基于标准化降水指数的1961-2020年昌吉地区气象干旱趋势分析

Analysis of Meteorological Drought Trend in Changji Region of Xinjiang from 1961 to 2020 Based on Standardized Precipitation Index

采用昌吉地区10个气象站1961-2020年降水量资料,计算昌吉地区年、季尺度标准化降水指数(SPI-12、SPI-3),并对SPI指数评价实际干旱的能力进行验证。运用趋势分析法、M-K突变检验法、小波分析法等方法,探究昌吉地区气象干旱变化特征;在此基础上分析年、季尺度上的干旱频率、干旱强度和干旱覆盖面积的变化趋势。结果表明:SPI指数可以表征昌吉地区的干旱特征;1961-2020年昌吉地区年SPI值呈明显的阶段性特征,年代变化趋势呈变干-变湿-变干的变化波动,进入21世纪以来,变干趋势较为明显;昌吉地区春、夏、秋季SPI呈不显著的湿润化态势,但进入21世纪以后,春、夏季逐年变干旱化,冬季呈显著的湿润化态势;干旱强度在全区范围内主要为轻旱和中旱等级,2010年以来春、夏、秋季干旱强度明显增大;1961-2000年干旱发生面积有轻微减少,进入21世纪以来干旱范围向扩大趋势发展,全域性和区域性干旱发生较为频繁;在周期性变化方面,存在着3~5 a、8~18 a、20~30 a的多重周期振荡,且随时间尺度降低,表现的“干-湿”交替渐趋频繁,但不同时间尺度表现出不同的干湿震荡规律。

In this paper,the precipitation data of 10 meteorological stations in Changji area from 1961 to 2020 were used to calculate the standardized precipitation index(SPI-12 and SPI-3)at the annual and seasonal scales in Changji area,and the ability of the SPI index to evaluate the actual drought was verified.Trend analysis method,M-K mutation test method,wavelet analysis method and other methods were used to explore the characteristics of meteorological drought in Changji area.On this basis,the changes of drought frequency,drought intensity and drought coverage area at the annual and seasonal scales were analyzed.The results showed that the SPI index could characterize the drought characteristics of Changji area.From 1961 to 2020,the annual SPI value in Changji area showed obvious phased characteristics,the annual change trend showed the change and fluctuation of drying-wetting-drying,and the drying trend has been more obvious since the 21st century.The SPI in spring,summer and autumn in Changji area showed an insignificant wetting trend,but since the 21st century,spring and summer became arid year by year,and winter showed a significant wetting trend.The drought intensity was mainly light and medium drought in the whole region,and the drought intensity increased significantly in spring,summer and autumn since 2010.From 1961 to 2020,the area of drought decreased slightly,but since the 21st century,the scope of drought has expanded towards an expanding trend,and global drought and regional drought have become more frequent.In terms of periodic changes,there are multiple periodic oscillations of 3~5 a,8~18 a and 20~30 a,and the"dry-wet"alternations become more frequent as the time scale decreases,but different time scales show different dry and wet oscillation rules.