Spatiotemporal evolution and atmospheric circulation response of DWAA events in the Yellow River Basin, China, under climate warming
摘要
To clarify the impact of climate warming on Dry–Wet Abrupt Alternation (DWAA) events in the Yellow River Basin (YRB) and examine their relationship with atmospheric circulation, this study applies the Daily Scale Dry–Wet Abrupt Alternation Index (DWAAI), based on daily precipitation data from 240 national meteorological stations, to identify DWAA events from 1960 to 2023. Analytical methods include the M-K mutation test, hotspot analysis, Kernel Density Estimation, linear regression, and partial correlation analysis. Results show that light and moderate DWAA events display a typical “more in the east, less in the west” distribution. June–July is the peak occurrence period, with higher-grade events occurring earlier in the year. Following the temperature shift in 1997, high-frequency zones move northward and expand eastward. Coverage of light and moderate events increases significantly in the lower reaches (by 4.48% and 4.07%), while severe events contract slightly. After the temperature shift, the onset of DWAA events in the upper and middle reaches occurs earlier, while the temporal concentration of severe events becomes more pronounced.Event frequency trends reverse in the post-shift period, changing from decreasing to increasing (except for severe events). The influence of atmospheric circulation factors on DWAA events is primarily associated with the Dry Period in June and the Wet Period in July, with teleconnection factors contributing more to the Dry Period, exhibiting a greater lag effect. teleconnection factors contributing more strongly to the Dry Period exhibiting a greater lag effect. After climate warming, the influence of most atmospheric circulation factors on DWAA events in the YRB has increased, and some indices have shifted from predominantly affecting the Dry Period to predominantly affecting the Wet Period.