us one minute shy of three hours! So explaining the EEBD and the EPIRB will have to wait so that I can describe the awesome sampling we did at station 381, Cashes Ledge.
Before I get to describing the actual catch, I want to give you an idea of all of the work that has to be done in the acoustics lab and on the bridge long before the net even gets into the water.
The bridge is the highest enclosed deck on the boat, and it is where the officers work to navigate the ship. To this end, it is full of nautical charts, screens that give information about the ship’s location and speed, the engine, generators, other ships, radios for communication, weather data and other technical equipment. After arriving at the latitude and longitude of each sampling station, the officer’s attention turns to the screen that displays information from the Olex Realtime Bathymetry Program, which collects data using a ME70 multibeam sonar device attached to bottom of the hull of the ship .
Traditionally, one of the biggest challenges in trawling has been getting the net caught on the bottom of the ocean. This is often called getting ‘hung’ and it can happen when the net snags on a big rock, sunken debris, or anything else resting on the sea floor. The consequences can range from losing a few minutes time working the net free, to tearing or even losing the net. The Olex data is extremely useful because it can essentially paint a picture of the sea floor to ensure that the net doesn’t encounter any obstacles. Upon arrival at a site, the boat will cruise looking for a clear path that is about a mile long and 300 yards wide. Only after finding a suitable spot will the net go into the water.
The ME70 Multibeam uses sound waves to determine the depth of the ocean at specific points. It is similar to a simpler, single stream sonar in that it shoots a wave of sound down to the seafloor, waits for it to bounce back up to the ship and then calculates the distance the wave traveled based on the time and the speed of sound through the water, which depends on temperature. The advantage to using the multibeam is that it shoots out 200 beams of sound at once instead of just one. This means that with each ‘ping’, or burst of sound energy, we know the depth at many points under the ship instead of just one. Considering that the multibeam pings at a rate of 2 Hertz to 0.5 Herts, which is once every 0.5 seconds to 2 seconds, that’s a lot of information about the sea floor contour!
The stations that we sample are randomly selected by a computer program that was written by one of the scientists in the Northeast Fisheries Science Center, who happens to be on board this trip. Just by chance, station number 381 was on Cashes Ledge, which is an underwater geographical feature that includes jagged cliffs and underwater mountains. The area has been fished very little because all of the bottom features present many hazards for trawl nets. In fact, it is currently a protected area, which means the commercial fishing isn’t allowed there. As a research vessel, we have permission to sample there because we are working to collect data that will provide useful information for stock assessments.
My watch came on duty at noon, at which time the Bigelowwas scouting out the bottom and looking for a spot to sample within 1 nautical mile of the latitude and longitude of station 381. Shortly before 1pm, the CTD dropped and then the net went in the water. By 1:30, the net was coming back on board the ship, and there was a buzz going around about how big the catch was predicted to be. As it turns out, the catch was huge! Once on board, the net empties into the checker, which is usually plenty big enough to hold everything. This time though, it was overflowing with big, beautiful cod, pollock and haddock. You can see that one of the deck crew is using a shovel to fill the orange baskets with fish so that they can be taken into the lab and sorted!
At this point, I was standing at the conveyor belt, grabbing slippery fish as quickly as I could and sorting them into baskets. Big haddock, little haddock, big cod, little cod, pollock, pollock, pollock. As fast as I could sort, the fish kept coming! Every basket in the lab was full and everyone was working at top speed to process fish so that we could empty the baskets and fill them up with more fish! One of the things that was interesting to notice was the variation within each species. When you see pictures of fish, or just a few fish at a time, they don’t look that different. But looking at so many all at once, I really saw how some have brighter colors, or fatter bodies or bigger spots. But only for a moment, because the fish just kept coming and coming and coming!
Finally, the fish were sorted and I headed to my station, where TK, the cutter that I have been working with, had already started processing some of the huge pollock that we had caught. I helped him maneuver them up onto the lengthing board so that he could measure them and take samples, and we fell into a fish-measuring groove that lasted for two hours. Grab a fish, take the length, print a label and put it on an envelope, slip the otolith into the envelope, examine the stomach contents, repeat.
Some of you have asked about the fish that we have seen and so here is a list of the species that we saw at just this one site:
Red deepsea crab
I think it’s human nature to try to draw conclusions about what we see and do. If all we knew about the state of our fish populations was based on the data from this one catch, then we might conclude that there are tons of healthy fish stocks in the sea. However, I know that this is just one small data point in a literal sea of data points and it cannot be considered independently of the others. Just because this is data that I was able to see, touch and smell doesn’t give it any more validity than other data that I can only see as a point on a map or numbers on a screen. Eventually, every measurement and sample will be compiled into reports, and it’s that big picture over a long period of time that will really allow give us a better understanding of the state of affairs in the ocean.
It seems like time is passing faster and faster on board the Bigelow. I have been getting up each morning and doing a Hero’s Journey workout up on the flying bridge. One of my shipmates let me borrow a book that is about all of the people who have died trying to climb Mount Washington. Today I did laundry, and to quote Olaf, putting on my warm and clean sweatshirt fresh out of the dryer was like a warm hug! I am getting to know the crew and learning how they all ended up here, working on a NOAA ship. It’s tough to believe but a week from today, I will be wrapping up and getting ready to go back to school!
NOAA Teacher at Sea
Aboard NOAA Ship Okeanos Explorer
March 16-April 3rd
Mission: Caribbean Exploration (mapping) Geographical Area of Cruise: Puerto Rico Trench Date: April 2, 2015
Weather Data from the Bridge: Partly Cloudy, 26 C, Wind speed 12 knots, Wave height 1-2ft, Swells 2-4ft.
Science and Technology Log:
What are the mappers up to?
After we completed our two priority areas of the cruise, the mappers have been using Knudson subbottom sonar to profile the bottom of the trench. Meme Lobecker, the expedition coordinator sends that data directly to the United States Geological Survey (USGS) for processing. They returned some interesting findings.
The subbottom sonar sends a loud “chirp” to the bottom. It penetrates the ocean floor. Different sediment layers reflect the sound differently so the variation and thickness of the layers can be observed. The chirp penetration depth varies with the sediments. Soft sediments can be penetrated more easily. In the picture below, provided by USGS, you can see hard intrusions with layers of sediments filling in spaces between.
How does the bathymetry look?
In the last two days, I have been really enjoying the incredible details in the bathymetry data the multibeam sonar has gathered. We mapped over 15,000 square miles on our voyage! Using computer software we can now look at the ocean floor beneath us. I tried my hand at using Fledermaus software to make fly-over movies of the area we surveyed (or should I say swim-over movies). Check them out:
I also examined some of the backscatter data. In backscatter images soft surfaces are darker, meaning the signal return is weaker, and the hard surfaces are whiter due to stronger returns. One of the interns, Chelsea Wegner, studied the bathymetry and backscatter data for possible habitats for corals. She looked for steep slopes in the bathymetry and hard surfaces with the backscatter, since corals prefer those conditions.
On the next leg, the robotic vehicle on the ship will be used to examine some of the areas we were with high-definition cameras. You can watch the live stream here. You can also see some of the images and footage from past explorations here.
This is a short video from the 2012 expedition to the Gulf of Mexico to tempt you into tuning in for more.
The people on this vessel have been blessed with adventurous spirits and exciting careers. Throughout the cruise, I heard about and then came to fully understand the difficulty of being away from family when they need us.
I would like to dedicate this last blog to my father, Tom Wichman. He passed away this morning at 80 years of age after battling more than his share of medical issues. As I rode the ship in today I felt him beside me. Together we watched the pelicans and the boobies fly by. I am very glad I was able to take him on a “virtual” adventure to the Caribbean. He loved the pictures and the blog. I thank the NOAA Teacher at Sea program for helping me make him proud one last time.
“To know how to wonder is the first step of the mind toward discovery” – L. Pasteur. These words decorate my classroom wall but are epitomized by the work that the NOAA Okeanos Explorer and the Office of Exploration and Research (OER) do each day.
