东北季风期台湾海峡的逆温现象

利用2006-2008年3个航次水文资料,结合日本海洋数据中心(JODC)的历史温度数据分析了东北季风期台湾海峡的逆温现象。结果显示,除台湾浅滩及海峡西岸浅水区外,几乎整个台湾海峡皆有逆温现象。逆温幅度和发生频率在海峡西部较高,海峡东部及粤东近海较低。逆温层上界深度春季较秋、冬季深,逆温频发区(发生频率大于60%)随着季节南北向移动,秋季频发区的最南端位于厦门近海,冬季扩展至台湾浅滩北部,春季回退至平潭近海。分析表明,浙闽沿岸水随季节南北向伸缩导致了逆温频发区的同步移动。除了季节变化外,逆温现象在2006年和2007年冬季有显著差异,2006年逆温仅出现在海峡西部近岸海域,2007年扩展至海峡东部且向南伸至粤东近岸,浙闽沿岸水的横向伸缩是造成此差异的主因。

Temperature inversion in the Taiwan Strait during northeast monsoon

Hydrographic data from three cruises during 2006 and 2008 and historical temperature data from Japan Oceanographic Data Center (JODC) were used to study temperature inversion (TI) in the Taiwan Strait during northeast monsoon. The result shows that TI occurs almost in the whole strait except Taiwan Bank and shallow waters along western coast of the strait. The magnitude (occurrence frequency) of TI is large (high) in the western strait, but small (low) in the eastern strait and the coastal waters of Guandong. The start depths of TI layers are deeper in spring than that in autumn and winter. The area where TI occurs frequently (ATOF) with occurrence frequency above 60% has a southnorth movement with seasons. The southern edge of ATOF locates around Xiamen coastal sea in autumn and extends southward to the north of Taiwan Bank in winter, and then recedes northward to Pingtan coastal sea in spring. The seasonal southnorth migration of ZheMin Coastal Water (ZMCW) is found to induce ATOF’s movement. Besides seasonal variability, there was a distinct difference of TI between 2006 and 2007 winter. TI only occurred in the coastal area of western strait during 2006 winter, but in the western and eastern strait and the coastal waters of Guandong during 2007 winter. The lateral shift of ZMCW is suggested to be the major causative factor.