基于SPEI指数的京津冀地区干旱特征分析

Analysis of Drought Characters Based on SPEI Index in Beijing-Tianjin-Hebei Region

为明确不同尺度的干旱特征及其对气候变化的响应,选取1961—2016年京津冀地区24个气象站逐日气象观测数据,计算不同时间尺度的标准化降水蒸散指数(SPEI),应用Mann-Kendall突变检验、干旱评价指标、气候倾向率、旋转经验正交函数(REOF)等方法,分析了京津冀地区近56 a来的干旱特征,结果表明:从年际变化看,京津冀地区呈干旱减轻趋势;从季节变化看,除夏季具干旱化趋势外,春、秋、冬季均呈湿润化趋势,秋季湿润化显著;干旱范围呈全域性,干旱强度以轻旱和中旱为主;从空间分布上看,京津冀地区总体表现出西部湿润化、东部干旱化的趋势;根据载荷向量的空间异常分布,京津冀地区可分为北部中区(Ⅰ区)、北部东区(Ⅱ区)、北部西区(Ⅲ区)和南部区(Ⅳ区),其中Ⅰ、Ⅱ区干旱加剧,Ⅲ、Ⅳ区则呈现湿润化趋势。

In order to define the spatial temporal distribution of drought characteristics and its response to climate change in the Beijing-Tianjin-Hebei region at different time scales, daily climatic data of 24 meteorological stations from 1961 to 2016 were selected in this study. The standardized precipitation evapotranspiration index （ SPEI） was established by using precipitation and reference crop evapotranspiration （ET0） data at different time scales, in which ET0 was calculated by FAO Penman Monteith equation. In order to find out the drought characteristics, Mann Kendall test, drought indices, climate tendency rate and rotated empirical orthogonal function （REOF） analysis were carried out on the SPEI. The results show that from the inter annual changes, there is a humid trend in Beijing-Tianjin-Hebei region; from the sea-sonal perspective, it is getting wet in spring, autumn （P〈0. 05） and winter, and there is a drought trend in summer. The drought coverage appears as the features of the domain drought at the annual scale and the intensity of drought is light and moderate mainly. Viewing form spatial distribution, the western region has a humid trend, while it is dry in the eastern part of Beijing-Tianjin-Hebei region. According to spatial abnormal distribution of loading vectors in the Beijing Tianjin Hebei region, it can be divided into 4 sub regions： central area in the north region （sub-regionⅠ）, east area in the north region （sub-region II）, west area in the north region （sub-region III） and southern region （sub-region IV）. Drought in Ⅲ and Ⅳ sub regions gradually alleviates, while Ⅰ and Ⅱ sub regions shows a trend of getting dry.