黄河故道砀山酥梨花期低温冷害风险的评估方法初探

低温冷害为砀山酥梨花期的主要气象灾害之一,其风险评估具有重要意义。运用数理统计方法研究分析1983-2006年砀山酥梨物候资料和同期气象资料,从酥梨始花期和整个花期的日最低气温的概率分布入手,建立了酥梨花期低温冷害风险评估模型。结果表明：（1）砀山酥梨花期内遭受某一级别的低温冷害的风险,可由始花期出现的概率与花期内逐日出现某一级别低温冷害的概率之和的乘积来表示,一般是酥梨始花期越早、花期历时越长,遇到某一级别低温冷害的风险越大。所得风险评估方程,可用于风险评估。（2）砀山酥梨开花始期具有正态分布特征,即始花期早和迟的出现频率较小,处于历年始花期均值附近的频率较大。（3）砀山酥梨花期遭受低温冷害的指标可分为花期内出现日最低气温≤7℃、≤5℃、≤3℃三个级别。（4）酥梨始花后到某一日遭受某一级别低温冷害的累积概率,除始花日出现≤3℃低温冷害的概率与始花期早晚呈线性关系外,其他日期的累计概率均与始花期的早晚呈指数关系。

Risk Assessment Method of Cold Damage to Florescence of Dangshan Crisp Pear in Old Course of the Yellow River

Cold damage was one of the main meteorological disasters on florescence of Dangshan crisp pear, so risk assessment for cold damage was very important. Risk assessment model for cold damage to florescence of Dangshan crisp pear was established by using mathematical statistics methods based on the phenological data and meteorological data from 1983 to 2006, especially considering the probability distribution of the daily minimum temperature during florescence. The results showed that the cold damage risk levels during florescence of Dangshan crisp pear could be expressed with the probability of cold damage during flowering beginning multiply the total probability of cold damage during florescence day to day. As usual, the cold risk was more serious if flowering beginning was earlier or florescence was longer. The date of flower beginning accorded with normal distribution, that is, the probability of cold damage from flowering beginning too early or too late would be small. The cold damage during florescence of Dangshan crisp Pear suffered could be divided into three levels, depending on daily minimum temperature ≤7℃, ≤ 5 ℃, ≤ 3 ℃ respectively. There was an exponential relationship between the total probability of cold damage after flowering beginning and the date of the flowering beginning, but there was a linear relationship between them if cold damage below or equal to 3℃ occurred at the date of flower beginning.