Generation and propagation of baroclinic tides modified by the Kuroshio in the Luzon Strait

Abstract

Using a three‐dimensional model with idealized settings, this study evaluated the effect of the Kuroshio on the generation and propagation of semidiurnal M2 and diurnal K1 baroclinic tides (BCTs) in the Luzon Strait (LS). The influences of the varied Kuroshio transport, the location of the Kuroshio, and the separation distance of the two meridional ridges were investigated. The absence of the Kuroshio in the model leads to 30% decreases in the westward baroclinic energy flux (Fbcx) emanating from the west slope of the east ridge compared to the Fbcx with the presence of the Kuroshio. Compared to the Fbcx without the Kuroshio's influence, the westward Fbcx is increased by 20–40% when the Kuroshio is located in either the middle or the west portions of the LS, whereas both the westward and eastward Fbcx are 25–40% decreased as the Kuroshio is moved to the east of the east ridge. The wavelength of the mode 1 M2 BCT is similar to the separation distance of the two ridges, favoring a resonance generation for M2 rather than K1 BCTs. The increase of the Kuroshio transport from 20 to 30 Sv (1 Sv = 106 m3 s−1) enhances the density front but weakens the westward Fbcx owing to the effects of energy advection and lateral friction from the Kuroshio. The influence of the Kuroshio on the westward Fbcx of K1 is opposite of that on M2. The characteristic slope of K1 is closer to the isopycnal slope across the Kuroshio than M2, thereby causing the discrepancy.