Thermodynamic Response of a High-Resolution Tropical Indian Ocean Model to TOGA COARE Bulk Air–Sea Flux Parameterization: Case Study for the Bay of Bengal (BoB)

This study analyzes the thermodynamic response of an ocean model to two different flux parameterizations. We compared two experiments, a control run (CR) with the flux formulation proposed by Kara et al. [Journal of Atmospheric and Oceanic Technology, 17(10):1421–1438, 2000] with relative wind effect, and an experimental run (ER) with the Tropical Ocean-Global Atmosphere (TOGA) Coupled Ocean–Atmosphere Response Experiment version 3.0 [COARE3.0, Fairall et al. (J Geophys Res Oceans 101(C1):1295–1308, 1996; J Geophys Res Oceans, 101(C2):3747–3764; J Clim 16(4):571–591, 2003)] flux algorithm in the tropical Indian Ocean. Both experiments are performed for the period 2014–2017. The model is forced with daily analyzed fields of winds, radiation and freshwater fluxes from ERA-Interim. The performance of the CR and ER with respect to in situ and satellite observations is examined for the year 2015 in the Bay of Bengal (BoB). COARE3.0 weakens the surface wind stress by ~ 20% and increases the basin-averaged net heat flux by ~ 14%, and makes the sea surface temperature (SST) warmer by around 0.3–0.9 °C in the BoB in the ER. SST simulations were compared with observations, which revealed that in the ER, the SST errors were reduced by 5–40%, and errors in the temperature profile were significantly reduced by ~ 10 to 40% up to a depth of 80 m. BoB heat budget analysis showed that COARE3.0 significantly increased the upper ocean heat content, caused by a reduction in meridional heat transport across the 10° N latitude. This reduction in meridional heat transport is attributed to the reduced strength of upper ocean circulation resulting in the weakening of meridional volume transport (~ 25%). These findings indicate that COARE3.0 derived fluxes better simulate upper ocean thermal structure in the BoB.