| 摘要: |
| 上升流是长江口外海域的重要水文现象, 为深入了解该海域上升流的活动特征及其月际变化,于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123°E断面为例进行分析。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15m以浅水层,最高达到约10m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特征表明, 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 水文特征 长江口 春季 |
| DOI：10.11759/hykx20170307002 |
| 分类号: |
| 基金项目:国家自然科学基金项目(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 upwelling area off the Changjiang River Estuary in spring |
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YAO Jin,WANG Zhen-yan
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| Abstract: |
| To analyze the monthly variation in the hydrographic upwelling features off the Changjiang River Estuary in spring, we investigated the hydrographic environment of the sea area using conductivity–temperature–depth (CTD) sensors in April, May, and June 2015. The survey data of the 123°E section show that the upwelling was persistent during spring. The upwelling water was mainly characterized by high salinity and originated from Taiwan Warm Current water, which upwelled along the submerged slope off the estuary as it flowed northward. We observed the upwelling to strengthen monthly and reach the 10 m layer in June. During the investigation period, the surface cold saline water was rapidly replaced by warm fresh water, whereas the upwelling water was relatively stable. Thus, the intensities of the thermocline and halocline tended to increase and the halocline gradually advanced northward. According to our analysis results, the strength of the northward flow of the Taiwan Warm Current became stronger from April to June, so it could be a major factor influencing the monthly variation in upwelling. The results also show that the influence of diluted the Changjiang River water increased monthly and caused an intensive thermocline and halocline, which ultimately restrained the upwelling. In addition, although the Northern Jiangsu coastal current is an important water mass in the adjacent Changjiang River Estuary area, it had the least effect on upwelling. |
| Key words: upwelling hydrographic features the Changjiang River Estuary spring |
