| Water resource is an indispensable and significant resource for human survival,and it is connected with each circle of the earth through the water cycle.Atmospheric precipitation is an important part of the water cycle process.The stable isotopes 18O and 2H(D),as components of water molecules,have been widely used in the study of complex climate change and hydrological processes.Sub-cloud secondary evaporation refers to the evaporation effect experienced by precipitation as it falls from the bottom of the cloud to the ground.The Stewart model is often used for evaluating the changes in isotope ratios when raindrops fall from cloud base to the ground.Sub-cloud secondary evaporation is easy to occur and the phenomenon is obvious in the arid and semi-arid area with low precipitation amount and high evaporation capacity.In the isotope hydrology studies,it is necessary to have a better understanding of variability in stable hydrogen and oxygen isotopes of raindrops from cloud base to the ground Therefore,in this article isotope space-time distribution of precipitation in Xinjiang was analyzed based on literature data,based on the daily climate data from Chinese surface stations.By using hourly meteorological observations at surface as well as the daily radiosonde observation and observation data of upper-air meteorological stations at regular intervals of Xinjiang from July 2016 to June 2017,the effect of sub-cloud secondary evaporation in Xinjiang was analyzed through the contrastive analysis of daily data and hourly data and the mean hypothesis and hierarchical hypothesis.Results showed that:(1)This study analyzed the spatial distribution of ?D value and ?18O value in the precipitation in Xinjiang,indicating that there are significant spatial differences between the ?D values and ?18O values in the precipitation of Xinjiang.And the ?D value and?18O value in the winter half year are significantly lower than that in the summer half year.(2)There were obvious seasonal differences of sub-cloud secondary evaporation based on daily data and hourly data and the mean hypothesis and hierarchical hypothesis.f and Ad showed a trend of larger in autumn and winter,smaller in spring and summer ??D and ??18O showed a trend of larger in spring and summer,smaller in autumn and winter in each partition except for the Tianshan mountain calculate by daily data in the area of Xinjiang.(3)From the perspective of space,the mean value off and Ad calculated by hourly data is larger than that calculated by daily data which means ??D and ??18O calculated by hourly data is smaller than calculated by daily data and f is larger(more than 80%)in the Altai region,the middle of Junggar Basin,the Tianshan mountain,the southern margin of Tarim Basin in four seasons.?d is smaller in the Western of Junggar basin and in the northeast of Tarim Basin,?d calculated by the mean hypothesis is larger than calculated by hierarchical hypothesis.f.??D,??18O and ?d have different performances in different regions.The differences of f,??D,??18O,?d calculated by mean hypothesis and hierarchical hypothesis mainly reflect in the Tarim basin.(4)f and ?d exist correlation.In terms of two data,the slop of each partition of Xinjiang is larger than 1.0‰/%expect slop off and ?d is 0.789‰/%.In terms of two scenarios,f and ?d exist correlation,the slope calculated by the mean hypothesis and hierarchical hypothesis are shown that Tarim Basin is highest,The Altai region took the second place and the Junggar Basin is the following step.And the Tianshan mountain was lowest.On the whole,The slope calculated by the mean hypothesis is larger than the slope calculated by hierarchical hypothesis.The slope off and ?d in two schemes is obviously larger than 1.0‰/% in Xinjiang. |
PDF Full Text Request