Iris Ekmanis is currently a Junior Officer with the NOAA Corps.
On this Teacher at Sea mission,
Officer Ekman is currently on bridge watch, and is a training and small craft
Current Position: Junior
Deck Officer on Bridge Watch, training officer, small boats officer
3-4 other duties in addition to
Years at NOAA: 2.5 months after a 4-month basic training
College and/or specialized training:
2017 Bachelors of Marine Science from
University of Hawaii
Junior Officer Ekmanis worked as a deckhand on tourism boats, dive boats, whale watching, and worked on a small live-aboard cruise ship.
When you were a child, what was your dream career?
I wanted to be a marine biologist – but then I fell in love with being out on the water and on boats. Surrounded by the science of hydrography, I really like driving small boats and like the navigation part of my job.
2. Do you have any plans to continue your education while working for NOAA?
We get the GI bill since we are uniformed service (after 3 years with NOAA) so I’m considering a master’s in marine biology.
3. What was your favorite subject in school?
My favorite subject was outdoor education. I went to high school in New Zealand so there were outdoor education, whitewater kayaks, rock climbing, caving. My favorite academic subjects were biology & geography.
4. At what point in your life did you realize you wanted to do the work you are doing now?
I heard about NOAA in college, so I applied, I completed basic training and have been working for 2 ½ months.
5. What would you tell an elementary school student about your work that is most important?
We are out here charting the seafloor to ensure safe navigation for other mariners who are traveling through the Pacific. All kinds of cruise ships, fisherman, and cargo ships travel through the Pacific and must get there safely. Also, it is important that we are researching the fault lines to learn more about earthquakes and tsunamis.
We navigate the ship to ensure safety and collaborate with the hydrotechs (hydrographic technicians) to make sure the ship’s travels are resulting in good hydrographic surveys.
6. What is the most enjoyable or exciting part of your work?
I would say it is constantly learning new skills. Every day, I’m on the bridge learning about navigation, on the launchers learning about hydrography, and the “office view” changes every day. Every single day is different, and most times wake up in a new place. I’m learning something new every day!
7. Where do you do most of your work?
Mostly on the bridge 8 hours a day, rest of the time working on computers, or my training workbooks, plotting courses, planning our next route. A lot of charting.
8. What tool do you use every day that you couldn’t live without?
Definitely the software systems that allow us to navigate, radar, etc.
9. What tool would you bring aboard to make your job easier?
Multi beam sonar that could see in front of us instead of below us, since we are in uncharted waters that would alleviate the possibility of us running into something.
10. Is there any part of your NOAA job that you didn’t expect?
The job is hands on right away, and the job is fast paced and very diverse. You started doing the jobs right away. I’m looking forward to learning more about hydro.
11. How could teachers help student understand and appreciate NOAA science?
12. What is the favorite part of your day and why?
My favorite time was in Alaska, in the launches (small boats) and navigating a vessel though the Inside Channel. Navigating through SE Alaska was beautiful! I also enjoyed seeing humpback whales and occasionally orcas.
13. What was your favorite book when you were growing up?
My favorite book series was Harry Potter when I was growing up. My idols were Jacques Cousteau and Sylvia Earle .
14. What would you be doing if you weren’t working for NOAA?
If I didn’t work for NOAA I would definitely be doing something in the marine science field or in the maritime industry, I love boats! I would probably be working on a boat or doing something in the ocean.
15. Do you have an outside hobby?
My outside hobbies include: paddle boarding, surfing, scuba, free diving, outrigger canoes were my passion growing up, hiking, camping, anything outdoors.
16. What is your favorite animal?
Hawaiianspinner dolphin and whale sharks.
17. If you could go back in time and tell you 10-year-old self something, what would it be?
Keep pursuing your dreams, don’t take life too seriously, enjoy life and enjoy the ride.
Interested in a career as a NOAA Corps Officer like Junior Officer Ekamanis? Want to learn more? See the resource links below:
Latitude: 58° 27.67 N Longitude: 152 ° 53.00 W Wind Speed: 5.96 knots Wind Direction: 152° Air Temperature: 12.4°C Sea Temperature: 15°C Barometric Pressure: 1008 mbar
Science and Technology Log
I feel the need to start off by stating that the shark did in fact swim away. During our mid-afternoon trawl haul back, Chief Boatswain Ryan Harris called over the radio that we had caught a shark in the trawl net. We quickly put on our boots, hard hats, and life preservers and headed to the back deck. Unfortunately, a 3.2m female Pacific Sleeper Shark had gotten caught in our trawl as bycatch. Thanks to the quick response of our NOAA deck crew, we were able to release the shark back into the water alive.
