Seasonal and Interannual Variability in the Wind-Driven Upwelling Along the Southern East China Sea Coast

Abstract

The southern East China Sea coast (ECSC) is strongly influenced by the eastern Asian monsoon. During the summer when the southerly monsoon dominates, coastal upwelling is favored. This paper applies a coastal upwelling index (CUI) proposed by Bakun to quantify the upwelling intensity. Using observed sea surface wind and chlorophyll concentration (Chlc) data, we examine the seasonal and interannual variations of the upwelling in the ECSC, as well as its spatial distribution. The high correlation between the CUI and Chlc indicates the validation of the CUI. The temporal variation is linked to the basin-scale variation—the El Nino southern oscillation (ENSO) and pacific decadal oscillation (PDO)—to interpret its long-term variation. A high eddy kinetic energy (EKE) band is coincidently located at the upwelling front along the ECSC, which implies that the mixing caused by frontal instabilities could further modulate the Chlc.