Impact of African orography and the Indian summer monsoon on the low-level Somali jet

Abstract

The low-level jet (LLJ) over the Indian region, which is most prominent during the monsoon (June–September) season, has been studied with a general circulation model (GCM). The role of African orography in modulating this jet is the focus of this article. The presence of African orography intensifies the cross-equatorial flow. Contrary to previous modelling studies we find that cross-equatorial flow occurs even in the absence of African orography, though this flow is much weaker even when the Indian monsoon rainfall is high. However, the location of the meridional jet near the equator in the Somali region is linked to the Indian monsoon rainfall rather than to the land–sea contrast over Somalia. Also, the presence of African orography, and not the strength of the Indian monsoon, controls the vertical extent of the equatorial meridional wind.