Linda Kurtz: Hydrographic Surveys – Not your Mama’s Maps! August 17, 2019

NOAA Teacher at Sea

Linda Kurtz

Aboard NOAA Ship Fairweather

August 12-23, 2019


Mission: Cascadia Mapping Project

Geographic Area of Cruise: Northwest Pacific

Date: 8/17/2019

Weather Data from the Bridge

August 17th 2019

Latitude & Longitude: 43◦ 53.055’ N 124◦ 47.003’W
Windspeed: 13 knots
Geographic Area: @10-15 miles off of the Oregon/California coast
Cruise Speed:  12 knots
Sea Temperature 20◦Celsius
Air Temperature 68◦Fahrenheit

Future hydrographer button
Is this you?

Navigation is how Fairweather knows its position and how the crew plans and follows a safe route.  (Remember navigation from the last post?)  But what “drives” where the ship goes is Hydrographic survey mission.  There is a stunning amount of sea floor that remains unmapped, as well as seafloor that has not been mapped following a major geological event like an earthquake of underwater volcano.

Why is Hydrography important?  As we talked about in the previous post, the data is used for nautical safety, creating detailed maps of the ocean floor,  setting aside areas are likely abundant undersea wildlife as conservation areas, looking at the sea floor to determine if areas are good for wind turbine placement, and most importantly to the residents off the Pacific coast, locating fault lines — especially subduction zones which can generate the largest earthquakes and cause dangerous tsunamis.

In addition to generating the data needed to update nautical charts, hydrographic surveys support a variety of activities such as port and harbor maintenance (dredging), coastal engineering (beach erosion and replenishment studies), coastal zone management, and offshore resource development. Detailed depth information and seafloor characterization is also useful in determining fisheries habitat and understanding marine geologic processes.

The history of hydrographic surveys dates back to the days of Thomas Jefferson, who ordered a survey of our young nation’s coast.   This began the practice and accompanying sciences of the coastal surveys.  The practice of surveys birthed the science of Hydrography (which we are actively conducting now) and the accompanying science of Bathymetry (which we will go into on the next post.)  This practice continues of providing nautical charts to the maritime community to ensure safe passage into American ports and safe marine travels along the 95,000 miles of U.S. Coastline. 

Want to learn more about Hydrographic Survey history?  Click on THIS LINK for the full history by the NOAA.

Scientists have tools or equipment that they use to successfully carry out their research.  Let’s take a look at a few of the tools hydrographic survey techs use:

Want to learn more about the science of SONAR? Watch the video below.

ps://www.youtube.com/watch?v=8ijaPa-9MDs

On board Fairweather (actually underneath it) is the survey tool call a TRANSDUCER which sends out the sonar pulses.

Multibeam sonar illustration
Multibeam sonar illustration

The transducer on Fairweather is an EM 710- multibeam echo sounder which you can learn more about HERE

The Transducer is located on the bottom of the ship and sends out 256 sonar beams at a time to the bottom of the ocean.  The frequency of the 256 beams is determined by the depth from roughly 50 pings per second to 1 ping every 10 seconds.  The active elements of the EM 710 transducers are based upon composite ceramics, a design which has several advantages, which include increased bandwidth and more precise measurements. The transducers are fully watertight units which should give many years of trouble-free operation.  This comes in handy since the device in on the bottom of Fairweather’s hull!

Here is the transducer on one of the launches:

transducer
View of transducer on a survey launch

The 256 sonar beams are sent out by the transducer simultaneously to the ocean floor, and the rate of return is how the depth of the ocean floor is determined.  The rate of pulses and width of the “swath” or sonar beam array is affected by the depth of the water.  The deeper the water, the larger the “swath” or array of sonar beams because they travel a greater distance.  The shallower the water, the “swath” or array of sonar beams becomes narrower due to lesser distance traveled by the sonar beams.

The minimum depth that this transducer can map the sea floor is less than 3 meters and the maximum depth is approximately 2000 meters (which is somewhat dependent upon array size).  Across track coverage (swath width) is up to 5.5 times water depth, to a maximum of more than 2000 meters. This echo sounder is capable of reaching deeper depths because of the lower frequency array of beams. 

The transmission beams from the EM 710 multibeam echo sonar are electronically stabilized for roll, pitch and yaw, while they receive beams are stabilized for movements. (The movement of the ship) What is roll, pitch, and yaw? See below – these are ways the Fairweather is constantly moving!

Roll, Pitch, and Yaw
Roll, Pitch, and Yaw

Since the sonar is sent through water, the variable of the water that the sonar beams are sent through must be taken into account in the data. 

Some of the variables of salt water include: conductivity (or salinity) temperature, depth, and density.

