Development of the Sri Lanka Dome and Links to Air-Sea Interaction

The Sri Lanka Dome (SLD) is an upwelling recirculation feature found in the Southwest Monsoon Current that may significantly influence both biological productivity and air-sea interactions in the Bay of Bengal. Here, the twenty-year time series of detrended AVISO satellite absolute dynamic topography is used to track and measure the intensity of the SLD, which shows both a strong seasonal cycle and considerable interannual variability. The dome typically forms in May to the east of Sri Lanka, intensifies through July and August, and migrates to the north and then west before dissipating in September off the coast of northeast Sri Lanka. SLD formation and dissipation, migration path, and magnitude display considerable interannual variability. We also quantify the SLD internal structure using the ARGO float record. The SLD is associated with an elevated pycnocline that is often capped with a fresh surface layer, limiting direct communication of upwelled cold water with the surface. The sea surface temperature response is complex as the subsurface temperature structure is not necessarily monotonic with with height. We also address forcing by remote and local winds and the relation between the SLD and surface heat fluxes through its influence on SST.