Energetics of Semidiurnal Internal Tides in the Andaman Sea

Abstract

AbstractA detailed energetic estimate of the barotropic and baroclinic semidiurnal internal tides over the Andaman Sea is performed by using the three‐dimensional Massachusetts Institute of Technology general circulation model. Model‐simulated currents and density fields are validated using in situ observations with high temporal resolution from a buoy located at 10.5°N, 94°E. The generation and dissipation regions of internal tides and their propagation in the domain are identified by quantifying the distribution of total tidal energy among generation, radiation, and dissipation. The model simulation suggests that the internal tides are mainly generated in the north of Sumatra coast, in the Sombrero channel, south of the Car Nicobar Island, and north of the Andaman Island. From these generation sites, a portion of the energy propagates into the Andaman Sea and the remainder propagates toward the southern Bay of Bengal. The depth‐integrated baroclinic energy fluxes are found to be a maximum of ~30 kW/m at the major generation sites in the domain. The model‐estimated energy dissipation rates suggest that the maximum amount of energy dissipates near the generation sites themselves. In the region north of the Sumatra coast, almost 87% of the barotropic energy is converted into baroclinic energy and 23% (0.91 GW) of the converted baroclinic energy is ultimately radiated out from the generation sites. The barotropic‐to‐baroclinic conversion rate over the whole domain is estimated to be ~23 GW, out of which, a major part ~18 GW (80%) dissipates near the generation sites. This reveals that the local dissipation of baroclinic energy dominates in the Andaman Sea.