| 摘要: |
| 2015年春季(4月、5月和6月)对长江口外海域的水文环境进行逐月综合调查,并以12300E断面为例对长江口外海域上升流活动的水文特征及其月际变化进行分析。结果显示,在春季调查期间,长江口外海域始终存在上升流现象,是由台湾暖流挟带底层高盐海水自南向北不断推进,并在长江口外海域沿海底斜坡涌升而形成。上升流强度在春季逐月增大,表现为：上升流涌升高度逐月变浅,至6月高盐上升流水体的涌升高度已普遍抬升到约15 m以浅水层,最高达到约10 m水深处；其影响范围不断向北扩展。春季,上升流活动区上层海水的温、盐特征逐渐由相对低温、高盐转变为高温、低盐；位于下层的上升流水体的温、盐特征比较稳定,变化幅度较小；上升流活动区的温、盐跃层现象总体呈现出逐月增强的趋势,盐度跃层现象尤为显著,其水平分布呈现出自南向北逐月扩大的变化趋势；跃层深度不断抬升。调查结果的月际变化表明,台湾暖流北进强度的逐月增大是导致春季长江口外上升流活动不断增强的主要因素；随着春季低盐长江冲淡水的强度和范围逐月增大,其与下层上升流挟带的高盐涌升水之间的跃层效应逐渐增强,对下层上升流水体的涌升有抑制作用；春季苏北沿岸流活动对该海域上升流现象的影响不显著。 |
| 关键词: 上升流,月际变化,长江口,春季,影响因素 |
| DOI：10.11759/hykx20170307002 |
| 分类号:P736.21 |
| 基金项目:国家自然科学(41476045)；中国科学院战略性先导科技专项(A类)(XDA11020600；XDA11030103)。 |
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| MONTHLY VARIATION OF THE UPWELLING AREA OFF CHANGJIANG ESTUARY IN SPRING |
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YAO Jin, WANG Zhenyan
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Institute of Oceanology of the Chinese Academy of Sciences
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| Abstract: |
| Based on the hydrographic data acquired by CTD in April, May and June 2015,we analyzed the monthly variation of the upwelling area off Changjiang estuary in spring. Results of the typical 12300E section show that, the upwelling existed persistently during spring. The upwelling water, mainly characterized by high salinity, came from the Taiwan Warm Current water which upwelled along the submerged slope off the estuary when it flowed northward. The upwelling appears to be increasingly strengthened monthly that it climbed higher and reached up to 10 m layer in June. During the investigation, the surface cold saline water was replaced by warm fresh water rapidly, while the upwelling water was relatively stable. Thus, the intensity of thermocline and halocline tended to be increased and the halocline advanced northward gradually. According to the analysis, the strength of the northward flowing Taiwan Warm Current became stronger from April to June, and then it could be the major impact factor of the monthly variation of upwelling. The results also show that the impact of Changjiang Diluted Water increased monthly and caused intensive thermocline and halocline which finally restrained the upwelling. What’s more, although the Subei coastal current is an important water mass in the Changjiang Estuary adjacent area, it had rear effects on the upwelling. |
| Key words: Upwelling monthly variation Changjiang estuary spring impact factors |