Seasonal evolution of fine-scale sea surface temperature fronts in the East China Sea

Abstract

This study demonstrates the seasonal evolution of fine-scale sea-surface temperature (SST) fronts in the East China Sea (ECS) by applying an entropy-based edge detection algorithm to high-resolution (1.1km) satellite SST images obtained between 1996 and 2009. Five major SST fronts are detected. The Jiangsu Fronts exist all year round along the 20-m isobath near the Jiangsu coast. In summer, the Jiangsu Fronts exhibit several frontal bands, closely corresponding to the shape of radial sand ridges off the Jiangsu coast. The Yangtze Bank Front forms a ring-shaped structure off the Yangtze River estuary in winter, and creates a boundary between the cold shelf water over the Yangtze Shoal and the warm Kuroshio water. The China Coastal Front evolves in winter along the 50-m isobath from the northern ECS southwestward into the Taiwan Strait. The Kuroshio Front is enhanced to the northeast of Taiwan between the 100-m and 200-m isobaths. The Cheju Island Front emerges along the southern coast of the Korean Peninsula and extends between Cheju Strait and Tsushima Strait, and is sustained in the summer months. Thus, this study reveals hitherto undescribed fine-scale structures of SST fronts, and shows their seasonal variations and relation to the bathymetry.