Temperature Inversion in the Thermohaline Frontal Zone at the Yellow Sea Entrance in Winter

Abstract

Temperature inversion (higher temperature at deeper depth) in winter as waell as its relation to advection was investigated by analyzing both CTD data in the southern Yellow Sea (YS) and northwestern East China Sea in the winter of 2002-2003 and time series data of tenperature, salinity, and current at a buoy station at the YS entrance. Significant temperature inversions occurred mostly along the thermohaline front at tye YS entrance where the Cheju Warm Current water (CWCW) and the cold coastal waters met together. In the northern frontal zone along 34 N in February 2003 where isotherms and isohalines were declined downward to the north, particularly large inversions with temperautre difference larger than 2 degree were observed in troughs of the wave-like frontal meander whre the cold Korean coastl water(KCW) was advanced farther southward than in crests. At the buoy station in the frontal zone, the inversion persisted until mid April and both temperature and salinity showed simultaneous variations in the same manner. At episodic occurrences of large inversion, temperature and salinity decreased sharply in the upper layer, but increased concurrently in the lower layer. The episodic inversions were found to be closely related to the westward advection of the KCW in the upper layer and the northward advection of the CWCW in the lower layer.3 and time series data of tenperature, salinity, and current at a buoy station at the YS entrance. Significant temperature inversions occurred mostly along the thermohaline front at tye YS entrance where the Cheju Warm Current water (CWCW) and the cold coastal waters met together. In the northern frontal zone along 34 N in February 2003 where isotherms and isohalines were declined downward to the north, particularly large inversions with temperautre difference larger than 2 degree were observed in troughs of the wave-like frontal meander whre the cold Korean coastl water(KCW) was advanced farther southward than in crests. At the buoy station in the frontal zone, the inversion persisted until mid April and both temperature and salinity showed simultaneous variations in the same manner. At episodic occurrences of large inversion, temperature and salinity decreased sharply in the upper layer, but increased concurrently in the lower layer. The episodic inversions were found to be closely related to the westward advection of the KCW in the upper layer and the northward advection of the CWCW in the lower layer.