Diurnal difference of stable isotopes of precipitation in the summer half-year in Lanzhou City
Based on the measured precipitation stable isotope data and related meteorological data in Lanzhou City from April 2019 to October 2022,this study used the HYSPLIT backward trajectory model to systematically examine the characteristics of variation of hydrogen and oxygen stable isotopes of precipitation and the difference of isotopes between day and night under different types of precipitation events(convective precipitation,stratiform precipitation),and trace the water vapor sources.The results show that:1)Both δ2H and δ18O in precipitation presented a trend of enrichment and then depletion,while d-excess in convective precipitation showed a trend of depletion and then enrichment during the daytime and continuous depletion at night,and d-excess in stratiform precipitation all showed a trend of depletion and then enrichment.2)The local atmospheric water line slope(8.01)and intercept(15.55)of convective precipitation at night were the largest and closer to the global atmospheric water line,while the local atmospheric water line slope(6.81)and intercept(4.08)of stratiform precipitation during the day were the smallest,indicating that stratiform precipitation was more susceptible to evaporative fractionation.3)There was a positive correlation between air temperature and δ18O values,and the influence on the daytime stratiform precipitation isotope was most significant(r=0.59,P＜0.01).There was a significant negative correlation between relative humidity and δ18O values,and the most significant effect was on the isotopic values of convective precipitation at night(r=-0.52,P＜0.01).There was no significant correlation between precipitation and precipitation isotope during the day,but a negative correlation at night(r=-0.26,P＜0.05).4)In the summer half year(April to October)in Lanzhou,the precipitation-producing water vapor mainly comes from Central Asia,Mongolia,and other northern regions and is transported to Lanzhou through the control of the westerlies and continental air masses,and only a small part of it is affected by the southwest monsoon.The results of this study can provide a new perspective for exploring the key drivers of precipitation isotope change in arid areas,and have important significance for modern climate research and water resources management.
precipitationhydrogen and oxygen isotopeswater vapor sourcesdiurnal differencesLanzhou City
万方数据
维普
