Climatology of mixed layer depth in the Gulf of Aden derived from in situ temperature profiles

Abstract

For the first time in the Gulf of Aden, the climatology of mixed layer depth (MLD) is derived from in situ profiles of temperature at a spatial resolution of 0.5° × 0.5°. The climatology has captured all major features of the MLD variability in the Gulf of Aden. Deepening of the mixed layer is noticed during December–February associated with surface heat loss and cooling induced by strong convection. Further, the heat gain during March–May and subsequent warming strengthens the stratification and results in diminished mixing. The westward-moving cyclonic and anticyclonic eddies during winter change the mixed layer, especially along the northern and western Gulf of Aden. The observed permanent anticyclonic eddy during summer in the central part of the Gulf of Aden induces an additional deepening of the MLD by 30–40 m, even in the presence of a relatively strong stratification. The presence of nearly uniform north-easterly winds from October to April makes the MLD of the northern Gulf of Aden greater than the southern side during this period, while the south-westerly winds from June to August reverse the scenario and makes the northern Gulf of Aden shallower than the southern side.