Hydrographic scientists must use tools to measure these factors in sea water, other tools are built into the hydrographic survey computer programs. 

One of the tools used by the hydrographic techs is the XBT or Expendable Bathy Thermograph that takes a measurement of temperature and depth.  The salinity of the area being tested is retrieved from the World Ocean Atlas which is data base of world oceanographic data. All of this data is transmitted back to a laptop for the hydrographers.  The XBT is an external device that is launched off of the ship to take immediate readings of the water. 

Launching the XBT:  There is a launcher which has electrodes on it, then you plug the XBT probe to the launcher and then XBT is launched into the ocean off of the back of the ship.  The electrodes transmit data through the probe via the 750-meter copper wire.  The information then passes through the copper wire, through the electrodes, along the black wire, straight to the computer where the data is collected.  This data is then loaded onto a USB then taken and loaded into the Hydrographic data processing software.  Then the data collected by the XBT is used to generate the sound speed profile, which is sent to the sonar to correct for the sound speed changes through the water column that the sonar pulses are sent through.  The water column is all of the water between the surface and seafloor. Hydrographers must understand how the sound moves through the water columns which may have different densities that will bend the sound waves.  By taking the casts, you are getting a cross section “view” of the water column on how sound waves will behave at different densities, the REFRACTION (or bending of the sound waves) effects the data.

See how the XBT is launched and data is collected below!

Videos coming soon!

The other tool is the MVP or moving vessel profiler which takes measurements of conductivity, temperature, and depth.  These are all calculated to determine the density of the water.  This is a constant fixture on the aft deck (the back of the ship) and is towed behind the Fairweather and constantly transmits data to determine the speed of sound through water.  (Since sonar waves are sound waves.)

MVP and launching wench
MVP (left) and the launching wench (right)

The sonar software uses this data to adjust the calculation of the depth, correcting for the speed of sound through water due to the changes in the density of the ocean.  The final product?  A detailed 3d model of the seafloor!

current survey area
Our current survey area! (Thanks Charles for the image!)

All of this data is run through the survey software.  See screen shots below of all the screens the hydrographers utilize in the course of their work with explanations.  (Thanks Sam!)  It’s a lot of information to take in, but hydrographic survey techs get it done 24 hours a day while we are at sea.  Amazing!  See below:

ACQ software screenshot
Hydrographic Survey “Mission Control”
HYPACK Acquisition Software
HYPACK Acquisition Software
Real time coverage map
Real time coverage map

Did You Know?  An interesting fact about sonar:  When the depth is deeper, a lower frequency of sonar is utilized.  In shallower depths, a higher sonar frequency. (Up to 900 meters, then this rule changes.)

Question of the Day:  Interested in becoming a hydrographic survey tech?  See the job description HERE.

Challenge yourself — see if you can learn and apply the new terms and phrases below and add new terms from this blog or from your research to the list!

New Terms/Phrases:

Multibeam sonar

Sound speed

Conductivity

Salinity

Sonar

Sound waves

Refraction

Water column

Roll, Pitch, and Yaw

Animals seen today:

Humpback Whale

Bathymetry and USGS friends coming soon!

Plot room
Hydro-technician Sam Candio (right) collaborating with USGS Research Geologist James Conrad and Physical Scientist Peter Dartnell.

David Madden: Land Ho! Return Home, August 2, 2019

NOAA Teacher at Sea

David Madden

Aboard NOAA Ship Pisces

July 15 – 29, 2019

Back on land, in Tallahassee, FL

Mission: South East Fisheries Independent Survey

Geographic Area of Cruise: Atlantic Ocean, SE US continental shelf ranging from Cape Hatteras, NC (35°30’ N, 75°19’W) to St. Lucie Inlet, FL (27°00’N, 75°59’W)

Weather report in Tallahassee
Conditions early on Friday morning, Tallahassee, FL

Date: August 2, 2019

sunset over aft deck
Sunset aboard Pisces on my last night.

Gratitude Log:

My time on NOAA Ship Pisces is complete. Huge thanks to the folks who made it possible. I am grateful for the grand opportunity and grateful to the many people who helped me along the way. Starting with Emily and Jennifer at NOAA Teacher at Sea. They made everything smooth and easy on my end. Special thanks for allowing me to participate in Teacher at Sea this year, considering I was originally assigned to go last year. I was unable to go last year because my Dad got diagnosed with cancer right before the trip, and I elected to stay home with him during surgery and treatment. Emily, and the NOAA scientists involved, Zeb and Nate, made this year’s trip preparation a breeze. Thank you. Additionally, my Dad is doing well (and even back on the golf course)!

