Regional modeling of surface and sub-surface dynamics in the Bay of Bengal using Modular Ocean Model

TL;DR

This study uses the Modular Ocean Model with high resolution and boundary conditions to analyze surface and sub-surface dynamics in the Bay of Bengal, revealing regional energy transfer mechanisms and validating key ocean parameters.

Contribution

It demonstrates successful regional modeling of the Bay of Bengal with detailed analysis of energy cascades and boundary exchanges using MOM and KPP scheme.

Findings

Successful implementation of open boundary conditions in regional MOM simulations.

Good agreement of SST and SSS with SODA reanalysis.

Identification of inverse energy cascade and regional differences in turbulence.

Abstract

Regional dynamics of Bay of Bengal is studied using Open Boundary Condition (OBC) in Modular Ocean Model (MOM) to understand the effect of primary and secondary mesoscale features on various bulk ocean products and turbulent fluxes. A horizontal resolution of 0.1o is adopted to resolve a range of mesoscale features. In order to parametrize the vertical mixing, K-Profile Parametrization (KPP) scheme is implemented. The results show successful implementation of OBC in a regional domain with exchange of mass and energy and conservation of mass at the boundaries. The Sea Surface Temperature (SST) and Sea Surface Salinity (SSS) are validated with SODA reanalysis, which are found to be in good agreement. The Mixed Layer Depth (MLD) pattern is very well represented, albeit the magnitude is slightly under-predicted in comparison with SODA reanalysis. Additionally, analysis of flow energetics reveal regional differences in turbulent kinetic energy (K), production flux (P), buoyancy flux (B), and dissipation ({\epsilon}). Our results clearly reveal the presence of inverse energy-cascade in the southern Bay of Bengal, wherein energy flows back into mean flow structures from the turbulent eddies. The re-energization of mean flow structures is likely to allow the large-scale circulation to persist for longer periods, thereby modifying the local dynamics. Further analysis shows that the B term is the major source of turbulence production in the north and central Bay of Bengal regions. These results convey the various mechanisms by which energy is produced and transferred in different regions of Bay of Bengal.