Simulated Biological Response
to Various Wind Products

Plankton biomass distributions in the western Arabian Sea region undergo strong seasonal variations as the surface winds change semiannually. Strong coastal upwelling occurring along the Somali coast in summer brings fresh nutrients to the surface, favoring the generation of phytoplankton blooms. These type of blooms are intense and long-lasting, and therefore have a large impact on zooplankton and fishery production in the region. It has been pointed out in previous studies that the intensity of the blooms is sensitive to the atmospheric winds. In this project, a physical-biological coupled system is used to examine how different wind products influence biomass distribution in the western Arabian Sea area. The physical model is the three-dimensional Miami Isopycnic Coordinate Ocean Model (MICOM). The biological model is a multi-species Nutrient, Zooplankton, Phytoplankton, and Detritus model. Two food chains representing macro- and micro-species for zooplankton and phytoplankton are incorporated. Figure 1 shows the simulated distributions of biological variables during the summer monsoon. There is a distinct maximum associated with the Great Whirl, an anticyclone embedded in the summer Somali Current, in all of the biological variables. A relatively weaker maximum associated with the Southern Gyre, an anticyclonic eddy south of the Great Whirl, can be seen in all fields except macro-phytoplankton. The surface current vector field at the height of the summer monsoon, and the time series of plankton at a near-coast location for the various wind product runs, are shown in Figure 2. For a description of the coupled model system and a copy of the manuscripts on this project, please send e-mail to Ge Peng at gpeng@rsmas.miami.edu.

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   Last revised: 5 May 1999