Mechanism of formation of seasonal sea surface temperature fronts in the northeastern Arabian Sea
Abstract
Using simulations from a high-resolution (?2.3 km) Regional Ocean Modelling System (ROMS), we investigate the mechanism of formation of two seasonally occurring long-lived sea-surface-temperature (SST) fronts, namely the West India Shelf-Slope Front (WISSF) and the West India Mid-Shelf Front (WIMSF), which have been shown to occur during the winter monsoon in the northeastern Arabian Sea (NEAS). The simulations reveal that the WISSF forms along the edges of the poleward West India Coastal Current (WICC). This occurs as the WICC advects warm water along the shelf break into cooler ambient waters on either side of the NEAS, which are cooled by surface heat loss. Even though the surface heat loss in the Gulf of Khambhat (GoKb) is less than offshore on the shelf or in the deeper NEAS, the lowest SSTs occur in the gulf owing to its shallowness. This differential cooling leads to the formation of WIMSF, which forms the boundary between the cold waters of the gulf and the warmer waters offshore. Our study show that though these large-scale processes, advection by the WICC and surface cooling by atmospheric fluxes, drive the formation of the SST fronts in the NEAS, tidal forcing is important to simulate their positions accurately because the tidal currents control advection of cold water from the GoKb onto the shelf and vertical mixing due to the tides determines the location of the front at the shelf break.
URI
https://www.sciencedirect.com/science/article/pii/S0924796326000333http://drs.nio.res.in/drs/handle/2264/9647
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