渤海、黄海热结构分析

在多年观测资料基础上,以月平均风应力和周平均海表水温(SST)作为外强迫,对黄海、渤海热结构进行了数值模拟.模拟结果显示渤海的热结构特征自10月至翌年3月为水温垂直均一的冬季型;5～8月为分层结构(由上混合层、跃层、潮混合层组成)的夏季型.4月和9月为两型的过渡期,最低水温出现在2月,最高水温表层出现在8月,底层则在9～10月.黄海沿岸浅水区与渤海有相似的热结构,黄海冷水团和黄海暖流对其中央槽深水区的热结构有重要影响.对底层水的影响而言,前者夏季显著而后者冬季显著,从而导致黄海(槽)的底层水与环境相比呈现夏季冷而冬季暖的特征,底层水温基本上与表面水温的年变化反相;深水区的热结构与渤海相比,均一型结构(1～3月)变短,分层型结构(5～11月)变长,底温年变幅(5℃以内)变小,跃层强度增强.模拟结果还表明,黄海暖流的动力仍然是季风环流,而对黄海冷水团的形成和发展有无动力影响提出质疑.

Thermal structural analysis and simulation of the Bohai Sea and the Huanghai Seas

The thermal structures of the Bohai Sea and the Huanghai Sea are analyzed by observations and simulated by POM model with monthly mean wind stress and weekly surface water temperature as exter nal forcing respectively.The thermal structure is characteristic homogeneous winter style from October to March of the next year,but is stratified structure(consists of mixed layer,thermocline and tidal mixed layer) summer style from May to August,April and November are transition periods of both styles.The lowest water temperature occurs in February for the whole water column,the highest occurs in August for the surface layer and in November to October for bottom layer.Except for some similar thermal structure between the Bohai Sea and coastal shallow water zone of the Huanghai Sea,for the thermal structure of deep water area in central trough,the Huanghai Sea Cold Water Mass and the Huanghai Sea Warm Current are two special factors.As for effect on the deep water,the former is significant in summer,the later is significant in winter,so that the low layer water appears to be cold in summer,while warm in winter compared with the environment,basically is converse to annual variation of SST.As for the three-dimensional structure of above area,compared with the Bohai Sea,the period of homogeneous structure(from January to March) is shorter and the period of stratified structure(from May to October) is longer,the amplitude of annual variation of low water temperature is smaller(no more than 5) and the intensity of the thermocline layer is stronger.The simulated result shows that the driving power of the Huanghai Sea Warm Current is monsoon circulation,and therefore the question whether there is some dynamic effect on the for mulation and development of the Huanghai Sea Cold Water Mass is deduced.