强降水过程风廓线雷达资料的极值特征

为提高强降水天气的短临预报水平,分析了云南大理2008—2012年汛期地面强降水发生前风廓线雷达资料的极值特征。结果表明:强降水前0~1h最大探测高度最高,强降水的强度与最大探测高度的量值和增幅呈正相关。强降水出现前1h左右,向下的垂直速度极值最大,所对应的高度最低;且向下的垂直速度极值越大,强降水的强度也越大。在强降雨发生前1h出现信噪比极值的峰值,该峰值越大,强降水的强度也越大。较强的强降水发生前3~4h,在4.0km高度附近有中尺度急流出现。

Characteristics of Extremes in WPR Data during Severe Convective Rainfall

In order to promote the levels of short term forecasting and nowcasting of severe convective weather, the extremes of WPR (Wind Profiler Radar) data observed ahead of the occurrence of severe convective rainfall during rainy season from 2008 to 2012 in Dali are analyzed on the basis of large sample of related data. The results show: The maximum detection height of WPR reached its maximum 0 to 1 hours ahead of the appearance of heavy rainfall. The intensity of severe convective rainfall was positively associated with the maximum detection height and its increased range. Meanwhile, the negative vertical speed increased to maximum and its corresponding height decreased to the lowest 1 hour prior to the beginning of strong rainfall. The greater the negative vertical speed, the bigger the intensity of heavy rainfall was. Furthermore, the peak value of the extreme SNR (Signal to Noise Ratio) appeared 1 hour ahead of the appearance of strong rainfall. The intensity of strong rainfall was positively correlated with the peak value. The mesoscale low level jet appeared 3 to 4 hours ahead of the occurrence of strong rainfall.