基于SPI指数近57年肇庆市干旱特征分析

选取肇庆市6个国家基本气象站1962—2018年逐月降水资料,基于标准化降水指数SPI,利用线性回归、M-K突变检验、Morlet连续复小波分析和EOF分解等方法对肇庆市近57年干旱时空变化特征进行分析。结果表明:(1)1962—2018年肇庆市SPI12呈震荡上升趋势,但线性趋势不显著;序列存在6、11、18年的周期,其中以18年为第1主周期;干旱主要发生在春、秋两季,春季干旱趋于加强;夏季干旱呈波浪变化趋势;秋、冬季干旱变化不明显。(2)干旱呈自西北向东南逐渐增强的分布特征。怀集县SPI12呈下降趋势且旱涝变化相对其他地区较敏感,其余地区SPI12值均为上升趋势,干旱趋于缓解。

Analysis of Drought Characteristics of Zhaoqing for the Past 57 years Based on SPI index

Using monthly rainfall data from six national basic meteorological stations in the city of Zhaoqing from 1962 to 2018 and based on standardized precipitation index(SPI)and the methods of linear regression,Mann-Kendall abruptness test,Morlet continuous complex wavelet transform and EOF decomposition,this paper studies the spatiotemporal variation characteristics of droughts in Zhaoqing for the 57 years studied.The result is shown as follows.(1)In the years studied,the city’s SPI12 shows a fluctuating rising tendency though the linear trend is insignificant.The series shows periods of 6,11 and 18 years,with the last period being the first primary period.Droughts mainly happen in spring and autumn and spring droughts tend to intensify.While summer droughts vary in fluctuation,autumn and winter droughts vary insignificantly.(2)Droughts are so distributed that they gradually enhance from the northwest to the southeast.For the county of Huaiji,the SPI12 tends to decrease and droughts and floods vary more sensitively than in other parts of Zhaoqing where the index tends to rise and droughts tend to relieve.