Unlike most sharks, the Pacific Sleeper Shark is predominantly a scavenger and rarely hunts. They are slow swimmers, but move through the water quite gracefully without much effort of body movement. This lack of movement allows them to catch prey easy since they don’t make much noise/ vibrations in the water. They feed by cutting and suction. The sleeper shark’s large mouth allows it to suck its prey in. Its spear-like teeth help cut prey down into smaller pieces. It then swallows its prey by rolling its head. For more info about this cool shark, visit: https://www.sharksider.com/pacific-sleeper-shark/ .
Bycatch is defined as the unwanted fish and other marine creatures caught (e.g. hooked, entangled or trapped) during commercial fishing for a different species. Bycatch is both an issue ecologically and economically. Bycatch can slow the rebuilding of overfished stocks. Organisms that are discarded sometimes die and cannot reproduce. These mortalities put protected species such as whales and sea turtles even further at risk. Bycatch can change the availability of prey and cause cascading effects at all trophic levels. Bycatch can also occur when fishing gear has been lost, discarded, or is otherwise no longer being used to harvest fish (aka marine debris).
NOAA Fisheries works hand in hand with fishing industries to better understand fishing gear, and to develop, test, and implement alternative fishing gear. For example, NOAA Fisheries and their partners developed turtle excluder devices to reduce sea turtle mortality in the southeastern shrimp trawl fishery. NOAA Fisheries funds the Bycatch Reduction Engineering Program that supports the development of technological solutions and changes in fishing practices designed to minimize bycatch. Laws like the Marine Mammal Protection Act and the Endangered Species Act also uphold the reduction of current and future bycatch of species.
It’s hard to believe that today is already day eight at sea. To be honest, I don’t even notice that I am on a ship anymore. We have been very lucky weather wise and the seas are still very calm. I have been spending more time on the bridge assisting with the ‘marine mammal watch’. As I said in blog two, we must keep an eye out for any marine mammals in the area before conducting any water surveys. The bridge is amazing because not only do you get the best view, but you also get to observe how the ship operates in terms of headings, maneuverability, and navigation.
The Shelikof Strait is breathtaking. Chief Electronics Technician Rodney Terry pointed out the white ‘cloud’ above one of the snow-capped mountains was actually an active volcano with a smoke plume rising above it. It was incredible to be able to look out and see a glacier and an active volcano in the same panorama.
During one of my marine mammal watches on the bridge, I noticed an oddly flat area of land in the middle of the mountain range that ran along the shoreline. NOAA Corps Officer LT Carl Noblitt explained to me this was actually where a glacier had once weathered down part of the mountain range over time. The glacier has since melted so now all that remains today is its glacial trough.
Animals Seen Today
Besides our unexpected visitor today in the trawl, I was thrilled to hear Chief Boatswain Ryan Harris call out from the scientific deck for Orcas on the horizon. Orcas (aka Killer Whales) have always been a dream of mine to see in the wild. They were pretty far away from the boat, but I was able to see the trademark black dorsal fin rising and sinking at the surface for a few minutes. Hoping to get a photo of one of these pods before our expedition ends.
Another fun organism I got to see in person today was a Lanternfish that was caught in one of our deeper bongo net surveys. Lanternfish are a deep-water fish that gets its name from its ability to produce light. The light is given off by tiny organs known as photophores. A chemical reaction inside the photophore gives off light in a chemical process known as bioluminescence.
Bathymetry is defined as “the study of the “beds” or “floors” of water bodies, including the ocean, rivers, streams, and lakes.”
The term “bathymetry”
originally referred to the ocean’s depth relative to sea level, although it has
come to mean “submarine topography,” or the depths and shapes of underwater
terrain. In the same way that
topographic maps represent the three-dimensional features of land, bathymetric
maps illustrate the land that lies underwater. Variations in sea-floor relief may be depicted
by color and contour lines called depth contours or isobaths. (Click
here for source credit and more information from NOAA)
A bathymetric map looks like this (thanks Sam!):
Above are the first views of this part of the seafloor with a bathymetric map! (Color coded for depth – see the chart on the left)
Science and Technology Log:
Among the NOAA officers Navigating the ship, Hydrographic Technicians, and wage mariners aboard Fairweather, and the Teacher at Sea, there are also two guest USGS scientists: James Conrad, a research Geologist and Perter Dartnell, a physical scientist. USGS stands for United States Geographical Survey. The USGS was created by an act of Congress in 1879 and is the sole science agency for the Department of the Interior.
