Anomalous variations in stable precipitation isotopes driven by high-temperature events

Abstract. Stable hydrogen and oxygen isotopes in atmospheric precipitation have the potential to identify abnormal weather events, and climate change will cause more intense and frequent high-temperature events, which already pose a threat to human health and the development of the global economy. Based on precipitation isotope data from 37 high-temperature events that occurred in various global regions between 2010 and 2022, this article examines the impacts of high-temperature events on stable precipitation isotopes. The results show that (1) stable precipitation isotopes are more enriched under the influence of high-temperature events than in the same month of previous years; the slope and intercept of the precipitation local meteoric water line (LMWL) are lower than in the same month of previous years and the global meteoric water line (GMWL); and the precipitation d-excess is lower than the global average. (2) Temperature is the primary meteorological factor that produces abnormal variations in precipitation isotopes under the influence of high-temperature events, and the impact of temperature on precipitation isotopes is significantly amplified (P<0.05). (3) Furthermore, variations in atmospheric circulation patterns, water vapor transport fluxes, regional water vapor background, and surface morphology can lead to regional differences in anomalous variations in precipitation isotopes. This study reveals the impact of high temperatures on precipitation isotopes and their mechanisms, which is instructive for disentangling the influence of high-temperature events on water cycle processes. It may also offer fresh perspectives for the reconstruction of paleo-high-temperature events based on isotopes.