Hydrographic indications of advection/convection effects in the Gulf of Elat

Abstract

The convective/advective balance at the northern end of the Gulf of Elat was investigated by comparing observed data to a numerical model's predictions. The data, monthly temperature and salinity profiles collected from July 1988 to August 1989, indicate a continuously developing annual cycle, with the water column reaching vertical homogeneity in February and the new thermocline beginning to develop in March. In the summer, an upper 200 m thermally stratified layer (surface temperatures reaching 26°C) overlies a thermally homogeneous layer of 21°C. Salinity is close to 40.5% and varies by less than 0.5% throughout the year, although a salinity minimum develops in the upper layer in late spring and erodes and deepens in the fall and winter as the water column becomes mixed. The strictly one-dimensional convective model successfully reproduces the thermal structure, with a slight lag in summer thermocline development, but is unable to predict the observed salinity minimum. The addition of some advected Red Sea water (40.3%) to the model enables the reproduction of the salinity minimum. This inflow of warmer water also may account for the relatively early thermocline development.