Characterizing surface circulation in the Taiwan Strait during NE monsoon from Geostationary Ocean Color Imager

Abstract

The Taiwan Strait is the only channel connecting the South China Sea (SCS) and the East China Sea (ECS), and plays a key role in the material exchanges between SCS and ECS. The region however is poorly sampled during the northeast (NE) monsoon when severe weather hinders shipboard measurements. In this study, the surface circulations in the Taiwan Strait and the adjacent East China Sea are derived from the Geostationary Ocean Color Imager (GOCI) with a high spatiotemporal resolution. The satellite observations are limited by cloud over. Nevertheless, they provide the only surface flow observations useful in hypothesis testing. It is demonstrated that the transient surface currents can be classified into three regimes: a southwestward flow for strong winds, a northeastward flow for weak winds, and a cross-strait flow for moderate winds. The satellite observations are also valuable in validating model currents. Two high-resolution global ocean reanalysis products, the Hybrid Coordinate Ocean Model (HYCOM) and the Copernicus Marine Environment Monitoring Service (CMEMS), are examined. The reanalysis products are generally consistent with the satellite observations. The CMEMS moreover shows a superior performance. This study illustrates the unique capability of the geostationary ocean color satellite in providing spatially extensive surface flow observations in broad shelf regions where current meter data are sparse or non-existent.