Thank you to the Meme, the CO, XO, the science team, and the entire crew aboard the Okeanos for teaching me as much as you did and for helping me get home when I needed to be with family. I wish you all the best as you continue to explore our vast oceans! My students and I will be watching and learning from you!
I would also like to thank all of the people who followed this blog. Your support and interest proves that you too are curious by nature. Life is much more interesting if you hold on to that sense of wonder, isn’t it?
Answers to My Previous Questions of the Day Polls:
1. Bathymetry is the study of ocean depths and submarine topography.
2. The deepest zone in the ocean is called the hadal zone, after Hades the Greek God of the underworld.
3. It takes the vessel 19 hours and 10 minutes to make enough water for 46 people each using 50 gallons per day if each of the two distillers makes 1 gallon per minute.
The visiting sonar technician left this afternoon on NOAA’s Shark Cat boat after working diligently to fix the ship’s sonar system throughout the past few days. As of now, the ME 70 sonar is up and running. This equals exciting news for the sonar team that has been waiting patiently to begin their projects. The Shimada actually has two sonar machines; one works with a single beam, while the other, the ME 70 has multiple beams that can cover a much greater amount of territory in the same amount of time.
How does sonar work?
Sonar technology is a way for us to create images of what is below the surface of the ocean. The sonar system, which is attached to the bottom of the ship, sends out an acoustic signal towards the ocean floor and then measures how long it takes for the sound to bounce back to the boat. By measuring this, the sonar creates a picture of the depth of the ocean floor in that area.
A secondary measurement that is also occurring when the sonar machine is running is called backscatter. Backscatter measures the intensity, or loudness, of the sound as it echoes back to the ship. The softer the sound when it reflected back means the softer the type of surface it is bouncing off of, such as sand. The louder and more severe the sound is equates to a harder surface floor, such as rocky ledges. As Andy explained to me, think about bouncing a ping-pong ball on a carpet vs. hardwood floor. The ping-pong ball will have a much stronger bounce off of a hard surface v. a softer one. Will also explained that based on the backscatter sound we can determine fine details such as whether the sand is fine or coarse.
Both of these sonar features create an image of what the ocean floor looks like, its physical features, habitat types and any potential hazards that may exist below the surface. This is critical for creating nautical charts and it is also important for the navigation of the ROV, so it doesn’t stumble upon any unexpected obstacles while traveling underwater.
Another feature that sonar is used for on this ship is to measure fish abundance. The sound waves travel down and bounce off of the fishes’ swim bladders. Swim bladders are gas filled bladders found in many fish that helps them stay buoyant. Using this method, scientists could use sonar to gauge fish populations, instead of catching fish to see what is out there.
So far in the trip, Laura Kracker and her team (Mike Annis, Will Sautter and Erin Weller) have been using the working sonar to map fish populations in the area. Tonight, however, they will use the ME 70 for a test run to map out areas of the Channel Islands National Marine Sanctuary that have never been mapped before! This data could be used to create brand new nautical maps, to help scientists have a better idea of what the hidden part of our sanctuary looks like and to determine which regions might be best habitats for fish or coral. Tomorrow, the ROV team will send the ROV to the sites that were mapped the previous night to check out features that were discovered on the seafloor and to explore the newly mapped regions.
Life at Sea
When setting out on this journey, students asked me what life would be like living on a ship. I spoke with several of the crew members on the ship about what it is like to be out at sea for days at a time. So here is an image of what it has been like so far, from the perspective of some of the crew and from my own experiences:
The Bell M. Shimada is an enormous ship, over 200 feet in length. I have been here for four days now and still have not explored the entire place! The ship is approx. six stories tall, though on the ship they refer to the different levels as decks, not stories. The Shimada is run from a platform on the third deck, known as the bridge. The steering of the ship takes place from the bridge and there is always an assigned lookout person, whose job is to look out the windows to see what is going on around the ship. The bridge is also equipped with radars that can detect boat traffic or other obstacles.
A lot of communication goes back and forth between the scientists in the ROV command room and the bridge. The bridge must ensure that the ship stays steady and follows the ROV during its dive. If the ship moves too much it can yank the ROV around or the cables from the ROV could get caught or damaged under the ship.
The areas where we sleep on the ship are called staterooms. Almost all of them consist of bunk beds and have a toilet and shower area. I am rooming with Erin, one of the scientists working on the sonar mapping project. Erin and her team work during the night after the ROV runs, so typically she is going to bed shortly before I wake up for the day. We have both been working hard to stay quiet enough to let each other catch up on our sleep!
The Shimada has many features that I was not expecting on a ship, such as an exercise room equipped with treadmills and weights. We even have Internet access here! Another unexpected feature is the lounge/ theater room that is across the hall from my stateroom. It has plush reclining chairs, a huge flat screen TV, and all the DVDs you could ever hope to watch, including the newest movies.
When talking with the crew about what they love most about their jobs, many of them referred to how being part of a NOAA boat allows them incredible travel opportunities. One person I spoke with has been to 52 different countries throughout his career with NOAA! Another benefit of a maritime career such as this is that NOAA pays for part of your education. It requires special schooling and credentials to be able to be an engineer or commanding officer on a ship, and NOAA helps offset those costs. One of the biggest challenges of the job, however, is being away from family and friends for such long periods of time. Some of the crew explained to me that they may be out at sea for 30 days at a time, sometimes even longer.
One great perk to life aboard is the food. Two chefs prepare all of the meals on the Shimada for us. Similar to our lunch time at school, the meals are served at the same time each day in what is called the mess hall. If you oversleep and miss breakfast, not too worry; there is cereal and other snacks available around the clock. They serve breakfast, lunch and dinner on the ship, and we have even had the treat of fresh salads and homemade desserts!
The ship stays running smoothly thanks to the help of the engineers and crew members. They work behind the scenes around the clock to keep the ship afloat.
My absolute favorite location on the ship is called the flying bridge. It has 3 tall chairs that look out over the ocean and an almost 360 degree view of the sea. The chairs have been used on previous excursions for scientists to sit and count marine mammals as part of their survey. It is a great place to watch the sunset from.
NOAA Teacher at Sea Lauren Wilmoth Aboard NOAA Ship Rainier October 4 – 17, 2014
Mission: Hydrographic Survey Geographical area of cruise: Kodiak Island, Alaska Date: Wednesday, October 15th, 2014
Weather Data from the Bridge Air Temperature: 4.4 °C
Wind Speed: 5 knots
Latitude: 57°56.9′ N
Longitude: 153°05.8′ W
Science and Technology Log
Thank you all for the comments you all have made. It helps me decide what direction to go in for my next post. One question asked, “How long does it take to map a certain area of sea floor?” That answer, as I responded, is that it depends on a number of factors including, but not limited to, how deep the water is and how flat the floor is in that area.
To make things easier, the crew uses an Excel spreadsheet with mathematical equations already built-in to determine the approximate amount of time it will take to complete an area. That answer is a bit abstract though. I wanted an answer that I could wrap my head around. The area that we are currently surveying is approximately 25 sq nautical miles, and it will take an estimated 10 days to complete the surveying of this area not including a couple of days for setting up tidal stations. To put this in perspective, Jefferson City, TN is approximately 4.077 sq nautical miles. So the area we are currently surveying is more than 6 times bigger than Jefferson City! We can do a little math to determine it would take about 2 days to survey an area the size of Jefferson City, TN assuming the features are similar to those of the area we are currently surveying.
Try to do the math yourself! Were you able to figure out how I got 2 or 3 days?
Since we’re talking numbers, Rainier surveyed an area one half the size of Puerto Rico in 2012 and 2013! We can also look at linear miles. Linear miles is the distance they traveled while surveying. It takes into account all of the lines the ship has completed. In 2012 and 2013, Rainier surveyed the same amount of linear nautical miles that it would take to go from Newport, Oregon to the South Pole Station and back!
