Shih Ching-Hung, Jang Yi-Shin, Yang Tzu-Ying, Huang Cho-Ying, Juang Jehn-Yih, Lo Min-Hui
Department of Atmospheric Sciences, National Taiwan University, Taipei, Taiwan.
Department of Geography, National Taiwan University, Taipei, Taiwan.
Sci Adv. 2025 Jun 27;11(26):eadu5713. doi: 10.1126/sciadv.adu5713.
Vapor pressure deficit (VPD), a key indicator of atmospheric dryness, is strongly influenced by diurnal cycles of temperature () 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 and RH; yet, its impact on VPD under changing climates remains poorly understood. In this study, we examine how diurnal /RH hysteresis modulates VPD across different climates using observational data alongside high-resolution reanalysis and simulations. Here, we find that regions exhibiting strong diurnal /RH hysteresis, especially in some waterside and montane regions, experience earlier daily VPD peaks. We also demonstrate that global warming weakens diurnal /RH hysteresis, leading to amplified VPD increasing trends and greater ecosystem stress. These results highlight the need for improved representation of diurnal /RH interactions in climate models to better predict atmospheric dryness and its impacts on land-atmosphere feedbacks, ecosystems, and regional water cycles.
水汽压亏缺（VPD）是大气干燥程度的关键指标，受温度（）和相对湿度（RH）的日循环强烈影响。虽然这些循环通常呈反相锁定，但最近的研究发现了日滞后现象，其特征是温度与相对湿度之间存在时间滞后；然而，在气候变化情况下其对VPD的影响仍知之甚少。在本研究中，我们利用观测数据以及高分辨率再分析和模拟，研究日温度/相对湿度滞后如何在不同气候条件下调节VPD。在此，我们发现表现出强烈日温度/相对湿度滞后的区域，特别是在一些水边和山区，每日VPD峰值出现得更早。我们还证明，全球变暖会削弱日温度/相对湿度滞后，导致VPD上升趋势加剧以及更大的生态系统压力。这些结果凸显了在气候模型中更好地体现日温度/相对湿度相互作用的必要性，以便更准确地预测大气干燥程度及其对陆地-大气反馈、生态系统和区域水循环的影响。
