Connections between the summer east African and Indian rainfall regimes

Abstract

Rainfall over parts of east Africa and India is observed to be positively correlated and associated with variations in the low‐level height field over the northern Indian Ocean and the Arabian Peninsula. A regional climate model is used to understand the mechanisms of this covariability. SST anomalies in the Arabian Sea are imposed to generate anomalies to analyze. Variations in the monsoon trough, which is located over east Africa extending eastward to southeastern Asia, regulate the connection between east Africa and India and mediate the precipitation covariability in the model. When the monsoon trough is weak, northern Ethiopia and western India are dry, in association with a weaker Somali jet, but rainfall is enhanced over southern Ethiopia. Over east Africa, rainfall decreases over northern Ethiopia are related to increased dry air advection from the north. The atmospheric response when the monsoon trough is strong is not the opposite of the weak trough simulation as conditions are wetter over West India, but drier over all of Ethiopia. Hydrodynamical processes including latent heating are more influential in the vicinity of the western Indian Ocean when the monsoon is perturbed by warm Arabian Sea SSTAs.