资源环境科技发展态势分析平台

Assessing the long-term drought changes is of large interest for understanding the impact of climate change on water resources. Here we have attempted to assess the long-term drought changes (1948-2012) over China using the self-calibrating Palmer drought severity index with Penman-Monteith (scPDSI(PM)) and Thornthwaite (scPDSI(Th)) methods for potential evapotranspiration (PET) estimations, respectively, so as to understand the impact of different PET methods on drought assessment. Both scPDSI(PM) and scPDSI(Th) appear to have drying trends in the humid and transitional climatic regions, which are particularly significant in the north China. Compared to scPDSI(PM), the scPDSI(Th) data have resulted in exaggerated drought severity in the north China since 1980s, and such exaggeration is particularly significant for extreme droughts in terms of the occurrences and the intensity. In the dry climatic regions of northwest China, both scPDSI(PM) and scPDSI(Th) appear to exhibit adequate wetting trends; however, both data have shown drying trends of intensity when drought occurs, indicating there are more extreme dry conditions in the context of generally wetting background. Surprisingly, scPDSI(PM) is found to result in exaggerated droughts rather than scPDSI(Th) in the northwest China.