Coupling Between The North Indian Ocean And The Monsoons: A Model Based Study Of The Thermal Structure Cycling In The Central Arabian Sea

Abstract

To examine the role of various intervening processes in controlling the upper ocean thermal structure in the central Arabian Sea, a 1-D mixed-layer model based on turbulent closure scheme is forced by atmospheric fluxes and advective heat fluxes over the one-year period of the JGOFS time-series starting from mid-October 1994 in the central Arabian Sea at (61.5°E & 15.5°N). Atmospheric forcing data are available from the moored array observations (Weller et al. [2]). The horizontal advective contributions at the study location are available from two different sources. The first estimate is based on local in situ measurements (as earlier estimated by Fischer et al. [4]). The second estimate is based on optimally interpolated satellite SST field and in situ currents. The vertical velocity, as in all oceanography problem, poses a challenge. Two possible approaches have been considered for the diagnostic analysis. In the first approach, the model was used to predict the temperature profile (using atmospheric fluxes and estimates of horizontal and vertical advection). In the second approach, the observed temperature profiles (and atmospheric fluxes and estimates of horizontal advection) were used to force the model in order to predict the vertical velocity. Besides the main experiments carried out using the above two approaches, additional experiments were also performed mainly for two purposes: (i) to support the analysis of the results obtained from the main experiments, and (ii) to examine the role of auxiliary parameters (salinity and biomass) in the seasonal evolution of upper-ocean temperature. Finally, model-based heatbudget analysis for the four monsoon seasons: winter, spring, summer, and autumn has been carried out. The following are the three important conclusions of the thesis.