摘要:咸海的迅速萎缩导致中亚五国的干旱问题引起了科学界的特别关注。为厘清中亚五国近30年来水分条件状况，探究影响其变化的气候驱动要素，本文使用帕默尔干旱指数（PDSI）对1990-2019年中亚五国干旱时空变化特征进行评估，并结合交叉小波变换揭示了大气涛动对其干旱状况的驱动影响。结果表明：中亚五国的干旱指数呈现周期性交替变化，年际变化率增大；夏秋旱、冬春湿的季节性干旱特征减弱，不同时间段的PDSI变异程度加剧，并表现出2018年后进入新一轮干期的可能。干旱程度总体呈现自西南向东北逐渐减轻、自东南山区向中西部平原逐步加重的格局；1990-2019年干旱重心由西南内陆腹地向哈萨克斯坦中西部地区转移，帕米尔和西天山山脉干旱程度呈波动上升态势。青藏高原指数（TPI）对PDSI变化表现出明显的驱动作用，在1990-2019年整个时间序列上均有较高的周期性强度，拥有1~3年（1995-2000年）、4~5年（2010-2015年）和8~10年（2015-2019年）3个明显年际尺度的震荡周期。总之，1990-2019年中亚五国整体干旱状况趋好，干旱变异程度加剧，干旱空间分异明显，TPI在年际尺度上是驱动PDSI变化的大气涛动要素。
关键词:帕默尔干旱指数(PDSI)/
中亚五国/
干旱/
驱动力/
大气涛动/
交叉小波分析
Abstract:The rapid shrinking of the Aral Sea has prompted the scientific community to focus on Central Asian drought. To clarify the moisture conditions of Central Asia over the past 30 years and to investigate the climate drivers of change, in this study, we used the Palmer Drought Index (PDSI) to assess the spatial and temporal characteristics of drought in the five Central Asian countries (Kazakhstan, Uzbekistan, Turkmenistan, Tajikistan and Kyrgyzstan) from 1990 to 2019. PDSI was combined with the cross-wavelet transformation to reveal the driving influence of climate oscillations on drought conditions. The results showed that the drought indicators displayed a cyclical alternation with an increasing variability, a weakening of the dry summer/autumn and wet winter/spring seasonal drought characteristics, and the possibility of a new dry period after 2018. The general drought intensity gradually decreased from the southwest to the northeast and progressively increased from the southeast mountainous area to the central and western plains. The drought center shifted from the southwestern hinterland to the northwestern regions of Kazakhstan. The Pamir and West Tianshan Mountains showed a fluctuating and increasing drought trend. The Tibetan Plateau Index (TPI) showed an apparent driving effect on PDSI changes, with high cyclical intensity throughout the 1990-2019 period (1-3 years [1995-2000], 4-5 years [2010-2015], 8-10 years [2010-2015], and 8-10 years [2016-2019]) with three distinct interannual-scale oscillatory cycles. Overall, drought conditions tended to improve, with increased drought variability and significant spatial variability; the TPI is the atmospheric oscillator driving PDSI variability.
Key words:Palmer Drought Index (PDSI)/
Central Asia/
Drought/
Driving force/
Climatic oscillations/
Cross-wavelet analysis
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