Monday, I went on a launch to collect sonar data. This is my first time to collect sonar data since I started this journey. Before we could get started, we had to cast a CTD (Conductivity, Temperature and Depth) instrument. Sound travels a different velocities in water depending on the salinity, temperature, and pressure (depth), so this instrument is slowly cast down from the boat and measures all of these aspects on its way to the ocean floor. Sound travels faster when there is higher salinity, temperature, and pressure. These factors can vary greatly from place to place and season to season.
Imagine how it might be different in the summertime versus the winter. In the summertime, the snow will be melting from the mountains and glaciers causing a increase in the amount of freshwater. Freshwater is less dense than saltwater, so it mainly stays on top. Also, that glacial runoff is often much colder than the water lower in the water column. Knowing all of this, where do you think sound will travel faster in the summertime? In the top layer of water or a lower layer of water? Now you understand why it is so important to cast a CTD to make sure that our sonar data is accurate. To learn more about how sound travels in water, click here.
After casting our CTD, we spent the day running the sonar up and down and up and down the areas that needed to be surveyed. Again, this is a little like mowing the lawn. At one point, I was on bow watch. On bow watch, you sit at the front of the boat and look out for hazards. Since this area hasn’t been surveyed since before 1939, it is possible that there could be hazards that are not charted. Also, I worked down in the cabin of the boat with the data acquisition/sonar tuning. Some important things to do below deck including communicating the plan of attack with the coxswain (boat driver), activating the sonar, and adjusting the sonar for the correct depth. I helped adjust the range of the sonar which basically tells the sonar how long to listen. If you are in deeper water, you want the sonar to listen longer, because it takes more time for the ping to come back. I also adjusted the power which controls how loud the sound ping is. Again, if you are surveying a deeper area, you might want your ping to be a little louder.
Tuesday, I helped Survey Tech Christie Rieser and Physical Scientist Fernando Ortiz with night processing. When the launches come back after acquiring sonar data, someone has to make all that data make sense and apply it to the charts, so we can determine what needs to be completed the following day. Making sense of the data is what night processing is all about. First, we converted the raw data into a form that the program for charting (CARIS) can understand. The computer does the converting, but we have to tell it to do so. Then, we apply all of the correctors that I spoke about in a previous blog in the following order: POS/MV (Position and Orientation Systems for Marine Vessels) corrector, Tides corrector, and CTD (Conductivity, Temperature, and Depth) corrector. POS/MV corrects for the rocking of the boat. For the tides corrector, we use predicted tides for now, and once all the data is collected from our tidal stations, we will add that in as well. Finally, the CTD corrects for the change in sound velocity due to differences in the water as I discussed above.
After applying all of the correctors, we have the computer use an algorithm (basically a complicated formula) to determine, based on the data, where the sea floor is. Basically, when you are collecting sonar data there is always going to be some noise (random data that is meaningless) due to reflection, refraction, kelp, fish, and even the sound from the boat. The algorithm is usually able to recognize this noise and doesn’t include it when calculating the location of the seafloor. The last step is manually cleaning the data. This is where you hide the noise, so you can get a better view of the ocean floor. Also, when you are cleaning, you are double checking the algorithm in a way, because some things that are easy for a human to distinguish as noise may have thrown off the algorithm a bit, so you can manually correct for that. Cleaning the data took the longest amount of time. It took a couple of hours. While processing the data, we did notice a possible ship wreck, but the data we have isn’t detailed enough to say whether it’s a shipwreck or a rock. Senior Tech Jackson noted in the acquisition log that it was “A wreckish looking rock or a rockish looking wreck.” We are going to have the launches go over that area several more times today to get a more clear picture of is going on at that spot.
Monday was the most spectacular day for wildlife viewing! First, I saw a bald eagle. Then, I saw more sea otters. The most amazing experience of my trip so far happened next. Orcas were swimming all around us. They breached (came up for air) less than 6 feet from the boat. They were so beautiful! I got some good pictures, too! As if that wasn’t good enough, we also saw another type of whale from far away. I could see the blow (spray) from the whale and a dorsal fin, but I am not sure if it is was a Humpback Whale or a Fin Whale. Too cool!
Did You Know?
Killer whales are technically dolphins, because they are more closely related to other dolphins than they are to whales.
NOAA Teacher at Sea Lauren Wilmoth Aboard NOAA Ship Rainier October 4 – 17, 2014
Mission: Hydrographic Survey Geographical area of cruise: Kodiak Island, Alaska Date: Sunday, October 12, 2014
Weather Data from the Bridge Air Temperature: 1.92 °C
Wind Speed: 13 knots
Latitude: 58°00.411′ N
Longitude: 153°10.035′ W
Science and Technology Log
In a previous post, I discussed how the multibeam sonar data has to be corrected for tides, but where does the tide data come from? Yesterday, I learned first hand where this data comes from. Rainier‘s crew sets up temporary tidal stations that monitor the tides continuously for at least 30 days. If we were working somewhere where there were permanent tidal station, we could just use the data from the permanent stations. For example, the Atlantic coast has many more permanent tidal stations than the places in Alaska where Rainier works. Since we are in a more remote area, these gauges must be installed before sonar data is collected in an area.
We are returning to an area where the majority of the hydrographic data was collected several weeks ago, so I didn’t get to see a full tidal station install, but I did go with the shore party to determine whether or not the tidal station was still in working condition.
A tidal station consists of several parts: 1) an underwater orifice 2) tube running nitrogen gas to the orifice 3) a nitrogen tank 4) a tidal gauge (pressure sensor and computer to record data) 5) solar panel 6) a satellite antennae.
Let me explain how these things work. Nitrogen is bubbled into the orifice through the tubing. The pressure gauge that is located on land in a weatherproof box with a laptop computer is recording how much pressure is required to push those bubbles out of the orifice. Basically, if the water is deep (high tide) there will be greater water pressure, so it will require more pressure to push bubbles out of the orifice. Using this pressure measurement, we can determine the level of the tide. Additionally, the solar panel powers the whole setup, and the satellite antennae transmits the data to the ship. For more information on the particulars of tidal stations click here
The tidal station in Terror Bay did need some repairs. The orifice was still in place which is very good news, because reinstalling the orifice would have required divers. However, the tidal gauge needed to be replaced. Some of the equipment was submerged at one point and a bear pooped on the solar panel. No joke!
After the tidal gauge was installed, we had to confirm that the orifice hadn’t shifted. To do this, we take manual readings of the tide using a staff that the crew set-up during installation of the tidal station. To take manual (staff) observations, you just measure and record the water level every 6 minutes. If the manual (staff) observations match the readings we are getting from the tidal gauge, then the orifice is likely in the correct spot.
Just to be sure that the staff didn’t shift, we also use a level to compare the location of the staff to the location of 5 known tidal benchmarks that were set when the station was being set up as well. As you can see, accounting for the tides is a complex process with multiple checks and double checks in place. These checks may seem a bit much, but a lot of shifting and movement can occur in these areas. Plus, these checks are the best way to ensure our data is accurate.
Today, I went to shore again to a different area called Driver Bay. This time we were taking down the equipment from a tidal gauge, because Rainier is quickly approaching the end of her 2014 season. Driver Bay is a beautiful location, but the weather wasn’t quite as pretty as the location. It snowed on our way in! Junior Officer Micki Ream who has been doing this for a few years said this was the first time she’d experienced snow while going on a tidal launch. Because of the wave action, this is a very dynamic area which means it changes a lot.
In fact, the staff that had been originally used to manually measure tides was completely gone, so we just needed to take down the tidal gauges, satellite antenna, solar panels, and orifice tubing. The orifice itself was to be removed later by a dive team, because it is under water. After completing the tidal gauge breakdown, we hopped back on the boat for a very bumpy ride back to Rainier. I got a little water in my boots when I was hopping back aboard the smaller boat, but it wasn’t as cold as I had expected. Fortunately, the boat has washers and driers. It looks like tonight will be laundry night.
