舟山近海海域夏季上升流时空特征及其与风场的关系

利用2002-2013年期间的卫星遥感海表温度(SST)数据分析了舟山海域夏季上升流的时空特征,并结合同时期的海面风场数据探讨了风对该海域夏季上升流的影响。对多年夏季月平均的SST进行经验正交函数(EOF)分解结果表明,7月份前两个模态方差贡献率分别为71.66%、16.55%,8月份前两个模态方差贡献率分别为87.03%和7.30%,并均通过了显著性检验,舟山近海海域的上升流存在较为明显的年际变化。相关分析显示,经向风速和SST异常存在显著的负相关关系,即夏季盛行的西南风有利于上升流的发展。并且,艾克曼(Ekman)体积输运计算结果表明,舟山海域7、8月份风生上升流的量级分别为3.0×10~(-5)m/s和1.5×10~(-5)m/s,7月上升流显著强于8月,这与8月份观测到的海表显著低温异常相关。

Study on the temporal and spatial characteristics of Zhoushan coastal upwelling and relationship with wind field in Summer period

Based on the monthly Satellite remote sensing Sea Surface Temperature (SST) from 2002 to 2013, Empirical Orthogonal Function (EOF) analysis was accomplished to analyze the temporal and spatial characteristics of upwelling over Zhoushan Coastal region. The effect of wind on upwelling was analyzed by using sea surface wind field data. The result showed that first two modal variance contribution rates are 71.66% and 16.55% in July, 87.03% and 7.3% in August respectively, all of which pass the North test. The Zhoushan coastal upwelling displayed inter-annual variability and had a negative relationship to the meridional wind. The prevailing southeast wind in summer was conductive to development of the upwelling. According to the calculation of Ekman Volume transport, the order of mean velocity of upwelling in Zhoushan coastal region are respectively 3.0×10-5 m/s and 1.5×10-5 m/s in July and August. The upwelling in August was significantly weaker than in July, which was relevant with a significant low SST anomaly observed in August.