Southern Ocean Iron Experiment (SOFeX) Cruise
January 5 - February 26, 2002

January 10, 2002: Day 6
Latitude: 55 13S, Longitude: 172 00 W

Ken Johnson writes: Whew, after a bumpy night, the wind laid down and were having a beautiful day.Ginger says, Thank you, Neptune. Weve just crossed into the SubAntarctic Front and the air temperature has dropped into the low single digits (C that is). Stocking caps and big coats on deck. The crew brought the Mustang Suits out for work on deck, they have some serious insulation and, also, flotation if you decide to go swimming.

Well, the water temperature finally dropped shortly after I sent my update last evening.There is a very sharp front at 51S to 51.5S.Nutrients jump across the front and are remarkably uniform for about 240 kilometers (150 miles) down to the SubAntarctic Front, which is just where its supposed to be around 55S. Nitrate concentrations are about 12 micromolar, the Si is < 1 micromolar and there is very little chlorophyll (our measurement of the amount of phytoplankton in the water).These are just the conditions weve been looking for.I just wish the other front (the Sub-Tropical Front) was further north.We dont have much room north and south.Flow in the uniform area is to the west in the north, strongly to the south in the middle and it turns to the east at the SAF boundary.Well keep looking a bit more to the south before we make a final decision on where to put the iron, but the area around 52.5S is looking pretty good, if a little cramped.Its a big ocean, but homogenous its not.

Well put the SeaSoar in for a test in two hours.After that, well decide whether to keep going south or to head back north.

Good night.

tempsalt.jpg (57543 bytes)
Salinity and Temperature profiles across where we think that the fronts are (click to see larger image).

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