Effect of the El Niño–Southern Oscillation on hydrogen and oxygen isotope ratios of precipitation in Guilin, SW China

ABSTRACT

This study monitored the isotopic compositions of precipitation in Guilin as well as the influence of El Niño–Southern Oscillation (ENSO) on the isotope ratios and water vapour sources from 2015 to 2016. The results indicate that the lower isotope values of precipitation from ocean water vapour source are affected by long transport distance and fractionation during summer and autumn. In contrast, the isotope values of winter and spring precipitation are affected by continental air masses and their evaporation sources yielding higher values. The intercepts of the local meteoric water line in Guilin are larger than those of the global meteoric water line, which is typical for subtropical monsoon climate. During the El Niño event, development of anomalous anticyclonic circulation enhances the northbound transport over the western Pacific and brings abundant water vapour to the southern part of China. During El Niño event prevailing period, precipitations exhibit a lower δ¹⁸O value and low d (deuterium excess) value, indicating that the 2015/2016 ENSO event had a significant effect on the precipitation distribution, precipitation amount, and isotope ratios in regional precipitation.

KEYWORDS:

• Deuterium excess
• El Niño–Southern Oscillation
• Guilin
• hydrogen-2
• isotope hydrology
• oxygen-18
• precipitation

Acknowledgments

The authors would like to thank Dr Gerhard Strauch (Editor-in-Chief, Isotopes in Environmental and Health Studies) and two anonymous reviewers for their valuable comments and feedback, which helped to improve this manuscript.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This study was financially supported by the National Natural Science Foundation of China (Nos 41501222, 41530316, and 41701235), Natural Science Foundation of the Guangxi Province (No. 2018GXNSFAA281320), major science and technology innovation-based construction project of Guangxi (No. 2018-242-Z01), and Chinese Academy of Geological Sciences Research Fund (No. 2020006).