This book summarizes achievements of the study on circulation and air–sea interaction and development of the ocean observation network in the South China Sea in the last 20 years, thus serving as a comprehensive reference book to understand the dynamic environment in the SCS. It consists of seven chapters, briefly reviewing our understanding of the SCS circulation and air–sea interaction in chapter 1, then describing in detail the upper layer circulation from large scale (SCS through flow, SCS western boundary current, etc.), to meso- and submeso-scale in Chapters 2 and 5, dilute river...