Estimation of Latent Heat Flux using Satellite Based Observations over North Indian Ocean

摘要

A larger part of the heat supplied by the tropical oceans, through evaporation is utilized for development of large-scale weather systems. The knowledge of evaporation rates/Latent Heat Flux (LHF) over the ocean is essential for parameterizing Ocean-atmospheric coupled predictive models.There are several methods in estimating evaporation rates/LHF over the ocean. Among them, the prominent are (1) eddy correlation or direct method, (2) profile or gradient method and (3) bulk aerodynamic method. Here bulk-aerodynamic method is conceived, since the implementation of this method is easy and spatial and temporal coverage is very high. To calculate evaporation rate/LHF using bulk-aerodynamic formulae the parameters required are Wind speed, saturated vapour pressure at sea surface temperature and vapour pressure at air temperature. We estimated LHF using Tropical Rainfall Measuring Mission (TRMM) Microwave Imager (TMI) data for a period of 5 years (2001-2005) during monsoon over North Indian Ocean (N1O). The LHF values found to be high in Somali region during onset phase of summer monsoon and slowly become less, though the winds become stronger. This could be due to sudden fall of SST with the onset and intense upwelling. The variations found to be larger from year to year and these variations are discussed in relation to the intensity of monsoon activity. The LHF estimates are found to be useful in studying the large-scale weather systems. The results pertaining to the study period over NIO are presented.