Marla Crouch: The Mystery and Surf Your Berth, June 14, 2013


NOAA Teacher at Sea
Marla Crouch
Aboard NOAA Ship Oscar Dyson
June 8 – 26, 2013 

Mission:  Pollock Survey
Geographical area of cruise:  Gulf of Alaska
Date: June 14, 2013

Weather Data from the Bridge: as of 1900
Wind Speed 9.57 kts
Air Temperature 6.84°C
Relative Humidity 81.00%
Barometric Pressure 1,030.5 mb

Latitude:  53.52N   Longitude: 166.34W

Science and Technology Log

The sonar on the Oscar Dyson recently created the graph below.  The graph displays the sea floor, the red, yellow, and green bands toward the bottom and along the top a few meters from the surface the layer of green and red, is the mystery.

Graphic provided by NOAA

Graphic provided by NOAA

The echoes, that create the graph do not look like fish.  The scientists recognize that something is there, the questions is, what?  Further exploration is done, but nothing definitive is found. This creates a bit of a dilemma, which initiates a whole series of conversations about trouble shooting the equipment, using different data gathering techniques (something different than a trawl), and hypothesizing about what is creating the image since there are no apparent biology.  Could the image be created by something physical in the water?  Until the make-up of the image can be identified the sonar signature, is titled and recorded as Mystery Mix One.

Taina Honkalehto, one of the scientists on this cruise, tells me that they have been encountering Mystery Mix One for a number of years here, in the Gulf of Alaska, and in different parts of the ocean at different times of the year. Mystery Mixes Two and Three are floating around as well.

Investigating Mystery Mix One:  Time stamp 12 June 2013, 050952 GMT (This time stamp equates to 8:09 almost 8:10 p.m. June 11, 2013 PDT.)

The stereo camera, which I talked about in my last blog, is a new piece of equipment that scientists are using to collect data about the ocean floor and the biology of the region.  The stereo camera was launched and submerged to a depth of 50m into the middle of Mystery Mix One, and left at that depth for 30 minutes while the Oscar Dyson drifted with the mix.  When the pictures were downloaded, the only identifiable objects were copepods, big copepods. Remember “big” is a relative term, big compared to what? Copepods can be smaller than 1 mm in length.  These big copepods are probably 6 to 8 mm.

The light image in the upper left-hand corner is a copepod.  Picture provided by NOAA

The light image in the upper left-hand corner is a copepod. Picture provided by NOAA

This is a clearer picture of a copepod. This is a clearer picture of a copepod.     Picture courtesy of comenius.susqu.edu

This is a clearer picture of a copepod.
Picture courtesy of comenius.susqu.edu

The strong sonar image created by the copepods heighten the mystery; starting another round of questions and discussions by the scientists.  Why are copepods creating such a strong sonar signature?  Why are the copepods so prominent on 18 kHz? (18 kHz is a low frequency that usually captures echoes from large objects, while small things like copepods would be seen at higher frequencies, like 200 kHz.)   Could something else be in Mystery Mix One, something that was not seen by the camera?  The discussion goes on creating a working hypothesis; the signature is being created by a combination of the copepods themselves, whatever they are feeding on and gases, being produced.  Not all the scientists are in agreement.  If Mystery Mix One was to be sampled again, would you get similar results?

Pictures from the stereo camera provided one piece of possible evidence that may lead to answering the question, “What is in Mystery Mix One?”

The next day another piece of possible evidence is added.  Oscar Dyson’s sea water intake filter is cleaned and what is found?  Krill and big copepods.  Pictures are taken and the evidence is recorded in the scientists’ journal. More evidence needs to be collected, but advances are being made to identify Mystery Mix One.

Krill are in the red ringed filter.  Copepods can be seen at the bottom of the bucket.

Krill are in the red ringed filter. Copepods can be seen at the bottom of the bucket.

Personal Log 

The first few days out at sea the waters were really calm, 1 to 3 foot swells or seas, which feels like the soothing glide of a rocking chair.  Now however, weather is moving in; wind speed is up around 15kts and the swells are about 9 ft.  Friday’s forecast is for 30kt winds and 12ft. seas.  Looking at the big picture, 9 to 12 foot seas are not very big.  But, walking around the ship with seas of that height requires due diligent to safely navigate the passage ways and steep stairs.  And you definitely need to mind the doors, make sure the door is securely latched and when opening hold on tight, as you don’t want the door to get away from you. Somebody might be standing on the other side.  Another activity that can prove challenging is getting into and out of your bunk.

The berths, or rooms, aboard ship are, for the most part, designed for two people. Look at the picture of my berth.  You can see a desk, chair, dresser and two draped bunk beds.  Mine’s the top bunk.  Our room is just about even with the water line.  That is important to know, because the lower you are in the ship the less dramatic the motion.  I’ll talk about the pitch and roll of the ship in a future blog

This is my berth.

This is my berth.

Now imagine yourself lying on a teeter totter.  You are right above the fulcrum, so you are nice and level.  An unbalanced force is now affecting your teeter totter, your feet go up your head goes down and you slide a little.  Then there is a change and you head goes up your feet go down and you slide back.  This back and forth motion is continuous, and the motion presses you into the teeter totter.  I call this the sloshing phenomena, because all the while you are teeter tottering you hear the sea water rushing pass the hull.  But wait, there is more.  Your teeter totter only moves in two dimensions, but we live in three dimensions.  Keep your teeter totter going, up and down, hear the water stream by and add a sideways roll, back and forth.  Don’t fall off your teeter totter.  You are not quite ready to surf your berth yet, sometimes the up and down, and side to side movements occur so quickly that you actually loose contact with your teeter totter.  Now you’re surfing!  I have yet to find the seat belt for my bunk.

Remember I said that my berth was low in the ship, there are only a few berths on this level, and more berths are two and three floors above me. Now think about a metronome.  If you’re not sure what a metronome is think about a windshield wiper on a car.  Both the metronome and the windshield wiper make small movements at the pivot point or fulcrum; the further away from the fulcrum the greater the range of motion. Think about how the motion is magnified as you move up from the water line.  Those folks above me are really surfing.

Did You Know?

When Taina and I were talking about Mystery Mix One she said the 18 kHz frequency ensonifying the larger fish.  I think ensonify is a cool word. I wonder if Mrs. Sunmark or Mrs. Delpez (our school’s band and orchestra teachers) have used the word ensonify in their classes?  Can any of you tell me what ensonify means?

Did you know you can follow my voyage on NOAA’s ship tracker website?  Here is the link.

http://shiptracker.noaa.gov/shiptracker.html

In my next blog, I have another fashion statement – Gumbi Marla!  And maybe something about the moon and Apollo 17.


2 responses to “Marla Crouch: The Mystery and Surf Your Berth, June 14, 2013

    • That depends, is the hammock far enough away from the walls so you are not rhythmically slamming into a solid surface as the ship pitches and rolls? What is the hammock made out of? The idea of rope burns is not real appealing. I think I’ll stick with the mattress.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s