Southern Ocean Iron Experiment (SOFeX) Cruise
January 5 - February 26, 2002
Logbook
Skip to Log Entry from the R/V Melville
February 8, 2002: Day 35
R/V Revelle:
Position @ 2/8/02 0555Z, -54 6.04, -169 11.63
R/V Revelle Log Entry: Hi again.I woke up this morning like a kid on Christmas Day - got up at 0530 and came down ready to open presents. When were we getting to the North Patch? Come on everybody, GET UP, GET GOING! Lets see whats up there! Those bright pixels on the 2/5 SeaWIFS image had really captured my imagination. Frankly, a few days ago I didnt think we had much chance of even finding it.
I had predicted an arrival time in the patch of about 1300, after we had slowed to put the iron sampling fish in the water. At 1315 the fluorometer started going up and PCO2 began to plummet. Holy Cow - theres a great big, blooming patch of phytoplankton here. We dont have quantitative numbers for the amount of phytoplankton yet, but the CO2 draw down and nitrate draw down would appear to equal, maybe exceed, that found in IronEx II. We all stood around watching the screen of the PCO2 monitor, pretty much slack jawed, for the first two passes through the patch.The nitrate analyzer looks about the same, as does the fluorometer - in reverse.
Were still mapping the patch, but were closing in on the northern boundary. The next pass through should capture it. Then its a station in the patch, SeaSoar survey, station outside the patch, station inside the patch and, finally, we add Fe again to spur it along for MELVILLEs arrival. Id love to talk more, but have to get back to work. Ken J.
R/V Melville:
Position: 66 degrees, 10 minutes South, 171 degrees, 58 minutes West
R/V Melville Log Entry: Although yesterdays mapping effort ran over the scheduled time a bit, it was a huge success. We mapped about 400 square miles of ocean surface, dodging icebergs and slurping water samples from the ships flow through system. The navigation system functioned perfectly and enabled us to run our transects and collect our samples relative to a continuously drifting reference. In spite of these efforts, when we turned around, it was gone. So, how can one lose something that is over 1,000 square kilometers?Well, (it takes a PhD, or a whole ship-load of them) it must have been hiding behind an iceberg because it doesnt stay hidden forever. Our station today is Inside and we are trying to stick with it. We are in iceberg alley and some of them seem to be passing us by at a knot or more. We did have some sunshine and are hopeful for a satellite image soon. We think there would definitely be something to see. The maximum in chlorophyll was several times the background values and depletions in carbon dioxide and nitrate were readily apparent. So, the ecosystem is rolling along, but how it is functioning and where it is going is still for us to find out.
Figure: Contoured map of the inert chemical tracer used to follow the patch (see Ken Johnsons description of SF6). This map was reconstructed from geocentric coordinates corrected for In Station Buoy drift. Red indicates high tracer values, blue to white indicate low tracer values (values are not fully corrected). The x and y axes are in meters, dots represent ships position at the time of underway sampling. Note that the (0,0) origin is not in the center of the plot. This is the position of the drifting navigational buoy that seems to be trying to get away from us. Tracer data:David Cooper, Contour Plot:Wendy Wang and Max Gorbunov