Tag: thermocline

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Tammy Orilio, A Little Bit of Science…, June 18, 2011

NOAA Teacher at Sea: Tammy Orilio
NOAA Ship Oscar Dyson
Mission: Pollock Survey
Geographical Area of Cruise: Gulf of Alaska
Date: 18 June 2011

Weather Data from the Bridge:
Latitude: 52.34 N
Longitude: -167.51 W
Wind Speed: 7.25 knots
Surface Water Temp: 6.6 degrees C (~43.9 degrees F)
Water Depth: 63.53 m
Air Temp: 7.1 degrees C (~44.8 degrees F)
Relative Humidity: 101% (it’s very cloudy/foggy, but not raining)


Science & Technology Log:

The XBT Launcher mechanism.
The XBT Launcher mechanism.

Today I used the Expendable Bathythermograph (XBT) a few times. The WHAT??   The expendable part means we use it once and don’t recover it.  Let’s break down the second part into the two main roots:  bathy– which refers to depth, and thermo– which refers to temperature.  This probe measures the temperature and depth of the water when it is dropped over the starboard (right) side of the ship.

“Dropping” isn’t exactly the correct phrase- we use a launcher that kind of resembles a gun.  The probe sits inside of the black tube, and after we uncap the end of the tube, we basically fling our arm out over the side of the ship to launch the probe into the water.  I can’t show you any pics of the probe, because if we take it out of the black tube, it’ll start recording data.  The probe is connected to a length of copper wire, which runs continuously as the probe falls through the water column, collecting data.  It’s important to launch the probe as far away from the ship as possible, because if the copper wire touches the metal on the ship, the data feed will be disrupted and we’d have to launch another probe.  Big waste of money and equipment! One of the survey technicians decides to cut the wire (or tells me to) when they’ve decided that a sufficient amount of data has been collected, and we can then look at a graph to see the relationship between temperature and depth.
The XBT is a quick and easy method of data collection, and can be run while the ship is in motion.  The ship does have another piece of equipment- the Conductivity, Temperature, and Depth meter (CTD)- to collect the same data, but the CTD is very big and bulky, and the ship must be stopped in order to deploy the CTD.  The CTD can also measure parameters such as dissolved oxygen concentration, current velocity, and other things (depending on the additional equipment on the meter).  The main advantage the XBT has is that it is quick and can be deployed as the ship is sailing.

from www.windows2universe.org
from http://www.windows2universe.org

Data Collected from an XBT probe today:
Latitude: 53.20 N
Longitude: -167.46 W
Water Temp at Surface: 6.7 degrees C
Water Temp at Bottom: 5.1 degrees C
Thermocline located from 0-25 meters depth

What is a thermocline, you ask?  Root word time!  We’ve already gone over thermo, and cline refers to a gradient, or where things change rapidly.  So, the thermocline is the area where you see the greatest change in temperature.  See the diagram as an example (it’s not our actual data).  Beneath the thermocline, the water temperature remains relatively constant.
Personal log:

Launching the XBT in full safety gear (minus the hardhat, it fell off)
Launching the XBT in full safety gear (minus the hardhat, it fell off)
Safety first, my friends.
Safety first, my friends.

Yesterday, as we were finally on our first transect of many, we needed to use the XBT to collect temperature and depth data.  A couple of the scientists told me that I could do it- yay, something for me to do!!  So I go to the lab room and see a ton of safety gear out- heavy coat, hardhat, gloves, soundproof earmuffs, goggles.  The survey tech tells me that I have to use all that protective gear because the XBT launcher is just like a gun- have I shot a gun before?  No!  So this is interesting.  I don the gear, and he explains what I need to do…which doesn’t seem that dangerous.  So now here I am, all geared up, and the rest of the scientists come trickling in to the lab to watch me.  That should’ve been a red light right there.  Why would they want to watch me do something so simple?  Turns out that it’s something that all the new people on the boat go through- we get all hyped up about shooting a loud gun, get loaded with gear, and then…not much.  So I basically got all dressed up in my protective gear for no other reason than the entertainment of the crew!!


