Abstract:

The water vapor condition of a short –time heavy rainstorm in Shenyang on 16 August 2013 was analyzed in detail by using the Micaps data，the analytic fields of mesoscale numerical mode data，conventional observation data and automatic meteorological observing data．The results indicated that water vapor content below 850 hPa accounted for more than 80% of the whole layer water vaporcontent．The change of ground specific humidity in rainstorm area presented increasing fast firstly and then decreasing．The maximum of specific humidity was not corresponding to the strongest moment of the heavy rain．Before the heavy rain occurrence，the distribution of humidity on surface was uneven in Shenyang，and water vapor transported mainly in northsouth direction．Wind direction changed fast at the low level， which caused humidity increasing suddenly，thereinto，it was the main contribution of the south wind component．The vertical water vapor was transported from 850 hPa to upper level，the intensity of transportation falled into a decline below 850 hPa．With the heavy rain occurring，the vertical water vapor transportation changed，the lower the height，the higher the intensity of transportation，and water vapor flux reduced rapidly on surface in U and V direction． After the heavy rain，water vapor transportation on surface and upper layer changed． There was a corresponding relationship between the atmospheric precipitable water and precipitation．The atmospheric precipitable water in heavy rainstorm area primarily depended on the vapor flux convergence in horizontal direction，while vapor flux convergence was largely decided by convergence of horizontal wind．

Key words: heavy Rain, transformation of water vapor, moisture budget

摘要：

利用Micaps实况资料东北区域中尺度数值模式分析场资料和常规观测资料，对2013年8月16日沈阳城区暴雨的水汽条件进行了分析。结果表明:850 hPa以下城区上空水汽含量占整层的80%以上，地面比湿呈现快速增加后减少的变化，比湿峰值对应的并不是强降水的最强时刻，强降水发生前，城区地面周围的湿度分布不均匀，水汽输送主要以南北向为主，比湿的迅速增加主要是由于降水前风向和风速的快速变化，其中主要是南风分量的贡献城区上空垂直方向上水汽主要是850 hPa向上输送，850 hPa以下送强度逐渐减弱伴随着强降水的开始，水汽的垂直输送转为高度层越低，输送强度越大强降水发生时，地面U、V方向上水汽通量快速减小强降水发生后，地面和高空水汽输送均发生了变化大气可降水量与降水量之间具有一定的对应关系，可降水量的大小主要是取决于水平水汽通量辐合的大小，水汽局地变化对可降水量的贡献较小。水汽通量的辐合辐散的大小主要取决于水平风场引起的辐合辐散的大小。

关键词: 强降水, 水汽输送, 水汽收支