基于概率与权重的雷暴大风潜势客观预报方法研究

Research on objective forecast method of thunderstorm potential based on probability and weight

采用2007—2015年5—8月NCEP再分析资料和国家站、区域站雷暴大风实况观测资料,利用权重和概率统计相结合的方法,确定与雷暴大风联系紧密的物理量,统计其在所选物理量不同阈值范围内出现的概率,建立雷暴大风概率潜势预报方程,并对预报结果进行检验。结果表明:(1)雷暴大风出现在白天与夜间所选物理量参数有所不同。无论白天或夜间,其在山区与其它地区的物理量阈值亦不同。(2)所选每个预报因子的概率统计结果与雷暴大风发生的环境条件基本相符,该概率由因子达到阈值范围内的样本数和在此区间内出现雷暴大风的样本数两者共同决定的。(3)该方法对08—20时和20—08时两个时段雷暴大风预报的命中率均较好,尤其2016年7月最高,预报概率为“60%以上”的命中率接近93%,可预报出雷暴大风出现的概率潜势和可能发生的区域;同时,空报率较高;预报概率为“80%”的预报临界指数更高。

Based on NCEP reanalysis data and the observation data of thunderstorms at national and regional stations from May to August between 2007 and 2015,using the method combining weights and probability statistics,the physical quantities that are closely integrated with the thunderstorm were determined,and the probability within different thresholds was calculated.Finally,thunderstorm potential prediction equation was established,and the forecast results were tested.The results showed the following.1)Physical quantities selected are different between day and night.Meanwhile,whether it is during the day or at night,thresholds of physical quantities are also different between mountain areas and other areas.2)The probability of each selected physical quantity appeared to be basically consistent with environmental conditions of thunderstorm,which was determined by the number of samples of physical quantities and thunderstorms within the threshold.3)The method showed a good forecast of thunderstorm in from 08:00 to 20:00 BT and from 20:00 to 08:00 BT,especially in July 2016,during which the hit rate of more than'60%'was close to 93%.It can well predict the potential and possible areas of thunderstorm.At the same time,its vacancy rate was also high.The critical success index of'80%'was even higher.