基于改进三维识别方法的西北地区干旱事件分析

Analysis of drought events in Northwest China based on an improved three-dimensional identification method

以标准化降水蒸散指数(SPEI)为基础,基于改进的干旱三维识别方法,提取多个反映干旱空间动态演变过程的特征变量,对西北地区识别的气象干旱事件进行分类并分析其时空演变模式,揭示季节干旱发展规律。结果表明:改进的干旱三维识别方法能够准确提取出时空连续的干旱事件,提高了干旱时空动态演变监测的可视化程度;1960—2018年西北地区气象干旱事件以同向迁移规律为主,青海省北部和甘肃省中部为两个主干旱中心区域,且呈现出历时逐渐变短、大面积干旱事件占比逐渐降低的趋势;西北地区季节连旱事件多集中在青海省,春夏秋连旱事件由东南向西北方向迁移,夏秋冬连旱事件由西南向东北方向迁移,且两种季节连旱事件在发展后期的迁移速率相对较快。

On the basis of standardized precipitation evapotranspiration index(SPEI),the traditional 3D drought identification method is improved to extract more characteristic variables that can reflect the spatial dynamic evolution process of drought.Then the spatio-temporal patterns of classified droughts are analyzed.The results show that the improved 3D drought identification method can accurately extract spatio-temporal continuous drought events,and improve the visualization of spatio-temporal dynamic evolution of drought.From 1960 to 2018,the meteorological drought events in Northwest China were mainly in the same direction of migration.The northern part of Qinghai Province and the central part of Gansu Province were the two main drought centers,and showed a trend of gradually shortening the duration and decreasing the proportion of large-scale drought events.The seasonal continuous drought events in Northwest China are mostly concentrated in Qinghai Province.The continuous drought events in spring,summer and autumn migrate from southeast to northwest,and the continuous drought events in summer,autumn and winter migrate from southwest to northeast.The migration rate of the two seasonal continuous drought events is relatively fast in the late development period.