| Stable isotopes of precipitation are very sensitive to environmental changes. Stable isotopes contain a variety of climate information and record the evolution of water cycle. The information can be used in inversing the atmospheric processes and reconstructing paleoclimate.In this thesis, based on the data of precipitation samples from Jan.2009to Dec.2011in Kunming, Tengchong, Mengzi, Yunnan Province. The author analyze the variable characteristics of stable isotopes of precipitation in the three stations, the relationship between stable isotopes of precipitation and meteorological factors data analyzed, the author also analyze the relationship between stable isotopes of precipitation and reanalysis data. According to the Lagrange Backwards Trajectory4.8,the moisture sources of the area are tracked. The main conclusions are as follows.(1) The research result indicates a significant seasonal effect of δ18O value in the three stations. During dry seasons, the δ18O in precipitation is low. However, during wet seasons, the δ18O in precipitation is high. The variations between δ18O and meteorological factors show significant inverse phase.(2) Under daily timescales, it suggests significant negative correlation between the δ18O in precipitation and the temperature, the precipitation amount, the air pressure. So, it shows that the variations of δ18O in precipitation have significant anti-temperature effect, precipitation amount effect, humidity effect. However, durning dry and wet seasons, it also suggests negative correlation between the δ18O in precipitation and meteorological factors, but the significant test is different.(3) Based on the reanalysis data of total column water vapour and wind speed in different height from the European center for medium-range weather forecasts, it indicates significant negative correlation between the δ18O in precipitation and the total column water vapour. Besides, it shows significant positive correlation between the δ18O in precipitation and the speed in different height, which indicates that the wind speed of different height is also an important factor in changing the δ18O of precipitation in some way.(4) We put forward the meteoric water line of the three stations.At Kunming station, the meteoric water line is8D=8.02818O+8.17, and the correlation coefficient is0.995. At Tengchong station, the meteoric water line is8D=8.18δ18O+11.77and the correlation coefficient is0.996. At Mengzi station, the meteoric water line is δD=8.16δ18O+8.70, and the correlation coefficient is0.992. Obviously, these meteoric water lines are similar to the world meteoric water line, which indicates the climate of this region is humid and rainy, and it is greatly influenced by the ocean water vapour.(5) The d-excess of precipitation also shows a significant seasonal variation in the three stations. During dry seasons, the d-excess is higher than that in wet seasons. The value of d-excess in precipitation is related to water vapour. We can see that based on the backwards trajectory model and the water vapour flux, the moisture sources mainly come from the inland water vapour of westerlies and the local water vapour circulation in dry seasons; the moisture sources come from the Bay of Bengal, the Arabin Sea and the South China Sea during wet seasons. |
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