东北地区强降雪过程综合评估模型初探

Comprehensive Assessment Model of Heavy Snow Process in Northeast China

根据界定的降雪范围和降雪强度,筛选出东北地区的冬季强降雪过程,然后选取过程平均降水量、单日降水量极值和覆盖范围3个评价指标,对19612010年冬季192个强降雪过程进行数理统计分析,并基于重现期理论,构建了东北地区冬季强降雪过程综合评估模型。在构建模型过程中,首先对各单项指标数据进行多个函数分布拟合或正态变换,选取拟合度最佳的函数分布或变换函数,然后利用其反函数确定不同概率下各单项指标对应的理论值,并将其作为各等级划分的阈值;之后运用变异系数法确定3个指标的权重,建立东北地区冬季强降雪过程综合评估模型,并将降雪过程强度划分为5个等级。该模型对东北地区20112017年冬季35次强降雪过程的评估结果与中国气象局决策气象服务产品信息对照结果表明,该综合评估模型及强度等级划分能较好地评价和反映强降雪过程的影响程度,对未来开展强降雪过程影响预估业务有重要参考价值。

Based on winter surface meteorological precipitation daily data from China’s national stations in 1961—2010,192 snow processes in Northeast China are selected according to the scope and intensity of snow process.Average process precipitation amount,extreme daily precipitation and snow cover scope are chosen as the three evaluation indexes.A comprehensive assessment model for winter heavy snowfall process in Northeast China is established based on mathematical statistical analysis of the 192 heavy snow processes and the recurrence period theory.During the model building process,firstly,we perform multiple function distribution fitting or normal transformation,and select the optimum distribution.Then,we calculate the theoretical value of each index under different occurrence probabilities through the anti-function of the optimum distribution and use it as the threshold value of each grade division.Lastly,the weight of three indexes is determined with the method of variation coefficients,and the comprehensive assessment model for winter heavy snowfall process in Northeast China is established,and the intensity of the snowfall process is divided into five categories.We apply the model to evaluating the 35 winter heavy snow processes from 2011 to 2017.Through comparing the assessment results to the decision-making meteorological service reports of China Meteorological Administration,we find that the comprehensive assessment model and the intensity category classification can better evaluate and reflect the influence degree of the heavy snow process,and it has an important reference value for future impact prediction of heavy snowfall process.