一个中国冻雨潜在发生指数的建立

Creation of a New Freezing Rain Genesis Potential Index over China

利用中国高空和地面观测资料,分析了贵州等地冻雨发生时的气象要素变化特征.结果表明：冻雨发生时地面温度较低,处于-7.3～0.9℃;湿度较高,温度露点差0～3.9℃;风速1～2 m/s;降水量不太大;且高空存在逆温层,在对流层中下层随高度升高,温度在某一特定值上下波动,达到某一高度后,温度随高度递减.根据冻雨发生的气象要素变化特征,定义了一个新的中国冻雨潜在发生指数,用以表征冻雨发生的潜在可能性,并对2005-2014年中国冻雨的发生进行效果检验.结果表明,效果检验对各台站冻雨情况模拟准确率在90％以上,对几次冻雨过程均能很好地表征出来.进一步的研究表明,将该指数与降水结合,模拟准确率显著提高.

By using the upper-air and surface observations over China,we analyzes the features of meteorological elements during freezing rain events in China.The results show that when Chinese freezing rain occurs,the surface temperature is usually-7.3～0.9 ℃;The surface dew point temperature is 0～3.9℃;The wind speed is 1～2 m/s;Precipitation is usually little.Most of freezing rain is associated with temperature inversion layer in the upper-air.The temperature fluctuates in the lower troposphere and then decreases with elevation.Based on that,a freezing rain genesis potential index （FRGPI） is defined to indicate the possibility of freezing rain occurrence.The accuracy is tested by using the observation data （2005-2014）.The result illustrates that the accuracy rate of each station is above 90％ and the process of freezing rain events can be indicated well.The accuracy can be much higher if combine FRGPI with precipitation,which is benefit for freezing rain disaster prevention and mitigation.