New Insights into Dynamics of Coastal Low-level Jets

Abstract:

Coastal low-level jets are equatorward lower tropospheric winds along the eastern boundaries of extratropical and subtropical oceans extending from the surface to about 2 km height. These jets are one of the main components of the surface branch of the Hadley circulation, and have a profound influence on local land climate conditions and local ocean circulation and upwelling. In this study, we examine the occurrence and distribution of these jets using both reanalysis data and a global climate model simulation, and use their vorticity budget to understand their dynamics. We find that in the regions of these eastern boundary jets, the most important term in the vorticity budget is the stretching term. The stretching term is balanced by a combination of meridional advection of the planetary vorticity (β effect) as well as the curl of friction, which also play a non-negligible role in the vorticity budget of these jets.