2011年夏季台湾海峡上升流的变化特征及其与风场的关系

Variation characteristics of upwelling in Taiwan Strait and its relationship with wind in summer 2011

根据2011年6月27日至7月4日台湾海峡航次的调查资料,结合6月1日至8月31日海表温度和风场的卫星遥感数据,分析了平潭附近海域、澎湖北部海域、东山附近海域、台湾浅滩东南部海域上升流的变化特征及其与风场的关系.以海表温度差值(SSTd)来反映上升流强度,该值负值越大,上升流强度越强,分析可知:在2011年夏季,平潭附近海域上升流的强度除了7月中、下旬和8月底外,其余时段较为稳定.SSTd值与局地沿岸风速存在滞后3 d左右的相关关系,特别是稳定持续的西南风对其强度有较大的影响.澎湖北部海域上升流的SSTd值在-1℃左右,强度相对较小,且6、7月比8月时强盛,局地风场对澎湖北部海域上升流有一定的影响,但不是主要影响因素,而是由地形和风共同作用.东山附近海域上升流的强度并不稳定,在6、7月变化较剧烈,到8月SSTd值稳定在-3℃左右,SSTd值的变化对于局地沿岸风的响应同样存在一个3 d左右的滞后时间,除此之外还与上升流中心的水平变动有关.而台湾浅滩东南部海域上升流虽有波动,但持续存在,且6、7月比8月时强盛,其变化与局地风场的关系不大,主要受海流和地形等其他因素的影响.

The cruise data of June 27-July 4,2011 and the satellite remote sensing data of sea surface temperature（SST） and wind of June 1-August 31,2011 were combined in the analysis of the variation characteristics of four upwelling regions in the Taiwan Strait and their relationship with wind.The upwelling regions are located near the Pingtan Island（PTU）,off the north of the Penghu Island（PHU）,near the Dongshan Island（DSU） and off the southeast of the Taiwan Bank（TBU）,respectively.The SST difference（SSTd） was employed to reflect the upwelling intensity,with greater negative values indicating more intensified upwellings.Analytical results revealed that the intensity of PTU was relatively stable except in mid and late July and late August,which was especially related to stable southwesterly winds;There was a 3 days lag of correlation between SSTd and along-shore wind speed.The SSTd of the PHU was about-1℃,indicating a relatively weak upwelling which was stronger in June and July than in August;the PHU was induced by wind and topography,while the local wind was a inducing factor but not a major one.The intensity of DSU was not stable in June and July but stable in August with the SSTd of about-3℃;the SSTd varied in response to the local along-shore wind and had a lag time of about 3 days,while the DSU also related with horizontal shift of the upwelling center.The TBU fluctuated but persisted throughout the summer season,stronger in June and July than in August;the TBU was not well-correlated with wind,but was induced by current and topography.