QUESTION OF THE DAY:
Why is it important to know the temperature and/or depth of the water that we’re trawling in?

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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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Michele Brustolon, June 30th, 2010

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

NOAA Ship Oscar Dyson
Mission: Pollock Survey  
Geographical area of cruise: Eastern Bering Sea (Dutch Harbor)  
Date: June 30th, 2010  

Weather Data from the Bridge

Time: 1600 hrs
Latitude: 57.16 N
Longitude: 169.09 W
Cloud Cover: Dense fog
Wind: 11.56 knots
Air Temperature: 5.30  C/ 420 F
Water Temperature: 5.090 C/ 410 F
Barometric Pressure: 1005.02 mb

Science and Technology Log

Time with Birds and Mammals
Once we finally left Dutch Harbor behind, I spent some time on the bow with birder, Nate Jones.

As I know very little about birds, I quizzed him on every flying specimen we encountered and used his binoculars to observe the birds up close. After a few sightings, I was able to identify the Fulmar by its unique wing movement (quick quick quick soar). We also saw tufted puffins and a black footed albatross. There are two birders on this leg who are responsible for scanning the horizon and counting and identifying the sea birds they observe from the bridge.  We were distracted from our bird watching by a call of orcas. I hustled up to the “flying bridge” to join the marine mammal observers. There are three “mammals” on this leg and they are constantly scanning the horizon with their “big eyes” to observe and identify cetaceans. I was able to observe two separate groups of orcas and heard that porpoises were also spotted.

Although I am technically on the fish shift, I hope to check in with the “birds” and “mammals” later in the cruise.

What’s in your water?
I began my shift this morning at 0400 and reported to the Acoustics Lab to meet with head scientist, Neal Williamson. In addition to Neal, my shift includes Abby McCarthy, a NOAA research fisheries biologist, Katie Wurtzell, awesome biologist and my fellow TAS Rebecca. We began the shift by observing our first CTD (Conductivity Temperature Depth)  profiler which will be deployed approximately 10 times throughout our trip. The CTD measures conductivity, temperature, and depth (used to calculate salinity) and gathers samples to measure dissolved oxygen. In addition, fluorescence is measured to monitor chlorophyll up to a 100 m from the surface.

The CTD – measures Conductivity, Temperature, and Depth

After our first CTD, we completed our first Methot trawl. A Methot trawl is named after the scientist who designed the net used. A Methot 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.

Following our Methot, I observed the deployment of an XBT (eXpenable Bathymetric Thermograph). The XBT is used to measure quick temperature data from the surface to the sea floor. The data are graphed at depth vs. temperature to highlight the thermocline, which 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.

Methot – graphing temperature vs. depth – shift in graph shows thermocline.

Personal Log

As I approached Dutch Harbor, I began taking photos from the plane. It sounds crazy, but the landscape is like nothing I have ever seen. Once I was off the plane, my smile grew because of the crisp air and the smell of saltwater. After two days of travel I had finally made it to Dutch Harbor and my luggage made it with me! I was brought to the boat to drop off my bags and then into town to catch up with others on Leg 2. The Oscar Dyson was having work done on its large generator so we didn’t leave port until June 29 at 1430 hours. It actually gave me time to get to know a good portion of the people on this leg (the crew, scientists, “birders,” mammalian observers, and the stewards). I was also able to explore Dutch Harbor, Unalaska (we tried to find wild horses…no luck!), and take some walks from the Oscar Dyson. Some of the most common flowers and birds seen are the lupines, orchids, and bald eagles EVERYWHERE! They are incredibly loud too! They remind me of seagulls and squirrels back home because there are so many! Wednesday, June 30 was the first day of our 0400- 1600 work shift so we won’t see everyone until we are transiting back because of the different shifts. The Oscar Dyson has 40 bunks and we are occupying 39 of them-talk about a full ship! For information about what happens during our shift, take a look in the science and technology log. I am truly enjoying my time and there are plenty of people to make me laugh which is the best medicine when you are a tyro!

