Given the special geographical location of the Northwestern Pacific and its marginal seas， and the im-portant roles that they play in global climate change， there has been increasing national and international research focus on this region since the 1980s. Over the years， China has launched numerous research pro-grams and organized many projects related to this region， with its marine scientists achieving outstanding and fruitful results.
　　In a research career that has spanned nearly four decades， the author of this book has mostly focused on the circulation in the Northwestern Pacific and its marginal seas. In the process， he has directed and or participated in the research projects， inclusive of the international collaborative projects， including 13 under the Ministry of Science and Technology of China （ MOSTC） and State Oceanic Administration （ SOA） ， and another 11 under the National Natural Science Foundation of China （ NSFC）. The author's work has produced a series of important achievements and findings， which have been published in Chinese or English in many renowned national and international scientific journals and publications. On the one hand， these achievements and findings represent to a certain extent the progress made in research on the circulation in the Northwestern Pacific and its marginal seas， on the other hand， these can serve as the foundation for future explorations in this and other related fields. The author's lifetime work and major a-chievements and findings in this field since the 1980s until the present have been compiled and published in this collection titled Circulation in the Northwestern Pacific and its Neighboring Marginal Seas.
　　The collection contains more than 200 papers organized into four volumes. Volumes Ⅰ and Ⅱ contain a total of 106 papers in Chinese. Volume III has 50 English papers， and Volume IV has 50 English papers.
　　Volume I comprises three chapters： Chapter 1. Circulation in the Yellow and East China Seas， var-iations in the Kuroshio in the East China Sea and south of Japan， and the current east of the Ryukyu Islands （ 36 papers） ； Chapter 2. Study of the air-sea interaction of the process of cyclone outbreak over the Yellow and East China Seas （ 10 papers） ； and Chapter 3. Review （6 papers）.
　　Volumell is made up of five chapters： Chapter 1. The currents in the Taiwan Strait， the Kuroshio and its influence on the circulation east of Taiwan， and the currents east of the Ryukyu Islands （ 24 pa-pers ） ； Chapter 2. Current in the Luzon Strait， and the circulations in the South China Sea and their inter-actions with the Pacific waters （ 15 papers） ； Chapter 3. Circulation in the Northwestern Pacific， and the Equatorial current system （ 3 papers） ； Chapter 4. Circulation east of the Philippines （ 2 papers） ； and Chapter 5. Review （ 10 papers）.
　　Volume m is divided into three chapters： Chapter 1. Circulations in the Yellow and East China Seas， variability of the Kuroshio and the currents east of the Ryukyu Islands （ 30 papers） ； Chapter 2.Study on the air-sea interactions of the process of cyclone outbreak over the Yellow and East China Seas
　　（13 papers） ； and Chapter 3. Reviews in the China National Report （7 papers）.
　　Volume Ⅳ will contain five chapters： Chapter 1. Currents in the Taiwan Strait， the Kuroshio and its influence on the circulation east of Taiwan， and the currents east of the Ryukyu Islands （ 18 papers） ；
　　Chapter 2. Currents in the Luzon Strait， variability of circulations in the South China Sea and their inter-actions with the Pacific waters （ 29 papers） ； Chapter 3. Study of models for the calculation of the equato-rial flow （2 papers） ； and Chapter 4. Circulation in the North Pacific （ 1 paper）. In order to avoid input errors， the format of this book follows that of the original papers where had be published.
　　Separately， the author has undertaken a comprehensive analysis of all the contents found in this col-lection ， highlighting the important contributions in each specific area. These are summarized in a paper ti-tled \" Overview of concluded and ongoing research projects and their contributions，\" which is placed after the preface. The purpose of that overview is to facilitate readers' understanding of the context for the pro-gress that has been achieved through the various research findings， and make it more convenient for them to zoom in on the main points and access relevant contents based on their individual needs.
　　The author hopes that this series of research findings can provide people with a more comprehensive and in-depth understanding of the circulation in the Northwestern Pacific and its marginal seas， and will provide important guidance to the next generation of' marine scientists in their future research innovations and discoveries， as well as being at the forefront of research and development. It is also sincerely hoped that this collection of papers will have a positive effect on the development and use of the marine environ-ment and its resources.
　　The research findings presented in this collection were from 24 fund projects under the National Natu-ral Science Foundation of China， the Ministry of Science and Technology of China， and State Oceanic Ad-
　　ministration （ SOA） （ please refer to \"Overview of concluded and ongoing research projects and their con-tributions\" for details）. In addition， the attainment of the findings in this collection and its publication would not have been possible without the strong support and funding of various agencies and organizations，including the State Key Laboratory of Satellite Ocean Environment Dynamics， and Second Institute of Oce-anography， SOA. We would like to take this opportunity to express to them our sincere gratitude and ap-preciation.
　　We would also like to give our heartfelt thanks to our many collaborators in the aforementioned re-search projects and findings： Academicians Jilan Su， Yeli Yuan， Guohong Fang， Dunxin Hu， Dake Chen； Professors Bingxian Guan， Zenghao Qin， Mingyu Zhou， Xiangping Sun， and Professors Cho-TengLiu， Chen-Tung Arthur Chen and Yu-Heng Tseng from Chinese Taiwan； and international collaboratorsProfessors Takano Kenzo and Kaneko Arata from Japan， and Dr. Heung-Jae Lie from Korea. The collabo-rative research projects would not have been successfully completed without all of their sincere cooperation and support. They have certainly made very important contributions to the various findings obtained and detailed in this collection.
　　Last but not least， I would like to express my sincere thanks to all the other authors of papers in this collection， especially for their important contributions to the related papers. The editorial team has inves-ted a lot of time and effort into the publication process of this collection. The quality of this collection was ensured through their detailed and meticulous proofreading and editing of the manuscripts. Their hard work and dedication are much appreciated.