Tag: XBT

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Story Miller, August 1, 2010

NOAA Teacher at Sea: Story Miller
NOAA Ship: Oscar Dyson

Mission: Summer Pollock III
Geographical Area: Bering Sea
Date: August 1, 2010
Launching the XBT
Time: 1233 ADT
Latitude: 60°51N
Longitude:179°11W
Wind: 17 knots (approx. 19.6 mph or 31.5 km/h)
Direction: 171° (S)
Sea Temperature: 9.9°C (approx. 49.8°F)
Air Temperature: 12.8°C (approx. 55.0°F)
Barometric Pressure (mb): 1009
Wave Height 2-3 feet
Swell Height 4-6 feet

Scientific Log:
Think about your morning routine from the moment you wake up to just after eating breakfast. Now imagine spending that morning on a boat in the middle of the Bering Sea. Perhaps you take a shower or wash your face and hopefully brush your teeth. Where does the water come from? Where does the waste water go? I bet at some point you will use the bathroom (Hey, it’s a fact of life and everybody does it!). Where does that waste go? How is it processed? I also bet that at some point you turned on the light. How does a boat get its electricity?

The Oscar Dyson has a truly remarkable system that allows a crew of up to 39 live on the ship for as long as we have food and fuel! The fuel used is diesel and the diesel is converted into electricity through the engine, which turns the generator and the generator makes AC power. A rectifier ridge turns the AC power into DC power and the DC power runs to the shaft which is able to turn the propeller. However not all the power goes to DC power. The rest is turned into AC power so that we can use lights, heaters, fans, and the ovens in the galley.

Below the deck of the ship is where the engineers maintain all the components that make the ship function.

The Machines:

The main shaft (what turns the propeller on the ship)

Because we would not be able to go anywhere without fuel, let’s start with it. The fuel goes from the fuel tank to a primary filter and then through a secondary filter to clean the fuel. The fuel then travels to the fuel pump which transfers it to the injector and the injector sends it to the engine.

The centrifuges that clean the fuel.

Whatever fuel is not used is returned to a storage tank where it will wait until we need it again. Because fuel can become dirty when it sits, and dirty fuel is not good for engines,  the old fuel is run through a centrifuge (a device that spins and uses centrifugal force to separate mixtures) to become purified. As you can see in the picture, there are two centrifuges because it is important to have a backup in case of a breakdown. One is currently running for the month of July and the other will run for the month of August. We have this alternating pattern because we want to make sure there is even wear on each.

Access hatch to the waste oil storage.
Entering confined spaces are dangerous
as noted by the bolted entry. Special protective materials, a work plan, and
an initial safety test must be in place prior to entry

Periodically, the ship requires an oil change and the waste oil from machines such as the crank case, winches, and hydraulics are placed in a storage tank. Because it costs a considerable amount of money to haul waste fuel, the ship has a method for disposing it. From this waste oil storage tank, it is pumped up to the incinerator where it is burned.
The ship will also obtain oily water from locations such as the bilges and that water is recycled by going through the Oily Water System (OWS) and currently it is able to clean the water to 15ppm (parts per million) of oil to water. After the purification it is released into the ocean. We are currently in the process of installing another filtration system that will run the 15ppm concentration and reduce the contaminants to 5ppm and possibly even 3ppm. The oil that is extracted from the water is put into the waste oil storage tank for future incineration.

Engineering Control Room

As stated earlier, all the machinery, including the coffee maker, is maintained by the engineers. In the control room the engineers are able to monitor all functions of the ship. If needed, they could even take away the power from the bridge (where the NOAA Corps officers control the ship) and drive the ship from underneath! So, if you really want to be in control…

Sanitation: 
Some may wonder what we do with all of the garbage we collect on the ship. For example, where does all the uneaten food go? What about all the paper waste from used cups, napkins, and wrappers? In the mess hall, there are two garbage bins, one to scrape uneaten food and the other for paper. Because food is biodegradable, that bin is tossed overboard. The paper waste is sent to the incinerator to be burned. I am told that the incinerator gets hot enough that if a soup can was placed inside and incinerated, it would appear to look normal after the incineration, except once you touch it, it crumbles into dust!To get clean drinking water, we pump the salt water from the ocean into a desalination unit (a distiller). The distilled water is then sent to a 10,000 gallon holding tank. When water is needed, it is pressurized which, like in your house, sends it to the faucets, drinking fountains, and shower. Perhaps you have heard of the pens using UV light to purify water when you are camping. Well, right after the water is pressurized the boat has a large UV Pen to kill any additional microbes that might be inhabiting the water.

