Coupled Modelling of Air-Sea Interaction over the Bay of Bengal during the 2018 Southwest Monsoon
Abstract
Simulations of oceanic and atmospheric conditions and air-sea interaction over the Bengal are presented from a high resolution fully coupled from atmosphere-ocean-waves models based on the Coupled Ocean Atmosphere Mesoscale Prediction System (COAMPS). The model is covering the Indian Ocean north of 18S, with a horizontal resolution of about 3.5 km in the ocean, 9 km in the atmosphere and 10 km for the spectral surface wave model component. Both the atmosphere model and ocean model have up to 60 vertical levels. The ocean model has a minimum of 0.5 m resolution between the surface and 10 m and at least 45 levels between the surface and 330 m. Fluxes between each model module are exchanged every 10 min. The wave model is Simulating Waves Nearshore and has 33 frequency bands and 48 directions. A three-dimensional variational method (3D-var) of data assimilation is applied in the atmosphere and ocean models. The model runs on 622 cores on the Cray XC40 at the Navy DoD Supercomputing Resource Center.
A remarkably strong anti-cyclonic eddy developed in mid-June 2018 between 2N and 6N centered on 85E. It was connected to a strong eastward flow from the Arabian Sea into the Bay of Bengal and a westward flow from Sumatra along the equator and present for 2 weeks. The eddy advected cold surface water from the coastal upwelling region near the southern Sri Lankan coast to the equator and advected warmer equatorial water northward. High temperature anomalies in the core of the eddy were found at depth above 100 m. The eddy impacted net surface heat flux over its northern and western edges, where the colder water gained heat as it moved toward the equator. Its strong currents had an impact on surface wave height driven by the southwest monsoon. The eddy reduced the significant wave height in its northeast quadrant and increased it in the southwest quadrant due to differences in surface stress induced by strong ocean currents.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFMOS23F1694J
- Keywords:
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- 3364 Synoptic-scale meteorology;
- ATMOSPHERIC PROCESSESDE: 4215 Climate and interannual variability;
- OCEANOGRAPHY: GENERALDE: 4263 Ocean predictability and prediction;
- OCEANOGRAPHY: GENERALDE: 4504 Air/sea interactions;
- OCEANOGRAPHY: PHYSICAL