Relation of ice conditions with climate change in the Bohai Sea and the northern Huanghai Sea

The ice conditions in the Bohai Sea and the northern Huanghai Sea greatly change from year to year with winter climate.Ice only covers less than 15% of waters during the warmest winter,while it covers more than 80% during the coldest winter.Ice obser vation and data acquisition are outlined.The ice covered area,the position of ice edge and the ice grades give indication of the ice conditions.The local climate of waters can be expressed by using the air temperature of Stas Dalian and Yingkou.The variation of the ice condition index es with the monthly mean air temper ature at Sta.Dalian from 1952 to 2000 is shown as well.The local climate and ice conditions in the waters are affected by many factors,such as evolution of the general atmospheric circulation and the solar activity.The delayed correlation between the ice conditions and affecting factors is analysized.The ice conditions are continuously mild since the 1990s,which is related to the tendency of the global warming.The ice condition variation of the Bohai Sea is related to the El-Nino event and the sunspot period.The seasonal evolution of the ice conditions is also described.