Marine Sanitation Device

From the toilet, the waste material is pulled down by a vacuum and travels through a pipe to the Marine Sanitation Device (MSD) tank. All the waste, including what we call “gray water” which basically is waste water from the shower and the sink, is agitated with an aroator. Solid waste will sink to the bottom of the tank where it is ground to fine particles. Oddly enough the grinder is also responsible for the vacuum in the sewage line via the eductor. The dirty water mixture is then sent through the chlorinator and is stored in the chlorination tank. When the water rises to a certain point, a sensor signals the pump to send the chlorinated water over the side of the boat.Cool fact! On other ships in the past, the catch water in the toilets was salt water (the Oscar Dyson uses fresh water). Because the water in the toilets did not need to be distilled, little bioluminescent organisms would sit inside. The thrilling activity is that when a person would flush the toilet in the dark, the organisms would become agitated and glow. Therefore, in your toilet, you could have your own light show with each flush!

Personal Log: 

Squid

Today we processed one batch of fish. The odd part to this scenario was that we caught a group of Pacific Herring. We measured, weighed, and extracted stomach samples as it is equally important to gather data about other fish we catch. The internal body structure of a Pacific Herring is very different from that of a Walleye Pollock and so I had the opportunity to dissect and study a different kind of fish. Leftover critters from the trawl that occurred last night while I was sleeping also appeared in the catch – tiny jellyfish, squid, and shrimp – and I spent some time sorting them out. Tonight, our chef is cooking up a few of the herring so we can see what they taste like. Another highlight to working with the herring is that I was challenged to locate and extract the otoliths. The otoliths of Pacific Herring are much smaller than those of the Walleye Pollock. To provide an idea, imagine clipping your pinky toenail. The clipping would be just a little larger than the otolith! Otoliths of pollock are a little less than one centimeter long and 1/2 of one centimeter wide.

Jellyfish

Today we crossed the 180° line of Longitude and entered the future, putting me a day ahead of the United States. Currently our transect has placed us near Cape Nevarin, Russia and unfortunately it is too foggy outside to see land. Because I have crossed the  dateline, I will receive the Order of the Golden Dragon, a certificate proving my adventure across the line!I am exceptionally excited for dinner tonight as we are having King Crab legs, prime rib, mashed potatoes and gravy, and of course, some herring! With Ray as our chef, it is evident that nobody goes hungry! Today he constructed a shortcake in the shape of the Oscar Dyson, decorated it, and set aside a bowl of strawberry sauce. I would have taken a picture but by the time I finished processing the herring, the cake ships were in fatal condition for sailing but I feel the crew are quite satisfied!

Animals Spotted Today:

Immature Gull

Humpback whales
Walleye Pollock
Pacific Herring
Shrimp
Squid
Jellyfish
Northern Fulmars
Black-legged Kittiwakes
Slaty-backed Gulls

Something to Ponder:
I decided that it was important to inquire what it took to be an engineer on the boat. After talking with a few members of the crew who had been doing this line of work for a long time, I was loaded with valuable insight to pass along to my readers.
According to the engineers, the best way to guarantee a well-paying job on a boat and allow one to have more options available would be to attend a maritime school because graduates will walk onboard with an officers ticket. While college is expensive, consider this: If you attend the US Merchant Marine Academy (USMMA), your college is paid for as it is one of the five US service academies. www.usmma.edu

However, because admission is difficult, if you were to attend a maritime academy, you could potentially have a situation similar to one of our engineers on board. He attended Maine Maritime Academy for four years and earned a Bachelors of Science in Engineering. Additionally, within six months of working onboard a ship with his credentials, he had ALL of his student loans paid for! Most college students in the US spend approximately five years paying off their student loans!

