NOAA Teacher at Sea
Onboard Research Vessel Kilo Moana
May 23 – June 10, 2009
Mission: Woods Hole and Hawaii Ocean Time Series
Geographic Region: Hawaiian Islands
Date: June 1, 2008
We just got underway yesterday, and today is very exciting. We’re deploying a new buoy a few miles from an old one, and we intend to leave both in for some days, and finally remove the old one before departing the area. The overall concept here is to get a really good dataset about the ocean and the atmosphere in one location over a long period of time. This program has been ongoing since 2004. These data will serve as a piece of the puzzle in the larger question of how global warming works, and what roles the tropical ocean and atmosphere play. The buoy, shown here sitting at the stern of the ship, is loaded with scientific instruments, distributed in three layers.
On top are the meteorological gadgets, which measure air temperature, humidity, solar radiation, wind speed and direction, and barometric pressure. A GPS unit there keeps track of the buoy’s location, elevation and orientation. There’s a fin to keep the buoy facing into the wind (preventing, for example, temperature sensors from being in contact with air that has already passed over other instruments or surfaces), and on the fin is a white capsule-looking object containing instruments to reflect radar from ships to avoid collisions, and a metal box which contains an antenna. With this antenna, all the meteorological instruments can send data to a satellite at regular intervals. You can see this data, graphed in nearly real time, at the website http://uop.whoi.edu/projects/WHOTS/whotsdata.html. On the buoy’s top you can also see bird wire, and I’m told I’ll understand fully the importance of this component when I see how guano-covered the old buoy will be.
A few instruments are located at sea level: carbon dioxide sensors (not shown) and sea surface temperature (SST) sensors. One SST sensor is embedded in foam and moves freely on a vertical rail, going up and down as the buoy bobs, trying to stay just at the surface of the water, and the second is fixed in place and is there for redundancy. The carbon dioxide sensors are important, especially to us in Hawaii. As you probably know, the earth’s carbon budget is intimately tied to questions about global warming, and since a great deal of carbon is in carbon dioxide molecules, and since carbon dioxide dissolves so readily in ocean water, any measured changes in carbon dioxide levels in the surface water are interesting to climate scientists. The carbon dioxide also contributes to carbonic acid, lowering the pH of the ocean water to potentially damage anything that dissolves in acid – like coral reefs and shells. Chief Scientist Bob Weller thinks this rising pH is actually a bigger concern than global warming. Very early data about climate change came from a long term data set of atmospheric carbonic dioxide collected here on Mauna Loa. If you’ve seen Al Gore’s movie, you recall this jagged sawtoothed graph depicting the rising carbon dioxide levels. It is a prime example of how useful a long term dataset from one spot on earth can be. This WHOTS project hopes to create an analogous dataset, but one about ocean conditions instead of about atmospheric conditions, and in this study (as in the Mauna Loa one) carbon dioxide is likely to play a key role.
The third layer consists of instruments hanging below the buoy: CTDs (the bread and butter of physical oceanography) tell us about the temperature and salinity at different depths; and two types of current meters measure how the water moves, one uses little propellers, the other bounces sound off of plankton in the water. These are connected to the buoy and to one another by a segmented strand – including metal chain and cable at depths where sharks would bite through anything weaker, and nylon and synthetic lines to allow some elasticity at depths where sharks aren’t a concern. Nowhere in this length is a communication wire of any kind, and electromagnetic radiation won’t travel through water, so these gadgets can’t communicate with the above water world. Instead, they hoard their data. When we pull up the old buoy, we’ll be able to download a year’s worth of data from each instrument (after we clean off the gunk). We’ll also get to look for shark bites on the chains, cables and lines.
I have the bottom bunk in a stateroom that I share with another observer. She’s a college student interning with Woods Hole. Our room and the one next to it (housing two University of Hawaii students) connect to a shared bathroom. The ship has a wide stance so it is very stable but a little unpredictable. It doesn’t rock much at all, but still you can’t predict in which direction the next rock will tip you. I have no feelings of seasickness yet (the seas are very calm and I don’t know of anyone on board feeling queasy yet), but keep your fingers crossed because I know I’m prone to it.
The food is remarkably good. The cook is fantastic and a hard worker. In fact, the ship seems to be divided between people working really hard (from seamen and cook on up to chief scientist and captain) and people looking for something to do (like me and other observers). I’m hoping to get connected with the guy in charge of CTD stations and water sampling so I can contribute a little more. That type of work will get underway after the new buoy is finished launching. I’m told there is sometimes fishing off the stern, especially when we get near the old buoy, with all its accumulated fish food. No poles yet, but I’ll keep you posted. I have good internet connection, so feel free to write to me at email@example.com or post a comment on the blog. I’ll answer your questions as quickly as I can.
In total, the ropes, chains and cables connecting the anchor to the buoy is about 7 miles long. How would you store that much thick rope? I’ll show you the empties tomorrow…