Assessment of Different Complementary-Relationship-Based Models for Estimating Actual Terrestrial Evapotranspiration in the Frozen Ground Regions of the Qinghai-Tibet Plateau

Remote Sensing

Tonghua Wu¹  Xiangfei Li¹  Jie Chen¹  Guojie Hu¹  Jimin Yao¹  Ren Li¹  Sizhong Yang¹  Xiaofan Zhu¹  Chengpeng Shang¹  Jiemin Wang¹  Cheng Yang¹  Ning Ma²  Tianye Wang³ 

[1] Cryosphere Research Station on the Qinghai-Tibet Plateau, State Key Laboratory of Cryospheric Science, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, China;Key Laboratory of Water Cycle and Related Land Surface Processes, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China;School of Water Conservancy Engineering, Zhengzhou University, Zhengzhou 450001, China;

关键词: actual evapotranspiration;    complementary relationship;    permafrost;    seasonally frozen ground;    Qinghai-Tibet Plateau;   

DOI  :  10.3390/rs14092047

来源: DOAJ

【 摘 要 】

Actual evapotranspiration (ET_a) is important since it is an important link to water, energy, and carbon cycles. Approximately 96% of the Qinghai-Tibet Plateau (QTP) is underlain by frozen ground, however, the ground observations of ET_a are particularly sparse–which is especially true in the permafrost regions–leading to great challenge for the accurate estimation of ET_a. Due to the impacts of freeze-thaw cycles and permafrost degradation on the regional ET process, it is therefore urgent and important to find a reasonable approach for ET_a estimation in the regions. The complementary relationship (CR) approach is a potential method since it needs only routine meteorological variables to estimate ET_a. The CR approach, including the modified advection-aridity model by Kahler (K2006), polynomial generalized complementary function by Brutsaert (B2015) and its improved versions by Szilagyi (S2017) and Crago (C2018), and sigmoid generalized complementary function by Han (H2018) in the present study, were assessed against in situ measured ET_a at four observation sites in the frozen ground regions. The results indicate that five CR-based models are generally capable of simulating variations in ET_a, whether default and calibrated parameter values are employed during the warm season compared with those of the cold season. On a daily basis, the C2018 model performed better than other CR-based models, as indicated by the highest Nash-Sutcliffe efficiency (NSE) and lowest root mean square error (RMSE) values at each site. On a monthly basis, no model uniformly performed best in a specific month. On an annual basis, CR-based models estimating ET_a with biases ranging from −94.2 to 28.3 mm year⁻¹, and the H2018 model overall performed best with the smallest bias within 15 mm year⁻¹. Parameter sensitivity analysis demonstrated the relatively small influence of each parameter varying within regular fluctuation magnitude on the accuracy of the corresponding model.

【 授权许可】

Unknown