While a maritime academy would be ideal, I asked the engineers of other ways one could obtain an engineering/mechanic job on a ship. They shared that there were 2-year schools available but the largest drawback to that path is that upon graduation, you would have some skills but would not be fully licensed. One rule of thumb that I have learned over the years, and the engineers echoed this, is the key to having choices in your job is to become as versatile as possible.I then asked the engineers if there were any other ways to get a job on a boat and they mentioned that one could attend a union school and learn a trade such as in refrigeration or mechanics. Keep in mind though, that person would be unlicensed and not have as many choices available to them.

I also asked the engineers what subjects in school they thought were the most important to learn. The first subject mentioned was mathematics but they brought up a very important concept: “It’s not necessarily how much math you take, but how well you understand the math.” Think of a student who aces the test and then forgets everything afterward. In other words, it would be great if a student made it to Calculus in high school but if he or she doesn’t fully understand the processes behind the algebra, that student will have difficulty in his or her engineering occupation. The engineers also shared that trigonometry was essential.
Regarding the sciences, for engineering, it was highly recommended that students wanting to get off on the right foot should take chemistry, physics, and biology.

However, one of the most important subjects they mentioned that may surprise some readers is English Composition because “You must have the ability to express yourself effectively and communicate with the people you work with everyday.” The engineers shared that, for example, they often would have to write reports and if they needed a part, the engineers would need to write to a supervisor and provide reasons to prove why they would need a part. “The better you are at communicating, the farther you will be able to go with your job and get what you want.”

So, in closing, the next time you think, “Geeze, why do I need to learn this equation and how to use it in this silly word problem?” or, “Why do I need to write this paper about persuading my English teacher that peanut butter and jelly sandwiches are the best?” remember this: Your teachers really are not torturing you and really, are simply training you to develop the skills you will need to utilize in your job and in adulthood. The more advantage you take of this training, the more versatile and successful you will become. Ultimately though, it’s up to you to make that move!For more information a valuable website is:http://www.omao.noaa.gov/about.html

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Obed Fulcar, July 24, 2010

NOAA Teacher at Sea Obed Fulcar
NOAA Ship Oscar Dyson
July 27, 2010 – August 8, 2010

Mission:Summer Pollock survey III
Geograpical Area:Bering Sea, Alaska
Date: July 24, 2010

