近40年宁夏热量条件的不稳定性探析

计算宁夏20个测站1961—2004年的≥0℃、5℃、10℃、15℃、20℃持续日数及其积温,熵分析表明,≥0℃积温,兴仁最不稳定,相对最稳定的是固原地区;≥5℃积温,青铜峡最不稳定,陶乐最稳定;≥10℃积温最不稳定的是海原,相对稳定的是惠农、吴忠、陶乐、永宁等地;≥15℃积温最不稳定的地方在海原以南地区,最稳定的是青铜峡。对一地而言,界限温度越高,积温越不稳定。宁夏各地的逐月平均气温在5—9月的变异系数较小且地域之间变化比较稳定,10月至翌年4月变异系数较大且地域差别较大。在80%保证率下,宁夏的各界限温度持续日数在引黄灌区最多,相应的积温也多,中部干旱带次之,黄土丘陵区最少,积温也最少。

Unstability Analysis on Heat Conditions of Ningxia in Recent 40 Years

Calculated lasting days and accumulated temperatures,which were ≥0℃,5℃,10℃,15℃ and 20℃ from 1961 to 2004 in 20 weather stations of Ningxia,Entropy were analysed.Results indicated:accumulated temperature more than 0℃ was the most unstable in Xingren,the relatively most stable in Guyuan area;more than 5℃ of accumulated temperature was the most unstable in Qingtongxia,the most steady in Taole;more than 10℃ of accumulated temperature was the most unstable in Haiyuan,the relatively steady areas were Huinong,Taole,and Yongning;as to more than 15℃ of accumulated temperature,the most unstable place was in the former areas to the south of Haiyuan,the most steady one was Qingtongxia.As to one place,the higher the temperature of radius was the more unstable the accumulated temperature was.The variation coefficients of monthly temperature were smaller in May-September and the changes among the regions were more steady in all parts of Ningxai.The variation coefficient was larger and the region difference was relatively large from October to April of next year.Under guaranteeing rate 80%,the lasting days of every radius temperature in Ningxia were the most in areas of Yellow River irrigation,corresponding accumulated temperature was much too,the aridity of middle part was taken second place,the loess hill areas were the least,accumulated temperature was the least too.