As a Teacher at Sea, I had time to talk with these USGS scientists and learn more about Bathymetry and why it is important not only to scientists, but also how this information can be used to keep us safe.
Discussion with James Conrad research Geologist who is utilizing the science of Bathymetry among others to map the Cascadia Region of the Pacific seafloor. The USGS scientists’ focus is mapping the Cascadia Subduction Zone where the Juan de Fuca tectonic plate is “diving” below the North American tectonic plate. Areas of particular interest to these scientists are finding new faults, faults that are known but we have little information about, mud volcanoes and subsequent “seeps,” and the overall goal is to understand the behavior of the mega thrusts in the Cascadia Region.
the visiting scientists:
James Conrad has a bachelor’s degree from U.C. Berkley and a master’s degree from San Jose State and has been at the USGS for 38 years.
A conversation with Research Geologist James Conrad:
do you want students to know about Geology?
Geology is a field where
there is still so much to discover, especially if you are doing hazards research
work-like earthquakes, tsunamis, landslides, coastal change, and climate change
you always interested in geology?
Not as a child, but I became a geology major because I had taken an introductory course – and was guided to geology by the university.
met you on a ship-where do most of your work?
Office is in Santa Cruz, but we go out in the field 1-4 times a year for a week up to 3 weeks.
Geology is a very young
science, the fact that continents move wasn’t proven until 1963. There is very little known about the earth,
and there is so much more to discover.
Peter Dartnell has Bachelor of Science in Oceanography from Humboldt State University and a Masters of Geography from San Francisco State and has been with the USGS for 28 years.
A conversation with Physical Scientist Peter Dartnell:
does a physical scientist study?
Physical Science is a
combination of the studies earth and computer sciences using computers &
technology to study earth.
Physical Science allows you
to do everything along the scientific “study train” from data collection, interpretation,
are your publications used for?
Scientific publications from
the USGS (which is the science agency of the government) are used widely to
inform about potential geohazards and changes in the earth. We don’t make policy, but the information we
provide may be used drive policies, especially safety.
you want an aspiring physical scientist to know?
Even though you are studying
earth sciences in school, you’ll truly enjoy once you get out and start applying
what you’ve learned in the field with hands on science.
met on a ship, where is it you do most of your work?
I spend 75% of my time in the
office and 25% in meetings or traveling to study
is your favorite part of being a Physical Scientist?
Seeing part of the ocean that nobody has ever seen for the first time. We are the first ones to see these recently mapped parts of the sea floor.
types of technology you use in physical science?
We use specialized software to acquire data and analyze the data we collect.
We also use Multibeam sonar software – bathymetry and acoustic backscatter
do you think are some misconceptions about physical science?
Because we are working off shore and water covers 71% of the earth, marine geology is in its infancy — we really need to have a complete map of the sea floor which is vitally important to understand the geology of the earth. When we don’t have all of these details, we are essentially operating blind. That’s why the work that NOAA is doing is so important and the research partnerships with USGS are so valuable.
Much of the geography of the
seafloor is driven by the oil industry which is required to release their acquired
data every 25 years. A lot of the deep
penetration data is all from oil surveys. Sea floor mapping is limited for pure research
purposes due to limited resources.
Interested in learning more from
Check out these resources for students and teachers:
More about bathymetry and the NOAA and USGS mission:
I was lucky enough to attend a “Science Talk” by these USGS scientists which was titled the Subduction Zone Coastal & Marine Geohazards Project. The USGS scientists are guests aboard Fairweather like me.
The focus of the USGS research is along the 700-mile CascadiaSubduction Zone:
This area is where the Juan de Fuca plate dives below the North American Plate at an approximate rate of 1.6 inches per year.
Why is this subduction zone so important and why is NOAA Ship Fairweather out surveying the ocean floor in this area? That’s because the world’s largest and most destructive earthquakes occur along subduction zones. If we know the potential hazards, we can prepare people and potentially save lives.
