Estimation of Vertical Heat Diffusivity at the Base of the Mixed Layer in the Bay of Bengal
M. S. Girishkumar, K. Ashin, Michael J. McPhaden, B. Balaji, B. Praveenkumar
Abstract
Abstract One approach to estimating vertical heat diffusivity ( K T ) is to compute it from the residual of the mixed layer (ML) heat budget. Based on this approach, we use moored buoy data at 15°N, 12°N, and 8°N along 90°E over the period of 2007–2018 to estimate the seasonal average of K T at the base of the mixed layer in the Bay of Bengal (BoB). We find that K T is lower during spring and higher during winter compared to summer and fall at the mooring locations. Moreover, K T is generally higher in the southern BoB compared to the northern BoB. The present study also shows that the seasonal and spatial variability of K T is modulated both by stratification at the base of ML and by seasonal and spatial heterogeneity in atmospheric forcing, most notably wind stress and buoyancy flux. The availability of information on the spatial and seasonal variability of K T in the BoB will facilitate evaluation and validation of turbulent mixing parameterization schemes incorporated into ocean models.