The seas bordering the northern part of the Indian Ocean are very much influenced by the
continents and are highly responsive to the varying weather conditions in this region. Since the
Arabian Sea dynamics includes seasonal occurrence of various meso-scale oceanographic features
with dimensions less than even 20 km radius, many of the implemented modeling efforts are
inadequate to monitor the same in both spatial and temporal scale. Hence the present study is
carried out to model the circulation and upwelling processes along the Arabian Sea coast using a
medium scale resolution nested version of the MICOM model.
The model solves the primitive equations, using a split-explicit numerical scheme and is in the
horizontal discretized on an Arakawa C-grid. In the vertical, MICOM uses potential density as the
coordinate. The velocity components, salinity, temperature, layer thickness etc. are the variables
obtained through the simulations. The present implementation of the model has 15 layers based on
density from the investigation area. The upper layer is a mixed layer, which interacts with the
atmospheric forcing through freshwater and heat fluxes and the transfer of wind stress through
entrainment/detrainment processes when the mixed layer deepens/retreats. An orthogonal
curvilinear grid is used in the computations to enhance the resolution in the area of interest
(northern Indian Ocean) and coarser resolution in the peripheral domains. The domain extends from
5 o south to the northern boundary of the Indian Ocean. Parts of Red Sea and Persian
Gulf are also included in the model. All currents and meso-scale features in the model domain have
been well simulated using the model for the two monsoon periods. The features have appeared in
the right position at the right time. Current speeds of the SEC, NMC, IMC, EJ and EICC are in
good agreement with other published model results and observation data and the model seems to
represent the speeds better than reported by previous models. The speeds of the SC and GW are
slightly underestimated compared to observations, but are better than that reported by previous
models. The model has proven to be efficient to hind-cast the ocean circulations, to identify the
water masses well when compared to other model results. The zones of upwelling along the fringes
of the Arabian Sea, viz. Oman coast, Somali coast, the west coast of India, are also well simulated.
Some of the meso-scale features viz., secondary eddy formation in the Socotra region and seasonal
formation of eddies in the Bay of Bengal could not be validated with in situ measurements or with
any previous model results. The appearance of the Eddy G4, reported previously, is confirmed in
the present simulations. |
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