To properly prepare, we need the following details:
This is why the bathymetric maps of the sea floor are important, they can help predict the area and amount of shaking that may occur during an earthquake and predict the tsunami danger zones. Then we can make decisions for building codes, infrastructure (like strength of bridges), and escape routes for Tsunamis. I took the pictures below when I arrived in Newport, little did I know how the research the Fairweather is conducting and the science of hydrography and bathymetric maps play a part in warnings like these! (See below)
Through the hydrographic surveying being conducted aboard Fairweather, the NOAA crew and USGS scientists are creating bathymetric maps which have reveled exciting new finds, such as: new seafloor faults, mapping known faults in greater detail, discovering mud volcanoes and submarine landslides, and using the water column data to discover the “seeps” which are most likely releasing methane gas. See below.
(Image Credits: USGS scientists Peter Dartnell and James Conrad)
When I first heard the term BATHYMETRY I had no idea how these detailed maps of the seafloor could hold so much critical information! It’s fascinating to watch this science happen right here and see the discoveries in real time.
This post begins the last week aboard Fairweather. I’m surprised about how quickly the ship has begun to feel “normal” to me. I know my way around backwards (aft) and forwards (bow) and enjoyed getting to know everyone better. Sean the IT specialist makes an amazing pot of French press coffee around 10:00 am and is kind enough to share with all. Bekah, Sam, Joe, and Michelle in Hydrography patiently answer dozens of questions and allow me to participate when possible. And the officers on the bridge answer all the questions and are very welcoming and generous with sharing information and their amazing views! Carrie and the kitchen crew make 3 amazing meals a day, and I’ve made some new workout buddies to try to stay healthy with all this wonderful food! The visiting scientists have been very nice about answering all my questions about bathymetry and geology. It’s great when you are writing and studying about geology to be able to turn around and ask a geologist a question!
I can’t believe how well I sleep on a ship! The ship is constantly rocking and for this teacher at sea, and for me, that means some seriously deep sleep. One thing I learned is to make sure all my belongings are secure before I go to bed. If you leave something unsecured, chances are they will be banging around in the middle of the night or get tossed off a shelf (not the best middle of the night surprise!). My room is very dark at night and I really don’t hear anything beyond the noise of the engines. You can barely hear the foghorn from my area towards the back of the ship which is lucky since those sleeping in the front of the ship could hear it all night! (Those friends look a little weary today.) I have to set an alarm, or I will just keep sleeping with the constant rocking motion that is so relaxing! Only 3 more nights of good ship sleep for me!
Following the excellent tutelage of the NOAA officers, hydrographers, and USGS scientists, it’s exciting to look at the screen in the hydrography lab and start a conversation about features of the sea floor that we are seeing (or seeing in detail) for the first time. On this mission, there have been new faults, mud volcanoes, and underwater canyons discovered. The science is so fascinating and so little is known about the research being conducted aboard Fairweather. I honestly had to “Google” the terms I am now so familiar with like Hydrographic survey, multi beam echo sounders, bathymetry, water column data, just to name a few.
That’s the thing about science that has been reinforced being a Teacher at Sea, no matter how much you think you know about the earth, you learn just how much we don’t know yet, and we’re just beginning to realize the vast amount that is left to discover.
Did You Know?
-The ocean covers 71% of the
earth’s surface, but we actually know more about the surface Mars than the Earth’s
ocean floor- (Credit-Peter Dartnell)
Juan de Fuca Plate is part of the famous Ring of Fire, a zone responsible for volcanic
activity, mountainous regions, and earthquake activity.
Question of the Day:
you know how many tectonic plates there are?
Did you know they are all constantly moving?
you name the Earth’s major tectonic plates?
Can you find on a map the Pacific and Juan de Fuca plates that we are surveying
Latitude: 57° 01.32 N Longitude: 155 ° 01.21 W Wind Speed: 14.56 knots Wind Direction: 334° Air Temperature: 15.5°C Sea Temperature: 15°C Barometric Pressure: 1017 mbar
Science and Technology Log
Today marks our sixth day at sea. We are headed north into the Shelikof Strait between the Alaska Peninsula and Kodiak Island. We are continuing along our survey stations with bongo nets and midwater trawls. A bongo net consists of two plankton nets mounted next to each other. These plankton nets are ring nets with a small mesh width and a long funnel shape. Both nets are enclosed by a cod-end that is used for collecting plankton. The bongo net is pulled horizontally through the water column by a research vessel.
