Remote Sensing Studies of an Upwelling Jet in Guangdong Coastal Water

Summer upwelling is one of the most significant dynamic phenomena in the Guangdong coastal water, which transports bottom nutrients into the surface layer, facilities a high level of primary production in the offshore water, and plays an important role in the coastal ecosystem. In this study, we present detailed observations of an upwelling event that occurred in the Guangdong coastal water during July 14-16, 2003 using satellite multisensor data including the moderate resolution imaging spectroradiometer (MODIS) sea surface temperature (SST), QuikSCAT winds. The successive MODIS SST images reveal that the upwelled water in the surface layer is in a jet-like wedge shape. A quantitative method is developed to estimate the upwelling vertical and horizontal velocities of the upwelled water from the MODIS successive SST images, which are in good agreement with the observations. Based on the coastline geometry in the area, we derive analytical solutions to the upwelling system, which explain well the dynamic of the upwelling jet by comparison of the analytical solutions with the cross-shore expansion velocities of the upwelled water.