Wednesday, February 3, 2010

Science Fair, Antarctica style

It's science fair season at Dual Language Middle School, and I'm sorry I can't be there for it. But I've been working on my own science fair project out here and I'd like to report some results.

Topic: The speed of ocean currents in Antarctica

Question: How does the depth of the water affect its speed?

Hypothesis: Shallow water moves faster than deep water.

Background Information: Lowered acoustic Doppler current profilers (LADCPs) use sound energy to measure the speed and direction of ocean currents. Water in the ocean can be moved by wind, tides, and differences in pressure due to temperature or salt content.

Procedure: Use LADCP data to compare the depth of water (the independent variable) with the speed of the water (the dependent variable).

Results: I was able to collect data from 38 stations all around the Antarctica Peninsula. On average, the fastest water was at the surface as predicted (figure 1).

Discussion: Average speed does not tell the whole story. The maximum speed that was found in any location occurred at 60 m (figure 2), and the minimum was found at 175 m (figure 3). There is a lot of variability in water speeds, especially at depths above 100m. Below that, the speed changes very little but does not stay exactly steady.

These figures show average, maximum, and minimum water speeds. Please note the different scales.

Conclusions: On average, the fastest water is at the surface. However, there is variability between stations and there can be high speeds below the surface. Speed generally decreases with depth, but there are exceptions. Differences in tides, wind, and ice conditions might also effect water speed.

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