一次西太平洋副热带高压进退过程中暴雨的GPS可降水量特征

Characteristics of GPS precipitable water vapor during a heavy rain of western Pacific subtropical high

利用2010年8月石家庄地基GPS反演的可降水量资料、地面加密自动站和常规天气资料,对一次由副热带高压进退引起的强降水天气过程中的GPS可降水量和假相当位温的演变趋势进行了分析。结果表明:1)降水通常出现在GPS可降水量高于基值时,尤其是在GPS可降水量达到极大值前后,极大值阶段对应强降水;GPS可降水量上升后期若有高空槽扰动,则出现对流性强降水;GPS可降水量下降初期仍将维持弱降水。2)非对流稳定性降水的GPS可降水量呈波状变化,变化幅度相对较小,呈多峰型,强降水与GPS可降水量的大值阶段对应;对流性降水过程中,GPS可降水量升降剧烈,GPS可降水量和降水强度的峰值刚好对应。3)降水多发生在GPS可降水量偏离系数为正时,强降水一般出现在偏离系数超过1时。当GPS可降水量剧烈增长,降水性质为对流性雷雨或阵雨时,对应的偏离系数可比稳定性降水的略小。4)前期高能量的积累是降水发生的必要条件,副高降水出现在假相当位温的快速下降阶段或谷值区。假相当位温峰值越高、升降幅度越大、高值持续时间越长,相应的降水就越强。

Based on precipitable water vapor received from ground-based GPS,data of dense surface automatical meteorological stations,and conventional sounding data in Shijiazhuang on August 2010,this paper studied the evolution tendency of GPS precipitable water vapor and potential pseudo-equivalent temperature during a heavy rain induced by the advance and retreat of the west Pacific subtropical high.The results show：（1）Rainfall usually occurs when the GPS precipitable water vapor is higher than the average value,especially near its maximum value.The heavy rain period is corresponding to the maximum stage of GPS precipitable water vapor.Upper-level trough is helpful to the occurrence of the convective heavy precipitation at the late period of GPS precipitable water vapor increasing.Weak precipitation will continue at the early period of GPS precipitable water vapor decreasing.（2）In the stability precipitation process,the GPS precipitable water vapor shows a multi-peak wave shape,and its amplitude is relatively small.The heavy rain period is corresponding to the maximum stage of GPS precipitable water vapor.In the convective precipitation process,the GPS precipitable water vapor changes dramatically,and the peaks of GPS precipitable water vapor and actual precipitation are exactly corresponding.（3）Rainfall easily occurs when the deviation coefficient of GPS precipitable water vapor is positive,and the heavy rainfall generally happens while the deviation coefficient is higher than one.The deviation coefficient of convective thunderstorm or shower is slightly smaller than that of stability precipitation.（4）The prophase high-energy accumulation is a necessary condition of rainfall.The rainfall of subtropical high usually occurs in the rapid decline phase of potential pseudo-equivalent temperature or its valley areas.The precipitation will be stronger when the potential pseudo-equivalent temperature is at higher peak with more sharp movement and longer duration of high value.