Precipitation Variations in the Flood Seasons of 1910–2019 in Hunan and Its Association With the PDO, AMO, and ENSO

Floods in the middle reaches of Yangtze River threaten thousands million people, causing casualties and economic loss. Yet, prediction floods this region is still challenging. To better understand region, we investigate interdecadal-interannual rainfall variation flood season (April–September) Hunan province. The relationship between Pacific decadal oscillation (PDO), Atlantic Multidecadal Oscillation (AMO), El Niño-Southern (ENSO) are also analyzed. results show that precipitation seasons shows an interdecadal with a period about 20 years, which caused by joint effect PDO AMO. When AMO same phase, corresponding characterized more precipitation, conversely, it less precipitation. Further analyses year after Niño, when both positive favorable for west subtropical high (WPSH) to be stronger southward than normal. Such circulation anomaly conducive water vapor transport southern China, as result there Hunan. negative WPSH weaker normal, but India-Burma trough obviously stronger, southwesterly China. However, next La Niña year, regardless phase combination AMO, coast China controlled geopotential height retreats sea, not northward vapor, But if only cold SST background previous stage considered (without reaching standard event),is most Province. Therefore, at interannual scale, have modulating on signal. interannual-scale ENSO signal has greater influence seasons. Our will give implications predications