舟山群岛海域一次大风过程的诊断分析

Diagnosis analysis of a strong gale in Zhoushan islands

对舟山群岛一次冷空气大风过程进行了诊断分析。结果表明:大风产生在典型的贝湖脊型横槽形势下,高空横槽的转竖使得冷空气从低层到高层开始向南爆发。冷空气南下与东海低压强烈发展造成的强气压梯度以及中低层冷平流的作用是造成强风的重要原因。高低层散度场的耦合以及高空锋区过境时产生的动力下沉运动造成强烈的动量下传,进一步加大了地面风速。

In this paper, a strong cold air gale process in March 2010 was analyzed. The results showed that the strong cold air gale appeared in the typical synoptic situation of the horizontal trough before the ridge of Lake Baikal. The cold air breaked out from lower levels to higher levels because the upper lever trough changed from the horizontal direction to vertical direction. The main reason of this strong gale was the pressure gradient caused by the interaction of the cold air and the intense development of depression in the East China Sea, and the strong cold temperature advection in low and middle layer. In addition, the coupling of divergence with a negative （posi- tive） value at upper （low） level and intense momentum transportation downward, caused by the dynamic forcing descending due to the upper frontal zone passage, further increased the ground wind speed.