Dutch Harbor at low tide from the dock of
the Oscar Dyson
Dutch Harbor during a typical day

Animals Seen in Dutch Harbor

Bald eagles
Ground Squirrel
Sea Urchin
Sea Stars
Sea Cucumber
Pigeon Guillemont
Oyster Catchers
Mussels
Chiton
Limpets
Hermit Crabs
Snails
(but no horses…)

A Bald Eagle named “Charlie” sitting outside the Unisea Restaurant

Animals Seen in Transit

Orcas
Fulmars
Black Footed Albatross
Tufted Puffin

Animals Seen on First Shift

Euphausiids
Jellies
Pollock!!!
Pacific Cod

Word of the Day

Tyro: a novice or beginner

New Vocabulary:

CTD: (Conductivity Temperature Depth) A device used to measure conductivity, temperature and depth at specific locations within the Bering Sea

Methot: A net used for shallow trawls, named after the scientist

XBT: eXpendable Bathymetric Thermograph

Thermocline: the point when the temperature drops

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Scott Sperber, July 11-12, 2009

NOAA Teacher at Sea
Scott Sperber
Onboard Research Vessel Kilo Moana
July 9-17, 2009 

Mission:Woods Hole Oceanographic Institution Hawaii Ocean Time series Station; Albert J. Plueddemann, Chief Scientist
Geographical area of cruise: Central Pacific, north of O’ahu
Date: July 11-12, 2009

Weather Data from the Bridge 
Temperature: 24.2 C

Bringing in the SEABIRD CTD
Bringing in the SEABIRD CTD

Science and Technology Log 

Compared to yesterday today is a very slow scientific day.  After releasing the WHOTS buoy, things really calmed down.  Let me take this opportunity to tell you a bit about some of the instrumentation on the buoy itself.  The overall goal of the project is to collect data about the ocean and atmosphere over a long period of time.  These data will serve to help answer questions about such things as global warming and its impact in the tropics. On the buoy itself, pictured in a previous log, there are instruments that measure temperature, humidity, solar radiation, wind direction and speed. A GPS unit keeps track of the buoy’s location at all times. On the buoy there is also an antenna which transmits data to satellites. Each of the two buoys [explain why there are two in the ocean for this 4-day comparison period] in the water has enough slack in the lines to allow for an approximate 2-mile radius circle.

Profile of CTD on shallow casts
Profile of CTD on shallow casts

The weather balloon launching continues every four hours with teams of two or three taking each launch in shifts. Some CTD casts have been done with the small package SEABIRD CTD.  This is set over the side, lowered down by crane and yo-yoed up and down for about four hours.  During this time, data are sent directly to an onboard computer and collected by the scientists. These data include temperature and salinity. This is important information to assess changes going on in the crucial air/sea interface.

These particular locations, ones where temperature and salinity difference vary worldwide, the thermocline and halocline are dependent on variables such a currents and air temperature.  On the final assent collection bottles are closed to collect water samples for further analysis. With all of this sophisticated instrumentation onboard surface water temperature samples are still taken with the old fashioned method of lowering thermometers into the water several times to take an average reading. Some things never change. The information collected by both the oceanographic crew as well as the meteorological crew aboard is truly showing the links, the association between the interaction of the air and sky, in the crucial air/sea interface.

I found out today that the temperatures on the two thermometers on the WHOTS-6 buoy are not matching. They are off by about 0.4 degrees C; that is the level of precision necessary for this research.  The scientists are looking into which one is closest to the temperatures read on the ship before we move off to the old buoy’s location tomorrow. Apparently, this is not something that can be reconfigured so the scientists need to know which thermometer they can rely on for information. There are two of just about every instrument on the WHOTS buoys. This serves as a backup and a comparison for the same location and enables the greatest accuracy in the data.

