A062-0021
Regional Study of Turbulent and Radiation Fluxes In Bay of Bengal (BoB) Using Modular Ocean Model (MOM)
Wednesday, 9 December 2020
Poster
Siddhesh Tirodkar, Indian Institute of Technology Bombay, IDP in Climate Studies, Mumbai, India, Manasa Ranjan Behera, Indian Institute of Technology Bombay, Department of Civil Engineering, IDP in Climate Studies, Mumbai, India and Sridhar Balasubramanian, Indian Institute of Technology Bombay, Department of Mechanical Engineering, IDP in Climate Studies, Mumbai, India
Abstract:
Turbulent and radiation fluxes impacting on ocean surface controls the stability and properties of ocean. The regional domain study encourages, evaluation of parameters impacting the weather and climate pattern. In regional domains the open boundary condition (OBC) applied is important to understand mass and tracer exchange across the boundary. BoB basin in north Indian Ocean is one of the unique regional domains with geographical location trapped by 3 sides keeping only south boundary open for interaction. BoB has seasonal wind reversal and huge amount of fresh water flux. Previous studies found that air-sea fluxes play a dominant role in evolution of sea surface temperature (SST). Many studies are performed with Indian Ocean basin having sponge boundary condition to analyse dynamics of basin. This study focuses on implementation of radiation open boundary condition with only wind stress forcing and wind stress plus radiation fluxes.
A regional modelling approach is used with MOM5 developed by NOAA’s GFDL. A small domain in BoB is selected with horizontal resolution of 0.25o and vertical resolution of 5 m near surface and increases with depth. OBC is implemented at west, east and south boundary of the domain, based on the technique proposed by Orlanski in 1976. KPP vertical mixing scheme is used. Simple Ocean Data Assimilation wind stress and Japanese 25-year reanalysis radiation flux are forced for period of 10 years. Initial profile of temperature and salinity are prescribed from World Ocean Atlas. Model is forced with TOPEX sea surface height at boundary to account for incoming waves. First 5 years of simulations are considered for spin-up to ensure consistency of model results. The model result captures seasonal variability in ocean currents due to wind reversal of BoB perfectly. Combination of wind stress with radiation fluxes reduces bias in SST, SSS and MLD. Heat budget calculation shows good agreement with WHOI (OAFlux). Conservation of mass in domain confirms radiation open boundary suits well in our domain without prescription of data at boundary.
