Influence of the Indian Ocean Dipole (IOD) on Convectively Coupled Kelvin and Mixed Rossby-Gravity Waves

Abstract

Indian Ocean Dipole (IOD) is a mode of natural climate variability that arises from a zonal-dipole structure in interannual variations of the tropical Indian Ocean. Understanding the influence of IOD on atmospheric circulation is important in order to improve weather forecasts and climate predictions in the Tropics and the extratropics on time scales beyond a few days. This study investigates the role of IOD on convectively coupled equatorial wave (CCEW) activity, including Kelvin and MRG waves and examines the potential links between them. The results show that positive IOD event leads to enhance Kelvin wave and MRG wave activities over the eastern Africa and southern Indian Ocean. On the other hand, it suppresses Kelvin and MRG wave activities over the eastern Indian Ocean and the Maritime continent. It is also shown that IOD's influence on Kelvin and MRG waves activity is non-dependent to ENSO activity. These results highlight the importance of IOD in generating Kelvin and MRG waves in the tropics.