银川平原夏半年不同等级降雨水汽输送机制

Global warming intensifies regional water cycles and alters water vapor transport routes. Investigatingstable isotope traits in diverse precipitation grades and identifying water vapor origins can offer insights forefficient water resource utilization and drought- flood management. By analyzing precipitation samples fromYinchuan Plain in the May- October summer half- years of 2018- 2020, the hydrogen and oxygen isotopefluctuations across precipitation levels and their secondary evaporation effects were estimated in this study.Backward trajectory modeling and water vapor flux methods were applied to determine vapor sources andpotential evaporation areas. The findings revealed that the stable isotope signature in Yinchuan Plain during thesummer half-year decreased with increased rainfall levels; light rain exhibited negative d-excess values, whereasmoderate and heavy rains showed positive values. The slope and intercept of the regional atmosphericprecipitation line diminished as rainfall magnitude increased. Secondary evaporation intensified with higher airtemperature, but decreased with increased precipitation, air relative humidity, and raindrop diameter. Distinctwater vapor origins existed across precipitation levels: westerly vapor dominated light rain, whereas moderateand heavy rains originated not only from westerly vapor but also from high latitude land evaporation vapor andsoutheast ocean vapor, respectively. Potential evaporative vapor source areas predominantly influenced light andmoderate rainfall, encompassing the study areas vicinity as well as northwest and southeast regions. Moderaterainfall events were largely observed in the study areas vicinity, as well as northwest and southeast regions,whereas heavy rainfall clustered around the study area and the southeastern region.