Observed and modelled climatology of the land–sea breeze circulation over the Persian Gulf

Abstract

AbstractA combination of observations and a numerical model revealed the meso‐scale structure of the near‐surface atmospheric conditions over the Persian Gulf. Low‐level winds were dominated by a single, coherent, perennial land–sea breeze circulation (LSBC) that varied seasonally and diurnally. In summer the sea breeze was deeper and wider than in winter. At night the core of the LSBC over the Gulf was confluent with uplift, whereas in daytime it was difluent with subsidence. Sensitivity tests with the model revealed the influence on the LSBC of the land–sea distribution, orography and the ambient wind. The latter resulted in different conditions over the north, east, south and west coasts. Over the north coast, where the opposing ambient wind created a sea breeze front, landward penetration was very limited; over the south coast it was over 250 km. The thermal effect of the Iranian mountains accentuated the depth and penetration, landward and seaward, of the LSBC, thus influencing the duration of the land and sea breezes over the east coast. From spring to autumn the marine boundary layer over the Gulf was shallow, cool, moist and stable, with strong vertical gradients of temperature and humidity at its top. Its depth increased in the ambient flow from northwest to southeast and also, in daytime, from west to east, because of different magnitudes of the subsidence in the sea breeze circulation over the west and east coasts. Copyright © 2004 Royal Meteorological Society