NOAA Teacher at Sea
Aboard NOAA Ship Ka’imimoana
August 16-30, 2002
Day 16: Sunday, August 26, 2002
Today we are at the equator!!! (0° latitude, 140° west longitude)
The FOO (Field Operations Officer)’s quote of the day:
“The greatest thing in the world is to know how to be self-sufficient.”
– Michael de Montaigne
Here are our observations at 1400 today:
Visibility: 12 nautical miles (nm)
Wind direction: 140°
Wind speed: 9 kts
Sea wave height: 3-4′
Swell wave height: 5-7′
Sea water temperature: 27.1°C
Sea level pressure: 1010.3 mb
Cloud cover: 4/8, Cumulus, Altocumulus
Hurricane Fausto is currently located at 21.3°N, 132.7°W and continues to diminish in strength. It has sustained winds of 60 kt, gusting to 75 kt. and is moving toward 300° (WNW) at 15 kt. Its central pressure has risen to 987 mb.
First of all, I’d like to say WELCOME to my classes at Shippensburg University. Today is the first day of classes there and I want to acknowledge those people who are helping to cover my classes and are also assisting with the link between me and my students this week and next. Those who have helped tremendously include Drs. Niel Brasher, George Pomeroy, William Rense, Christopher Woltemade, and Holly Smith. Thank you!
I have already received email messages from many of you in my classes. Remember, part of your assignment for this first week is to email me at least 3 times asking me questions about the ship’s operations, science on board, or anything else that you feel would be of interest to you. Please read all of my logs, check out my photos, watch the previous videos, and follow the path that the ship takes across the Pacific Ocean. We’ll be referring to all of the information shared on the web throughout the semester. Welcome to the Pacific Ocean – glad you could join me!
Science and Technology Log:
I awoke and immediately starting preparing for our second general broadcast of the trip. Seven guests were scheduled to be interviewed during this broadcast. They did an excellent job. Unfortunately, Dave Zimmerman was immersed in the operations of the morning Acoustic Doppler Current Profiler (ADCP) retrieval and deployment, and so couldn’t join us for a short interview. I’ll try to catch him again when things aren’t quite as hectic. Overall, the show went well and I’ll spend the rest of the day preparing for the next three broadcasts with my students in Introduction to the Atmosphere, Meteorology, and the Atmospheric Environment at Shippensburg University. I’m anxious to meet everyone in the classroom from the ship to share some of the things that I’ve been learning on board the Ka’imimoana. Please check out all of the videos on this web site to see who I’ve interviewed in the past. The ship’s scientific equipment and research, and my interactions with scientists using them, will definitely add to what I teach in the classroom, which should make for a more interesting and valuable experience for all of you.
Here are some interesting facts about the ADCP. It is a subsurface mooring, which means that it is anchored to the bottom of the ocean but remains nearly 300 meters below the surface of the water, and it measures current velocity profiles. It is a large round floating orange sphere (see photo logs) that measures the velocity of ocean currents in approximately the upper 250 meters of the ocean using the Doppler effect. Today, after triggering the acoustic release separating the anchor from the old ADCP that was being replaced, the instrument emerged at the surface of the water, was spotted, and then dragged through the water to the ship where it was hoisted up with one of the ship’s cranes onto the fantail. The thousands of meters of line were then reeled in and later deployed again with a replacement ADCP attached. The instrument uses the Doppler effect meaning that there is a change in the observed sound pitch that results from relative motion of an object, in this case water. If something is coming toward you, the wave frequency appears to be higher and if something is going away from you, the frequency of waves appears to be lower. The example that is always used is that of a moving train. The train’s whistle has a higher pitch when the train approaches and a lower pitch when it moves away from you. The change in pitch is directly proportional to how fast the train is moving. If you measure the pitch and how much it changes, you can calculate the speed of the train.
ADCPs use the Doppler effect by transmitting sound at a fixed frequency and listening to echoes returning from waves and sound scatterers in the water, such as small particles or plankton reflecting the sound back to the ADCP. Scatterers float in the water and on average they move at the same horizontal velocity as the water. When these scatterers move toward the ADCP, the sound heard by the organisms is Doppler-shifted to a higher frequency. The ADCP uses four beams to obtain velocity in many dimensions. Overall, it’s an amazing instrument.
The equatorial buoy was retrieved tonight and a new one will be deployed tomorrow. That buoy will be dedicated to the Grace B. Luhrs Elementary School and Shippensburg University. It will be signed by the Captain, Chief Scientist, and me, and will be located at 0°, 140°W for the next year. Shippensburg’s name will be on the Pacific for at least 365 days!
Most of my afternoon and evening was spent answering emails and preparing lesson plans. I am looking forward to tomorrow’s activities but have many miles to go before I sleep. Keep in touch!
Question of the day:
At what heights in the atmosphere are altostratus or altocumulus clouds found?
One of my Meteorology students, Steve Osmanski, provided the correct answer to my previous question of the day, “what are crepuscular rays?” His answer is: “They are the classic ‘sunburst’ effect caused when sunlight is blocked by a cloud and appears to be “streaming in rays” around the shadow. They are visible from scattering of sunlight by dust or water droplets, and appear to diverge as a trick of perspective.” Excellent, Steve! I look forward to having you in class!