Satellite observation of the Zhejiang Coastal upwelling in the East China Sea during 2007-2009

In this article, EOS MODIS sea surface temperature (SST) data are used to observe the Zhejiang Coastal Upwelling in the East China Sea. MODIS SST data in summer from 2007 to 2009 are selected and processed. Based on the upwelling's temperature features in SST imagery, a temperature threshold approach is established to measure the physical parameters of the upwelling. And then the temporal and spatial characteristics of the upwelling are analyzed. Results show that the upwelling distributes along the Zhejiang Coast running from south to northeast, and covers an average area of 11,000 square kilometers. The mean temperature of the upwelling is about 25~28°C, and its temperature difference from surrounding non-upwelling waters is in the ranges of 2~4°C. The upwelling appears in June and develops to its strongest period in July and August, and then it weakens and vanishes in late September. Three years of observational results reveal that the upwelling has short-time, seasonal and interannual variances. The upwelling is also closely related to the coastal topography.