We are using a combination of four total bongo nets simultaneously to sample plankton. Two of our nets are 60 cm in diameter and the other two are 20 cm in diameter respectively. Depending on the depth at each station, the nets are lowered until they reach a depth of ten meters above the sea floor. Scientists and NOAA crew on the scientific deck must constantly communicate with the bridge via radio during this survey to maintain consistent wire angles. Ideally, the goal is to maintain the winch wire angle at 45° so that the water flow into the nets is parallel to the ocean floor.
Plankton are plants and animals that float along in the oceans’ tides and currents. Their name comes from the Greek meaning “drifter” or “wanderer.” There are two types of plankton: tiny plants called phytoplankton, and weak-swimming animals called zooplankton. Oceanic plankton constitute the largest reservoir of biomass in the world’s oceans. They play a significant role in the transfer of energy within the oceanic ecosystems. Ongoing plankton monitoring data is essential for evaluating ecosystem health and for detecting changes in these ecosystems.
Once the nets are brought back onto the deck, we immediately rinse the nets so that all of the plankton collects in the cod-end (the plastic tube attachment at the bottom). We carefully remove the cod-end tubes and bring them into the wet lab for processing. Using sieve pans, we filter the cod-end sample (plankton) into glass jars. We add formaldehyde and sodium borate to each jar to preserve the plankton for future analysis and study. NOAA Chief Scientist Matt Wilson informed me that all of the sample jars we collect on this expedition will actually be sent to the Plankton Sorting and Identification Center in Szczecin, Poland. Check out their website for more info: https://mir.gdynia.pl/o-instytucie/zaklad-sortowania-i-oznaczania-planktonu/?lang=en .
At even numbered stations, NOAA scientists on board will conduct a RZA (rapid zooplankton assessment) of samples collected using a microscope. This rapid assessment of plankton yields current data that allows scientists to quickly evaluate present-day ecosystem health and changes while they await more in-depth sample results and analysis from Poland.
Everything is still going great on day six at sea. Seas are remaining relatively calm, which I am very thankful for. I am actually sleeping more than I do at home. I am averaging about nine to ten hours sleep at night which is amazing! Most mornings, I get up and head down to the gym to run on the treadmill for some much needed exercise. As I said in my second blog, our meals have been delicious. Chief Steward Judy leaves us out some late night treats to help us get through our long shifts. I thoroughly enjoyed some late night ice cream to help me power through the last trawl of the night. I really like lunch and dinner time on the ship because it brings everyone together for a few minutes to catch up and enjoy each other’s company. Most of the scientists and NOAA crew and officers have traveled all over the world on scientific vessels. It is fascinating to hear about all of their stories and adventures. I have already decided to add the ‘PolarTREC’ (Teachers and Researchers Exploring and Collaborating in Antarctica and/or the Artic) Program to my bucket list for a few years down the road. My most favorite organism that we have caught in the trawl so far was this Smooth Lumpsucker.
Me and my buddy Mister Lumpsucker – Photos by Lauren Rogers
Did You Know?
The answers to day three blog’s temperature readings were 62.6°F for air temperature and 59°F for sea temperature.
All jellyfish are such weak swimmers that they too are considered plankton. There is also some scientific debate as to whether or not the Ocean Sun Fish (aka Mola mola) is considered a type of plankton. The sun fish is a passive planktonic creature which can only move vertically in the water column since it lacks a back fin. They have a long dorsal and anal fin that help them maneuver clumsily up and down in the water column.
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)
Date: August 19, 2019
This video was captured during my NOAA Teacher at Sea cruise aboard NOAA Ship Pisces. During the cruise I spent lots of time outside on the deck gazing into the blue seascape. Here’s some of the footage I collected.
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)
Date: August 19, 2019
This video is a collection of fish trap camera footage recorded during my NOAA Teacher at Sea adventure aboard NOAA Ship Pisces. Very special thanks to the NOAA science team: Zeb Schobernd – chief scientist and especially Mike Bollinger and Brad Teer – camera and gear experts.
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
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.
On board Fairweather (actually underneath it) is the survey tool call a TRANSDUCER which sends out the sonar pulses.
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:
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!
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
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.)
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!
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:
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!