Possible modulation of the connection between the Pacific and Indian Ocean variability by the solar cycle

Abstract

The Indian Ocean Dipole (IOD) mode and El Niño/Southern Oscillation (ENSO) exhibit a substantial correlation during boreal autumn. Although they are separate phenomena, coupling occurs under certain conditions. This study reveals that ENSO-related variability extends into the Indian Ocean, led by a developed South Indian Ocean (SIO) anticyclone, during periods of low solar (LS) activity. During periods of high solar (HS) activity, anomalous sea surface temperatures are confined to the Pacific with little amplification of the anticyclone in the South Indian Ocean. The direct cause of the difference in the SIO anticyclone arises from a shift in the location of the descending branch of the anomalous Walker circulation. This may be attributable to a change in the background Indian Ocean monsoon circulation which can be modulated by changes in solar irradiance. Copyright 2007 by the American Geophysical Union.