The food here is great! Last night we had spaghetti and meatballs, and they were phenomenal. Every morning I get eggs cooked to order. On top of that, there is dessert for every lunch and dinner! Don’t judge me if I come back 10 lbs. heavier. Another cool perk is that we get to see movies that are still in the theaters! They order two movies a night that we can choose from. Lastly, I haven’t gotten seasick. Our transit from Seward to Kodiak was wavy, but I don’t think it was as bad as we were expecting. The motion sickness medicines did the trick, because I didn’t feel sick at all.
Did You Know?
NOAA (National Oceanic and Atmospheric Administration) contains several different branches including the National Weather Service which is responsible for forecasting weather and issuing weather alerts.
NOAA Teacher at Sea Lauren Wilmoth Aboard NOAA Ship Rainier October 4 – 17, 2014
Mission: Hydrographic Survey Geographical area of cruise: Kodiak Island, Alaska Date: Wednesday, October 8, 2014
Weather Data from the Bridge Air Temperature: 3.82 °C
Wind Speed: 6.1 knots
Latitude: 60°07.098′ N
Longitude: 149°25.711′ W
Science and Technology Log
The launch that I participated in on Tuesday was awesome! We went to an area called Thumb’s Cove. I thought the divers must be crazy, because of how cold it was. When they returned to the boat from their dive, they said the water was much warmer than the air. The water temperature was around 10.5°C or 51°F while the air temperature was hovering right above freezing. One diver, Katrina, took an underwater camera with her. They saw jellyfish, sea urchins, and sea stars.
The ride to and from the cove was quite bouncy, but I enjoyed being part of this mini-adventure! Later that day, we did what is called DC (Damage Control) familiarization. Basically, we practiced what do in case of an emergency. We were given a pipe with holes in it and told to patch it with various objects like wooden wedges. We also practiced using a pump to pump water off of the ship if she were taking on water. Safety drills are also routine around here. It’s nice to know that everyone expects the best, but prepares for the worse. I feel very safe aboard Rainier.
Today, I got a chance to meet with the CO (Commanding Officer), and he explained the navigational charts to me. Before the ship leaves the port, there must be a navigation plan which shows not only the path the ship will take, but also the estimated time of arrival to various points along the way. This plan is located on the computer, but also, it must be drawn on a paper chart for backup.
This illustrates again how redundancy, as I discussed in my last blog post, is a very important part of safety on a ship. Every ship must have up-to-date paper charts on board. These charts get updated with the information collected from the hydrographic surveys. The ocean covers more than 70% of our planet which is why Rainier‘s mission of mapping the ocean is so important. There are many areas in Alaska where the only data on the depth of the water was collected before sonar technology was used. In fact, some places the data on the charts comes from Captain Cook in the 1700s! If you look at the chart below the water depth is measured in fathoms. A fathom is 6 feet deep. Places that are less than 1 fathom deep have a 05 where the subscript indicates how deep the water is in feet.
Today, I also spoke with the AFOO (Acting Field Operations Officer), Adam, about some work that he had been doing on Rainier‘s sister ship NOAA Fairweather. One project they are working on is connecting hydrographic data to fish distribution and abundance mapping. Basically, they want to find out if it is possible to use sonar data to predict what types of fish and how many you will find in a particular location
They believe this will work, because the sonar produces a back scatter signature that can give you an idea of the sea floor composition (i.e. what it is made of). For instance, they could tell you if the sea floor is rocky, silty, or sandy using just sonar, as opposed to, manually taking a bottom sample. If this hydrographic data is integrated with the data collected by other NOAA ships that use trawl nets to survey the fish in an area, this would allow NOAA to manage fisheries more efficiently. For example, if you have map that tells you that an area is likely to have fish fry (young fish) of a vulnerable species, then NOAA might consider making this a protected area.
On Tuesday, I had a little extra time in the afternoon, so I decided to ride my bike down to the Alaska SeaLife Center which is a must-see if you ever find yourself in Seward. There were Harbor Seals (Phoca vitulina), Stellar Sea Lions (Eumetopias jubatus), Puffins (Genus Fratercula), Pacific Salmon (Genus Oncorhynchus) and much more. I really appreciated that the SeaLife Center focused on both conservation and on organisms that live in this area. A local high school even had their art students make an exhibit out of trash found on the beach to highlight the major environmental issue of trash that finds its way to the ocean.
Can you think a project we could do that would highlight a main environmental concern in Eastern Tennessee? I also thought is was really interesting to see the Puffins dive into the water. The SeaLife Center exhibit explained about how Puffin bones are more dense than non-sea birds. These higher density bones are an adaptation that helps them dive deeper.
I officially moved into the ship today. Prior to that, I was staying at a hotel while they were finishing up repairs. We are expected to get underway on Friday afternoon. I am staying in the princess suite! It is nice and cozy. I have all of the essentials. I have a desk, bunk beds, 2 closets, and one bathroom (head).
Did You Know?
Junior Officers get homework assignments just like you. At the navigation briefing today, the CO (Commanding Officer) told the Junior Officers what that they needed to review several documents before going through the inside passage (a particularly tricky area to navigate). He is expecting them to lead different parts of the next navigation briefing, but he isn’t going to tell them which part they are leading until right before. Therefore, it is important that they know it all! It’s a little like a pop quiz and presentation in one.
Word of the Day
Bathymetry – the study of the “beds” or “floors” of bodies of water.
NOAA Teacher at Sea Lauren Wilmoth Aboard NOAA Ship Rainier October 4 – 17, 2014
Mission: Hydrographic Survey Geographical area of cruise: Kodiak Island, Alaska Date: Tuesday, October 7, 2014
Weather Data from the Bridge Air Temperature: 0.77 °C
Wind Speed: 12 knots
Latitude: 60°07.098′ N
Longitude: 149°25.711′ W
Science and Technology Log
Our departure from Seward was originally scheduled for today, but the ship is having some repairs done, so our expected departure is now Wednesday or Thursday. In case you were wondering, this doesn’t delay my return date. Regardless of the fact that we are not underway, there is still so much to learn and do.
Yesterday, I met with Christie, one of the survey techs, and learned all about the Rainier’s mission. The main mission of the ship is to update nautical charts. Up-to-date charts are crucial for safe navigation. The amount of data collected by Rainier if vast, so although the main mission of the Rainier is updating nautical charts, the data are also sent to other organizations who use the data for a wide variety of purposes. The data have been used for marine life habitat mapping, sediment distribution, and sea level rise/climate change modeling among other things. In addition to all of that, Rainier and her crew sometimes find shipwrecks. In fact, Rainier and her crew have found 5 shipwrecks this season!
Simplified, hydrographic research involves sending multiple sonar (sound) beams to the ocean floor and recording how long it takes for the sound to come back. You can use a simple formula of distance=velocity/time and divide that by two because the sound has to go to the floor and back to get an idea how deep the ocean is at a particular spot. This technique would be fine by itself if the water level weren’t constantly fluctuating due to tides, high or low pressure weather systems, as well as, the tilt of the ship on the waves. Also, the sound travels at different speeds according to the water’s temperature, conductivity and depth. Because of this, the data must be corrected for all of these factors. Only with data from all of these aspects can we start to map the ocean floor. I have attached some pictures of what data would look like before and after correction for tides.
I was also given a tour of the engine room yesterday. Thanks, William. He explained to me how the ship was like its own city. In this city, there is a gym, the mess (where you eat), waste water treatment, a potable (drinkable) water production machine, and two engines that are the same type of engines as train engines. Many of my students were interested in what happens to our waste when we are aboard the ship. Does it just get dumped into the ocean? The answer is no. Thank goodness! The waste water is exposed to bacteria that break down the waste Then, salt water is used to produce chlorine that further sterilizes the waste. After those two steps, the waste water can be dumped. The drinking water is created by evaporating the water (but not the salt) from salt water. The heat for this process is heat produced by the engine. William also explained that there are two of everything, so if something fails, we’ll still be alright.
Sunday, I drove from Anchorage to Seward. The drive was so beautiful! At first, I was surrounded by huge mountains that were vibrant yellow from the trees whose leaves were turning. Then, there was snow! It was actually perfect, because the temperature was at just the right point where the snow was melted on the road, but it had blanketed the trees. Alaska is as beautiful as all of the pictures you see. The drive should have been about 2.5 hours, but it took me 3.5 hours, because behind each turn the view was better than the previous turn, so I had to stop and take pictures. I took over 100 pictures on that drive. Once I arrived in Seward, I was given my first tour of the ship and then I had some time to explore Seward.