Processing fish
Processing fish with Mike B (the elder) and Todd K. photo by Mike B (the younger)

In some sense I was the little brother tag along on this cruise. “Aww come on, can I play?” was basically what I was saying each day to the scientists and NOAA officers. They were happy to oblige. Thank you for being patient and supportive while I learned how to work on your team.

  1. Zeb, Todd K, Todd W, and Brad were particularly helpful and knowledgeable and patient – thanks, guys!  * Thanks, Brad, for your rocks of the day.  Our minds and our chakras benefited.
  2. Thanks to my roommate, Mike B – for being a great roommate and for helping me out with a ton of things (including excellent slow mo footage of the XBT!)
  3. Thanks to the NOAA officers who were always happy to chat and tell me about how things work and about their careers. Thank you CO, XO, Jamie, Luke, Dan, and Jane. * Did you know that all NOAA officers have a college degree in a STEM field?
  4. And thank you to the scientific team of all stars: Dave H for always being hilarious, Zach for being hardworking and friendly to talk with, Mike B for being so wise and having good taste in music, Kevan, for lots of good chats during meal times, and Lauren, for making Oscar the octopus and being so friendly!
Engine Room
Just hanging out in the engine room one more time with Steve. Thanks to Steve and Garet!

Science and Technology Log

Todd W is the Senior Survey Technician. He works on Pisces full time and helped out the science team with running the CTD (conductivity, temperature, depth). Todd also helped me run a few experiments, and was overall real cool with helping me find random stuff during the cruise.

In particular, Todd and I, with Mike B’s help, tricked out the CTD to investigate how colors change with depth. We arts-and-crafted a few color strips and secured them to the CTD along with some GoPros to record video. We wanted to see what happened to various colors as the CTD descended to depth (~90m). See what it looked like at the top vs. the bottom (image below). You can see clearly that indeed the red color disappeared soonest while most everything took on a blue tone. This is because red is the longest wavelength on the visible spectrum and therefore the lowest energy (~ 700 nm); it’s the most easily absorbed by the water. Conversely, blue light has a shorter wavelength (~400 nm), and this means higher frequency and higher energy. I made a video with the footage we collected – coming soon. When it comes out you can see for yourself the reds disappear and the colors shift to blue. We also secured a Styrofoam cup to the CTD in order to watch what happens as the pressure increases on the way down. *See here for my pressure video covering similar topics. The CTD only went down to around 90 meters, but that was still enough to increase the pressure from 1 atm to around 9 atm. This nine fold increase shrunk the cup around 12%. Todd tells stories of taking Styrofoam manikin heads down to 300 + meters and watching them shrink to the size of a shot glass.

testing color and pressure
Science lab aboard the CTD – testing color and pressure.

In addition to CTD excitement, Todd let me conduct an XBT launch. XBT stands for Expendable Bathythermograph. * This cruise had the highest density of acronyms of any experience in my life. Geez. Here’s a link from NOAA describing XBTs.  And my pictures below.

 

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Bravo, Todd & NOAA Ship Pisces – you got me!!

XBT certificate
Don’t worry, my XBT bravery and expertise didn’t go unrewarded.

Neato Fact:

We stopped by the NOAA Beaufort Lab shortly after we docked in Morehead City. Todd K was awesome and showed me around and introduced me to a series of interesting characters – it was nice to see the lab and see what everyone had been talking about. I spent a short time walking near the sea wall outside the lab. I ran into Larisa who pointed out two cute baby green sea turtles. She said that recently they’ve started coming into the inlet to feed.  Related neato fact: Hawksbill sea turtles have been shown to exhibit biofluorescence.

Baby green sea turtle.
Baby green sea turtle.

Personal Log

It’s good to be back on land, and fun to trade the breezy blue ocean seascape for the hot humid green treescape of Tallahassee. I’m busy trying to process the information from the trip and figure out ways to incorporate it into my teaching and lesson plans. Surely it’ll take two forms – a little bit of distilling and planning now, and a slow seep of info from memories later. I’m hoping the trickle of revisited memories pop up at opportune times during the school year for me to take advantage. We’ll see.

I’m back to school in a few days.  This is the last full blog. Coming up I’ll post some quick hit blogs with links to some videos. Stay tuned.

Sunset
Until we meet again!

Jill Bartolotta: Sounds of the Deep, June 5, 2019

NOAA Teacher at Sea

Jill Bartolotta

Aboard NOAA Ship Okeanos Explorer

May 30 – June 14, 2019

Mission:  Mapping/Exploring the U.S. Southeastern Continental Margin and Blake Plateau

Geographic Area of Cruise: U.S. Southeastern Continental Margin, Blake Plateau

Date: June 5, 2019

Weather Data:

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

Sky: few

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).

