Southern Ocean Iron Experiment (SOFeX) Cruise
January 5 - February 26, 2002
Skip to Log Entry from the R/V Melville
February 7, 2002: Day 34
Ship: @ 2/7/02 0449Z,-58 9.0547, -170 19.9358
No. Patch Argos Drifter @ 2/5/02 1521Z,-54 1.32, -169 10.26
No. Patch SOLO Float @ 2/5/02 2300Z,-54 21.852-169 47.22
R/V Revelle Log Entry: Wow, excitement is building on board. We received an ocean color image today from the SeaWIFS satellite sensor that had been processed to estimate chlorophyll concentration. Guess where the hottest pixels (highest chlorophyll!) in the entire image (45S to 70S, 175W to 165W) are found? Right between the latest positions for the Argos Drifter (red dots) and the SOLO float (cyan dots) that we released inside the North Patch over 20 days ago. An enlargement of the image from 54S to 55S and 170W to 169W shows a hot patch about 8x20 km in size. Thats our target.Lots of curiosity about what well find there.Is this real? Itll be something if we find the patch 27 days after we created it. Were on schedule for two days of science and one more iron addition. Drive-by science as we cruise home to Lyttelton.
In preparation for our North Patch visit, we started filling the iron tanks for one last dose. No more iron left to add after that. Here, Steve, Pete, Eric, Craig and Oliver are moving a full IBC (Individual Bulk Container) onto the loading station - no theyre not lifting it, Tammy does that with the crane - they just guide it into the station.Each IBC with its 1500 kg load is craned up onto the loading station, where the iron is then moved automatically with a hydraulic auger system into the 16000 L (4000 gallon) dilution tanks on the deck below. Were filling the tank with the last 3 IBCs. Handling large masses of iron on a rolling ship in the Southern Ocean had been one of our major concerns before the experiment.This system works slick as goose stuff.
Were still passing icebergs, including this monster that we saw last night. The captain measured it with the sextant and found it to be 142 m (467) high. You can see crevasses across the top. Theres a good shore break on the right hand side. Waters still a little chilly though.
The weather is holding otherwise. Temperature has really gone up today and its almost shirt-sleeve weather on deck. The wind is down to nothing right now and the sea is glassy - must be getting farther from MELVILLE. Might be a nice sunset tonight. Well thats all for now. Well be on station at noon tomorrow.
- Ken J.
Position:66 degrees South,171 degrees West
R/V Melville Log Entry: Yesterdays activities were filled by a long Outside station in the vicinity of the wayward MBARI Outside drifter. This is the instrumented buoy that provides a suite of outside patch measurements similar to the buoy on the inside of the patch and can be used as a control for the enrichment experiment. Unfortunately, it is not talking to us and there is no radio signal from it during the day or during both search activities in the morning and again at night. We will continue to look for this buoy at its projected location as part of our out-station activities and hope it chimes in with its position and accumulated data as its better behaved counterpart has been doing faithfully.
The outside station was truly outside. Low chlorophyll, blue water and in the morning it was clear enabling us to see for miles. Large tabular icebergs were visible all around us as were spire shaped bergs, towering 30 meters above the water (and another 250 meters below). By breakfast time the clouds were again upon us and the station was windy and cold with corn snow flurries that stung exposed skin. With an extra pump cast and a deep CTD cast completed, we were underway and searching for the wayward buoy by about 10:00 pm and began our surface water mapping transect by about 0030 in the morning. It was a long day.
Todays activities are to continue the mapping transect. We intend to cover about 1,035 square kilometers (400 square miles) of ocean in seven, 32-kilometer (20-mile) lines spaced about 5.5 kilometers (3.4 miles) apart. All underway sensors and analyzers are abuzz. This includes analyses for nitrate, silicate, all carbon system parameters, sulfurhexafluoride tracer, fluorescence, oxygen, temperature, salinity, fast repetition rate fluorometry, etc. In addition we are taking discrete surface water samples every half hour and running them for extracted chlorophyll, HPLC pigments, species composition, biogenic silica and POC. Ironically, so many of our water analyses involve getting rid of the water that there is a dirge of vacuum pumps, a symphony of suction, that is the sound of work being done.
One would think that running such a grid would be routine, in fact the ships autopilot is set up to do this automatically.But there are so many icebergs and growlers out here that our transect lines look more like cow paths than they do like regular even rows.