30 March 2004

Tuesday, 30 March 2004

Time to stir things up again

Looking back at my diary notes, I see that the comment "Day dawns grey as usual" is my most common remark about our Southern Ocean environment. You will have gathered from other web entries that it has also often been windy with periods around 40 to 45 knots, and this has limited the range of activities. Altogether, it has been a very challenging environment to operate a very complex experiment in which we need to keep track of a patch of water labelled with inert tracers. We are constantly monitoring weather and the state of the patch and trying to respond in a way that best serves the overall objectives of the program. In summary, these objectives are to develop our understanding of how physics, chemistry and marine biology affect the exchange of trace gases between ocean and atmosphere. These have an important effect on our climate.

I'm thinking back to how this all began. We first started thinking about a regional SOLAS program in 2000 with some meetings in Australia. In particular, I remember a poolside meeting in Townsville in 2001, a far cry from the current environment. Planning started in earnest in mid-2002 and probably completely took over my days with co-ordinating and planning by November 2003. To get to where we are now has taken an incredible effort on the part of many people. Work on-board goes on around the clock. There are 29 hard working scientists with groups looking at various aspects of the gas exchange story and the biology that drives it. The on board planning group looking after all aspects of the science comprises Edward Abraham, Murray Smith, Cliff Law, David Ho, Craig Stevens, Brian Ward, Julie Hall and myself. There is the incredible support and assistance we have from Captain Roger Goodison and his crew on board Tangaroa. There is data support from back at NIWA with Mark Hadfield and Matt Pinkerton. And there was an incredible amount of hard work put in by Greg Foothead and engineering colleagues in NIWA Vessels as we worked on mobilising one of the most complex operations attempted on Tangaroa. It has been amazing to work with such a dedicated bunch of individuals. There are many I have not named. But we are indebted to them all, both in the organisations represented on-board and with non-participating collaborators that have provided us with equipment.

We are now almost halfway through the voyage and we have a clear biological response to the first infusion of iron that we added on 25th March. We can see this response most clearly at night with the fast repetition rate fluorometer measuring the fluorescence from plankton in seawater collected whilst the vessel is underway. What is happening today? Following 45 kt winds a couple of days ago, we had to spend some time finding out what had become of our labelled patch. We found a substantial part of this patch last night. Now that the sea has died down a bit, today has been spent recovering sediment traps that had drifted someway from the patch but couldn't be recovered in the rough weather. We have discovered that most of the tracer marking the patch has been lost so we are on the point of reinfusing a biologically active area with more fertiliser and tracer in order to further stimulate a phytoplankton bloom.

A day or two of sunshine wouldn't go amiss.

Mike Harvey (NIWA), Voyage Leader

Craig Stevens in the foreground involved in the launching of a GPS drifter, whose position will be used to track the patch.

"Infusiast" Andrew Marriner, helping with the second infusion of iron.

Mike Harvey (right) and Bill Maine working on the iron sulfate tanks during the second infusion.

Sediment Core - Geoffroy Lamarche

A school of pilot whales close to the ship.

Research subject: Oceans