3种干旱指标在庆阳的业务适应性分析

Business Adaptability Analysis of Three Drought Indexes in Qingyang

摘要: 利用甘肃省庆阳市8个站1978~2020年逐日降水量数据以及干旱灾情数据，采用线性趋势、对比分析、小波分析等方法，分析了降水距平百分率、气象干旱综合指数MCI、标准化降水指数SPI的演变规律。结果表明：1) 3种干旱指数在2017年的表现，SPI和降水距平百分率两个指数的变化趋势几乎同步，尤其在冬季两者变化趋势高度吻合，但在干旱等级上存在差异；MCI指数与其他两种指数变化趋势相差较大。2) 通过分析1978年~2020年516个月的3种干旱指数计算的五种干旱等级发生频率分布，3种干旱指数分布形态基本一致；典型区无旱发生频率为58.7%~63.8%之间，轻旱以上发生频率在36.2%~41.3%；降水距平百分率指数评定为特旱的频率远远大于其他两种指数。3) 通过小波分析发现，在2020年曲线即将达到闭合的状态，降水距平百分率在未来可能步入1个较小的时期。3种干旱指数评定结论与所选取的干旱年份实际旱情进行对比分析，得到降水距平百分率优于SPI指数，MCI指数表现较差的结论。

Abstract: Based on the daily precipitation data and drought disaster data of 8 stations in Qingyang City, Gansu Province from 1978 to 2020, the evolution rules of precipitation anomaly percentage, meteorological drought composite index MCI and standardized precipitation index SPI were analyzed by using linear trend analysis, comparative analysis and wavelet analysis. The results show that: 1) in 2017, the trends of SPI and precipitation anomaly percentage are almost synchronous, especially in winter, but there are differences in drought grade. MCI index differs greatly from other two indexes. 2) By analyzing the frequency distribution of five drought grades calculated by three drought indices during the period of 516 months from 1978 to 2020, the distribution patterns of the three drought indices were basically consistent. The frequency of no drought in typical region was 58.7%~63.8%, and the frequency of light drought was 36.2%~41.3%. The frequency of precipitation anomaly percentage index as special drought is much higher than the other two indexes. 3) According to the wavelet analysis, the curve will be closed in 2020, and the percentage of precipitation anomaly may enter a relatively small period in the future. Compared with the actual drought situation in selected drought years, the percentage of precipitation anomaly is better than SPI index and MCI index is worse.