Air‐sea interaction over the upwelling region of the Somali coast

During the southwest monsoon, two upwelling cells are established along the Somali coast, around 4°N–5°N and 10°N. The sea surface temperatures (SSTs) over these regions can fall to about 22°C on average during this time. Using satellite‐derived data, the covariability in wind and SST is examined for the months of June–August 2005, a particularly strong upwelling season. In July 2005, when a strong localized upwelling event occurred near 4°N–5°N, the Somali Jet, which establishes itself along the coast during June–August, was found to have oscillated at a frequency of about 4–8 weeks. High covariability in mesoscale winds and SSTs were found over the upwelling region. The observed covariability of wind and SSTs is argued to be the result of SST modulation of the atmospheric stability such that over warm temperatures, the unstable atmosphere brings down high winds, and over cold temperatures, the stable atmosphere decelerates the surface winds. These SST‐induced changes in the lower atmosphere lead to changes in wind stress divergence and a dipole in wind stress curl across the cold filament with negative (positive) curl upstream (downstream) of the cold tongue.