Diagnostics for near-surface wind convergence/divergence response to the Gulf Stream in a regional atmospheric model

This study proposes a novel diagnostics for near-surface wind responses to oceanic fronts. By separating two roles of wind stress, i.e. downward momentum input and the surface friction, the diagnostics can express near-surface winds as a sum of terms relating to pressure adjustment, downward momentum mixing, and horizontal advection. The diagnostics are applied to the climatological wind convergence/divergence over the Gulf Stream obtained from a regional atmospheric model. It is found that the pressure adjustment plays a primary role and is mainly responsible for the convergence, while the downward momentum mixing is a secondary contributing factor to the divergence.