Characteristics of salinity-controlled submesoscale fronts in the Bay of Bengal and their impact on the upper ocean

This study investigates the characteristics of salinity-controlled submesoscale fronts in the Bay of Bengal (BoB), based on a high resolution model output (MITgcm LLC4320). Large horizontal gradients of temperature, salinity, and density are found in the northern bay, with salinity and density gradients being notably more pronounced than those of temperature. Density fronts in this region are controlled by salinity rather than temperature due to the amount of freshwater input. Salinity fronts are most often compensated by temperature in the upper ocean of the BoB, especially at small scales. Fronts are classified into 4 types based on the value of the Turner angle. Among them, the salinity-controlled fronts compensated by temperature play a leading role in the northern BoB from October to March, while salinity-controlled fronts reinforced by temperature become equally numerous during the rest of the year. Heat fluxes significantly affect the temporal variations of temperature compensated versus reinforced fronts, while freshwater fluxes only play a minor role. When compensated fronts get arrested, warm water sinks beneath the cool water, favoring the formation of a temperature inversion layer and a barrier layer.