Mapping surface tidal currents and Changjiang plume in the East China Sea from Geostationary Ocean Color Imager

Abstract

The spatial pattern of the semidiurnal M2 tidal currents in the East China Sea (ECS) is mapped from the Geostationary Ocean Color Imager (GOCI), taking advantage of the satellite's unique 8 hourly local daytime sequential images. The GOCI-derived surface M2 tidal currents are validated with a comprehensive set of twenty-eight surface drifters and four mooring observations. The agreement is outstanding with the error variance less than 10% of the total variance. The gridded GOCI-derived tidal currents are also in good agreement with the Oregon State University (OSU) high-resolution regional tidal model of the China Seas. The detided mean flow shows a strong Changjiang plume extending hundreds of kilometers offshore, in agreement with the concurrent satellite sea surface temperature (SST) and sea surface salinity (SSS) distributions. The observed surface currents are compared with the daily mean flows derived from the Japan Coastal Ocean Predictability Experiment (JCOPE2). The model results are consistent with the observations, showing the sensitivity of Changjiang plume to wind forcing. The study clearly demonstrates the utility of geostationary satellite in mapping the surface currents over a wide (∼400 km), tidally dominated continental shelf.