This expedition is a joint Dutch/UK cruise, whose principal aim is to visit the sites of two sets of moorings. The first set has been deployed by NIOZ (Royal Netherlands Institute for Sea Research) across the narrows of the Mozambique Channel. This is part of a 5-year measurement programme called LOCO, and during the cruise we aim to recover all the moorings, download the data (they have been recording continuously for over a year), change the batteries and put them back again. There will also be some coring to take sediment samples from the bottom of the channel, as the contents will give a perspective on the flow through the channel over the past century.
The second set of moorings is to the south of Madagascar, and was placed there by NOCS (National Oceanography Centre, Southampton) just over a year ago, during the first MadEx cruise. These moorings are to be recovered and brought home. Together these two lines of moorings will have monitored the flow around Madagascar (to the west and the south), which feed into the Agulhas Current, one of the largest currents in the world.
Plot of region showing bathymetry, with dashed line showing intended track from Cape Town to Durban, up the west side of Mozambique Channel, down to southern tip of Madagscar and finally to Port Elizabeth. The red arrows show the main currents flowing around Madagascar and into the Agulhas Current. (Pink dots mark the locations of the moorings.) The track marked is an idealised one, if there are no problems with storms or equipment
The whole region has a lot of eddy activity, which show up in satellite altimetry as a series of highs and lows, rather like weather systems in the atmosphere. There are nutrient-rich waters along the Mozambican and Madagascan coasts that lead to enhanced biological productivity, which can be seen from space by ocean colour sensors. Sometimes the eddies are delineated by swirls of high-productivity waters brought out from the coast. Another aspect of this expedition is to study which particular organisms are present in these waters. To that end, we will be taking lots of samples for microscopic and other analysis. We will also be deploying more PODs (Pop-up Ocean Drifters), which allow a staggered release of buoys to follow the flow of the surface waters. They are scheduled for deployment and first surfacing in mid/late April; their progress can be followed through frequent position fixes via satellite, which are shown with daily updates.
The number of NOCS scientists on this cruise is small -- just three of us, after delays to the expedition forced a fourth member to retire. However, I have been able to call on the help of a Brazilian friend with Antarctic experience - it will be interesting to see what he makes of the temperature! Of course we do not go alone: as well as thirteen Dutch scientists and engineers, there is plenty of technical support from UKORS staff, and ready provision of remote-sensing data via RSDAS.
Ronald: The Brazilian from Antarctica!
Cruise News -- updated frequently once cruise starts
Satellite coverage -- see recent plots of ocean colour, temperature and inferred currents
Weather check -- Update on weather systems from S. African forecasters. Look out for the tropical storms that could threaten work programme.