Swath ranges for the multibeam sona
Swath ranges for the multibeam sonar at various depths. The y-axis shows the water depth in meters and the x-axis shows the swath width in meters. Photo credit: SST Charlie Wilkins, NOAA Ship Okeanos Explorer
Multibeam Sonar information
Some of the information that is collected using the multibeam sonar with labels describing their purpose. Photo Credit: NOAA OER

Backscatter

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.

Backscatter and Bathymetry
Top image is backscatter showing you a birds-eye view of the ocean floor. The bottom image shows you what it looks like when backscatter is overlaid over the bathymetry layer. You are able to see intensity of the sound return, but floor features are more noticeable. Photo credit: NOAA OER

XBT

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.

Loading the XBT Launcher
Senior Survey Technician Charlie Wilkins and Explorer in Training, Jahnelle Howe, loading the XBT launcher. XBTs are launched off the stern of the ship.
XBT Capture
Sound speed or velocity is determined by the density of the water, which is determined by temperature and salinity. Focus on the blue line in each graph. The first graph takes the information from the temperature and salinity graphs to determine sound speed. If we look at the first graph, we see that sound speed slows with depth. Sound speed slows because according to the second graph the temperature is colder making the water denser, thus affecting sound speed. Salinity does not vary much according to the third graph so its effect on density is most likely limited. Photo credit: NOAA OER

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.

Water column information
Water column information collected with the EK60 or EK80 split beam sonar. If you look at the first row you can see, in the image to the left, the blue dots are at the top and in the second image the blue dots are moving back down into the water column as the sun rises. The process of organisms’ movement in the water column at night to feed is known as vertical diurnal migration. Photo Credit: NOAA OER

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.

Cross section of the ocean seafloor
Cross section of the ocean seafloor shows you substrate characteristics. Photo Credit: NOAA OER

Telepresence

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.

Live interaction
Live interaction with Okeanos Explorer, Inner Space Center at URI/GSO, and a group of high school students. Photo credit: NOAA OER

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!

Personal Log

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.

Corn hole
General Vessel Assistant Sidney Dunn (left) and General Vessel Assistant Christian Lebron (right) playing corn hole on the bow at sunset.

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.

Meredith Salmon: Xtreme XBTs, July 14, 2018

NOAA Teacher at Sea

Meredith Salmon

Aboard NOAA Ship Okeanos Explorer

July 12 – 31, 2018

 

Mission: Mapping Deep-Water Areas Southeast of Bermuda in Support of the Galway Statement on Atlantic Ocean Cooperation

Geographic Area:  Atlantic Ocean, south of Bermuda

Date: July 14, 2018

Weather Data from the Okeanos Explorer Bridge – July 14, 2018

Latitude: 28.58°N

Longitude: 65.48°W

Air Temperature: 27.4°C

Wind Speed:  13.96 knots

Conditions: Rain and clouds

Depth: 5183 meters

 

Science and Technology Log

Temperature and salinity are two main variables when determining the density of water. The density of water or any acoustic medium is a very important factor in determining the speed of sound in water. Therefore, temperature data collected by Expendable Bathythermograph (XBT) probes, as well as historical salinity profiles from the World Ocean Atlas, are used to create sound velocity profiles to use to correct for sound speed changes in the water column.

Expendable Bathythermograph (XBT) probes are devices that are used to measure water temperature as a function of depth. Small copper wires transmit the temperature data back to the ship where it is recorded and analyzed. At first, I was surprised to learn that temperature data is such an important component of multibeam mapping operations; however, I learned that scientists need to know how fast the sound waves emitted from the sonar unit travel through seawater. Since these probes are designed to fall at a determined rate, the depth of the probe can be inferred from the time it was launched. By plotting temperature as a function of depth, the scientists can get a picture of the temperature profile of the water.

On our expedition, we have been deploying XBTs on a schedule as the ship is making its way to the survey area. The XBT Launcher is connected to a deck box, which translates information to computer systems onboard so the data can be logged when the probes are deployed into the water. Aboard the Okeanos Explorer, up to 8 tubes can be loaded at one time and launched by scientists.

XBT closet in the Dry Lab

XBT closet in the Dry Lab

 

XBT Launcher

XBT Launcher on the Okeanos

xbt 2

Loading the XBT Launcher

 

 

xbt 1

Savannah and I after a successful XBT load

 

XBT Data

XBT Data from a launch aboard the Okeanos Explorer. The colors on the graph indicate the XBT number and the data is plotted on a temperature and depth scale.

