1901～2022年长江流域降水年内分配时空演变规律OA

To assess the long-term spatiotemporal evolution of precipitation and its impacts on drought and flood disasters,this study employs the Precipitation Concentration Index(PCI),Seasonal Precipitation Concentration Index(SPCI),and Rainfall A-nomaly Index(RAI)to characterize the intra-annual precipitation distribution and associated drought-flood variations in the Changjiang River Basin from 1901 to 2022.The main findings are as follows:① Over the study period,the multi-year average PCI ranges from 11 to 26 across the basin,indicating a moderate to exceptionally concentrated intra-annual precipitation regime.Spatially,PCI values exhibit a northwest-high,southeast-low pattern.② On an interannual timescale,PCI shows an overall in-creasing trend(0.029 per decade),suggesting a strengthening of intra-annual precipitation concentration.Notably,the trend dif-fers markedly between the sub-periods 1901～1960 and 1961～2022,highlighting the temporal complexity of precipitation chan-ges.③ RAI analysis reveals a general wetting trend across the Changjiang River Basin(0.021 per decade)from 1901 to 2022.However,pronounced variations exist among different sub-periods and sub-regions.Some areas have transitioned from dry to wet conditions,whereas others have shifted from wet to dry,reflecting the diversity and dynamic nature of the basin's climate.④Abrupt change analysis shows that while the timing of abrupt changes in PCI and SPCI varies across study sub-periods,both in-dices experienced abrupt changes around the 1950s and 1990s.For the entire 1901～2022 period,PCI experienced three abrupt changes(in 1953,1988,and 2002).Abrupt changes in spring,autumn,and winter occurred earlier(1931,1920,and 1937,re-spectively),whereas another cluster of abrupt changes occurred around 1953 and 1989 in spring,summer,and winter.These find-ings reveal a shift in the precipitation regime of the Changjiang River Basin.The identified spatiotemporal evolution characteristics provide a scientific basis for predicting drought and flood disasters and contribute to a better understanding of regional climate re-sponses to global change.