Stable isotopes in atmospheric water vapour: Patterns, mechanisms and perspectives

Stable isotopes in atmospheric water vapour are important tracers for investigating water vapour transport, mixing and phase transition. In recent years, with the rapid development of analytical techniques, research on water vapour stable isotopes has been widely conducted worldwide. In this review, we summarize basic theory and examine various methodologies employed to study stable isotopes in atmospheric water vapour, ranging from traditional collection methods to more recent advancements in laser absorption spectroscopy, satellite remote sensing, and isotope general circulation models (iGCMs). We pointed out the critical role played by isotopes in tracing moisture sources, understanding precipitation patterns, and reconstructing past climates. We identify gaps in knowledge, particularly in the representation of isotopic processes in climate models. Furthermore, we highlighted future research should focus on enhancing isotopic measurement technologies, integrating isotopic data with climatic indicators to improve model accuracy, and expanding isotopic studies to underserved water cycle dynamics. This review aims to provide suggestions for future investigations to deepen our understanding of atmospheric water vapour stable isotopes and their significance in climatology and hydrology.