 

 In addition to launching XBTs and collecting data, we completed a Daily Product so that we can communicate the data we have collected to anyone on shore. The Daily Products are completed not only to ensure that the hydrographic software systems are working correctly but to also inform the public our current location, where we have collected data, and if we are meeting the objectives of the mission. Once onshore, NOAA uses this information to analyze the quality of the data and use it for analysis for dive planning. In order to generate the Daily Field Products, we use hydrographic computer systems such as QPS Qimera for advanced multibeam bathymetry processing, Fledermaus for 4D geo-spatial processing, and Geocap Seafloor for digital terrain modeling. In addition, the Daily Field Products allow us to double check the quality of the data and search for any noise interferences due to the speed of the ship or the type of seafloor bottom (hard vs soft).

 

Personal Log

One of the coolest parts of learning aboard the Okeanos Explorer is the fact that I am a part of scientific exploration and discovery in real time.  Known as “America’s Ship for Ocean Exploration,” the Okeanos Explorer is the only federally funded U.S. ship assigned to systematically explore our largely unknown ocean for the sole purpose of discovery and the advancement of knowledge. This is the first U.S.-led mapping effort in support of the Galway Statement on Atlantic Ocean Cooperation and all of this information is going to be available for public use. Not only do I get the opportunity to be involved with “real-time” research, but I am also responsible for communicating this information to a variety of different parties on shore.

Being immersed in the “hands-on” science, learning from the survey techs and watch leads, and observing all of the work that is being done to collect, process, and analyze the data is a really exciting experience. I am definitely out of my element when it comes to the content since I do not have any prior experience with seafloor mapping, sonars, etc., but I am really enjoying playing the role as the “student” in this situation. There is definitely a lot to learn and I am trying to soak it all in!

 

Did You Know?

XBTs contain approximately 1,500 meters of copper wire that is as thin as a strand of hair!

 

Resources: 

http://www.aoml.noaa.gov/phod/goos/xbtscience/news.php

https://oceanexplorer.noaa.gov/facts/xbt.html

Nichia Huxtable: Time to Make a Map, May 8, 2016

NOAA Teacher at Sea

Nichia Huxtable

Aboard NOAA Ship Bell M. Shimada

April 28 – May 9, 2016

Mission: Mapping CINMS
Geographical area of cruise: Channel Islands, California
Date: May 8, 2016
Weather Data from the Bridge:

Science and Technology Log

Seafloor in CINMS

Seafloor in the CINMS

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.

Nichia Huxtable, Diana Watters, ME70, and EK60; aboard Shimada

Nichia Huxtable, Diana Watters, ME70, and EK60; aboard Shimada

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.

Kayla Johnson aboard NOAA Ship Bell M. Shimada

Mapping maven Kayla Johnson

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.

Cross-section of the topography found in the CINMS

Cross-section of the topography found in the CINMS

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.

Completed map around San Miguel Island

Completed map around San Miguel Island

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.

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.

Endnote: A word about XBTs                                                                                                      

Deploying an XBT off Shimada

Deploying an XBT off Shimada

 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.

Cristina Veresan, Lights, Camera, Ocean! August 13, 2015

NOAA Teacher at Sea
Cristina Veresan
Aboard NOAA Ship Oscar Dyson
July 28 – August 16, 2015 

Mission: Walleye Pollock Acoustic-Trawl survey
Geographical area of cruise: Gulf of Alaska
Date: Wednesday, August 13, 2015

Data from the Bridge:
Latitude: 59° 18.31’N
Longitude: 141° 36.22’W
Sky: Overcast
Visibility: 10 miles
Wind Direction: 358
Wind speed: 8 knots
Sea Wave Height: < 1 feet
Swell Wave: 2-3 feet
Sea Water Temperature: 16.2°C
Dry Temperature: 15°C

Science and Technology Log

When my shift begins at 4am, I often get to participate in a few “camera drops” before the sun comes up and we begin sailing our transect lines looking for fish. We are conducting the “camera drops” on a grid of 5 km squares provided by the Alaska Fisheries Science Center bottom trawl survey that shows whether the seafloor across the Gulf of Alaska is “trawlable” or “untrawlable” based on several criteria to that survey. The DropCam footage, used in conjunction with a multi-beam echosounder, helps verify the “trawlability” designation and also helps identify and measure fish seen with the echosounder.

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The Drop Camera being deployed

The DropCam is made up of strobe lights and two cameras, one color and one black and white, contained in a steel frame. The cameras shoot in stereo, calibrated so scientists can get measurements from rocks, fish, and anything else on the images. When the ship is stopped, the DropCam can be deployed on a hydrowire by the deck crew and Survey Tech. In the Chem Lab, the wire can be moved up and down by a joystick connected to a winch on deck while the DropCam images are being viewed on a computer monitor. The ship drifts with  the current so the camera moves over the seafloor at about a knot, but you still have to “drive” with the joystick to move it up and down, keeping close to the bottom while avoiding obstacles. The bottom time is 15 minutes for each drop. It’s fun to watch the footage in real-time, and often we see really cool creatures as we explore the ocean floor! The images from the DropCam are later analyzed to identify and length fish species, count number of individual fish, and classify substrate type.

