On the observed synoptic signal in the Mississippi‐Alabama slope flow

Abstract

This communication discusses a strong near‐barotropic current signal and its dynamics observed on the Mississippi‐Alabama upper slope in the northeastern Gulf of Mexico. When the variability related to mesoscale eddies is not present or removed, the subinertial current is found to be controlled by the synoptic‐scale wind fluctuations, qualitatively in agreement with coastally trapped wave theory. Specifically, the along‐isobath synoptic velocity component on the Mississippi‐Alabama slope is correlated with the wind stress component in the direction along the Florida peninsula. Moreover, the observed along‐isobath flows on the Mississippi‐Alabama slope and on the west Florida shelf are highly coherent. These relations are pronounced in wintertime but less obvious during summertime, less energetic, wind forcing.