Latent heat flux variability over the tropical Indian Ocean

The seasonal evolution and interannual variability of latent heat flux (LHF) over the tropical Indian Ocean (TIO) region is examined for the period 1980-2019. The seasonal distribution of LHF is dominated by the winter pattern of each hemisphere in the TIO. Climatologically high LHF is mostly confined to the Arabian Sea and Bay of Bengal regions in the north Indian Ocean and the zonal belt between 10 degrees S and 25 degrees S in the south Indian Ocean. Warm and cold phases of El-Nino Southern Oscillation, Indian Ocean Dipole (IOD), and their co-occurrence events leave distinct LHF signatures over the TIO. The LHF anomalies during these events are more profound than pure events with enhanced latent heat loss when the La Nina and negative IOD events coincide. The LHF anomalies associated with the wind-evaporation-SST feedback is prominent when positive IOD co-occur with the El-Nino event. Both the vertical humidity gradient and wind speed changes play substantial roles in driving LHF anomalies during the co-occurring events of NIOD and La Nina.