Profile of weather balloon sonde
Profile of weather balloon sonde

Personal Log 

I’d like to share a bit more about my onboard life. I have gotten acclimated finding my way around the ship (sort of). Well, at least I don’t get lost going to the mess hall anymore.  I am in a berth on an upper bunk with Jeffrey Snyder, one of the primary researchers from the University of Hawaii. The berth is quite comfortable as berths can go since it has been years since I was in a bunk bed. Various alarm clocks go off at anytime at night so the crew can go on their watch.  There is even a ghost alarm that goes off at 01:15 that Jeff and I cannot locate.  Food is not at a shortage. It seems that every time you turn around it is time to eat, and what great food it is too.  There is fresh salad lunch and dinner, fresh fruit, at least 3 entries to choose from each mea and desserts. LA Fitness here I come. I received what I consider a gift today from Fernando Santiago, one of the principle scientists, a DVD of the procedures that are used on the Hawaii Ocean Time-series Project.

July 12, 2009 

Had some down time today after setting off another weather balloon and a great fruit and yogurt breakfast. Took a 7 mile bike ride. You may ask where in the middle of the ocean you can take a 7 mile bike ride.  They have a nice little fitness room on board.

Words of the day: Mahimahi, calibration, dissolved oxygen, interface, thermocline, conductivity, temperature, depth.

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Rachel Dane, May 2, 2005

NOAA Teacher at Sea
Rachel Dane
Onboard NOAA Ship Ka’imimoana
April 29 – May 10, 2005

Mission: Oceanographic Survey
Geographical Area: Puerto Ayora, Isla Santa Cruz, Galapagos
Date: May 2, 2005

Science and Technology Log

Today is the big day—my first day at sea! I am excited and nervous at the same time; with no experience sailing my main hope is that sea legs will develop quickly for me!  As Academy Bay receded behind us I was a bit wistful at having to leave the Galapagos with so much left unexplored, but I am phenomenally happy to have had the experience to travel here and truly hope to return someday.

Much of my afternoon was spent picking the brain of Patrick Rafter, our Ph.D. student from the Scripps Institution of Oceanography. Patrick boarded the KA in San Diego at the start of this cruise, and is amazingly knowledgeable about marine chemistry.  He is also super patient with all of my questions, and very fun to chat with! You rock, Patrick! I basically asked him for a crash course in oceanic interactions, and this is what he taught me—too cool!

Essentially, the ocean can be viewed as the shallow, warm “mixed layer” at the surface and the deep, cold ocean. The dividing line between these two is called the thermocline, and it is the level at which a rapid change in water temperature occurs. Think about it as a multi-layered cake, with each water layer maintaining a fairly unique and consistent salinity, density and water temperature.  Generally, the mixed layer at the surface is the warmest.  In the equatorial pacific this surface layer has a depth of about 100m, and it is this first layer of oceanic cake that NOAA is most interested in studying.  Normally, the thermocline that divides the high warm layer from the lower cold layer maintains a gradually increasing easterly slope.  Under normal conditions, there is also less convection occurring and less wind is present.  However, under El Nino conditions the dividing line between the two layers becomes more level, creating a deeper, warmer top layer. This increase in depth of the top layer affects marine interactions in several ways.  First, a much larger percentage of surface water is warmer.  Second, more convection is occurring due to the warmer water temperature, and third, more wind is present.  One of the major uncertainties that TAO project data is attempting to explain is the cause of this thermocline change.

Personal Log

After a long Monday and a fabulous shrimp dinner, I feel quite tired and ready to call it a day. Tomorrow, Joe will set up my ship email account; I am really looking forward to being in touch with friends and loved ones at home, and also communicating with my students! It pleases me to report that, surprisingly, my stomach feels more settled at sea then it did when we were anchored in the Bay!  I’m not feeling 100% yet, but definitely well enough to give the treadmill a try tomorrow—and maybe I can even skip the Dramamine… Until tomorrow!