Science & Technology Log:
Thursday, July 22: After a night of swinging and swaying from the waves at high seas, I am somewhat used to it already. Today is the start of my new shift from 0400 in the morning until 4:00 pm in the afternoon, 12 hours on, 12 hours off. Since yesterday we left the continental shelf and we are heading to deeper waters. There was a scheduled trawl to be done early this morning, but the Acoustic Lab reported no fish at all on the screens. As part of the survey it is necessary to perform a CTD launch every morning at sunrise. CTD stands for Conductivity, Temperature, and Depth, explained Darin Jones, one of the young scientists in charge of the Pollock survey.
CTD
CTD
The CTD unit is made up of a series of bottles used to collect water samples at different depths, and also includes remote sensors to collect data such as sea temperature, salinity, depth, water pressure, and fluorescence. Fluorescence is the presence of Chlorophyll in the water which depends on the amount of sunlight that penetrates the ocean, indicating the presence of Phytoplankton (algae and other microscopic plants). They rely on sunlight to produce the energy that zooplankton growth is dependent upon. Zooplankton is the foundation of the Bering Sea food chain,since is made up of krill, small shrimp like crustaceans that are the primary source of food for commercial fish such as Pollock, Cod, Salmon, and pretty much any other fish in the North Pacific Ocean.
CTD
CTD
As the CTD is dropped the ship needs to stop in order lower the unit, which is attached by cables to an A-Frame crane, including one to transmit data. The CTD can only be used to depths of 600 meters, so another device called the XBT for Expendable Bathy-Thermograph (for depth and temperature) is used for depths up to 700 meters. It can also be launched manually while the ship is in motion, and data is transmitted through a thin copper wire that splits, hence the name “Expendable”. Once the CTD is hauled back onto deck, the water bottles are drained and samples taken for dissolved oxygen (DO)analysis. DO is sequestered using chemicals that react with the oxygen taking a solid form that preserves it for lab analysis.
XBT
XBT
Personal Log:
Last night I took motion sickness pills to keep me from getting seasick. After breakfast weather got really bad, with waves up to 6 feet, battering the Oscar Dyson. These conditions, combined with a heavy breakfast, made feel really dizzy, and next I know I was throwing up. My roommate, Vince Welton, who is also the ship’s tech guy, got me some very tasty saltine crackers, and medication, that help me feel better. I laid down on my bunk bed and doze off while listening to some Jazz by Michel Camilo.
While trying to rest the waves were crashing into the hull of the ship with a loud noise, while the ship kept going up and down. I was thinking about how seafarers of the past and the conditions aboard were so much different than today. Ocean going trips now are made much easier by the technology and modern amenities commonly found on board. Staterooms with bath, galleys or kitchens fully equipped with fridge, microwave oven, and entertainment rooms with flat TVs and DVD players are the norm. I kept thinking that the next 2 weeks on board the Oscar Dyson will be a lot like space travel, will all the walking up and down stairs from deck to deck, closing of hatches, and not been able to step outside the ship for a walk until reaching port.
The connection I can make about the CTD is that it reminds me a lot of the citizen science data collection and water quality monitoring I conduct with my students after school on the Harlem River, as part of “A Day in the Life of the Hudson River” a yearly event sponsored by NYSDEC (NY State Dept of environmental Conservation) and Columbia University Lamont-Doherty Laboratory. just like in the CTD we collect samples of water from the river to test for Dissolved Oxygen, Chlorophyll, PH, Salinity, Nitrates, plus soil samples from the mudflats.
When we collect the chlorophyll samples we use the same methods just as it’s done on the Oscar Dyson, squirting the water through a circular paper filter until it turns brownish. I am planning a lesson for next school year called “NOAA in the Classroom:Student CTD Activity” where using a student water sampling bottle my Environmental Science Club class will collect water from the Harlem River at different depths with the help of our wooden boat “Boca Chica” built after school. We test the samples for DO, Salinity, PH and other protocols using a LaMotte water quality test kit to monitor the health of the Harlem/Hudson River Estuary. This data will be reported to the GLOBE.gov Program website to be used by scientists and schools all over the world. My middle schoolMS319 is a GLOBE Program partner school, and also we will be reporting data from our new Wireless Weather Station. I strongly believe that students learn science by doing science!
Boca Chica
Boca Chica
“Navegando en Alta Mar”
Jueves, 22 de Julio: Hoy comence my primera guardia de las 0400 am a las 4pm. Desde que zarpamos del puerto de Dutch Harbor hacia aguas profundas me habia librado del mareo, pero finalmente me agarro.
El mal tiempo de hoy temprano, con violetas olas que golpeaban la nave de hasta 18 metros, mas un desayuno muy pesado me provocaron unas nauseas que termine en mi camarote vomitando y tirado en la cama. Despues de tomarme una medicina y de comerme unas galletitas de soda, me tome una siesta y me levante mucho mejor. El Sonar Acustico de la nave no detecto presencia de peces por lo que fui a ver el lanzamiento de un CTD o unidad de Conductividad y Profundidad Termal. El CTD contiene botellas para recoger muestras de agua y sensores para medir la temperatura y salinidad del mar hasta 600 metros.
Para medidas mas profundas de hasta 700 metros se usa una unidad manual desechable llamada XBT. Ambas unidades son usadas para obtener datos cientificos como el nivel de Oxygeno disuelto, Salinidad, Profundidad, y Florescencia (nivel de clorofila), la ultima es muy importante pues refleja la abundancia de algas microscopicas de las que depende elZooplankton. El zooplankton esta compuesto de minusculos crustaceos que son la base del ecosistema alimenticio del Estrecho de Bering, del cual dependen especies comerciales como el Bacallao, Salmon y Arenque, asi como casi toda especie de pez en el Oceano Pacifico Norte. El uso del CTD es muy parecido al trabajo que hago con mis estudiantes analizando las aguas del Rio Harlem. Estos jovenes cientificos tambien toman muestras de agua y practican analisis de campo para Oxygeno disuelto, PH, Nitratos, Salinidad e incluso pruebas de Clorofila, como parte de un evento anual llamado “Un dia en la Vida del Rio Hudson” .
En este evento organizado por el Laboratotio Lamont-Doherty de la Universidad Columbia, y el Depto de Conservacion del Estado de NY, participan escuelas a todo lo largo del Rio Hudson, recaudando datos cientificos sobre el rio. Pensamos usar a “BOCA CHICA”,un bote de madera que armamos de tarde, para una practica de CTD tomando muestras de agua del rio, analizarlas, y reportar los datos en el internet. Tambien mis estudiantes de la Escuela Intermedia Maria Teresa Mirabal Ms319, de origen dominicano en su mayoria, aprenden ciencia ambiental al tomar datos de la Estacion Metereologica ubicada en el techo de la escuela. Ellos reportan los datos via internet en la pagina web del Programa GLOBE.gov, para ser usados por cientificos y estudiantes por todo el mundo.
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Michele Brustolon, July 1, 2010

