Extremely low δ2H signatures in tropical cyclone precipitation recorded by tree-ring lignin methoxy hydrogen isotopes

Against the backdrop of climate change, the destructive power of tropical cyclones (TCs) has intensified, highlighting the urgent need for a more comprehensive understanding of tropical cyclone activity beyond the records provided by meteorological observations and historical documents. In this study, we compiled TC events affecting the Hong Kong region of South China since 1980 and investigated their isotopic imprints in precipitation and tree rings. We compared the hydrogen isotopic composition of precipitation (δ²H_ppt) during TC-affected and TC-free months. After accounting for the rainfall amount effect and seasonal influences, we demonstrate that δ²H_ppt consistently captured the anomalously depleted isotopic signals associated with TC rainfall. Furthermore, robust regression analysis indicated that TC-related precipitation isotopic variability explained approximately 30.5% of the variance in lignin methoxy stable hydrogen isotopes (δ²H_LM) of tree-ring latewood in Pinus elliottii Engelm. at the Hong Kong site. Additionally, TC precipitation (TCP) exerted the strongest positive control on TC signals recorded in latewood δ²H_LM, with additional contributions from TC intensity (MaxInte) and a significant negative seasonal effect (SeasonalIdx), while storm duration (Days) and distance (MinDist) showed limited independent influence. Overall, TC signals preserved in latewood δ²H_LM reflect the integrated hydroclimatic effects of multiple storm characteristics at the annual scale, rather than being controlled by any single statistical descriptor of tropical cyclone activity. Our findings demonstrate that tree-ring latewood δ²H_LM in P. elliottii can serve as a robust recorder of tropical cyclone signals. This work broadens the application of tree-ring lignin hydrogen isotopes and provides a novel proxy for improving interpretations of historical TC variability.