Energetics and temporal variability of internal tides in Luzon Strait: a nonhydrostatic numerical simulation

Abstract

A fully nonlinear, three-dimensional nonhydrostatic model driven by four principal tidal constituents (M2, S2, K1, and O1) is used to investigate the spatial-temporal characteristics and energetics of internal tides in Luzon Strait (LS). The model results show that, during spring (neap) tides, about 64 (47) GW (1 GW=109 W) of barotropic tidal energy is consumed in LS, of which 59.0% (50.5%) is converted to baroclinic tides. About 22 (11) GW of the derived baroclinic energy flux subsequently passes from LS, among which 50.9% (54.3%) flows westward into the South China Sea (SCS) and 45.0% (39.7%) eastward into the Pacific Ocean, and the remaining 16 (13) GW is lost locally owing to dissipation and convection. It is revealed that generation areas of internal tides vary with the spring and neap tide, indicating different source areas for internal solitary waves in the northern SCS. The region around the Batan Islands is the most important generation region of internal tides during both spring and neap tides. In addition, the baroclinic tidal energy has pronounced seasonal variability. Both the total energy transferred from barotropic tides to baroclinic tides and the baroclinic energy flux flowing out of LS are the highest in summer and lowest in winter.