We will be going through another time change later this evening. Tomorrow we will be 3 hours ahead of EST.
There is progress being made aboard. The forward winch which we are now using, though slower than we would like, is keeping pace with the new schedule we have in place. There have been many successful casts made over the last few days and lessening stress levels.
This new system could not have been possible without the enormous amount of hard work being put into it by the crew of the Brown. There is an increased workload on everyone, including but not limited to the winch operators and second hands to make sure the line spools as well as it can, the survey crew, and all of the engineers. A big thanks to everyone already for the amount of work they are putting into making this a successful cruise.
Continuing again with a discussion upon the importance of this CLIVAR CO2 Repeat Hydrography cruise, the next group to talk about is Helium and Tritium sampling. The mention of Helium usually sends people's thoughts running the funny high pitched voices produced from inhaling the gas inside of super market bought balloons.
In this case Helium takes on a much more serious role. Helium and Tritium are both tracers much like the CFCs discussed earlier. They are used to 'age the water'. Samples taken for Helium are prepared for processing shipboard. The gas is actually extracted from the water and stored to be sent through a mass spectrometer. The spectrometer counts the atoms of Helium at each depth. These amounts are then compared to ratios known for decay rates and the age of the water at those depths can then be determined.
Why do you need to know the age of water? Since most of these tracers are introduced at surface level and are consequently mixed down over time to deeper depths, we can determine how long it took the water to sink based upon the age of the tracers in the water.
Tritium is sampled for as well, but those samples are collected and sent back to a lab where they are then prepared and processed.
Thanks for looking through.
-Elizabeth
Our current location is:
29 59.99' S and 20 46.76'W
*If you want more up to date information on where we are out here in the big, blue South Atlantic visit NOAA's shiptracker:
http://shiptracker.noaa.gov/ship.aspx?ship_code=RBSCSACQ&timeframe=cc&mapservi
Below are some photos of: a) The sunrise this morning, b) The Helium lab with Anthony Dachille, c) Helium sampling - Photo by Co-Chief Alison and d) CFC sampling - Photo by Co-Chief Alison
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