Comparison of near surface dynamic topography during the two monsoons in the western Indian ocean

Abstract

The dynamic topography of the near surface water, 0–400 dbar, relative to 1000 dbar, is shown for the western Indian Ocean during both the southwest and northeast monsoon periods using data acquired during the recent International Indian Ocean Expedition. Seven zonal sections between 20°N and approximately 10°S allow seasonal comparison of essentially the same areas. The areas of greatest seasonal differences were off the Arabian coast and particularly the Somali coast where the large high (> 1·8 dy m) during the southwest monsoon was not evident during the northeast monsoon. The means of the surface topography in the northern ocean show that the winter values were greater by 0·04 dy m than summer. This is attributed to the increased cloudiness, evaporation and coastal upwelling during summer.