Energy partitioning and controlling factors of evapotranspiration in an alpine meadow in the permafrost region of the Qinghai-Tibet Plateau

doi:10.1093/jpe/rtae002

J Plant Ecol ›› 2024, Vol. 17 ›› Issue (1): rtae002.DOI: 10.1093/jpe/rtae002

• Research Articles •

Energy partitioning and controlling factors of evapotranspiration in an alpine meadow in the permafrost region of the Qinghai-Tibet Plateau

Zhaoyong Hu¹, Genxu Wang¹, Xiangyang Sun¹, Kewei Huang², Chunlin Song¹, Yang Li¹, Shouqin Sun¹, Juying Sun¹, Shan Lin^{1, *}

¹State Key Laboratory of Hydraulics and Mountain River Engineering, College of Water Resource and Hydropower, Sichuan University, Chengdu 610065, China;
²Hubei Key Laboratory of Basin Water Security, Changjiang Survey, Planning, Design and Research Co., Ltd., Wuhan 430010, China

Received:2023-10-11 Revised:2023-11-18 Accepted:2023-12-28 Online:2024-01-06 Published:2024-02-01
Contact: *E-mail: linshan@scu.edu.cn

青藏高原冻土区高寒草甸能量分配及蒸散发影响因子

Abstract

Abstract: Energy partitioning and evapotranspiration (ET) of alpine meadows in permafrost areas are crucial for water cycle on the Qinghai-Tibet Plateau. However, seasonal (freeze-thaw cycle) variations in energy partitioning and ET and their driving factors must be clarified. Therefore, 4-year energy fluxes [i.e. latent heat (LE) and sensible heat (H)] were observed, and bulk parameters [i.e. surface conductance, decoupling coefficient (Ω), and Priestley-Taylor coefficient (α)] were estimated in an alpine meadow in the Qinghai-Tibet Plateau. Mean daily LE (27.45 ± 23.89 W/m²) and H (32.51 ± 16.72 W/m²) accounted for 31.71% and 50.14% of available energy, respectively. More available energy was allocated to LE during the rainfall period, while 67.54 ± 28.44% was allocated to H during the frozen period. H was half the LE during rainfall period and seven times the LE during frozen period due to low soil water content and vegetation coverage during the frozen season. Mean annual ET was 347.34 ± 8.39 mm/year, close to mean annual precipitation. Low mean daily Ω (0.45 ± 0.23) and α (0.60 ± 0.29) throughout the year suggested that ET in the alpine meadow was limited by water availability. However, ET was constrained by available energy because of sufficient water supply from precipitation during rainfall season. In contrast, large differences between ET and precipitation indicated that soil water was supplied via lateral flow from melting upstream glaciers and snow during the transition season. The results suggest that seasonal variations in bulk parameters should be considered when simulating water and energy fluxes in permafrost regions.

Key words: latent heat flux, sensible heat flux, freeze-thaw cycle, bulk surface parameters, alpine meadow

摘要：
高寒草甸的能量分配和蒸散发对青藏高原多年冻土区水循环至关重要。然而,能量分配、蒸散发及其驱动因素的季节变化(冻融循环)仍需要明确。因此,本研究在位于青藏高原风火山流域的高寒草甸进行了为期4年的能量通量(包括潜热和感热)观测,并估算了大气边界参数(包括表面导度,解耦系数和Priestley-Taylor系数)。研究结果表明,研究区日均潜热(27.45 ± 23.89 W/m²)和显热(32.51 ± 16.72W/m²)分别占可利用能量的31.71%和50.14%。在降雨期,更多可利用能量被分配到潜热;而在冻结期,67.54 ± 28.44%的可利用能量分配给显热。显热在降雨期间是潜热的一半,而由于冻结期较低的土壤水分含量及植被盖度,显热在冻结期间是潜热的7倍。研究区年均蒸散发为347.34 ± 8.39 mm/year,接近年均降水量。较低的日均解耦系数(0.45 ± 0.23)和Priestley-Taylor系数(0.60 ± 0.29)表明高寒草甸的蒸散发受水分供应限制。然而,在降雨期由于降水充足,蒸散发受到可利用能量的限制。在过渡期,蒸散发和降水之间存在较大差异,表明在该季节上游冰川和雪的融水通过侧向流动补给到土壤中。本研究的结果表明,在未来模拟多年冻土区水和能量通量时应考虑大气边界参数的季节变化。

关键词: 潜热通量, 显热通量, 冻融循环, 大气边界参数, 高寒草甸

Zhaoyong Hu, Genxu Wang, Xiangyang Sun, Kewei Huang, Chunlin Song, Yang Li, Shouqin Sun, Juying Sun, Shan Lin. Energy partitioning and controlling factors of evapotranspiration in an alpine meadow in the permafrost region of the Qinghai-Tibet Plateau[J]. J Plant Ecol, 2024, 17(1): 0-rtae002.

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Energy partitioning and controlling factors of evapotranspiration in an alpine meadow in the permafrost region of the Qinghai-Tibet Plateau

青藏高原冻土区高寒草甸能量分配及蒸散发影响因子

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