Leakage of the YSBCW into the Korea Strait due to Strong Southerly Wind during summer in 2013

The Yellow Sea (YS) is semi-enclosed sea surrounded by Korea and China. The maximum depth of the YS is less than 100 m. Water temperature in the YS has a large seasonal variation. A strong northerly wind results in vertically homogeneous water during winter. This well-mixed water column can be observed until spring. As the solar radiation increases in spring and summer, the well-mixed water becomes stratified. The vertical mixing between the surface and bottom water is prevented due to this stratification, and consequently the cold water formed in winter season remains beneath the thermocline. This cold water is known as the Yellow Sea Bottom Cold Water (YSBCW). Previous studies have shown that air temperature and wind speed in winter may affect the variability of YSBCW in temperature and distribution. The southern limit of YSBCW in summer tends to extend more when strong southerly winds blow. An abnormal cold water was found along the southern coastal sea of the Korean Peninsula during summer in 2013. This cold water damaged seriously to fisheries. In this study, the link between this abnormal cold water and the YSBCW was found out through analyzing the observed data and numerical model experiment. ECMWF wind data showed that there were abnormally strong southerly winds compared with other seasons during summer in 2013. Because of this strong southerly winds, the YSBCW might move southward more than the normal years. Observation and model result showed that this abnormally extended YSBCW was leaked into the Korea Strait through the southern coastal sea of the Korean Peninsula.