Nancy Lewis, September 19, 2003

NOAA Teacher at Sea
Nancy Lewis
Onboard NOAA Ship Ka’imimoana
September 15 – 27, 2003

Mission: Tropical Atmosphere Ocean (TAO)/TRITON
Geographical Area: Western Pacific
Date: September 19, 2003

Plan of the Day:

0700:    Recover /Deploy Equatorial ADCP
Recover CO2 Buoy (if there)  OR
Deploy CO2 Buoy ( if Buoy is missing)

Weather Observation Log:  0100

Latitude:  0 degrees,  0.7′ N
Longitude:  140 degrees., 2.3′ W
Visibility:  12 nautical miles (nm)
Wind direction:  120 degrees
Wind speed:  21 knots
Sea wave height:  3-5 feet
Swell wave height:  5-7 feet
Sea water temperature:  26.0 degrees C
Sea level pressure:  1011.2 mb
Dry bulb pressure:  26.0 degrees C
Wet bulb pressure:  23.8 degrees C
Cloud cover:  3/8 Cumulus, altocumulus

Science and Technology Log

The equator!  For me as for most people, it has always just been “that line around the globe,”  but now that I am out here on this project,  I realize that the equator defines more than just the northern and southern hemispheres of the earth.  It is here that the ocean currents are being intensively studied in order for us to understand the relationship between the oceans and climate.  The 1982-83 El Nino was not predicted by scientists, and it had far-reaching, damaging effects on such diverse places as South America and Australia.  It was then that NOAA funded the Tropical Ocean Global Atmosphere project that is the TAO/Triton array.  Approximately 50 of the buoys are maintained by the U.S. and the other 20 are maintained by Japan.  It took 10 years to complete and in essence, it is a 6,000 mile antennae for scientists to monitor conditions in the equatorial Pacific.

Normally,  the trade winds blow from east to west, but in an El Nino event,  the situation is reversed.

The phenomenon has long been observed by South American fisherman,  and usually occurs around the time of Christmas, hence its name which means “Christ child.”  The great ocean currents are moved by the wind, but around the equator, there are counter, below-sea currents.  Instruments in the TAO/Triton array are involved in collecting important data on these below surface currents.

Each TAO buoy is moored to the bottom of the ocean using steel cable surrounded in plastic and railroad wheels are the anchor.  At various depths on the Nilspin, temperature sensors called thermistors are strapped to the cable.  The cable conducts a signal to the surface of the buoy.  These cables can become damaged (by sharks biting them!) or otherwise degraded, and then the signal will be corrupted. Thus, there is the need for the periodic maintenance which is the main mission of the KA’IMIMOANA.

In addition, some of the buoys are equipped with CO2 sensors, which measure the amount of dissolved CO2 in the water, and which can then be used in studies of global warming.  The buoy which we retrieved today stopped working shortly after it was deployed, and it was not known if it had broken free or what had happened.  As it turned out, the buoy was there, and has been replaced with a fully functioning buoy. Right now, I am looking at innards of that CO2 sensor, which is in the computer lab and is being analyzed by the Chief Scientist.

Personal Log

Early this morning, we recovered the ADCP, which is a subsurface buoy.  Shortly thereafter, we deployed a new ADCP.  ADCP stands for Acoustic Dopplar Current Profiler, and this instrument is used to record data on the below surface currents. I will spend time later discussing this buoy, which looks like a giant orange ball.

I spent much of the day catching up on my daily logs, downloading photos and making several video clips to send to the website.  It appears that the hurricane did a number on the East Coast, and we probably will not have email communication until at least tomorrow.  I have been very happy to get some good questions from the students at Na’alehu School on the Big Island, and I am looking forward to hearing from many more of you next week.

I also spent time today chatting with the Chief Boatswain, Kamaka, a very hard working Hawaiian young man who spreads a lot of aloha wherever he goes.  I have invited Kamaka to come to my school when we get back to Hawaii since he is planning to visit the Big Island.  His girlfriend is Marquesan and lives on Nuku Hiva.

The sunset this evening at the equator was stunningly beautiful,  and there was a rainbow under some misty clouds in the east.  I am hoping my photo was able to capture it for you all.  We shall remain here at the equator overnight, and I am looking forward to the gentle rocking of the ship once I tumble into my berth later this evening.

Question of the Day:   What is the Coriolis effect and how does it relate to winds and ocean currents?

Aloha from the KA’IMIMOANA!

Nancy Lewis

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