中国亚热带干旱多尺度时空格局及演变趋势

为探讨不同时间尺度下中国亚热带区域干旱的时空特征,利用1 km气象数据计算1959—2019年亚热带区域标准化降水蒸散发指数(SPEI),并且结合干旱线性变化趋势、影响范围、强度及频率,分析了不同时间尺度(1月、3月、6月、12月)下中国亚热带区域干旱的时空特征。结果表明:(1)干旱时期主要集中在2004—2014年,干旱化区域空间上呈现明显的东西对比,时间尺度上秋季的干旱化趋势最为显著;(2)各时间尺度的干旱影响范围都处于不断波动上升的趋势,尤其是在1995年之后,干旱影响范围上升趋势尤为明显;(3)季节和干湿季较大干旱强度零星分布在亚热带西南部及湖南、江西等省,年际较大干旱强度则主要集中在亚热带东南部;(4)秋季发生干旱的频率最高,年际发生中度及以上干旱频率最高,春季高频中度及以上干旱频率集中在四川、西藏等地,秋季和年际主要集中在四川、重庆和贵州的交界处,夏季、冬季以及干湿季则零星分布在亚热带各省份。综上,亚热带总体呈现干旱化趋势,季节、干湿季和年际尺度的干旱影响范围时间序列变化趋势较为相似,但干旱强度和干旱发生频率在空间上存在一定差异。

Multi-scalar Spatiotemporal Pattern and Evolution Trend of Drought in Subtropical China

In order to investigate the spatio-temporal characteristics of drought in subtropical regions of China at different time scales, standardised precipitation evapotranspiration index(SPEI)was calculated using 1 km meteorological data from 1959 to 2019, and the linear variation trend, influence area, intensity and frequency of drought were combined. The temporal and spatial characteristics of drought in subtropical regions of China under different time scales(1, 3, 6, 12 months)were analysed. The results are as follows:(1)The drought period is mainly concentrated in 2004—2014, the spatial contrast between the east and the west of the drought area is obvious, and the drought trend in autumn is the most significant on the time scale;(2)The drought area is fluctuating with an increasing trend, especially obvious after 1995;(3)The time scalar of seasons and dry/wet seasons with high drought intensity has scattered distribution in Hunan Province, Jiangxi Province, and other southwestern provinces. The high intensity of yearly scalar is mainly concentrated in the southeast of the subtropical China;(4)droughts most frequently occurred in autumn, and the frequency of mid-above drought in interannual is the highest. In spring, the frequency of mid-above drought is concentrated in Sichuan Province and the Tibetan Autonomous Region. In autumn and inter-annual, it is mainly concentrated in the junction of Sichuan Province, Chongqing City and Guizhou Province. In summer, winter and dry/wet seasons, it is scattered in subtropical provinces. Above all, subtropical China generally presents a trend of aridification. The time series of seasonal, dry/wet seasons, and the inter-annual have similar trends in drought influence area, but the intensity and frequency have some differences throughout the whole study area.