Shih, Ching-HungChing-HungShihJang, Yi-ShinYi-ShinJangYang, Tzu-YingTzu-YingYangCHO-YING HUANGJEHN-YIH JUANGMIN-HUI LO2025-12-312025-12-312025-06-27https://www.scopus.com/pages/publications/105010093149https://scholars.lib.ntu.edu.tw/handle/123456789/734859Vapor pressure deficit (VPD), a key indicator of atmospheric dryness, is strongly influenced by diurnal cycles of temperature (T) and relative humidity (RH). While these cycles are typically inversely locked in-phase, recent research has identified diurnal hysteresis, characterized by a time lag between T and RH; yet, its impact on VPD under changing climates remains poorly understood. In this study, we examine how diurnal T/RH hysteresis modulates VPD across different climates using observational data alongside high-resolution reanalysis and simulations. Here, we find that regions exhibiting strong diurnal T/RH hysteresis, especially in some waterside and montane regions, experience earlier daily VPD peaks. We also demonstrate that global warming weakens diurnal T/RH hysteresis, leading to amplified VPD increasing trends and greater ecosystem stress. These results highlight the need for improved representation of diurnal T/RH interactions in climate models to better predict atmospheric dryness and its impacts on land-atmosphere feedbacks, ecosystems, and regional water cycles.trueAtmospheric humidityAtmospheric temperatureClimate modelsEcosystemsHysteresisChanging climateDiurnal cycleDiurnal temperaturesHumidity hysteresisIn-phaseKey indicatorRecent researchesTemperature and relative humidityTime lagVapor pressure deficitadultarticlecircadian rhythmclimateclimate modelcontrolled studygreenhouse effecthysteresisphysiological stresssimulationtemperaturevapor pressurewater cycleGlobal warmingjournal article2-s2.0-105010093149