The South China Sea (SCS) is a semi-enclosed marginal sea linked to the broader oceans via various geographically constrained channels. Beneath the main thermocline depth, Luzon Strait is the only conduit for water-mass exchanges. Observations indicate a substantial seasonal variability in the inflow transport of deep water from the Pacific Ocean. This study aims to identify and examine key drivers for such seasonal changes. It is found that seasonal variability of the deep-water transport into the SCS is primarily driven by surface wind stress. An imbalance in wind-driven exchanges of surface water between the SCS and external seas demands compensational transports in subsurface layers so that the net volume transport into the SCS is conserved, resulting in seasonal variations in deep-water overflow. Changes in Karimata Strait exert a particularly influential impact on deep-water inflow, likely due to its unique position as the sole connecting channel across the Equator.

中文翻译：

---

太平洋至南海深水溢流的风力季节变化

南海（SCS）是一个半封闭的边缘海，通过各种地理限制的通道与更广阔的海洋相连。在主要温跃层深度下方，吕宋海峡是水体交换的唯一通道。观测表明，来自太平洋的深水流入运输存在显着的季节性变化。本研究旨在确定并检查此类季节性变化的关键驱动因素。研究发现，进入南海的深水输送的季节性变化主要是由表面风应力驱动的。南海与外部海洋之间由风驱动的地表水交换的不平衡需要地下层的补偿输送，以保持进入南海的净输送量，从而导致深水溢流的季节性变化。卡里马塔海峡的变化对深水流入产生了特别重要的影响，这可能是由于其作为跨越赤道的唯一连接通道的独特地位。