NOAA Teacher at Sea
Michele Brustolon
Onboard NOAA Oscar Dyson
June 28 – July, 2010

NOAA Teacher at Sea: Michele
NOAA Ship Oscar Dyson
Mission: Pollock Survey
Geographical area of cruise: Eastern Bering Sea (Dutch Harbor)
Date: July 1, 2010

Weather Data from the Bridge

Time: 1400
Latitude: 58.19 N
Longitude: 170.01 W
Cloud Cover: 100%, dense fog
Wind: 11.49 knots
Air Temperature: 3.800 C/ 38.840 F
Water Temperature: 3.960 C/ 39.1280 F
Barometric Pressure: 1003.10 mb

Science and Technology Log

Here fishy fishy!
July 1st began by spending time in the Acoustics Lab learning about the equipment used to analyze the data. The Oscar Dyson has 5 transducers on its center board and 1 temporary transducer on the side of the center board that looks horizontally. The transducers allow us to see where the fish are. Because of where the transducers are placed, we can only see the pollock from 16m to the bottom. This means that if there are any fish between the surface and 16m they will not be detected. This is the near surface “dead zone”. Why this happens? The transducers are mounted on the bottom of the centerboard about 9 m below the water line, and near the transducer face (first 7 m), no good data are collected. Why it’s okay? Pollock tend to hang out in mid-water. Although a few baby pollock might be in the near surface “dead zone,” the majority of pollock will be in the area we are watching. There is also a bit of a “dead zone” at the other end near the ocean floor. Yesterday the bottom was around 69.35m.

Transducer data

Why acoustics?
Ideally, the acoustic data collection would allow us to track aggregations of pollock without actually having to fish them out of the water. All parties involved (scientists, fish, bank accounts) would benefit from this change but scientists are still in the process of perfecting this process. The Oscar Dyson is part of a fleet of five boats that was specifically designed for acoustics. Specifically, it is considered a “quiet boat” where the engine noise is decreased to prevent scaring the fish. Other Acoustic projects include: Pacific hake off the coast from California to Vancouver Island (run as a joint project with Canada), herring in the northwest Atlantic, and krill in the Antarctic. Acoustics are used throughout the globe and many countries depend on acoustics for their fish surveys.

A little help from UNH!
Along with the transducers, there is also a multibeam SONAR that produces the same information as the transducers but with a wider angle range. The multibeam ME70 sends its signal out after the transducers information is sent and returned. They alternate about 1.5 seconds apart. The University of New Hampshire (UNH) is helping to use the tool and also to analyze the data. To analyze the transducer data collected, a program is in place from Tasmania to help determine what the boat is seeing. The scientists use the program to help separate species in the water column. Scientists utilize the multibeam ME 70 along with the transducers and fish trawling to ensure they are capturing an accurate picture of the mid-waters.

Multibeam ME70 data

How the survey data we collect are used. The data we collect on the Oscar Dyson during the summer pollock surveys are used by scientists and policy makers to determine the fishing quota (the “take”) of pollock for the next season. Quotas are important for maintaining the population of pollock (and other species) for this generation and generations to come. The data we collect on the Oscar Dyson help ensure that maximum stock can be taken without negatively impacting the Eastern Bering Sea pollock population.

