黄河流域非平稳气象干旱特征的重构及时空演变规律

Reconstruction of non-stationary meteorological drought series and its spatiotemporal patterns in Yellow River basin

气候变化和高强度人类活动影响下,基于平稳性假设的传统方法难以准确描述非平稳时间序列的演变规律。本文基于黄河流域1960—2020年逐月气象资料,采用自适应噪声完备集合经验模态分解法和游程理论提取标准化降水蒸散指数的重构干旱特征,结合Pettitt法和旋转经验正交函数研究非平稳气象干旱时空特征。结果表明,多时间尺度黄河流域气象干旱均呈现显著性增强趋势,且各时间尺度标准化降水蒸散指数序列均于1996年发生显著变化。考虑非平稳性的重构干旱特征时间上呈现出更为显著的季节性变化,空间上更符合流域实际情况。研究结果对厘清非平稳气象干旱时空演变规律具有重要意义,可为黄河流域防旱抗旱提供科学依据。

Under the influence of climate change and high intensity human activities,it is difficult to accurately describe the evolution of non-stationary drought series under the traditional stationary hypothesis.This study uses the complete ensemble empirical mode decomposition with adaptive noise and the run theory to extract the reconstructed drought characteristics of the standardized precipitation evapotranspiration index(SPEI),based on monthly meteorological data from the Yellow River basin of 1960-2020.And the Pettitt method and rotating empirical orthogonal functions are combined to examine its non-stationary meteorological drought characteristics.Results indicate that its meteorological drought manifested a significant increasing trend on multiple time scales,and significant changes in SPEI occurred around 1996 on all time scales.More pronounced seasonal variations in time and more realistic distributions in space are found in the reconstructed drought characteristics when taking into account the non-stationarity.This study is of great significance in clarifying the spatiotemporal evolution patterns of meteorological drought under non-stationary conditions,and helps drought prevention and mitigation for the Yellow River basin.