Air-sea flux and SST Variability associated with Atmospheric Rivers in the Southeast Indian Ocean

A previous study demonstrated that atmospheric rivers (ARs) generate substantial air-sea fluxes in the northeast Pacific. Since the southeast Indian Ocean is one of the active regions of ARs, similar air-sea fluxes could be produced. However, the spatial SST pattern in the southeast Indian Ocean, especially along the west coast of Australia, is different from that in the northeast Pacific, because of the poleward flowing Leeuwin Current, which may cause different air-sea fluxes. This study investigates AR-associated air-sea fluxes in the southeast Indian Ocean and their relation with SST variability. A large-scale spatial pattern of latent heat flux (evaporation) associated with ARs in the southeast Indian Ocean is similar to that in the northeast Pacific. However, a significant difference is found near the coastal area where relatively warm SSTs are maintained in all seasons. While AR-induced latent heat flux is nearly zero around the west coast of north America where the upwelling generates relatively cold SSTs, a significant latent heat flux induced by ARs is evident along the west coast of Australia. Temporal variations of air-sea fluxes associated with landfalling ARs are investigated based on the composite analysis. While the latent heat flux is reduced by the moisture advection during landfalling, it is largely enhanced after a few days because the air humidity is largely reduced right after the landfalling whereas the relatively high wind speed is still maintained. A significant SST cooling along the coast is found due to the enhanced latent heat flux.