Yesterday (the first official day on the job), I learned so much. Getting used to the terminology is the hardest part. There are acronyms from everything! Immersion is the best way to learn a foreign language, and I have been immersed in the NOAA (National Oceanic and Atmospheric Administration) language. There is the CO (Commanding Officer), XO (Executive Officer), FOO (Field Operations Officer), TAS (Teacher at Sea or Me!), POD (Plan of the Day) and that is just the tip of the iceberg. I also had to learn all of the safety procedures. This involved me getting into my bright red survival suit and learning how to release a lifeboat.
Today, I am going on a dive launch. The purpose of this launch is to help some of the divers get more experience in the cold Alaskan waters. I will get to ride on one of the smaller boats and watch as the Junior Officers scuba dive.
Did You Know?
NOAA Corps is one of the 7 branches of the U.S. uniformed services along with the Army, Navy, Coast Guard, Marine Corps, Air Force, and the Public Health Service Commissioned Corps (PHSCC).
Geographic area of the cruise: Atlantic Ocean, off the coast of North Carolina and South Carolina
Date: July 28, 2014
Weather Information from the Bridge
Air Temperature: 27.5 C
Relative Humidity: 86%
Wind Speed: 15.03 knots
Science and Technology Log
There is a lot of work that goes into allowing the fishery team to be able to set traps every day. The acoustics lab/ night shift is responsible for creating the maps of the seafloor that will be used the following day. The team consists of David Berrane a NOAA fisheries biologist, Erik Ebert a NOAA research technician, Dawn Glasgow from the South Carolina Department of Natural Resources and a Ph.D student at the University of South Carolina, as well as Mary a college student studying Geology at the College of Charleston and Chrissy a masters student at the University of South Carolina. This team is amazing! Starting at around 5:00 pm the day before they stay up all night mapping the ocean floor.
Every night Zeb Schobernd lets the night shift know which boxes they will work on. These boxes are created in the offseason by the research scientists, they base their selection on information from fishermen, the proximity to already mapped areas, weather and previous experiences. The first step in creating a bathymetric map is to create a line plan, which lets the ship know which area will be covered. The average line takes about half an hour to complete but they can take up to several hours. The ship drives along these lines all night long while the team uses the information that is gathered to create their maps.
So how do they get this information? The ship uses sonar to collect data on the water column and the ocean floor. The Pisces has a 26 multi-beams sonar system, which allows the research team to create a better picture, compared to using single beam sonar. The beams width is about 3 times the depth of water column. This means that depending on how deep the water is in any given location, it will determine how many lines need to be run to cover the area.
The picture below is one of the computer screens that the scientists look at throughout the night. It provides the sonar information that will then be used to map the floor. Sonar works by putting a known amount of sound into the water and measuring the intensity of the return. A rock bottom will yield a stronger return while a sand bottom will absorb the sound and yield a less intense return. In the image red means that there is a more intense return while blue and yellow signifies a less intense return. You will notice in the center screen there is a strong red return at the top of the beam this is because the ship is sending out the sound and it takes about four meters until you start recording information from the sea floor.
Finally before the maps can be created the team has to launch an XBT (expendable bathy thermograph) two times per box or every four hours. The XBT measures the temperature and conductivity of the water, this is important because sound travels at different rates in cold versus warm water. This information is then used when the scientists calculate the sound velocity, which is used to estimate the absorption coefficient of sound traveling through the water column.
Once the data is collected the team begins the editing process. First they have to remove random erroneous soundings in order to get an accurate map; they fondly call this process dot killing (this basically means getting rid of outliers). They do this by drawing a box around the points of data they want to remove and deleting the point. Next they apply tide data to account for the deviations in the tides, this information is obtained from NOAA and is based on the predicted tides for the area. Finally they apply the sound absorption coefficient.
The final product is put into GIS (Geographic Information Systems), which the chief scientists will use to determine where the traps should be set the following morning. On the map below blue indicates the deepest areas while red shows the shallowest. The scientists want to place the traps in areas where there is a large change in depths because this is usually where you will find hard bottoms and good fish habitats.
I have spent the past three nights in the Acoustics/Computer Lab with the night shift mapping the ocean floor. While the ship sails along the plotted course, I have had the opportunity to see the sunrise and sunset on the Pisces as well as a lightning storm from the top deck.
On Thursday night a little after midnight after launching the XBT we see decided to go onto the top deck of the Pisces to get a better look at the lighting storm in the distance. Even at night it was still humid and hot and as we climbed up to the top deck it was dark all around us until suddenly there would be a flash of color in the clouds and you could see everything, until it went dark again. We tried to take a picture but the lightening was just too fast for our cameras. This is the closest picture I could find to what it was like that night except the water was not calm.
SPOTLIGHT ON SCIENCE
Name: Erik Ebert Title: Research Technician
Education: Cape Fear Tech (Wilmington, NC)
How long have you worked for NOAA/NOS: 6th field season, 5th year
Job Summary: I work on ecosystem assessments throughout the Gulf of Mexico South Atlantic & Caribbean
– Team oriented production of ocean floor maps
– System setup & keeping the acoustic systems operating correctly
How long have you participated in this survey: Since 2010
What do you like about your job: That the data we collect, and the maps we create can be used again for different studies. The types of data we collect includes bathymetric data, information on the water column, & fish that populate the water column.
How many days are you at sea: 60 days (April-November)
What do you do when you are not on the boat: Process & produce fish density maps from the data collected during the cruises. I also work for National Ocean Services (provide data to policy & decision makers to the state of the ecosystem)
Most challenging about research on a ship: Being away from home is the biggest challenge.
What would be your ideal research cruise: My ideal research cruise would be a cruise similar to what we just completed in Flower Garden Banks in the Gulf of Mexico. It was a 3-year assessment of the reef ecosystem using ROV, Diving and Acoustics to study how the ecosystem changed over time.
Favorite fish: Trigger Fish “cool swimming behavior”
Geographic area of the cruise: Atlantic Ocean, off the coast of North Carolina and South Carolina
Date: July 13, 2014
Weather Information from the Bridge
Air Temperature: 27.6 °C
Relative Humidity: 73%
Wind Speed: 5.04 knots
Science and Technology Log
Someone is always working on the Pisces. When Nate Bacheler and the other fishery scientists have finished their work for the day collecting fish, it is show time for the hydrographers, the scientists who map and study the ocean floor. Their job is to map the ocean floor to help Nate find the best places to find fish for the next day. Warren, Laura, David and Matt were kind enough to let me join them and explained how they map the ocean floor while on board the Pisces.
People have learned over the years that some fish like to hang out where there is a hard bottom, not a sandy bottom. These hard bottom areas are where coral and sponges can grow and it also happens to be where we usually find the most fish.
Instead of using a camera to find these hard bottom habitats, the mapping scientists use multibeam sonar. Here is a simple explanation on how sonar works. The ship sends a sound wave to the bottom of the ocean. When the sound wave hits the bottom, the sound bounces back up to the ship.
Since scientists know how fast sound travels in water, they can figure out how far it is to the ocean floor. If the sound wave bounces back quickly, we are close to the ocean floor. If the sound wave takes longer, the ocean floor is farther away. They can use this data to make a map of what the ocean floor looks like beneath the ship.
The neat thing about the Pisces is that it does not send down one sound wave only. It sends 70 waves at once. This is called multibeam sonar.
So, now you know how sonar works in simple terms.
But it gets a little more complicated. Did you know that sound speed can be affected by the water temperature, by how salty the water is (the “salinity”), by tides, and by the motion of the ship? Computers make corrections for all of these factors to help get a better picture of the ocean floor. But, computers don’t know the physical properties of our part of the ocean (because these properties change all the time) so we need to find this information and give it to the computer.
