我国冰冻日出现的气象条件分析及其判别模型

Meteorological Conditions in Ice Freezing Day of China and Its Discriminate Model

利用1954-2008年中国700个测站逐日气温、相对湿度、风速及603个测站天气现象观测资料,统计分析了出现冰冻天气(雨凇和雾凇)时的气象要素特征,研究了有利于冰冻产生的气象条件,并在此基础上研制了冰冻日判别模型。结果表明,低气温、高相对湿度和弱风速是产生冰冻的重要条件,有利于冰冻天气产生的日平均气温自北向南呈增高趋势,而相对湿度和平均风速在全国各地差别不大。利用日平均气温和天气现象资料构建的冰冻日判别模型可以较好地判断某日是否发生冰冻,该模型在冰冻频发的云南西北部、贵州、广西北部、湖南南部、江西南部等地的准确率普遍在60%以上,漏报和空报日数较少。该模型可以将常规观测或预报产品用于冰冻监测和预警,具有一定的实用性。

Characteristics of the ice freezing weather,especially the glaze and rime in China are first analyzed,using the daily observation data of temperature,relative humidity,wind speed at 700 stations and weather phenomena at 603 stations in China from 1954 to 2008.Then the favorable meteorological conditions for the formation of the ice freezing are obtained and the discriminate model of the ice freezing days is developed.It is found that the low temperature,high relative humidity and small wind speed are the important meteorological conditions for the formation of the ice freezing.Among the three meteorological variables,the daily mean temperature appears the decreasing trend from the north to the south,while the relative humidity and wind speed present little difference in China.The discriminate model of the ice freezing days,which is established basing the daily mean temperature and the weather phenomena,can distinguish well whether the ice freezing occur or not on the certain day.The accuracy rate of the discriminate model reaches up to 60% in northwestern Yunnan,Guizhou,northern Guangxi,southern Hunan,southern Jiangxi,and so on,where the ice freezing frequently occurs.And the simulated average false days are only 1 to 5 days.Totally,the discriminate model has a relatively high practicability for the ice freezing monitoring and early warning by routine observations and prediction.