Getting the right wind-forcing for an ecosystem model: A case study from the eastern Arabian Sea

Abstract

ABSTRACTThe state of the ocean simulated through a numerical model is extremely sensitive to the forcing and hence, the choice of appropriate forcing is essential, in particular wind-fields. We compared Regional Ocean Modeling System (ROMS) simulations when forced with two different wind-fields derived from satellite sensors (scatterometers), namely QuickSCAT and ASCAT, while keeping the remaining configurations the same. This study had been carried out during the operational overlapping period of these scatterometers (2007–2009). We observed that the simulations of upper ocean chlorophyll distribution and depth of sub-surface chlorophyll maximum were vastly diverging when the model was forced with different scatterometer forcings. In order to determine which of the forcings yielded coastal productivity closer to observations, we compared model-simulated upper ocean chlorophyll concentration with in situ observations along the eastern Arabian Sea. For all the sub-regions, the QuickSCAT wind-forced coastal productivity was better correlated with in situ chlorophyll than its counterpart. However, this signature was most prominent in the wind-driven upwelling regime of the south-eastern Arabian Sea. Additionally, when compared with surface chlorophyll derived from SeaWiFS and MODIS-Aqua satellites, we found that the QuickSCAT simulated interannual variability was in better agreement in comparison to its counterpart.