To understand the water, energy, and carbon cycles in the Tibetan Plateau (TP), it is essential to estimate seasonal and inter-annual variations in energy fluxes and evapotranspiration (ET) for alpine meadow ecosystems. The multiyear (2014–2019) energy fluxes and ET, for a typical alpine meadow at Arou station (northeastern TP), and their environmental and biophysical controls were evaluated using the eddy covariance method in this study. Latent heat flux (LE) was the dominant component of energy consumption during the growing season, whereas sensible heat flux (H) dominated energy partitioning during the non-growing season. H showed the opposite trend to LE, while the seasonal variation of soil heat flux (G) was small. The daily ET was primarily controlled by the available energy on the seasonal scale. Soil water content (SWC) and normalized difference vegetation index (NDVI) displayed secondary effects on ET during the non-growing and growing seasons, respectively. The inter-annual ET was relatively stable, ranging from 562.6 to 661.9 mm (coefficient of variation; CV = 7.4 %); this was slightly higher than the annual precipitation despite large variations in inter-annual precipitation (CV = 19.9 %) and was most likely due to snow and frozen ground melting. The cumulative ET in the growing season was about 77 % of the annual ET. There was a nonlinear increase in the daily Priestley–Taylor coefficient (α = ET/ET_eq, where ET_eq is the equilibrium evaporation) with an increase in bulk surface conductance (g_c), which was insensitive to increases in g_c that exceeded 15 mm s⁻¹. There was a good relationship between g_c and NDVI. This study provides insights into the driving mechanisms of long-term variations in the energy partitioning and biophysical controls on ET in alpine meadow ecosystems.

要了解青藏高原 (TP) 的水、能量和碳循环，有必要估计高寒草甸生态系统的能量通量和蒸散量 (ET) 的季节和年际变化。在本研究中，使用涡度协方差法评估了阿鲁站（高原东北部）典型高寒草甸的多年（2014-2019）能量通量和ET，以及它们的环境和生物物理控制。潜热通量（LE）是生长季节能量消耗的主要组成部分，而显热通量（H）在非生长季节主导能量分配。H与LE呈相反趋势，而土壤热通量（G）的季节变化较小。每日 ET 主要由季节性尺度上的可用能量控制。土壤含水量 (SWC) 和归一化植被指数 (NDVI) 分别在非生长季节和生长季节显示出对 ET 的次要影响。年际ET相对稳定，范围从562.6到661.9 mm（变异系数；CV = 7.4 %）；尽管年际降水量变化很大（CV = 19.9 %），但仍略高于年降水量，这很可能是由于积雪和冻土融化所致。生长季节的累积 ET 约为年 ET 的 77%。每日 Priestley-Taylor 系数呈非线性增加（α = ET/ET 尽管年际降水量变化很大（CV = 19.9 %），但仍略高于年降水量，这很可能是由于积雪和冻土融化所致。生长季节的累积 ET 约为年 ET 的 77%。每日 Priestley-Taylor 系数呈非线性增加（α = ET/ET 尽管年际降水量变化很大（CV = 19.9 %），但仍略高于年降水量，这很可能是由于积雪和冻土融化所致。生长季节的累积 ET 约为年 ET 的 77%。每日 Priestley-Taylor 系数呈非线性增加（α = ET/ET_eq，其中 ET _eq是平衡蒸发）随着体表面电导 (g _{c ) 的增加，这对 g c}超过 15 mm s ^-1的增加不敏感。_{g c}与NDVI之间存在良好的关系。本研究提供了对高寒草甸生态系统中 ET 能量分配和生物物理控制长期变化驱动机制的见解。