Dynamics and environmental controls of evapotranspiration for typical alpine meadow in the northeastern Tibetan Plateau
Dynamics and environmental controls of evapotranspiration for typical alpine meadow in the northeastern Tibetan Plateau
复制标题
青藏高原东北部典型高寒草甸蒸散发动态及环境控制
DOI：
10.1016/j.jhydrol.2022.128282
复制
发表时间：
2022
影响因子：
6.4
通讯作者：
Qiudong Zhao
中科院分区：
文献类型：
--
作者：
Yaping Chang;Yongjian Ding;Shiqiang Zhang;Jia Qin;Qiudong Zhao
• 使用涡度协方差构建了连续 6 年的原位蒸散发数据集。 • 分析了2014-2019年典型高寒草甸ET的季节变化。 • 典型高寒草甸ET主要受可用能量控制。 • 土壤含水量在一定范围内通过体表面电导影响蒸散。为了了解青藏高原（TP）的水、能量和碳循环，有必要估计高寒草甸生态系统能量通量和蒸散量（ET）的季节和年际变化。本研究使用涡度协方差方法评估了阿鲁站（青藏高原东北部）典型高寒草甸的多年（2014-2019）能量通量和蒸散及其环境和生物物理控制。潜热通量（LE）是生长季能量消耗的主要组成部分，而感热通量（H）在非生长季能量分配中占主导地位。 H与LE的变化趋势相反，土壤热通量（G）的季节变化较小。每日蒸散量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）分别在非生长季和生长季对ET产生次要影响。年际ET相对稳定，范围为562.6~661.9 mm（变异系数；CV=7.4%）；尽管年际降水量变化较大（CV = 19.9%），但该数字略高于年降水量，并且很可能是由于积雪和冻土融化所致。生长季累计蒸散量约为全年蒸散量的77%。随着体积表面电导 (g c ) 的增加，每日普里斯特利-泰勒系数 (α = ET/ET eq ，其中 ET eq 是平衡蒸发)呈非线性增加，这对超过 15 mm s -1 的 g c 增加不敏感。 g c 与NDVI 之间存在良好的相关性。这项研究为高寒草甸生态系统中蒸散能量分配和生物物理控制的长期变化的驱动机制提供了见解。
• A consecutive 6 year in-situ evapotranspiration dataset was constructed using eddy covariance. • The seasonal variation of ET was analyzed for the typical alpine meadow from 2014 to 2019. • ET was primarily controlled by the available energy in the typical alpine meadow. • Soil water content affected ET via bulk surface conductance within a certain range. 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.