Preface for Special Volume: “Quaternary paleoceanography of the Japan Sea and its linkage with Asian Monsoon”

摘要

The Japan (East) Sea is a semi-enclosed marginal sea located on the mid-latitude eastern margin of the Eurasian continent. It is connected with the East China Sea to the south, Pacific Ocean to the east, and Okhotsk Sea to the north through shallow nad narrow straits with sill depths of approximately 130m, which is close in magnitude to the sea level drop during the last glacial maximum. Thus, significant changes in oceanographic conditions are expected in response to glacio-eustatic sea level changes. Currently, the Tsushima Warm Current (TWC), a branch of the Kuroshio Warm Current is the only current flowing into the sea through the southern Tsushima Strait, and a major part of the TWC flows out through the northeastern Tsugaru Strait. The entrance of the Tsushima Strait is close to the mouths of the Yangtze and Yellow Rivers and the nature of the influx through the strait is influenced by the discharge from these rivers. As the discharge from these rivers is strongly controlled by precipitation from the East Asian Summer Monsoon, the latter should make a significant impact on the paleoceanography of the Japan Sea. The Japna Sea has its own deep water convection system with deep water being formed by strong winter cooling and consequent sea ice formation caused by strong winter monsoon winds in the northwestern part of the sea. Consequently, a linkage between the winter monsoon and deep water convection and/or sea ice formation is expected. Furthermore the Japan Sea is located beneath the wasterly jet that controls the position of the summer monsoon front and carries a large amount of aeolian dust from inland East Asia.