To find the temperature of the ocean water, the mapping scientists launch an “XBT” into the water. XBT stands for “expendable bathythermograph.” The XBT records the changes in water temperature as it travels to the ocean floor. It looks like a missile. It gets put into a launcher and it has a firing pin. It sounds pretty dangerous, doesn’t it! I was excited to be able to fire it into the water. But, when I pulled out the firing pin, the XBT just gently slid out of the launcher, softly plopped into the ocean, and quietly collected data all the way to the ocean floor.
With the new data on water temperature, the hydrographers were able to create this map of the ocean floor.
In the map above, blue indicates that part of the ocean floor that is the deepest. The green color indicates the part of the map that is the next deepest. The red indicates the area that is most shallow.
Nate talks to the hydrographers early in the morning and then predicts where the hard bottom habitats might be. In particular, Nate looks for areas that have a sudden change in elevation, indicating a ledge feature. If you had Nate’s job, where would you drop the 6 traps to find the most fish? Look at the map below to see where Nate decided to deploy the traps.
To find out more about using sound to see the ocean floor and to see an animation of how this works, click on this link:
We have now gotten into a regular routine on the ship. The best part of the day for me is when we are retrieving the traps. We never know what we will see. Sometimes we catch nothing. Sometimes we find some really amazing things.
Here are a few of my favorites:
Did you know?
The ocean is largely unexplored. Maybe someday you will discover something new about the ocean!
Geographical Area of Cruise: Bering Sea North of Dutch Harbor
Date: Sunday, July 6th, 2014
Weather Data from the Bridge:
Wind Speed: 6 kts
Air Temperature: 8.6 degrees Celsius
Weather conditions: Hazy
Barometric Pressure: 1009.9
Latitude: 5923.6198 N
Longitude: 17030.6395 W
Science and Technology Log
Part One of the Survey Trawl: Getting Ready to Fish
Today is my second day aboard the Oscar Dyson. We are anxiously waiting for the echosounder (more information on echosounder follows) to send us a visual indication that a large abundance of fish is ready to be caught. The point of the survey is to measure the abundance of Walleye Pollock throughout specific regions in the Bering Sea and manage the fisheries that harvest these fish for commercial use to process and sell across the world. The Walleye Pollock are one of the largest populations of fish. It is important to manage their populations due to over-fishing could cause a substantial decrease the species. This would be detrimental to our ecosystem. The food web [interconnecting food chains; i.e. Sun, plants or producers (algae), primary consumers, animals that eat plants (zooplankton), secondary consumers, animals that eat other animals (pollock), and decomposers, plants or animals that break down dead matter (bacteria)] could be altered and would cause a negative effect on other producers and consumers that depend on the pollock for food or maintain their population.
The main food source for young pollock is copepods, a very small marine animal (it looks like a grain of rice with handle bars). They also eat zooplankton (animals in the plankton), crustaceans, and other bottom dwelling sea life. On the weird side of the species, adult pollock are known to eat smaller pollock. That’s right, they eat each other, otherwise known as cannibalism. Pollock is one of the main food sources for young fur seal pups and other marine life in Alaskan waters. Without the pollock, the food web would be greatly altered and not in a positive way.
How do we track the pollock?
Tracking begins in the acoustics lab. Acoustics is the branch of science concerned with the properties of sound. The acoustics lab on board the Oscar Dyson, is the main work room where scientists can monitor life in the ocean using an echosounder which measures how many fish there are with sound to track the walleye pollock’s location in the ocean. They also use the ships’s GPS (Global Positioning System), a navigation system, to track the location of the NOAA vessel and trawl path.
What is sonar and how does it work?
Sonar (sound ranging & navigation; it’s a product of World War II) allows scientists to “see” things in the ocean using sound by measuring the amount of sound bouncing off of objects in the water. On this survey, sonar images are displayed as colors on several computer monitors, which are used to see when fish are present and their abundance. Strong echoes show up as red, and weak echoes are shown as white. The greater the amount of sound reported by the sonar as red signals, the greater the amount of fish.
How does it work? There is a piece of equipment attached to the bottom of the ship called the echosounder. It sends pings (sound pulses) to the bottom of the ocean and measures how much sound bounces back to track possible fish locations. The echo from the ocean floor shows up as a very strong red signal. When echoes appear before the sound hits the ocean floor, this represents the ping colliding with an object in the water such as a fish.
The scientists monitor the echosounder signal so they can convey to the ships’s bridge and commanding officer to release the nets so that they can identify the animals reflecting the sound. The net catches anything in its path such as jellyfish, star fish, crabs, snails, clams, and a variety of other fish species. Years of experience allows the NOAA scientists the ability to distinguish between the colors represented on the computer monitor and determine which markings represent pollock versus krill or other sea life. We also measure the echoes at different frequencies and can tell whether we have located fish such as pollock, or smaller aquatic life (zooplankton). The red color shown on the sonar screen is also an indicator of pollock, which form dense schools. The greater amount of red color shown on the sonar monitor, the better opportunity to we have to catch a larger sample of pollock.
Once we have located the pollock and the net is ready, it is time to fish. It is not as easy as you think, although the deck hands and surveyors make it look simple. In order to survey the pollock, we have to trawl the ocean. Depending on the sonar location of the pollock, the trawl can gather fish from the bottom of floor, middle level and/or surface of the ocean covering preplanned locations or coordinates. Note: Not all the fish caught are pollock.
The preplanned survey path is called transect lines with head due north for a certain distance. When the path turns at a 90 degree angle west (called cross-transect lines) and turns around another 90 degree angle heading back south again. This is repeated numerous times over the course of each leg in order to cover a greater area of the ocean floor. In my case we are navigating the Bering Sea. My voyage, on the Oscar Dyson is actually the second leg of the survey, in which, scientists are trawling for walleye pollock. There are a total of three legs planned covering a distance of approximately 6,200nmi (nautical miles, that is).
Trawling is where we release a large net into the sea located on the stern (the back of the boat). Trawling is similar to herding sheep. The fish swim into the net as the boat continues to move forward, eventually moving to the smaller end of the net. Once the sonar screen (located on a computer monitor) shows that we have collected a large enough sample of pollock, the deck hands reel the net back on board the boat.
We have caught the fish, now what? Stay tuned for my exciting experience in the wet lab handling the pollock and other marine wild life. It is most certainly an opportunity of a lifetime.
What an adventure!
I was lucky enough to spend a day exploring Dutch Harbor, Alaska before departing on the pollock survey across the Bering Sea. It took me three plane rides, several short lay-overs and and a car ride to get here, a total of 16 hours. There is a four hour time difference between Dutch Harbor and Dover, Delaware. It takes some getting used to, but definitely worth it. The sun sets shortly after 12:00 midnight and appears again around 5:00 in the morning. Going to sleep when it’s still daylight can be tricky. Thank goodness I have a curtain surrounding my bed. Speaking of the bed, it is extremely comfortable. It is one of those soft pillow top beds. Getting in and out of the top bunk can be challenging. I haven’t fallen yet.
During my tour through the small town of Dutch Harbor, I have encountered very friendly residents and fishermen from around the world. I was fortunate to see the U.S. Coast Guard ship Healy docked at the harbor. What a beautiful vessel. Dutch Harbor has one full grocery store (Safeway) just like we have in Delaware, with the exception of some of the local Alaska food products like Alaska BBQ potato chips. They have a merchant store that sells a variety of items ranging from food, souvenirs, clothing, and hardware. They have three local restaurants and a mom and pop fast food establishment. One of the restaurants is located in the only local Inn the Aleutian hotel, which also includes a gift shop. Dutch Harbor is home to several major fisheries. Dutch Harbor is rich in history and is home to the native Aleutian tribe. I took a tour of their local museum. It was filled with the history and journey of the Aleutian people. While driving through town, I got a chance to see their elementary and high school. They both looked relatively new. Dutch Harbor is also home to our nation’s first Russian Orthodox Church. Alaska is our 50th state and was purchased from Russia in 1867.