Here I am deploying the XBT (eXpendable bathymetric thermograph)

Personal Log

Although there was no fishing yesterday, I certainly was able to be involved. I launched the XBT off the Hero Deck just as we began our fire drill. Once that was completed I returned to the Acoustics Lab until we were cleared from the drill. We then had our abandon ship drill where we get our survival suits and head to our assigned position. My meeting location is at life raft 3 and 4. Once we learned how to deploy our life raft, we headed inside to the conference/lounge to practice donning our suits. While this is very serious, it is also worth a laugh or two watching people struggle and become orange gumbies! The goal is to be able to don your suit in under 60 seconds!

Zodiac ride into the cove of St. Paul’s Island

Yesterday I had the opportunity to head into St. Paul’s Island; the largest of the Pribilof Islands. St. Paul’s is also called the Galápagos of the north. The Zodiac was driven by Joel Kellogg and Amber Payne, and our CO (Commanding Officer Mike Hoshlyk) allowed Katie, Rebecca, and I the opportunity to take the trip inland. Our mission while on land was to bring science equipment (ice-flow detector) to the airport that needed to be sent to Anchorage. Stepping foot onto St. Paul’s Island seemed eerie and mysterious. There was the lurking fog along with a very industrial feel to the island. Because most of the island consists of coalescing small volcanoes, the sediment’s dark color is due to lava flow which didn’t brighten the land at all. We did not see many people other than those working on dredging the new causeway or the people in the airport. Our taxi driver said that they hadn’t gotten mail since Monday and it was Thursday which explained why the people waiting for flights at the airport seemed a bit anxious. On our way back to the boat, we were able to see sea lions and some puffins hanging out in the water and around the break wall. As we approached the boat, it was like an apparition appearing before us. Just another once in a lifetime chance that I have had this cruise!

Want more information about the Pribilofs? Check out http://www.amiq.org/aleuts.html

Oscar Dyson coming back from Pribilofs

Animals Seen

Auklets
Murre (2 different types differentiated by bill type)
Fox
Puffins
Sea lions

(but no fur seals…everyone told me I would see them but they were missing. It seems to be a question everyone is asking.)

Word of the day

Desmadre: troublemaker

New Vocabulary

Transducer: instrument used to send out signals that return and show where fish are located
Ground fishing: trawling on the ocean floor

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Rebecca Kimport, JUNE 30, 2010 part2

NOAA Teacher at Sea Rebecca Kimport
NOAA Ship Oscar Dyson
June 30, 2010 – July 19, 2010

Mission: Summer Pollock survey
Geograpical Area:Bering Sea, Alaska
Date: June 30,  2010

What’s in your water?

Now that we are at sea, I work a shift each day (as do all members of the crew and science team). I began my shift this morning at 0400 and reported to the Acoustics Lab to meet with chief scientist, Neal Williamson. In addition to Neal, my shift includes Abigail McCarthy, NOAA research fisheries biologist, Katie Wurtzell, awesome biologist and my fellow TAS, Michele Brustolon.We began the shift by observing our first CTD (Conductivity Temperature Depth) profiler which will be deployed at least 10 times throughout our trip. The CTD measures conductivity, temperature, and depth (used to calculate salinity) and gathers samples to measure dissolved oxygen. In other words, it measures many of the physical properties of the seawater mixture in a specific column of water. In addition, fluorescence is measured to monitor chlorophyll up to a 100 m from the surface.How it works: The CTD is lowered down to the ocean floor, collecting data on the way down. Then, on the way back up, the survey tech stops the CTD at specific depths to collect water for the samples. Upon its return, the water is collected and treated for future analysis.

Here is our CTD sensor before its launch

After our first CTD, we completed our first Methot trawl. A Methot trawl is named after the scientist who designed the net used. Here is a picture of the methot getting hauled back on deck (please note, it does actually get dark here. I woke up in the dead of night and had to wait two hours for sunrise. Sunrise is at the “normal” time of 6:30 am and I think that’s because we are on the western edge of the time zone)

Here Comes the Methot

A Methot net grabs the creatures and collects them into a codend (to make it easier for us to process) at 30-40 m below the surface – our Methot collected jellies and euphausiids (also known as krill). My first duty was to sort through the “catch” to pick out jellies. Next, we measured the weight of the krill before counting a small sample. We also preserved a couple samples for use in larger studies.

