Interannual variation in winter thermal front to the east of the Shandong Peninsula in the Yellow Sea

Abstract

Oceanic fronts play an important role in ocean dynamics and ecology systems. The ear-shape front (ESF), first detected in the1980s, is a winter thermal front to the east of the Shandong Peninsula in the Yellow Sea. Using high-resolution satellite observation and ocean reanalysis data, we investigated the interannual variation in ESF and underlying dynamics during 2006–2020. The results indicate that ESF shows a strengthening trend of approximately 0.1–0.5 °C/100 km/year, accompanying the temperature on its eastern side. This was caused by the westward shift and enhancement of the Yellow Sea Warm Current (YSWC) through transporting more warm water to the eastern side of the ESF. Further analyses indicate that changes in the YSWC resulted from the decrease in wind stress divergence. Decreasing wind stress divergence induced increasing sea surface height (SSH) anomalies in the central Yellow Sea. The resultant positive SSH anomalies generated an anti-cyclonic gyre anomaly via geostrophic effects, which led to the westward shift and enhancement of the YSWC on the eastern side of the ESF.