Influence of Sub-Cloud Secondary Evaporation and Moisture Sources on Stable Isotopes of Precipitation in Shiyang River Basin, Northwest China

Fractionation of stable isotopes in precipitation runs through the water cycle, and deuterium excess is a second-order parameter linking water-stable oxygen hydrogen isotopes. It strongly influenced by under-cloud evaporation unsaturated air, especially arid climates. Based on improved Stewart model, this study used 670 isotope data measured meteorological element from 11 sampling points January 2018 to September 2019 verify existence sub-cloud secondary Shiyang river basin quantitatively calculate intensity its influence The vapor flux Lagrangian model track moisture source analyze different paths precipitation. Therefore, helpful understand evapotranspiration loss mechanism recharge watershed. results showed that there River Basin, seasonal scale, stronger spring summer, but weaker autumn winter, which makes heavy enriched summer depleted winter. From perspective spatial distribution, midstream downstream river, resulting more enrichment In vertical direction, at 850 hPa–700 hPa strongest, enriches layer reduces excess. addition, main Basin westerly air mass, mid high-latitude land sources contribute However, supply sea very limited, higher does not show regional consistency seasonality well.