Launching the XBT

Following our Methot, I assisted with the completion of an XBT (eXpenable Bathymetric Thermograph). At left, you will see that I actually “launched” the XBT overboard. The XBT is used to collect quick temperature data from the surface to the sea floor. The data are graphed at depth vs. temperature to highlight the thermocline, that is where colder water meets water warmed by the sun. Here in the Bering Sea, the thermocline is not always noticeable as the water column is subject to mixing from heavy winds and shallow depths.

Lucky for us, it was a calm day on the water and we were able to see a distinct thermocline:

The thermocline
I think the CTDs and XBTs are really cool because they are pretty routine. Both processes are conducted all over the globe at consistent locations year after year. As you can see from the chart below, the CTDs and XBTs are marked out for the area the Oscar Dyson covers throughout the summer. (As I mentioned in my blog description, theOscar Dyson must travel the same route year after year for the pollock survey to ensure consistency in data collection).

XBT CTD locations

Beyond the Oscar Dyson, these data are collected on every NOAA cruise that I read about and that data can be used to measure how a body of water is doing in general as well as how the water column of a specific location has changed over time. For example, longitudinal data are needed to note climate change within the Bering Sea. Pretty cool huh?

Vocabulary Note: I tried to define all the new terms I used in my entry. Did you notice a term I didn’t define? Ask me about it in the comments and I will make sure to provide you with a definition.

Thought Question: In the XBT data graph, why is the X axis labeled on the top rather than the bottom? (think about your coordinate plane)

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Richard Chewning, June 13, 2010

NOAA Teacher at Sea
Richard Chewning
Onboard NOAA Ship Oscar Dyson
June 4 – 24, 2010

NOAA Ship Oscar Dyson
Mission: Pollock Survey
Geographical area of cruise: Gulf of Alaska (Kodiak) to eastern Bering Sea (Dutch Harbor)
Date: June 13, 2010

Weather Data from the Bridge

Position: Eastern Bering Sea
Time: 1530
Latitude: N 56 15.380
Longitude: W 164 14.010
Cloud Cover: Overcast with light spray
Wind: 30 knots
Temperature: 5.4 C
Barometric Pressure: 1002.7 mbar

Science and Technology Log

Around 0940 Thursday morning we began our first summer 2010 pollock survey transect. Researchers have been conducting acoustic pollock trawl surveys since 1979 and bottom trawl surveys since the1950’s. The 31 transects in this year’s survey run roughly north south and progress from the eastern Bering Sea across to Russian waters in the western Bering Sea. The transect lines range in length from 60 to 270 nautical miles and are spaced 20 nautical miles apart. A nautical mile is slightly longer than a standard mile and is useful for navigating charts (maps used at sea). Only surveying during daylight hours, the Dyson will continue to run these transects till the beginning of August. A transect is a path (usually a straight line) during which the number of occurrences of an observable fact are counted (such as the abundance of pollock).

The beginning transect was marked by the launching of an expendable bathythermograph (XBT) probe. While the name might seem long and somewhat complicated sounding at first, the instrument and data being recorded are actually quite straightforward. Expendable refers to the fact that the probe is not recovered after being deployed. How is the data sent back to the Dyson you ask? Two long thin copper wires uncoil from the launcher and probe allowing data transfer back to the Dyson. The wires are broken by hand once the probe has reached the bottom. The rest of the story is revealed by subdividing the word ‘bathythermograph’ and defining its parts. ‘Bathy’ is a prefix that means deep or at depth. ‘Thermo’ is another prefix that refers to heat or temperature. Finally the word ‘graph’ means to draw a relationship between multiple variables (such as depth of the water and temperature). So an expendable bathythermograph is a disposable probe that profiles the temperature from the surface to the sea floor.

