Southern Ocean Iron Experiment (SOFeX) Cruise
January 5 - February 26, 2002
January 16, 2002: Day 12
Ship: -55 57.7914 -171 54.861
New Drifter: -56 3.1902-171 51.2736(now in middle of patch)
Old Drifter: -56 0.5052-171 58.3362(at NW side of Patch)
Ken Johnson writes: Hi.Weve had a busy day.Up all night mapping the patch.Steve Pierce took the SF6 measurements and created this map of the patch.The drifter was at 0, 0 on the map, it had slipped about 7 km west and 4 km north of the middle of the patch.We think most of this happened early on when the wind was much stronger.Some tracer and iron also squirted out to the west as the patch took off rapidly to the north on the first day.
For the past two days it has been absolutely glassy out here, hardly a ripple.Someone on board must be a saint.I shouldnt complain, but the calm weather is a minor problem - the ocean is forming a thin (about 15 m thick) warm layer (warm is relative, its about 6.8C, while the water under is 6.5C).That layer may have trapped much of the iron and SF6 near the surface, rather than mixing it down about 40 m, as usual down here.
We spent most of the day collecting and analyzing water from inside the patch to determine the biological response to the iron we added.No results yet, except for the changes in variable fluorescence that I reported on yesterday.
We deployed sediment traps inside and outside the patch.These traps will collect particles that fall from the waters above them.They will stay until the MELVILLE picks them up on their return to New Zealand in late February.Steve Fitzwater, and Craig Hunter from MBARI and MLML, and Tammy Baiz, the Ships Resident Technician did the deployment.More on Tammy and Melissa Turner, the Ships Third Officer, when we can get them to slow down long enough for a good photo.
After deploying the traps, we put a new drifter (Larry) in the middle of the patch and picked up the original (Curly).Were now adding iron again before a last survey of the patch and day of stations.