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Emily “drives” the camera from the Chem Lab as the sun begins to rise

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DropCam images (clockwise from top left) a skate, brittle stars, a cruising halibut, two rockfish in rocky habitat

Technology enables scientists to collect physical oceanographic data as well. The Expendable Bathythermograph (XBT) is a probe that is dropped from a ship and measures the temperature as it falls through the water column. The depth is calculated by a known fall rate. A very thin copper wire transmits the data to the ship where it is recorded in real-time for later analysis. You launch the probe from a hand-held plastic launcher tube; after pulling out the pin, the probe slides out the tube. We also use a Conductivity Temperature Depth (CTD) aboard the Oscar Dyson; a CTD is an electronic device used by oceanographers to measure salinity through conductivity, as well as temperature and pressure. The CTD’s sensors are mounted on a steel frame and can also include sensors for oxygen, fluorescence and collecting bottles for water samples. However, to deploy a CTD, the ship must be stopped and the heavy CTD carousel lowered on a hydrowire. The hand-held XBT does not require the ship to slow down or otherwise interfere with normal operations. We launch XBT’s twice a day on our survey to monitor water temperatures for use with the multi beam echosounder.

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Cristina launching the XBT probe Photo by Alyssa Pourmonir

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Survey Tech Alyssa servicing the CTD carousel

 

 

 

 

 

 

 

 

 

 

 

 

 

Shipmate Spotlight: An Interview with Ensign Benjamin Kaiser

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Ensign Benjamin Kaiser, NOAA Corps

Tell me a little more about the NOAA Corps?
We facilitate NOAA scientific operations aboard NOAA vessels like hydrographic work making charts, fisheries data collection, and oceanographic research.

What do you do up on the bridge?
I am a Junior Officer of the Deck (JOOD), so when I am on the bridge driving the ship, I am accompanied by an Officer of the Deck (OOD). I am on my way to becoming an OOD. For that you need 120 days at sea, a detailed workbook completed, and the Commanding Officer’s approval.

What education or training is required for your position?
I have an undergraduate degree in Marine Science from Boston University. My training for NOAA Corps was 19 weeks at the Coast Guard Academy in New London, Connecticut– essentially going through Coast Guard Officer Candidate School.

What motivated you to join the NOAA Corps?
A friend of mine was an observer on a fisheries boat, and she told me about the NOAA Corps. When I was in high school and college, I didn’t know it was an option. We’re a small service, so recruiting is limited; there’s approximately 320 officers in the NOAA Corps.

What do you enjoy the most about your work?
I love not being in an office all the time. In the NOAA Corps, the expectation is two years at sea and then a land assignment. The flexibility appeals to me because I don’t want to be pigeonholed into one thing. There are so many opportunities to learn new skills. Like, this year I got advanced dive training for Nitrox and dry suit. I don’t have any regrets about this career path.

What is the most challenging part of your work?
There’s a steep learning curve. At this stage, I have to be like a sponge and take everything in and there’s so much to learn. That, and just getting used to shipboard life. It is difficult to find time to work out and the days are long.

What are your duties aboard the Oscar Dyson?
I am on duty 12pm to midnight, rotating between working on the bridge and other duties. I am the ship’s Safety Officer, so I help make sure the vessel is safely operating and coordinate drills with the Commanding Officer. I am also the Training Officer, so I have to arrange the officers’ and crew members’ training schedules. I am also in charge of morale/wellness, ship’s store, keys, radios, and inspections, to name a few.

When did you know you wanted to pursue a marine career?
I grew up in Rhode Island and was an ocean kid. I loved sailing and swimming, and I always knew I would have an ocean-related career.

How would a student who wanted to join the NOAA Corps need to prepare?

Students would need an undergraduate degree from a college or university, preferably in a STEM field. Students could also graduate from a Maritime Academy. When they go to Officer Candidate School, they need to be prepared for a tough first week with people yelling at them. Then there’s long days of working out, nautical science class, drill work, homework, and lights out by 10pm!

What are your hobbies?
I enjoy rock climbing, competitive swimming, hiking, and sailing.

What do you miss most while working at sea?
There’s no rock climbing!

What is your favorite marine creature?
Sailfish because they are fast and cool.

Inside the Oscar Dyson: The Chem Lab

chemlab

This lab is called the Chem Lab (short for Chemical). For our survey, we don’t have that many chemicals, but it is a dry lab with counters for workspace when needed. This room is adjacent to the wet lab through a watertight door, so in between trawls, Emily and I spend a lot of time here.  In the Chem Lab, we charge batteries for the CamTrawl and the DropCam. There are also two computer stations for downloading data, AutoLength analysis, and any other work (like blogging!). There is a window port to the Hero Deck, where the CTD and DropCam are deployed from. In the fume hood, we store Methot net samples in bottles of formalin. There is a microscope for viewing samples. Note the rolling chairs have their wheels removed and there are tie-downs on cases so they are safer at sea. Major cribbage tournaments are also played in this room!

