Southern Ocean GasEx Blog

Dispatches from the Southern Ocean Gas Exchange Experiment

Are we there yet?

Posted by sogasex on March 4, 2008

By David Ho, LDEO

Four days out of Punta Arenas, and we’re almost to the study site. We’ve been looking at satellite images (see Pete’s blog from Mar 2), and Joaquin Trinanes of AOML has been providing us with really cool animations of surface currents derived from altimeters to help us refine the general area.

Once we get to the site, we’ll spend 2 days conducting underway surveys, making sure it satisfies the criteria that we have set out here. The most important measurements we’ll make are underway pCO2, temperature, salinity, and ADCP (acoustic Doppler current profiler). The pattern for the survey we’ve planned is eerily reminiscent of the Columbia Business School logo, albeit upside down. We will start at 50°S 38°W, and head south to 52°S 38°W. Then we’ll head northeast to 51°S 38°W, at which point we have to decide whether to keep going east or head directly west to complete the logo. If we deem the site to be acceptable, we’ll conduct a survey with the SuperSoar to make sure that the vertical profiles also satisfies our criteria.

After we have selected the site, we’ll conduct a background CTD down to 150 m for 3He and SF6, then begin the tracer injection. For that, we’ll deploy a GPS-enabled drifter, and basically do doughnuts around the drifter for 12 hours while we pump tracer-infused water from the tank on the fantail into the ocean, until all 4800 L of water has been injected. The initial tracer patch size should be about 7 x 7 km. After that, the fun will commence.

In the meantime, the most eventful thing that’s happened out here is probably the fire and abandon ship drills. This usually takes place once a week, and we had our first a few days ago. It was mandatory that we try on our survival suits (aka Gumby suits), which is actually less fun than it looks. I remember my first cruise (from Barbados to Rio de Janeiro) in 1993, when I was still an undergraduate student. One day, a grad student, a technician and I decided to try on the Gumby suits for fun. The 2nd mate caught us and went into a tirade about how expensive the suits were, and how we’re ruining them. I think he just liked to yell and the situation gave him an excuse.

The weather has been incredibly nice, but according to the forecast at the Navy’s Fleet Numerical Meteorology and Oceanography Center, rough seas are coming. Southern Ocean, baby!

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The SuperSoar being assembled

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The 3He/SF6 tracer infusion tank

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Geoff Lebon, Dave Hebert, and David Ho in their Gumby suits

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