19 January, 1998
Hello! Things are going well here in Antarctica. I thought in today's journal I would describe some of equipment we are using to determine how far the glaciers extended into the Ross Sea during the last ice age. That seems to be the main question that we are looking at for this part of the cruise. Scientists are interested in knowing how much ice there was about 20,000 years ago. They want to know how stable the ice is around Antarctica so that they can hypothesize how it will react with changes in our climate. (ex. global warming). They know that the entire ice sheet around Antarctica will not melt -- but even if a little bit melts those cities located around the coast would feel the effects!
Scientists like to look at the bottom of the sea floor to find evidence of the glaciers (moraines, scratches from icebergs, etc.). We have been using equipment to look at the bottom of the sea floor constantly. In fact, we have three different machines that do this job (in slightly different ways). We have one piece of equipment called a "multibeam." This is attached to the underside of the boat and is a lot like a very expensive fish finder. The biggest difference is that is sends "pings" of sonar to the right and left as well as straight down. As a result, we can make a contour map that shows us what the bottom looks like.
Another instrument is called the Bathy-2000. It also sends out "pings" of sonar, but they are at a slightly different frequency. As a result, they can go down a little bit into the sediments. In other words, this instrument can not only show us what the bottom looks like, but also it can show us what the top layer of sediments looks like (large layering, for example). Whereas the multibeam shows us the contour map of the bottom, the Bathy-2000 shows us a side profile of what's beneath us.
The third one is called the Simrad. When biologists are on board, it truly is used as a fish finder. We monitor that it is up and working, but we don't rely much on it's data. If the Bathy-2000 crashes, the Simrad is a backup (but has much fewer details).
Every 15 minutes, we walk around to each of these machines and make sure that they are working properly. Being computers, they have a tendency to crash just like our computers at home. If the screen freezes, we aren't collecting any data! So why do you suppose that we walk around and check every 15 minutes instead of once each hour?
When I mentioned that we had to edit some of the data, we are editing the multibeam stuff before the contour map is drawn. Sometimes the pings don't make it all the way to the bottom (rought water, reflection, refraction, etc.). We have to had edit each set of pings on the computer and erase any wild points. It takes about an hour of editing (and we're getting faster) for every two hours of data. You would think that a computer could do this job, but according to our support staff there are no computer programs that do this job as well as people do. Almost all of the support staff do ping editing along with all but Dr. Anderson of the scientists. Each day, we have two or three sets of data to edit. Usually, it's the last thing that I do before I go to bed.
Well, that's enough for today. Yesterday's question was "How high do you suppose the waves can get in the Ross Sea?" I'm not sure about the record height, but some of the people on board have seen 16-18 foot seas on occasion!
I love all your questions! Thanks for the email! Until the next time . . .
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