The Contribution of Local Wind and Ocean Circulation to the Interannual Variability in Coastal Upwelling Intensity in the Northern South China Sea
The Contribution of Local Wind and Ocean Circulation to the Interannual Variability in Coastal Upwelling Intensity in the Northern South China Sea
复制标题
局地风和海洋环流对南海北部沿岸上升流强度年际变化的贡献
DOI：
10.1029/2018jc014223
复制
发表时间：
2018
影响因子：
3.6
通讯作者：
Liu Qin-Yan
中科院分区：
文献类型：
--
作者：
Shu Yeqiang;Wang Dongxiao;Feng Ming;Geng Binxu;Chen Ju;Yao Jinglong;Xie Qiang;Liu Qin-Yan
通俗易懂的总结 利用现场数据、卫星观测和模型输出，我们分析了南海北部沿海上升流强度的年际变化。比较 2008 年和 2016 年夏季 3 个航次观测到的沿海上升流，我们发现，尽管 2008 年当地上升流有利风较强，但 2016 年沿海上升流较 2008 年更强。近底跨陆架流较强，斜坡温跃层较浅，导致 2016 年夏季上升流强度较强。地形位置指数（TPI），由一个中心单元与其邻近单元之间的海面温度差定义，用于量化上升流的年际变化。上升流强度较强（较弱）的时期是2007年、2008年、2011年、2015年和2016年（2004年、2009年、2012年和2014年）夏季，当地风对沿海上升流较有利（较不利）。面积加权TPI与沿岸风速的相关系数为-0.60，证实局地风是控制上升流强度年际变化的主要动力因素。陆架75米和100米等深线平均面积加权TPI与东边界流输送的相关系数为-0.42，表明南海北部大尺度环流的年际变化也影响了上升流强度的年际变化。 2016年夏季异常浅的温跃层可能与2015-2016年强烈的厄尔尼诺事件通过行星波传播有关。
Plain Language Summary Using in situ data, satellite observations, and model outputs, we analyzed the interannual variability in coastal upwelling intensity in the northern South China Sea. Comparing coastal upwelling observed from three cruises during the summers of 2008 and 2016, we found that coastal upwelling was stronger during 2016 compared to 2008, although the local upwelling favorable wind was stronger in 2008. The stronger near-bottom cross-shelf current and shallower thermocline in the slope resulted in stronger upwelling intensity during the summer of 2016. The topographic position index (TPI), which is defined by the sea surface temperature difference between one center cell and its neighbors, was used to quantify the interannual variability in upwelling. Stronger (weaker) upwelling intensity occurred during the summers of 2007, 2008, 2011, 2015, and 2016 (2004, 2009, 2012, and 2014) when the local wind was more favorable (less favorable) to coastal upwelling. The correlation coefficient between the area-weighted TPI and alongshore wind speed was -0.60, thereby confirming that local wind is the primary dynamical factor controlling the interannual variability in upwelling intensity. The correlation coefficient between the area-weighted TPI and the eastward boundary current transport averaged between the 75- and 100-m isobaths on the shelf was -0.42, indicating that the interannual variability in large-scale circulation in the northern South China Sea also contributes to the interannual variability in upwelling intensity. The anomalously shallow thermocline in the summer of 2016 was likely associated with the strong 2015-2016 El Nino event through planetary wave propagations.