Water circulation in the Japan Sea is characterized as a formation of the Japan Sea Proper Water from the data observed in 1969 by research vessels belonging to the Japan Meteorological Agency.
   Below 500m depth in the Japan Sea, salinity is relatively high in the northern part and low in the southern. This is opposite to the conditions in the surface layer, where the northern part is generally the Cold Current Region and the southern part the Warm Current Region. In the southern part of the eastern Japan Basin of the northern Japan Sea, anticyclonic circulation occurs and sea waters sink towards the bottom. In the western Japan Basin and in the Yamato Basin, sea waters flow upward, in contrast to the southern part of the eastern Japan Basin. Therefore vertical water circulation generates in the deep layer of the Japan Sea, that is, downwelling appears in the southern part of the eastern Japan Basin, and upwelling occurs in the western Japan Basin and in the Yamato Basin.