完全Q矢量及其在暴雨过程诊断分析中的应用

Perfect Q-vector and its applications on rainstorms' diagnosis

通过对完全Q矢量的分解,把完全Q矢量分解为动力学部分QD和非绝热过程部分QL,并对我国3次暴雨过程中完全Q矢量变化进行了诊断分析．分析结果表明:完全Q矢量能够较好诊断暴雨过程的中尺度系统,完全Q矢量散度的负值区与强上升区有较好的对应;Qx和Qy的垂直剖面分析表明:垂直上升运动总是位于Qx或Qy的正负区域的交汇处;QD和QL水平散度的垂直分布及其随时间的演变表明,动力学强迫总是位于对流层低层,而非绝热过程的强迫主要位于对流层中层,它与积云对流过程中的潜热反馈有关;并且QD的强迫要比QL的强迫早,这也说明积云对流的最初触发机制是动力学的,积云对流过程中的潜热反馈机制只是在对流发生后对对流过程起激励作用．

The perfect Q-vector was decomposed to two parts in this paper, one being the dynamic element QD and the other the diabatic process QL which is mainly due to the release of latent heat associated with convection. And then the perfect Q-vector was applied to diagnosing three rainstorm processes in China. The results suggested that the perfect Q-vector could clearly reveal the mesoscale systems of rainstorms, the negative area of perfect Q-vector＇s divergence has better relation with the strong ascending area; the Qx and Qy＇s cross section analysis showed that the vertical ascending motion was always in the cross position of Qx＇s （or Qy＇s） positive and negative values; the divergence of QD and QL＇S cross section analysis indicated that the dynamic forcing was located in low level of troposphere and the forcing of diabatic process was related with the release of latent heat ; the temporal variety of divergence of QD and QL in low and middle level of troposphere showed that the forcing of QD for vertical ascending motion was clearly in the low level of troposphere and it was earlier than that of QL, which indicated that the primal spring mechanism of cumulus convection was dynamic forcing and the diabatic process had inspiriting effect on the convection after it started.