冷涡区域海水温度低，海水比容小，海平面通常低于周围海域，冷涡中心区常年存在低海平面闭合等值线，冬春季尤为明显。
Water specific volume is small . So the sea level is usually lower than the surrounding waters . The cold vortex center has a low-lying closed contour in year-round , especially in winter and spring .
海水比容