Energetics of the M[formula omitted] internal tides modulated by typhoons at the Luzon Strait

Abstract

This study investigates the influence of typhoons (a real typhoon, Megi in 2010, and four idealized typhoons) on the energetics of the M2 internal tides (ITs) at the Luzon Strait (LS) based on the numerical simulation. Results indicate that typhoon Megi caused intense low-frequency currents and stratification variation near the LS, which further induced significant temporal variations in the M2 conversion, baroclinic energy fluxes and dissipation at the LS. With a condition of no background currents, typhoon Megi reduced the M2 conversion at the LS by 4.5% and weakened the westward M2 baroclinic energy fluxes into the South China Sea by 14.3%. Typhoon Megi did not significantly change the averaged M2 dissipation at the LS, but it elevated the averaged local dissipation efficiency to some extent. When background currents were taken into consideration, the influence of typhoon Megi on the M2 conversion and baroclinic energy fluxes was weakened, but the influence on the M2 dissipation was enhanced. Experiments of idealized typhoons indicate that typhoons with different tracks have different influences on the M2 ITs at the LS. With the same characteristics (radius, maximum wind speed and translation speed), the typhoon that passes over the LS from east to west causes the largest variation in the energetics of the M2 ITs at the LS.