Composition Of Stable Isotopes Of Precipitation And The Water Vapor Sources In The Northern Part Of Qinling

The stable isotopes in precipitation have obvious disciplinary variations,which is closely related to the water vapor sources and many meteorological factors,such as precipitation,temperature and so on.Based on the determination of the stable isotopes(?D and ?18O)and the calculation of d-excess in the Northern Part of Qinling,we established the Local Meteoric Water Line(LMWL).According to the reanalysis daily variation data from the National Centre for Environmental Prediction/National Centre for Atmospheric Research(NCEP/NCAR),we got the change of ?18O and d-excess in the precipitation around the monsoon onset,and discussed the main meteorological factors affecting the change by using the bivariate correlation analysis method.On the other hand,based on the Interannual change of the ONI and ESSMI and the monthly date from NCEP/NCAR,we analysed the relationship between the variation of ?18O and the water vapor sources.Finally,utilizing the Hybrid Single-Particle Lagrangian Integrated Trajectory for 4.0(HYSPLIT-4)model,we traced the water vapor sources of typical precipitation events,to further explore the influence of the variation of water vapor sources on the ?18O and d-excess around the monsoon onset.the results are as follows:1?The intercept and slope of LMWL are lower than the global atmospheric precipitation line(GMWL),which is because the climate characteristics of drought.With the increasing rainfall levels,the secondary evaporation effect decreased,the intercept the slope of meteoric water line increased.2?The ?18O and d-excess in precipitation exhibited remarkable seasonal variations,which are higher in the dry season and lower in the rainy season,also higher before the monsoon precipitation and lower in the monsoon.The main meteorogical factor affecting the change are temperature,the temperature effect covered up the the precipitation effect.So the precipitation effect is only reflected on the scale of events.3?In winter and spring,the water vapor sources mainly came from the westerly and polar continental air mass,the ?18O tended to positive values.but in summer and autumn,the low latitudinal ocean became the main water vapor sources,the ?18O tended to negative values.The seasonal variation of ?18O in 2016 is similar to that of Hongkong,but in 2017,the seasonal variation of ?18O is similar to that of Urumchi.4?the tracing result of the water vapor sources in typical precipitation events showed that,in the monsoon period,the water vapor sources came from the Arabia sea,the bay of Bengal,and the Northwest Pacific,the ?18O tended to the negative values,but in the non-monsoon period,the sources mainly came from the westerly and the polar continental air mass,the ?18O tented to positive values.