高级检索

河西走廊东部干旱指数MCI和Pa的时空特征及干旱评估差异研究

Spatiotemporal Characteristics and Evaluation Discrepancies of MCI and Pa Drought Indices in Eastern Hexi Corridor

  • 摘要: 基于河西走廊东部1961—2020年气象与灾情数据,对比分析了干旱指数MCI与Pa的时空特征、季节干旱特征差异及等级划分适用性。结果表明:(1)全年及春、夏、秋3季干旱均呈缓慢减轻的趋势,MCI指数的年际倾向率高于Pa指数;在空间上凉州、民勤、天祝两种指数的年际变化趋势基本一致,均呈现出干旱缓慢减轻的态势,古浪则表现相反( Pa指数减轻、MCI指数加重)。(2) MCI指数显示南部山区的干旱发生频率高于中北部,Pa指数表现则相反;年尺度上MCI指数的干旱发生频率与强度均低于Pa指数,而春、夏、秋季中北部MCI值低于Pa值,南部则相反。(3)年尺度上干旱等级表现为MCI指数略低于Pa指数,季尺度区域分异显著; MCI指数与Pa指数间具有强正相关性,变化趋势与灾情变化趋势吻合,均适用于区域干旱监测评估,其互补性可为双指数协同应用提供参考依据。

     

    Abstract: Comparative analysis was conducted on spatiotemporal characteristics, seasonal drought variations, and classification applicability between MCI and Pa drought indices based on meteorological and disaster records in eastern Hexi Corridor from1961 to 2020.The results showed that: (1) Both annual and seasonal (spring, summer, autumn) drought conditions showed a slow alleviation trend, with MCI exhibiting a higher inter-annual tendency rate than Pa. Spatially, Liangzhou, Minqin and Tianzhu demonstrated consistent trends between the two indices, all showing slow drought alleviation, while Gulang displayed opposite trends (Pa indicated alleviation, whereas MCI suggested intensification). (2) The MCI index indicated higher drought frequency in the southern mountainous regions compared to the central-northern areas, while the Pa index showed the opposite pattern. At the annual scale, both the frequency and intensity of drought identified by MCI were lower than those detected by Pa. However, seasonal analysis revealed that MCI values were lower than Pa in the central-northern regions during spring, summer and autumn, with the reverse pattern observed in the southern areas. (3) Inter-annual drought severity assessments showed that MCI index was slightly lower than the Pa index, with seasonal analyses exposing pronounced spatial heterogeneity in classification disparities. Nevertheless, the indices exhibited remarkable concordance. The two indices exhibited strong positive correlation, with their trend variations well corroborated by historical drought disaster records. This demonstrates their joint applicability for regional drought monitoring and assessment. Their complementary characteristics provide reference for synergistic application of the dual-index system.