01 Sep 2022
01 Sep 2022
Status: this preprint is currently under review for the journal ESSD.

A daily and 500 m coupled evapotranspiration and gross primary production product across China during 2000–2020

Shaoyang He1,2, Yongqiang Zhang1, Ning Ma1, Jing Tian1, Dongdong Kong3, and Changming Liu1 Shaoyang He et al.
  • 1Key Laboratory of Water Cycle and Related Land Surface Processes, