Dispatch 27 - August 10, 2002
By C.A. Linder
Weather conditions: partly cloudy skies, winds 15-20 knots from the NE, 2-3 ft. seas, air temperature 53° F.
Fun and Games
Cheese or pepperoni? Tonight there were some different faces on the galley serving line -- the science party! Every Saturday night is pizza night on the Polar Star, and its the most popular meal of the week. Its great for the galley crew because different departments on the ship take turns cooking and cleaning for the night. Tonight it was our turn, so we were in charge of making the pizzas, cooking, serving, and cleaning up afterwards. Later on, some crew members put on a comedy show. The skits included A Few Sleepy Men (a hilarious spoof on A Few Good Men), a mock Jeopardy game, and a sing-along with accordian music! The entertainment provided a great reprieve from the day-to-day tasks on the ship.
In previous Dispatches we looked at the water temperature (Dispatch 22) and turbidity (Dispatch 25) of a cross-section spanning the Beaufort slope. I pointed out a blob (lens) of water we observed in the slope water. We surmise that this lens has come from shallow water because of its cold temperature and high turbidity. Is it possible to find out how it got across the Chukchi shelf? There are a number of different pathways for waters traveling across the Chukchi Sea (see Objectives section for schematic). So is the lens a bubble of modified Anadyr water that has traveled from the western Chukchi shelf through Herald Valley? Or perhaps it came from the Central Channel? It could also have passed through Barrow Canyon in the eastern Chukchi. All of these are possibilities. Our CTD sections across the Chukchi shelf and mouth of Barrow Canyon provide some clues. However, the temperature, salinity and turbidity data are inconclusive - they show similar values for waters flowing through Barrow Canyon AND along the western Chukchi shelf. Luckily, we have the benefit of another sensor called a fluorometer. Using a blue light source, it measures the amount of chlorophyll in the water on each CTD cast (see Dispatch 26 for a discussion about chlorophyll and phytoplankton). The figure at right shows the fluorescence across our Beaufort slope section. Just like the temperature and turbidity plots, the blob stands out - on this plot as a maximum in fluorescence (yellow/red colors indicate high fluorescence). Comparing this data to the upstream fluorescence measurements (to the west), we found comparably high values in Barrow Canyon but NOT along the Chukchi shelf! Our preliminary conclusions, therefore, point to the eastern Chukchi (through Barrow Canyon) as being the source of the detached lens of water found over the Beaufort slope. Physical oceanography often requires a bit of detective work, thats what makes it so fun.
Since escaping the ice, we have enjoyed light following seas - it still hardly feels like were moving! The forecast for tomorrow is pretty grim, though - 12 foot abeam seas, which will roll the ship from side to side. Were hoping the forecasters are wrong.
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