Seasonal influence of the Indonesian throughflow in the southwestern Indian Ocean

The warm ITF waters reach the subsurface SWIO from August to early December, with a detectable influence on weakening the vertical stratification and reducing the stability of the water column. As a dynamical consequence, baroclinic instabilities and oceanic intraseasonal variabilities (OISVs) are enhanced.

The temporal and spatial scales of the OISVs are determined by the ITF-modified stratification. Thermodynamically, the ITF waters influence the subtle balance between the stratification and the mixing in the SWIO. As a result, from October to early December an unusual warm entrainment occurs, and the SSTs warm faster than just net surface heat flux-driven warming.