Changes in Atmospheric Convection Over the Indo-Pacific Warm Pool and Coupled IOD and ENSO Patterns During the Last Glacial Maximum

Abstract

This study investigates how the convection over the Indo-Pacific Warm Pool responds to the Last Glacial Maximum conditions. Paleoproductivity records that can indicate seasonal wind dynamics are combined with modeling data. Seasonal southeasterly and northeasterly winds off Sumatra are both strengthened, meanwhile, anomalous westerly winds occur over the western Celebes Sea. This reflects a zonal “tripole” pattern of the changed convection that is weakened over the exposed Sunda and Sahul shelves and strengthened over the eastern equatorial Indian Ocean and western equatorial Pacific. Model results suggest that lower sea levels and larger ice sheets are responsible for these changes. Coupled with the changed atmospheric circulation, a positive Indian Ocean Dipole-like mean state forms in the Indian Ocean. The Pacific likely exhibits an “eastern Pacific La Niña”-like superposed by a “central Pacific El-Niño”-like mean state. Under such configuration, the Indian Ocean Dipole and El Niño-Southern Oscillation variability probably strengthen.