Role of Ekman Transport Versus Ekman Pumping in Driving Summer Upwelling in the South China Sea  

作　　者：WANG Dakui WANG Hui LI Ming LIU Guimei WU Xiangyu 

机构地区：[1]Physical Oceanography Laboratory,Ocean University of China [2]Horn Point Laboratory,University of Maryland Center for Environmental Science,Cambridge [3]Key laboratory of research on marine hazards forecasting,National Marine Environmental Forecasting Center [4]College of Environment Science and Engineering,Ocean University of China

出　　处：《Journal of Ocean University of China》2013年第3期355-365,共11页中国海洋大学学报（英文版）

基　　金：the China Scholarship Council for sponsoring Dakui Wang’svisit to Horn Point Laboratory of University of Maryland;the National Nature Science Foundation of China(Grants Nos.41076011,40531006,41106024 and 40976014);the National Basic Research Program of China(Grant No.2011CB403600)

摘　　要：Relative roles of Ekman transport and Ekman pumping in driving summer upwelling in the South China Sea （SCS） are examined using QuikSCAT scatterometer wind data. The major upwelling regions in the SCS are the coastal regions east and south- east of Vietnam （UESEV）, east and southeast of Hainan Island （UESEH）, and southeast of Guangdong province （USEG）. It is shown that the Ekman transport due to alongshore winds and Ekman pumping due to offshore wind stress curl play different roles in the three upwelling systems. In UESEV, Ekman pumping and Ekman transport are equally important in generating upwelling. The Ek- man transport increases linearly from 0.49 Sv in May to 1.23 Sv in August, while the Ekman pumping increases from 0.36 to 1.22 Sv during the same period. In UESEH, the mean estimates of Ekman transport and Ekman pumping are 0.14 and 0.07 Sv, respectively, indicating that 33% of the total wind-driven upwelling is due to Ekman pumping. In USEC~ the mean Ekman transport is 0.041 Sv with the peak occurring in July, while Ekman pumping is much smaller （0.003 on average）, indicating that the upwelling in this area is primarily driven by Ekman transport. In the summers of 2003 and 2007 following E1 Nifio-Southern Oscillation （ENSO） events, both Ekman transport and Ekman pumping decrease in UESEV due to the abnormally weak southwest monsoon. During the same events, however, Ekman transport is slightly enhanced and Ekman pumping is weakened in UESEH and USEG.Relative roles of Ekman transport and Ekman pumping in driving summer upwelling in the South China Sea(SCS) are examined using QuikSCAT scatterometer wind data.The major upwelling regions in the SCS are the coastal regions east and southeast of Vietnam(UESEV),east and southeast of Hainan Island(UESEH),and southeast of Guangdong province(USEG).It is shown that the Ekman transport due to alongshore winds and Ekman pumping due to offshore wind stress curl play different roles in the three upwelling systems.In UESEV,Ekman pumping and Ekman transport are equally important in generating upwelling.The Ekman transport increases linearly from 0.49 Sv in May to 1.23 Sv in August,while the Ekman pumping increases from 0.36 to 1.22 Sv during the same period.In UESEH,the mean estimates of Ekman transport and Ekman pumping are 0.14 and 0.07 Sv,respectively,indicating that 33% of the total wind-driven upwelling is due to Ekman pumping.In USEG,the mean Ekman transport is 0.041 Sv with the peak occurring in July,while Ekman pumping is much smaller(0.003 on average),indicating that the upwelling in this area is primarily driven by Ekman transport.In the summers of 2003 and 2007 following El Ni o-Southern Oscillation(ENSO) events,both Ekman transport and Ekman pumping decrease in UESEV due to the abnormally weak southwest monsoon.During the same events,however,Ekman transport is slightly enhanced and Ekman pumping is weakened in UESEH and USEG.

关 键 词：South China Sea UPWELLING Ekman transport Ekman pumping 

分 类 号：P731.2[天文地球—海洋科学]