Using stable isotopes to understand seasonal and interannual dynamics in moisture sources and atmospheric circulation in precipitation |
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| Authors: | Yu Tang Xianfang Song Yinghua Zhang Dongmei Han Likun Ai Tianbao Zhao Yajun Wang |
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| Institution: | 1. Key Laboratory of Water Cycle and Related Surface Processes, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Science, Beijing, China;2. International Programme Office, Third Pole Environment, Institute of Tibetan Plateau Research, Chinese Academy of Science, Beijing, China;3. Key Laboratory of Regional Climate‐Environment Research for Temperate East Asia, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, China |
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| Abstract: | Stable isotopes in precipitation are useful tracers to strengthen understanding of climate change and hydrological processes. In this study, the moisture sources of 190 precipitation events in Beijing were analysed using the Hybrid Single‐particle Lagrangian Integrated Trajectory model, based on which we studied the relation between variations in precipitation δ18O and dynamics in moisture sources and atmospheric circulation in seasonal and interannual timescales. Categorization of 7 groups of moisture sources was performed, among which oceanic moisture sources presented lower δ18O in precipitation than continental moisture sources. The results show that seasonal variations of precipitation δ18O were caused by changes of moisture sources. In summer, moisture from proximal oceans dominated vapour transport to Beijing due to increasing monsoon strength and resulted in a relatively small variation of precipitation δ18O. At the interannual timescale, the variations of δ18O in summer precipitation were related to dynamics in oceanic moistures, showing depleted values when the contribution of oceanic moistures, especially the proportion of long‐distance oceanic moisture, was high. Further analysis indicated that changes of oceanic moisture sources were controlled by the strength of summer monsoons. These findings address the complexity of moisture sources in midlatitude monsoon areas and suggest that isotopic signals in precipitation have the potential to deduce changes in moisture sources and atmospheric circulation and can therefore serve for palaeoclimate reconstruction. |
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| Keywords: | atmospheric circulation Beijing moisture sources oxygen‐18 precipitation events |
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