Climatological Characteristics of the Atmospheric Water Cycle in the Huaihe River Basin and Its Relationship With Summer Precipitation Anomalies

The Huaihe River Basin (HRB) is situated in a transitional climate zone between northern and southern China, where droughts and floods have significantly impacted socioeconomic development. In this study, we employed a two-dimensional bulk model to examine atmospheric water cycle processes and summer precipitation in the HRB. The region's precipitation primarily originates from advected moisture, mainly entering through southern and western boundaries. Although summer precipitation from advected moisture substantially exceeds that in winter, the precipitation recycling ratio is lower in summer (5.46%) than in winter (6.11%). Summer precipitation in the HRB shows a negative correlation with the precipitation recycling ratio, and its interannual variability is predominantly controlled by precipitation from advected moisture. Differences in water cycle processes between the years of summer drought and flood demonstrate that precipitation variations are largely driven by changes in the advected moisture. Composite analysis further reveals that precipitation in the HRB is influenced by anomalous moisture transport in the Indo-Northwest Pacific. During drought and flood years, the HRB is affected by the cyclonic and anticyclonic moisture transport anomalies, respectively, and both moisture transport patterns are fundamentally controlled by large-scale atmospheric circulation anomalies. This investigation of the atmospheric water cycle of HRB provides crucial insights for understanding the regional drought-flood disaster mechanisms.