The circulation of the Japan/East Sea is characterized by significant temporal and spatial variability due to several factors, including seasonal fluctuations in the warm inflow through Tsushima Strait, branching of the Tsushima Warm Current downstream of the strait, and the formation of mesoscale eddies along these branches The long-range objective of the Japan Sea study is to understand the dynamical processes that govern this variability.

This book reviews the research in various fields of oceanography on the responses of the East Japan Sea to climate change. The uniqueness of the East Japan Sea comes from the rapid and amplified response to climate change, which includes long-terms trends of physical and chemical parameters at a rate that almost doubles or even higher the global rate. This book aims to provide in an organized way the results from the previously published knowledge but also to introduce an updated view of the research recently carried out. The book is divided into several parts that comprise the physical, chemical, biological, and geological aspects of the region and fisheries. This book is made for researchers and students working on climate variability as well as for the oceanography community working on world’s marginal seas. The research presented in this work will also benefit to researchers from other fields such as social scientists and environmentalists, and also policy makers.

The Japan Sea, known as the East Sea in Korea, covers an area of 106 km2, has a maximum depth in excess of 3700 m, and is one of the four marginal seas of the North Pacific Ocean. The circulation of the Japan/East Sea (hereafter JES) has been studied for nearly a century by scientists from Japan, Korea, and Russia. While this legacy of exploration has left us with some zeroth order notions about the properties of the general circulation of the JES, the most basic questions concerning the JES circulation remain largely unanswered. In recent years, a new climate of scientific cooperation among the nations bordering the JES has resulted in significant advances in our knowledge of the circulation of the JES. It is clear, moreover, that the JES harbors a rich variety of physical phenomena, including wind- and buoyancy-driven effects, sea ice processes, western boundary currents, fronts, mesoscale eddies, topographic effects, flow through narrow straits, deep convection, and many others. Thus, it is conjectured that, beyond the obvious economic and environmental importance of the JES to the countries bordering the Sea, the JES might potentially serve as an important laboratory for examining many physical processes that are ubiquitous in other marginal seas and the global ocean.

The seasonal variability of the Japan/East Sea (JES) circulation was studied numerically using the Princeton Ocean Model (POM) with horizontal resolution varying from 11.54 to 18.53 km and 15 sigma levels conforming to a relatively realistic bottom topography. The model was integrated using climatological monthly mean wind stresses, heat and salt fluxes as surface forcing and observational oceanic inflow/outflow at open boundaries. The seasonally averaged effects of isolated forcing terms are presented and analyzed from the following experiments: 1)non-linear effects removed,2) no lateral transport at open boundary, and 3) wind effects removed. Major currents are simulated reasonably well compared to observations. The nonlinear advection does not affect the general circulation pattern evidently, but does affect the formation of the mesoscale eddies, especially the Ulleung/Tsushima Basin (UTB) eddy (all seasons) and the Japan Basin (JB) cyclonic gyre (spring). The lateral boundary forcing enhances (weakens) the JES volume transport in the summer (winter). The wind forcing is the most important factor (80%) for generating the JB cyclonic gyre. Besides, it drives the Liman Current and damps the East Korean Warn Current in the winter, and generates the UTB eddy, and eddies along the Japan Nearshore Branch (JNB) in all seasons. However, it has almost no effect on the JNB currents for all seasons.

This book presents the views of leading scientists on the knowledge of the global ocean circulation following the completion of the observational phase of the World Ocean Circulation Experiment. WOCE's in situ physical and chemical measurements together with satellite altimetry have produced a data set which provides for development of ocean and coupled ocean-atmosphere circulation models used for understanding ocean and climate variability and projecting climate change. This book guides the reader through the analysis, interpretation, modelling and synthesis of this data.