Xu, Q.; Zhang, S.; Cheng, Y., and Zuo, J., 2017. Interannual feature of summer upwelling around the Zhoushan Islands in the East China Sea.

The interannual feature of summer upwelling around the Zhoushan Islands off the Zhejiang coast over the East China Sea (ECS) shelf has been investigated using multiscale ultrahigh resolution (∼1 km) sea surface temperature (SST) data during the period from 2003 to 2014 and an auxiliary Pathfinder SST data set with a relatively low resolution of 0.05° × 0.05° during 1985–2002. Coastal upwelling usually occurs during April to June, reaches its peak intensity in July and August, and starts to decay in September. It has not strengthened or weakened obviously during the past 30 years. The influence of sea winds on the interannual variation of the summer upwelling is analyzed using the National Oceanic and Atmospheric Administration/National Climatic Data Center blended sea surface wind data. Results demonstrate that the sea wind over the ECS, which is part of the East Asian summer monsoon (EASM) system, plays a dominant role in determining the changes in upwelling intensity, and the southeasterly wind is favorable for the formation of the summer upwelling around the Zhoushan Islands. The El Niño–Southern Oscillation (ENSO) modulation of the interannual variability of the upwelling intensity is complex because of the unstable correlation between the EASM and the ENSO cycle.