Hydrographic condition and variability in the Yellow Sea and East China Sea during winter

This paper deals with the hydrographic condition and variability in the Yellow Sea and East China Seas during winter. It is based on data obtained from the joint Chinese(Norwegian surveys during the period 1984 to 1995. The results indicated that:(1) From November to March, the water temperature there was decreasing, the Yellow Sea Cold Water, the Yellow Sea Warm Current and Yellow Sea Coastal Current mainly dominated the survey areas;(2) The vertical distribution of hydrographic factors varied through the winter. From November to March the thickness of upper homogeneous layer became thicker and the thermocline, halocline and Yellow Sea Cold Water less pronounced, in January March, these features disappeared and the hydrographic conditions were almost homogenous through the whole water column from surface to bottom;(3) The Yellow Sea Cold Water mass and Yellow Sea Warm Current showed strong clear inter annual variation. The temperature and salinity of Yellow Sea Cold Water were more stable. However, its relative volume in the stronger year(November, 1986) was 4 44 times that in the weaker year(Novemner, 1985). The Yellow Sea Warm Current’s speed in the stronger year(January, 1986) was 1.21 times that in the weaker year(January, 1992);(4) Anchovy was mainly distributed in the warm or cold water tongue areas formed by Yellow Sea Warm Current or Yellow Sea Coastal Current with temperature of 11 13℃.The thermocline had apparent effects on their vertical migration and they tended to stay above it most of the day.