Alpine meadow is one of the most widely distributed vegetation types on the Tibetan Plateau—the Earth’s Third Pole. Characterizing the carbon and water vapor fluxes in alpine meadow ecosystems is of particular importance for elucidating the mechanisms underlying the carbon budget and water cycle in high-altitude areas, especially under changing climatic conditions. Thus, the quantitative relationships between carbon and water fluxes and environmental drivers were examined based on a continuous eddy covariance (EC) dataset from 2013 to 2015 over the alpine Kobresia meadow on the northeastern Tibetan Plateau. The results show that (1) the net ecosystem CO₂ exchange (NEE) was − 152.89 g C m⁻² year⁻¹, − 197.69 g C m⁻² year⁻¹, and − 160.09 g C m⁻² year⁻¹ from 2013 to 2015, respectively, suggesting that this alpine meadow ecosystem is a strong and consistent carbon sink. (2) Both the multiple stepwise regression analysis (MSRA) and the structural equation model (SEM) analysis confirmed the dominant role of T_s in controlling the carbon flux and that of R_n in controlling the water vapor flux. (3) The inherent water use efficiency (IWUE = GPP×VPD/ET) and underlying water use efficiency (uWUE = GPP×VPD^0.5/ET), which incorporates the vapor pressure deficit (VPD) effect, better described the carbon-water coupling characteristics at daily and hourly scales than did the traditional water use efficiency (WUE = GPP/ET). These findings highlight the dominant climatic factors controlling CO₂ and water vapor exchanges and contribute to our knowledge of the land surface-atmosphere exchange in alpine meadows on the Tibetan Plateau.

高寒草甸是青藏高原上分布最广泛的植被类型之一，即地球的第三极。阐明高山草甸生态系统中的碳和水蒸气通量的特性对于阐明高海拔地区（尤其是在气候条件变化的情况下）碳收支和水循环的基础机制特别重要。因此，基于青藏高原东北部高山嵩草草甸2013年至2015年的连续涡动协方差（EC）数据集，研究了碳和水通量与环境驱动因素之间的定量关系。结果表明：（1）净生态系统CO ₂交换量（NEE）为-152.89 g C m - ² 年^-1， - 197.69克C M ^-2 年^-1，以及- 160.09克C M ^-2 年^-1 2013年至2015年，分别，这表明该草甸生态系统是一个强和一致的碳汇。（2）多元逐步回归分析（MSRA）和结构方程模型（SEM）分析都证实了T _s在控制碳通量中的主导作用和R _n在控制水蒸气通量中的主导作用。（3）固有水利用效率（IWUE = GPP×VPD / ET）和基础水利用效率（uWUE = GPP×VPD ^0.5 / ET），其中包括蒸气压不足（VPD））效应，比传统的水利用效率（WUE = GPP / ET）更好地描述了日尺度和小时尺度的碳水耦合特征。这些发现突出了控制CO ₂和水蒸气交换的主要气候因素，并有助于我们了解青藏高原高山草甸的地表-大气交换。