Imprints of coastal mountains on ocean circulation and variability

Coastal mountains often induce large wind curls in the lee, exerting a significant forcing on ocean circulation via the Rossby wave and other mechanisms. This study compares the ocean response to coastal mountain forcing in the summer South China Sea and winter far-east Pacific off Central America. Both oceans feature high sea surface temperatures and can potentially affect the atmosphere. Orographic forcing in the former and latter regions comes from the western and eastern boundaries of the respective basins. In the summer South China Sea, the southwest monsoon winds are accelerated at the southern tip of the Annam Cordillera. The dipole wind curls force a double-gyre circulation, cyclonic to the north and anticyclonic to the south. The offshore ocean jet in between advects cold upwelled water from the Vietnam coast, forming cold filaments (Xie et al. 2003). This double-gyre circulation displays pronounced intraseaonal and interannual variability, forced by the atmospheric Madden-Julian Oscillation (Xie et al. 2007) and El Nino/Southern Oscillation. The OFES QuikSCAT run simulates the seasonal development and intraseasonal to interannual variability of the double gyre circulation, in response to variations in the southwesterly wind jet