Personal Log

It has been so calm on this cruise, but I have to say that I was looking forward to some bigger waves! Well, Sunday night to yesterday afternoon we experienced some rain and rough seas due to a nearby storm. For a while the ship would do big rolling motions and then a quick lurchy crash. Sea waves were about 2 feet in height, but the swell waves were over 5 feet at times. When I was moving about the ship, I’d have to keep a hand on a rail or something else secured. In the wet lab while I was working, I would lean against the counter and keep my feet spread apart for better balance.

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Seas picked up and the ship was rocking and rolling!

Remember the Methot net? It is the smaller net used to catch macroplankton. We deployed one this week and once it came out of the water, it was rinsed and the codend was unscrewed. When we got the codend into the wet lab, we realized it was exclusively krill!

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The Methot net is deployed by the Survey Tech and deck crew members

Krill

#krillfordays

Krill are  small crustaceans that are found in all the world’s oceans. Krill eat plant plankton (phytoplankton), so they are near the bottom of many marine food chains and fed on by creatures varying from fish like pollock to baleen whales like humpbacks. They are not so small that you need a microscope to see them, but they are tiny. We took a subsample and preserved it and then another subsample to count individuals…there were over 800 krill in just that one scoop! Luckily, we had them spread out on a board and made piles of ten so we did not lose count. It was tedious work moving individual krill with the forceps! I much prefer counting big things.

I love it when there is diversity among the catch from the AWT trawls. And, we caught some very memorable and unique fish this week.  First was a beautiful Shortraker Rockfish (Sebastes borealis). Remember, like the Pacific Ocean Perch, its eyes bulge when its brought up from depth. The Shortraker Rockfish is an open-water, demersal species and can be one of the longest lived of all fish. There have  been huge individuals caught in Alaskan waters that are over 100 years old. This fish was not particularly big for a Shortraker, but I was impressed at its size. It was probably my age.

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Holding a Shortraker Rockfish. Photo by Emily Collins

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Smooth Lumpsucker fish: so ugly it’s cute?! Photo by Mackenzie Wilson

We also caught a Smooth Lumpsucker (Aptocyclus ventricosus). It was inflated because it was brought up from depth, a form of barotrauma. This scaleless fish got its name for being shaped like a “lump” and having an adhesive disc-shaped “sucker.” The “sucker,” modified pelvic fins, are located ventrally and used to adhere to substrate. These pelagic fish are exclusively found in cold waters of the Arctic, North Atlantic, and North Pacific. The lumpsucker fish, and its roe (eggs) are considered delicacies in Iceland and some other countries.

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You can see the “sucker” on the bottom of its body. Photo by Mackenzie Wilson

Pollock are pretty slimy and they have tiny scales, so when we process them, everything gets covered with a kind of speckled grey ooze. However, when we trawled the other day and got a haul that was almost entirely Pacific herring (Clupea pallasii), I was amazed at their scales. For small fish, the herring had scales that were quite large and glistened like silvery sequins. The herring’s backs are an iridescent greenish-blue, and they have silver sides and bellies. The silver color comes from embedded guanine crystals, leading to an effective camouflage phenomenon in open water.

As this last week comes to a close, I am not ready to say goodbye…

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Herring scales are nature’s sequins

Vincent Colombo, Dynamic Positioning, June 15, 2015

NOAA Teacher at Sea
Vincent Colombo
Aboard NOAA Ship Oscar Dyson
June 11 – 30, 2015

Mission: Annual Pollock Survey
Geographical Area of Cruise: The Gulf of Alaska
Date: June 15, 2015

Weather Data from the Bridge:

  • Wind Speed: 4.52 knots
  • Sea Temperature: 8.5 degrees C
  • Air Temperature: 6.4 degrees C
  • Air Pressure: 1034.33 mb

A United States Coast Guard Sikorsky MH-60 Jayhawk flying over the Oscar Dyson

A United States Coast Guard Sikorsky MH-60 Jayhawk flying over the deck of the Oscar Dyson

Science and Technology Log:

Are you a morning person? How about a night owl? Well if you said yes to the first question, then Alaska during the summer is your place to be. Currently where we are right now, the sun officially rises at 5:08 and sets at 23:12 (that’s 11:12 pm for those of you not used to 24 hour format). But, do not think that it means it turns dark by any means. Sunrise and Sunset are when the sun is officially seen, or disappears on the horizon respectively. So far in my time spent here in Alaska, I have only seen it dark for about one hour.

