Super Cyclones Induce Variability in the Aerosol Optical Depth Prior to Their Formation Over the Oceans

Abstract

We report the variability in aerosol optical depth (AOD) (550 nm) from the Moderate Resolution Imaging Spectroradiometer, surface winds from QSCAT, and air mass trajectories from HYSPLIT, about 15 days prior to the formation of the super cyclones GONU (over the Arabian Sea during June 2-5, 2007) and SIDR (over the Bay of Bengal during November 11-16, 2007) in the Indian Ocean. The analysis reveals a persistent “aerosol low” with AOD at 0.1 in the region of the cyclone formation and a region with AOD at 0.7-0.9 in the adjacent domains. The variability in the QSCAT wind fields and air mass trajectories also supports the presence of the “aerosol low.” Analysis of the seven deadliest hurricanes (Katrina, etc.) in the last decade over the North Atlantic also reveals the “aerosol low” patterns of AOD variability, about 15 days prior to the occurrence of these hurricanes.