黄海冷水团的环流结构

运用定性分析和数值模拟，对黄海冷水团的环流结构进行了探讨，结果表明黄海冷水团的垂向环流结构为双环结构：跃层以上区为中心上升，边缘下降的弱环流;跃层以下区为中心下降，边缘上升的强环流；在冷水团的中心区域，流动很弱，且无穿越温跃层的垂向流动。同时也对以往有关黄海冷水团垂向环流结构的工作进行了讨论。

ON THE CURRENT FIELD ASSOCIATED WITH THE YELLOW SEA COLD WATER MASS

An idealized axi-symmetric model is used to study the current field associated with the Yellow Sea Cold Water Mass (YSCWM), a bottom pool of remnant Yellow Sea Winter Water resulting from summer stratification. Two approaches are employed to obtain the results: one is a qualitative analysis based on an observed vertical temperature distribution in summer (Fig. 1) and a set of simplified equations derived from scaling; the other is a numerical integration of the full equations with specified time-dependent surface heat flux and a vertically homogeneous initial state.

Both methods yield similar results. Besides the characteristic alongfront cyclonic circumferential circulation (Fig. 3b), the vertical circulation in the (r, z)-plane has a distinct double-gyre structure (Figs. 2, Fig. 3c). Within the thermocline the current flows from the outer boundary of YSCWM towards its center. The upper layer gyre is smaller and weaker, with upwelling in the center and downwelling within the surface frontal zone. The lower layer gyre is larger and more intense, with strong upwelling reaching the surface over the edge of the bottom front and downwelling elsewhere. Outside the frontal zone there is a very weak gyre spanning the whole depth with the same sense of circulation as that of the bottom layer gyre.

Finally, we discussed possible reasons why previous works resulted in different. patterns, basically three types, for the YSCWM induced vertical circulation.