The impact of trends in South Asia Low pressure center on North Indian Ocean air-sea heat fluxes

Abstract

This paper examines the interannual variability of latent (LE) and sensible (H) heat fluxes over the North Indian Ocean for the summer season (June, July, August), that show positive linear trends during 1958–2017. Using Air-Sea Flux (OAFlux) from NCEP/NCAR reanalysis-I, the variability and trends in LE and H heat fluxes are compared with changes in the position and pressure of the South Asia Low (SAL). Investigation of interactions between the air-sea heat fluxes and SAL pressure center through correlations analysis and with analysis of composites of humidity gradient, temperature gradient and vector wind fields is carried out. The results show that the SAL plays an important role in the variability of air-sea heat fluxes over North Indian Ocean. There is a negative correlation between SAL pressure and its latitude position. A change of the SAL from a north location to a south location induces changes in North Indian Ocean surface winds, humidity and temperature. These, combined with sea surface warming trends, produce trends in summer latent and sensible heat fluxes.