XBT probe and launcher

The XBT is a very helpful tool that enables the scientists onboard the Dyson to gather temperature data while on the move. Being able to capture this data without slowing down and stopping is a big time saver. Bringing a ship to a stop on the water takes much more time than stopping a car on the highway, and deploying a reusable instrument to the bottom and back takes even more time, manpower, and resources. Temperature data allows fish biologists to better understand how water temperature and the abundance of pollock and their food supply are related.

Darin deploying XBT

Later that afternoon, we also performed our first Tucker trawl. The Tucker trawl is a cleverly designed system of three nets that allows for three discrete (separate) samples during a single deployment. The Tucker trawl is designed to catch the zooplankton (animal-like plankton) that pollock eat such as euphausiids. This net allows researchers to study the differences of zooplankton distribution at various layers in the water.

Deploying the Tucker trawl
Tucker trawl messenger

To catch these small organisms, the net needs to a have very small openings. In fact, the openings in the net are only half a millimeter in width or roughly 1/3 the thickness of a dime! The three nets are attached to a metal frame mounted on metal skis that resembles a backwards dog sled. These skis allow the sled to slide along the seafloor and avoid snagging any obstructions. The Tucker trawl is initially deployed with one net open. The first net is closed and the next net is opened using a heavy brass messenger sent down the wire connecting the Tucker trawl to the Dyson. The messenger is attached to the wire cable at the surface and allowed to slide down the cable to the net being towed in the water. The impact of the messenger triggers a spring in a latch that closes one net and opens another net. The second net is closed and the third net is opened in the same fashion. Samples are taken at the surface, at the bottom, and evenly from the seafloor all the way to the surface. Attached to the sled are sensors to record temperature and depth, the flow of water passing through the net, and the time the net spends on the bottom. The catch is collected at the end of the net in a removable cod end jar. Any jellyfish are removed from the catch, identified, and measured. The remaining zooplankton is weighed, and a small subsample is saved and preserved for later identification.

Richard sending messenger down to the Tucker trawl
Euphausiid
Hyperiid amphipod

Personal Log

At sea, a person can easily lose track of time and even forget the day of the week as work aboard the Oscar Dyson continues uninterrupted seven days a week. I was reminded that today was Saturday by a special meal served by the galley. Rick and Floyd prepared a delicious dinner of real Alaskan king crab, prime rib, baked potatoes, vegetables, and fresh baked bread. This was a real treat (along with the cookies and cream ice cream, always a fan favorite) for the crew. There was plenty to go around, and all were well satisfied.

This was actually not my first encounter with king crab on this cruise. The day before, we had the unprecedented surprise of catching a red king crab with the Tucker trawl during the bottom net deployment. To the best of the knowledge of all the scientists onboard, this had never happened before. You might remember that the Tucker trawl is designed to catch zooplankton, which are typically small in size. This unlucky crab was so large she didn’t even fit in the cod end collection jar at the end of the net. In the end the crab was lucky as we opted to release her after recording her weight and species as we already had enough crab in the freezer for dinner the following night!

Richard holding red king crab
Dinner! Lucky for her, the crab Richard’s holding was released back to the sea!

Leisure Activities

Time spent not working onboard the Dyson can be considered among a person’s most precious possessions. Working long hours, the NOAA Corps officers, visiting scientists, and crew aboard the Dyson usually only have a few hours of time before starting their next scheduled watch or shift. Sleeping is often the first order of business on a person’s to do list. Whether you take only a short nap or can sleep for several blissful hours, time in one’s rack (bed) is essential for a productive, happy, and safe crew. Often one’s sleep schedule will necessitate missing a meal but the rest gained seems well worth the trade off. A very nice service offered by the galley is making and setting aside a plate for those crew members missing a meal if requested.

Other down time activities include reading, listening to music, and working out. The Dyson also has an impressive movie collection (including many recent titles not yet released on DVD) that is administered by the Department of the Navy. New titles are added monthly. The Dyson has a very comfortable lounge for watching movies that also includes a wide selection of magazines and books. Keeping connected with the outside world is also very important while at sea. With relative reliability, people can access the internet to answer emails, pay bills online, and surf the web for news and can call friends and family back home using the satellite phone.