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

Longitude: 172° 00 W

1700 January 10, 2002

Whew, after a bumpy night, the wind laid down and we’re having a beautiful day. Ginger says, Thank you, Neptune. We’ve 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 51°S to 51.5°S.  Nutrients jump across the front and are remarkably uniform for about 240 kilometers (150 miles) down to the SubAntarctic Front, which is just where it’s supposed to be around 55°S. 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 we’ve been looking for. I just wish the other front (the Sub-Tropical Front) was further north.  We don’t 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.  We’ll keep looking a bit more to the south before we make a final decision on where to put the iron, but the area around 52.5°S is looking pretty good, if a little cramped. It’s a big ocean, but homogenous it’s not.

We’ll put the SeaSoar in for a test in two hours. After that, we’ll decide whether to keep going south or to head back north. 

Good night.