Abstract
Based on the precipitation δ18O values from the datasets of the Global Network of Isotopes in Precipitation (GNIP), the National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) Reanalysis data, and previous researches, we explored the temporal and spatial variations of precipitation δ18O in a typical monsoon climate zone, the Pearl River basin (PRB), and adjacent regions. The results showed that the temporal variations of precipitation δ18O for stations should be correlated with water vapor sources, the distance of water vapor transport, the changes in location, and intensity of the intertropical convergence zone (ITCZ) rather than “amount effect.” Meanwhile, local meteorological and geographical factors showed close correlations with mean weighted precipitation δ18O values, suggesting that “altitude effect” and local meteorological conditions were significant for the spatial variations of precipitation δ18O. Moreover, we established linear regression models for estimating the mean weighted precipitation δ18O values, which could better estimate variations in precipitation δ18O than the Bowen and Wilkinson model in the PRB and adjacent regions.
Highlights
Meteoric precipitation is a significant part of the circulation of natural water, and the composition of stable isotopes is closely related to meteorological factors and geographical factors, which have shown a sensitive response to environmental change [1,2,3]
Based on the Global Network of Isotopes in Precipitation (GNIP) established by the International Atomic Energy Agency (IAEA) and the World Meteorological Organization, a number of scholars have explored the characteristics of precipitation δ18O and factors controlling precipitation δ18O variations [2, 8,9,10], revealed the original moisture sources of precipitation [11, 12], calculated the contribution ratio of every moisture source to precipitation [9], found significant impacts of climatic events on precipitation δ18O [13], and utilized models to predict the temporal and spatial distribution of precipitation δ18O [3, 14,15,16]
Order to compare the factors controlling precipitation δ18O values among stations under different time scales in the Pearl River basin (PRB) and adjacent regions, linear correlations between the mean weighted precipitation δ18O values of all stations and their corresponding mean meteorological values and altitude were calculated on the three time periods, while stations of Liangfengdong, Huanjiang, Ailaoshan, and Mengzi were only calculated for the annual time scale
Summary
Meteoric precipitation is a significant part of the circulation of natural water, and the composition of stable isotopes is closely related to meteorological factors (e.g., temperature, relative humidity, and precipitation amount) and geographical factors (e.g., latitude, altitude, and distance from the moisture transport source), which have shown a sensitive response to environmental change [1,2,3]. River basin (PRB) and adjacent regions, which have the closer distance to the moisture transport sources for being located in the south of China. This may reveal the more complicated patterns of temporal and spatial distribution of precipitation δ18O and controlling factors. This study utilizes precipitation δ18O data from the GNIP and previous studies to (1) understand the temporal and spatial variations of precipitation δ18O in the PRB and adjacent regions; (2).
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