HR: 0800h
AN: OS51A-1296    [Abstracts]
TI: Enhanced Primary Productivity at the Subtropical Convergence
AU: LLIDO, J
EM: llido@notos.cst.cnes.fr
AF: LEGOS - CNRS, 18 Avenue Edouard Belin, Toulouse Cedex 9, 31401 France
AU: * GARCON, V
EM: veronique.garcon@cnes.fr
AF: LEGOS - CNRS, 18 Avenue Edouard Belin, Toulouse Cedex 9, 31401 France
AU: LUTJEHARMS, J
EM: johann@ocean.uct.ac.za
AF: Department of Oceanography University of Cape Town, Private Bag RW James Building, Rondebosch, 7700 South Africa
AU: SUDRE, J
AF: LEGOS - CNRS, 18 Avenue Edouard Belin, Toulouse Cedex 9, 31401 France
AB: The Subtropical Convergence is one of the major frontal systems in the world ocean. It is not just simply a biogeographical boundary, but forms a unique biological habitat of its own. Ocean colour satellite data indicate that it is a region of enhanced chlorophyll a and thus a potential key region of carbon drawdown from the atmosphere. Ship crossings sometimes show peaks in chlorophyll a at the front, but at other times these peaks are absent. If the normal mode of primary productivity at the front consists of intermittent bloom events, as these observations suggest, organisms endemic to this habitat may have to be adapted to a boom-or-bust situation. We have studied the presence of chlorophyll a using daily SeaWiFS images and showed that bloom events with limited spatial and temporal scales are indeed the norm. A coupled physical-biological model simulates this process with a fair degree of verisimilitude. We use this model to investigate the physico-biogeochemical requirements for bloom events and demonstrate that in most cases the limiting factor is intensity of vertical stratification combined with light availability.
DE: 4855 Plankton
DE: 4279 Upwelling and convergences
DE: 4528 Fronts and jets
DE: 4572 Upper ocean processes
SC: Ocean Sciences [OS]
MN: 2004 AGU Fall Meeting