Aerosol optical depth variability over Arabian Sea during drought and normal years of Indian monsoon

Abstract

We investigated MODIS (MODerate Resolution Imaging Spectroradiometer) derived Aerosol Optical Depth AOD (at 550 nm) and its variability in the mid monsoon month of July, over the Arabian Sea (45°E-75°E; 10°N-27°N), for the years 2001-2004, encompassing 2 normal (2001, 2003) and 2 drought years (2002 and 2004). Over the Arabian Sea, positive AOD anomalies (+0.2 to +0.7) during the normal years and negative AOD anomalies (-0.2 to -0.6) during drought years were observed. Variability in the concurrent Outgoing Long wave Radiation (OLR) anomalies from NCEP/NCAR reanalysis, rainfall anomalies from Tropical Rainfall Measuring Mission (TRMM) and NCEP surface winds had been used to examine the observed AOD variability. It is found that the wind direction was responsible for the negative/positive AOD anomalies corroborating to the negative/positive rainfall anomalies and positive/negative OLR anomalies during the drought years and vise a versa for the normal years. Copyright 2008 by the American Geophysical Union.