Upper ocean high resolution regional modeling of the Arabian Sea and Bay of Bengal
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Upper ocean high resolution regional modeling of the Arabian Sea and Bay of Bengal Dwivedi Suneet1*, Mishra Alok Kumar1, Srivastava Atul1 1 K Banerjee Centre of Atmospheric and Ocean Studies and M N Saha Centre of Space Studies, University of
Allahabad, Allahabad UP 211002, India Received 6 December 2017; accepted 26 February 2018 © Chinese Society for Oceanography and Springer-Verlag GmbH Germany, part of Springer Nature 2019
Abstract
In this paper, effort is made to demonstrate the quality of high-resolution regional ocean circulation model in realistically simulating the circulation and variability properties of the northern Indian Ocean (10°S–25°N, 45°–100°E) covering the Arabian Sea (AS) and Bay of Bengal (BoB). The model run using the open boundary conditions is carried out at 10 km horizontal resolution and highest vertical resolution of 2 m in the upper ocean. The surface and sub-surface structure of hydrographic variables (temperature and salinity) and currents is compared against the observations during 1998–2014 (17 years). In particular, the seasonal variability of the sea surface temperature, sea surface salinity, and surface currents over the model domain is studied. The highresolution model’s ability in correct estimation of the spatio-temporal mixed layer depth (MLD) variability of the AS and BoB is also shown. The lowest MLD values are observed during spring (March-April-May) and highest during winter (December-January-February) seasons. The maximum MLD in the AS (BoB) during December to February reaches 150 m (67 m). On the other hand, the minimum MLD in these regions during March-April-May becomes as low as 11–12 m. The influence of wind stress, net heat flux and freshwater flux on the seasonal variability of the MLD is discussed. The physical processes controlling the seasonal cycle of sea surface temperature are investigated by carrying out mixed layer heat budget analysis. It is found that air-sea fluxes play a dominant role in the seasonal evolution of sea surface temperature of the northern Indian Ocean and the contribution of horizontal advection, vertical entrainment and diffusion processes is small. The upper ocean zonal and meridional volume transport across different sections in the AS and BoB is also computed. The seasonal variability of the transports is studied in the context of monsoonal currents. Key words: Indian Ocean modeling, Arabian Sea and Bay of Bengal, mixed layer depth, transport Citation: Suneet Dwivedi, Alok Kumar Mishra, Atul Srivastava. 2019. Upper ocean high resolution regional modeling of the Arabian Sea and Bay of Bengal. Acta Oceanologica Sinica, 38(5): 32–50, doi: 10.1007/s13131-019-1439-x
1 Introduction Understanding the Arabian Sea (AS) and Bay of Bengal (BoB) circulation and the variability of the Indian Ocean exhibits on different time scales (seasonal, interannual, decadal and longer) is very important for the Indian subcontinent. The better understanding of the AS and BoB circulation and variability of the surface and sub-surface variables shall not only
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