Moored observations of the surface meteorology and air-sea fluxes in the northern bay of Bengal in 2015

Time series of surfacemeteorology and air-sea fluxes from the northern Bay of Bengal are analyzed, quantifying annual and seasonal means, variability, and the potential for surface fluxes to contribute significantly to variability in surface temperature and salinity. Strong signals were associated with solar insolation and itsmodulation by cloud cover, and, in the 5- to 50-day range, with intraseasonal oscillations (ISOs). The northeast (NE) monsoon (DJF) was typically cloud free, with strong latent heat loss and severalmoderate wind events, and had the only seasonalmean ocean heat loss. The spring intermonsoon (MAM) was cloud free and had light winds and the strongest ocean heating. Strong ISOs and Tropical Cyclone Komen were seen in the southwest (SW)monsoon (JJA), when 65% of the 2.2-m total rain fell, and oceanic mean heatingwas small. The fall intermonsoon (SON) initially hadmoderate convective systems and mean ocean heating, with a transition to drier winds andmean ocean heat loss in the lastmonth. Observed surface freshwater flux applied to a layer of the observed thickness produced drops in salinity with timing and magnitude similar to the initial drops in salinity in the summer monsoon, but did not reproduce the salinity variability of the fall intermonsoon. Observed surface heat flux has the potential to cause the temperature trends of the different seasons, but uncertainty in how shortwave radiation is absorbed in the upper ocean limits quantifying the role of surface forcing in the evolution of mixed layer temperature.