Simulating and understanding the gap outflow and oceanic response over the Gulf of Tehuantepec during GOTEX

Two sensitivity experiments were conducted to understand the relative roles of the wind stress and heat flux on the ocean cooling. The control has more cooling right under the gap flow region than either the wind-stress-only or the heat-flux-only experiment. Overall, the wind stress has a slightly larger effect in bringing down the ocean temperature near the surface and plays a more important role in local ocean circulations beneath the mixed layer. The impact of surface heat flux on the ocean is more limited to the top 30 m within the mixed layer and is symmetric to the gap flow region by cooling the ocean under the gap flow region and reducing the warming on both sides. The effect of surface wind stress is to induce more cooling in the mixed layer under the gap wind through upwelling associated with Ekman divergence at the surface. Its effect deeper down is antisymmetric related to the nearby thermocline dome by inducing more upwelling to the east side of the gap flow region and more downwelling on the west side. Diagnostics from the mixed layer heat budget for the control and sensitivity experiments confirm that the surface heat flux has more influence on the broader area and the wind stress has more influence in a deeper region.