The Xiamen Symposium on Marine Environmental Sciences (XMAS 2027)

This study investigated the seasonal dynamics of deep-water overflow in the Luzon Strait (LS) based on numerical simulations. The results suggest a strong interplay between the upper- and deeper-layer processes that modulate overflow seasonality. The bottom pressure gradient force (PGF_along) across the Bashi Channel and Luzon Trough appears to be the primary factor shaping these dynamics. In general, both the upper (above 500 m) and deeper (below 2,000 m) layers of the LS contribute to deep PGF_along and overflow. Upper PGF_along is influenced by sea-level differences crossing the strait, whereas deep PGF_along is largely related to the density difference between the Pacific Ocean and South China Sea. Seasonally, variations in the intensity and pathways of the Kuroshio Current affect the surface sea levels, leading to oscillations in the isopycnal surfaces. These surface oscillations are transmitted downward and affect bottom PGF_along over the Bashi Channel. Together with density oscillations originating from the deep Pacific Ocean and the deep South China Sea, these processes contribute to the variability of the deep-water overflow in the LS. Weakening wind stress or reductions in Kuroshio strength could potentially reduce the variability of this overflow, underscoring the interconnectedness of atmospheric influences and oceanic responses in this region.