One of the coolest parts of my tour was walking around the area known as the “spit”. The “spit” is located directly behind the airport. I’m told it is called the “spit” because the land and water are spitting distance in length and width. We walked along the shoreline and discovered hundreds of small snails gathered around the rocks. We also found hermit crabs, starfish, sea anemones, jellyfish, and red algae. We saw red colored water, which is a bloom or a population explosion of tiny algae that get so thick that they change the color of the water.
Another animal in abundance in Dutch Harbor is the bald eagle. There is practically one on every light post or tall structure. Often the bald eagles are perched in small groups. Watch out: if you walk too close to a nesting mother, she will come after you. They are massive, regal animals. I never get tired of watching them.
Did You Know?
Did you know that Alaska’s United States Coast Guard vessel has the ability to break through sea ice?
This is especially helpful if you want to study northern areas, which are often ice covered, in the winter, and to assist a smaller boat if it gets trapped in the ice.
Did you know that scientists set time to Greenwich Mean Time (GMT) which is the time in a place in England?
This reduces confusion (e.g. related to daylight savings, time zones) when the measurements are analyzed.
Meet the Scientist:
Leg II Chief Scientist Dr. Alex De Robertis
Title: NOAA Research Fishery Biologist (10 years)
Education: UCLA Biology Undergraduate Degree
Scripps Institute Oceanography San Diego, CA PhD.
Newport, Oregon Post Doctorate work
Born in Argentina and moved to England when one-year old.
Lived in Switzerland and moved to Los Angeles,CA at the age of 13.
Currently lives in Seattle, Washington, and he has two kids aged one and five.
Responsible for acoustic trawl surveying at Alaska Fisheries Science Center
Was able to help with the Gulf of Mexico oil spill clean-up using the same echo sonar used on trawl surveys.
What is cool about his work:
He enjoys his work, especially the chance to travel to different geographic locations and meet new people. “You never know what you are going to encounter; there is always a surprise or curve ball, when that occurs you adjust and just go with it”.
In the near future, he would love to see or be part of the design for an autonomous ocean robot that will simplify the surveying process.
He has been interested in oceans and biology since a small boy. He remembers seeing two divers emerge from the sea and was amazed it was possible.
NOAA Teacher at Sea Dave Murk Aboard NOAA Ship Okeanos Explorer May 7 – 22, 2014
Mission: EX 14-03 – Exploration, East Coast Mapping Geographical Area of Cruise: Off the Coast of Florida and Georgia – Western portion of the Blake Plateau (Stetson Mesa) Date: May 10, 2014
Weather data from Bridge:
Temperature 25 degrees celsius (can you convert to Fahrenheit?)
WInd – From 160 degrees at 14 knots (remember north is 0 degrees)
Latitude : 28 degrees – Longitude: 79 degrees.
Science and Technolgy Log:
Two of the goals for this expedition. (There are a lot more)
Expedition coordinator Derek Sowers said his best case scenario for this mission is to meet all the cruise objectives. The main one- an aggressive 24/7 campaign to map as much seafloor as possible within top priority mapping areas offshore of the Southeast United States and along the canyons at the edge of the Atlantic continental shelf.
In addition to that mapping goal, he wants the visiting fisheries scientist on board to get good water samples for the Ocean Acidification Program and good samples from the plankton tows. Last but not least, he “wants the mission team to have a great learning experience.”
The ship has three different sonars, each of which is good for different things. One sonar sends out a single beam of sound that lets you see fish and other creatures in the water column. Another sonar sends powerful sounds that bounce back off the bottom and gives you information about the geology (rocks and sediment) of the seafloor. Perhaps the most impressive sonar onboard is the multi-beam sonar. You know how your garden hose has a setting for jet spray when you want to aim it at your brother who is 10 feet away? The water comes out in a straight narrow line. But there’s also another setting called ‘shower” or wide spray. The multibeam sonar is like combining the best of both of these sprays into one and sends out a fan of sound that allows the scientists to map a broad section of the seafloor. By measuring how long it takes this sound to reach a patch of seafloor and return to the ship, it is possible to estimate the distance and that is how the shape of the seafloor can be mapped. Using this technology enables NOAA to map the seascape in order to better protect marine habitat and reduce harm from human activities. Mapping the marine protected areas off the east coast of Florida and Georgia is important because there are deep sea corals in this area and it is important fisheries habitat.
This cruise features a visiting scientist from NOAA Fisheries, named Chris Taylor. Chris’s part of the expedition includes collecting water samples and towing a net that can collect very small creatures called plankton. Chris is specifically examining the plankton he catches to see if bluefin tuna use this part of the ocean to lay eggs and raise young tuna. Samples from the net will go back to a lab to be analyzed to make sure they are bluefin and not yellowfin tuna.
Chris spent most of this windy but warm night tying a rope to the net that he’ll use for HOPEFULLY – catching some baby Bluefin Tunas. Like insects, Bluefin tuna go through an egg stage THEN a larva stage. When they are very small they drift with the currents with the rest of the ocean community. Once a larva is over 7 millimeters, they can avoid the net. But If we find some Bluefin tuna – it may mean that we have found a new spawning ground for Bluefin tuna in the southern North Atlantic.
Two people who make this ship run so well:The operations officer – Lieutenant Emily Rose. Officer Rose can usually be found on the bridge of the NOAA ship Okeanos Explorer. Today she was teaching a course on small craft navigation before I caught up with her. The thing she really loves about this position is that there are new set of challenges each day. She is always learning (and I’ll add that she is almost always sharing that knowledge with others) but the ship is her first responsibility. The most difficult thing is getting up every morning before 3:00 a.m. and being away from everyone back home.
Chief Electronics Technician Richard Conway and Electronics Technician Will Okeson are the Tech guys and they are always busy. Since Okeanos Explorer is America’s premier ocean exploration ship, there are a lot of computers, miles of cable and lots of video equipment to maintain. Richard and Will’s favorite part of the job is when all the parts work together and the public can see their product and when they can trouble shoot and help the science team reach their objectives. The most difficult thing it so be away from families when there is a crisis or joyous moment.
Two things about my personal experiences so far on EX-14-03 (our mission)
First – – “SCIENCE RULES” to quote Bill Nye. Every Okeanos Explorer crew member and scientific crew member are all about the science of the mission. When one of the science crew is going to launch something called an XBT over the side, they call and get an OK from the bridge (where the captain or second in command and the crew that are on “watch” are located). No one hesitates to ask questions of each other. Why is this? What is that? Where is the nearest ship? What’s for lunch? (just kidding ! Chief Steward Randy posts a menu every day and it beats out Golden Corral any day of the week for tastiness and diversity). But the important thing of the mission is the science and every single person on the ship works to make the mission a success.
Second – RESPECT – There is so much respect shown on the Okeanos Explorer. It’s respect for other people, for the ship, for the environment, for rules and for commons spaces. Yesterday while on the bridge, Ensign Nick Pawlenko was taking over from Commander Ramos and they both showed such respect for rules and for each other by going over all the observations of the ship’s speed, the weather conditions and whether there were any other ships in the area. When breakfast was over – I saw Operations Officer Rose stick her head in the galley (kitchen) and thank Chief Cook Ray and Chief Steward Randy for a great meal. No one slams doors since it might wake the crew and scientists who are on night duty. Everyone cleans up after themselves. If you ever have a question and if the crew or scientists can answer it, they will. There is respect for the environment when we separate our garbage each meal. If only the whole world was like the Okeanos.