The 23.5 degree tilt of the Earth exaggerates the effect of the sun during the time around a solstice

The 23.5 degree tilt of the Earth exaggerates the effect of the sun during the time around a solstice

The reason why is easily explained, seasons. Students in Delaware learn about seasons in 8th grade, and again if they take Physics or Astronomy in high school. The tilt of the earth causes the northern hemisphere to be more exposed to the sun for longer periods of time. Thus the concept of day and night is greatly changed.

In order to fully grasp this concept, you must also understand why it never gets dark either. The term we use is twilight, or the time between darkness and sunrise in the morning,  and sunset and complete darkness in the evening. Twilight is also defined as when there is light outside, but the sun is below the horizon.

There are 3 types of twilight: civil, nautical, and astronomical.

  • Civil twilight occurs when the Sun is between 0 degrees and 6 degrees below the horizon. In the morning, civil twilight begins when the Sun is 6 degrees below the horizon and ends at sunrise. In the evening, it begins at sunset and ends when the Sun reaches 6 degrees below the horizon. Typically civil twilight begins and ends one half hour before or after sunrise or sunset. Most outdoorsmen know this as the 1/2 hour before and after rule. If you’re a deer hunter, civil twilight signifies legal shooting time has begun or ended.
  • Nautical twilight occurs when the geometrical center of the Sun is between 6 degrees and 12 degrees below the horizon. Nautical twilight is usually an hour before and after sunset. This twilight period is less bright than civil twilight and artificial light is generally required for activities.The term, nautical twilight, dates back to the time when sailors used the stars to navigate the seas. During this time, observers on Earth can easily see most stars. Although not completely dark outside, one could safely get around.
  • Last is Astronomical twilight, and this occurs when the Sun is between 12 degrees and 18 degrees below the horizon. In the morning, the sky is completely dark before the onset of the astronomical twilight, and in the evening, the sky becomes completely dark at the end of astronomical twilight. This is typically an hour and a half before or after sunrise or sunset respectively.
  • During the summer months, especially around the Summer Solstice, the North and South Poles experience several days with no complete darkness at all. Currently our civil, nautical, and astronomical twilights are exaggerated, only leaving about an hour of actual darkness.

My next scientific topic I would like to discuss is the system the vessel Oscar Dyson uses called Dynamic Positioning. When we were calibrating the acoustic equipment in my last post, the ship did not move more than 0.3 meters in any direction.

Dynamic positioning diagram

Dynamic positioning diagram

The ship uses GPS systems to hold it in one single place for a period of time. Using a minimum of three satellites and triangulation, the ship’s position is able to be maintained. The ship uses its main engines as well as bow thrusters to keep it steady in one position.  I was also introduced to some new vocabulary:

  • surge: moving the ship forward or back (astern)
  • sway: moving the ship starboard (right) or left (port)
  • heave: moving the ship up or down
  • roll: the rotation about surge axis
  • pitch: the rotation about sway axis
  • yaw: the rotation about heave axis

How a ship is able to maintain it's position

How a ship is able to maintain its position

Not only can the ship stay in one position, I also learned that it can stay in one position over a column of water, which is vital for a research ship like the Oscar Dyson when conducting research one specific area of the ocean.

A view of the dynamic positioning monitor from the bridge

A view of the dynamic positioning monitor from the bridge

A view of the current state of the rudder of the ship. It changes as the dynamic positioning controls the ship

A view of the current state of the rudder of the ship. It changes as the dynamic positioning controls the ship

The bow thruster control on the bridge of the ship

The bow thruster control on the bridge of the ship

Personal Log:

It took us almost three days to reach where the scientific study was to begin. For those of you who know me, it is hard for me to stay in one place for an extended period of time. Luckily the ship has an abundance of DVDs to watch, Direct TV and a fantastic galley (aka kitchen) to make it feel more like home. I can honestly say the food is some of the best I have ever eaten.

Luckily (knocking on wood), our ship has not hit any rough seas. It has taken a day or so to get used to the rocking, just make sure you have a free hand to grab hold of something when moving about.

Underway, I got to deploy the first An Expendable Bathy Thermograph or XBT for short. You can find out more by going to this NOAA website: XBT uses

Getting briefed on use of the sensor

Getting briefed on use of the sensor. Notice I am harnessed in.

Deploying the sensor

Deploying the sensor

According to our Executive Officer, LT Carl Rhodes, we will be seeing some AMAZING Alaskan geography including volcanoes. Check back for some awesome photos.

Did You Know?

Most modern oil rigs are not fixed to the sea floor! They also use dynamic positioning. Learn more about dynamic positioning here.