Presenter: Daquan Guo (KAUST)

Description:
As a semi-enclosed marginal sea, the Red Sea connects with the open ocean through only one narrow strait in its southern end and the water exchanges at the strait is crucial for the water mass transformations and thermohaline circulation in the Red Sea. In this study, a 3D high-resolution non-hydrostatic MIT general circulation model (MITgcm) is utilized to investigate the tidal influences on the water exchanges at the Bab al Mandeb (BAM) strait through numerical simulations with and without a tidal forcing mechanism. We found that the summer intrusion of Gulf of Aden Intermediate Water (GAIW), is strongly affected by tidal influences. With the tides included, the along-axis northern extension of the intrusion is reduced by up to 100 km and the volume transport is reduced by 20 percent on average. Two aspects are suggested to contribute to the tidal hindering effects: (i) tidal residual currents that propagate in an opposite direction against the pathway of the summer intrusion currents; (ii) enhanced vertical mixing at the pycnocline and near the benthic topography at the strait, which brings more instabilities along the pathway of the intrusion.