MYSTERY PICTURE – Here are two photos – what’s different about them? And WHY?? That’s the million dollar question (or an even better prize –bluefin tuna larva in our trawl nets )
NOAA Teacher at Sea Susy Ellison Aboard NOAA Ship Rainier September 9-26, 2013
Mission: Hydrographic Survey Geographic Area: South Alaska Peninsula and Shumagin Islands Date: September 13, 2013
Weather: current conditions from the bridge
You can also go to NOAA’s Shiptracker (http://shiptracker.noaa.gov/) to see where we are and what weather conditions we are experiencing
GPS Reading: 55o 15.037’ N 162o 38.025’ W
Wind Speed: 9.8 kts
Barometer: 1021.21 mb
Visibility: foggy on shore
Science and Technology Log
Since leaving Kodiak 5 days ago, I have been immersed in a hydrographic wonderland. Here’s what I’ve learned, summed up in two words (three, if you count the contraction); it’s complicated. Think about it. If I asked you to make a map of the surface of your desk you could, with a little bit of work and a meter stick, make a reasonably accurate representational diagram or map of that surface that would include the flat surface, as well as outlines of each item on the surface and their heights relative to that surface, as well as their location relative to each other on a horizontal plane. You might want to get fancy and add notes about the type of surface (is it wood, metal, or some sort of plastic), any small irregularities in that surface (are there some holes or deep scratches—how big and how deep?), and information about the types of objects on the desk top (are they soft and squishy, do they change location?). Now, visualize making this same map if your desktop was underwater and you were unable to actually see it. Not only that, the depth of the water over your desktop can change 2 times each day. If that isn’t complicated enough, visualize that the top of the water column over your desk is in constant motion. OK, not only all those variables, but pretend you are transformed into a very teeny person in a small, floating object on that uncertain water over the top of your desk trying to figure out how to ‘see’ that desktop that you can’t actually see with your own eyes? Welcome to the world of the hydrographer; the challenge of mapping the seafloor without actually touching it. It is, indeed, a complex meld of science, technology, engineering, and math (STEM, in educational parlance), as well as a bit of magic (in my mind).
Challenge number one—how do you measure something you can’t see or touch with your own hands? Long ago, sailors solved that obstacle by using a lead line; literally, a line with a lead weight attached to the end. They would drop the weighted line over the side of their ship to measure the depth. These soundings would be repeated to get enough data to provide a view of the bottom. This information was added to their maps along with estimates of the horizontal aspects (shoreline features and distance from the shoreline) to create reasonably good charts that kept them off most of the underwater obstacles. A simple solution to a complex problem. No electricity required, no advanced degrees in computer science needed, no calculus-based physics necessary. Fast- forward to 2013 and the world of complex calculations made possible by a variety of computer-based algorithmic calculations (i.e. some darn fancy computing power that does the math for you). The NOAA Ship Rainier’s hydrographers use sound as their lead line, traveling in small boats known as launches that are equipped with multibeam sonar that send a series of sound ‘pings’ to the ocean floor and measures the time between sending and receiving the ping back after its trip to the bottom. Sounds simple enough, doesn’t it? If it were all that simple I wouldn’t be typing this in a room on the Rainier filled with 20 computer monitors, 10 hard drives, and all sorts of other humming and whirring electronic devices. Not only that, each launch is equipped with its own impressive array of computer hardware.
So far on our survey days 2 launches have been sent out to cover identified transects. Their onboard crew includes a coxswain (boat driver), as well as 2-3 survey technicians and assistants. Each launch is assigned a polygon to survey for the day.
EVERY PING YOU TAKE…
Once they arrive at their assigned area, it’s time to ‘mow the lawn’—traverse back and forth systematically collecting data from one edge of your assigned polygon to the other until the entire area has been surveyed. Just in case you haven’t realized it yet, although that sounds pretty straightforward, it isn’t. Is the area shallow or deep? Depth affects how much area each traverse can cover; the sonar spreads out as it goes downward sending it’s little pings scampering to the ocean floor. Visualize an inverted ‘V’ of pings racing away from the sonar towards the sea floor. If it’s deep, the pings travel further before being bounced back upwards. This means that the width of each row the sonar cuts as it “mows the lawn” is wider in deeper water, and narrower in shallow. Shallower areas require more passes with the launch, since each pass covers a more limited area than it might if the water were deeper. As the launch motors back and forth ‘mowing the lawn’, the sonar signature is recorded and displayed on monitors in the cabin area and in front of the driver. Ideally, each lap overlaps the previous one by 25-50%, so that good coverage is ensured. This requires a steady hand and expert driving skills as you motor along either over or parallel to ocean swells. All you video gamers out there, take note–add boat driving to the repertoire of skills you might need if you want to find a job that incorporates video gaming with science!
Here’s a small list of some of the variables that need to be considered when using sonar to calculate depth; the chemistry of the water column through which you are measuring, the variability of the water column’s depth at specific times of day, the general depth (is it shallow or deep), and the movement of the measuring device itself. So many variables!!
HOW FAST DOES SOUND TRAVEL?
When you’re basing your charts on how sound travels through the water column, you need to look at the specific characteristics of that water. In a ‘perfect world’, sound travels at 1500m/second through water. In our real world, that speed is affected by salinity (the concentration of salts), temperature, and depth (water pressure). The survey crew uses a CTD meter to measure Conductivity, Temperature, and Depth. The CTD meter is deployed multiple times during the day to obtain data on these parameters. It is attached to a line on the rear of the launch, dropped into the water just below the surface for 2 minutes, and then lowered to near the ocean floor to collect data. After retrieval, it’s hooked to the computer on the launch to download the data that was collected. That data is stored in its own file to use when the data is reviewed in the evening back on board the Rainier. This is one of the variables that will be applied to the sonar data file—how fast was the sound moving through the water? Without this information to provide a baseline the sonar data would not be accurate.
ROCKING AND ROLLING…
When you’re out on the ocean in a boat, the most obvious variable is the instability of the surface, itself. This is called ‘attitude’. Attitude includes changes to the boat’s orientation fore and aft (pitch), side-to-side (roll), and up and down (heave) as it is gently, and not-so-gently rocked by ocean swells and waves. This means that the sonar is not always where you think it is in relation to the seafloor. This is like trying to accurately measure the height of something while you, the measurer, are on a surface that is constantly moving in 3 different directions. Good luck. Luckily for this crew of hydrographers, each boat is equipped with a little yellow box whose technical name is the IMU (inertial measurement unit) that I call the heave-o-meter, as we bob up and down on this might ocean. This little box contains 3 gyroscopic sensors that record all those forward and backward pitches, sideways rolls, as well as the bobbing up and down motions that the boat does while the sonar is pinging away. This information is recorded in the launch’s computer system and is applied to the sonar data during analysis back at the Rainier.
TIME AND TIDE…
Now that you’ve gotten your launch to the correct polygon (using GPS data to pinpoint your location), taken CTD readings to create a sound transmission profile for your transect area, and started up the heave-o-meter to account for rocking and rolling on the high seas, it’s time to start collecting data. Wait—there’s still another variable to think about, one that changes twice daily and affects the height of the water column. You also have to factor in changes in the depth of the water due to tidal changes. (for an in-depth look at how tides work, check out this link: http://oceanservice.noaa.gov/education/kits/tides/tides01_intro.html). At high tide, there’s a greater likelihood that subsurface obstacles will be covered sufficiently. At low tide, however, it’s pretty important to know where the shallow spots and rocks might lurk. NOAA’s hydrographers are charting ocean depths referenced to mean lower low water, so that mariners can avoid those low-water dangers.
You might be asking yourself, who keeps track of all that tide data and, not only that, how do we know what the tide highs and lows will be in an area where there are no other tide gauges? NOAA has tide gauges along many coastal areas. You can go online to http://tidesandcurrents.noaa.gov/and find out predicted tide heights and times for any of these locations. While we are working here in Cold Bay, we are using a tide gauge in nearby King Cove, as well as a tide gauge that the Rainier’s crew installed earlier this summer. More data is better.
What do you do if you’re surveying in an area that doesn’t have existing tide gauges? In that case, you have to make your own gauge that is referenced to a non-moving point of known elevation (like a rock). For a detailed description of how these gauges are set, check out NOAA TAS blogs from some of the teachers who preceded me on the Rainier. On Wednesday, I helped dismantle a tide gauge on Bird Island in the Shumagin Islands that had been set up earlier this season (check out TAS Avery Martin’s July 12th posting), but had ceased to report reliable data. Our mission on Wednesday was to find out if the station had merely stopped reporting data or if it had stopped collecting data entirely.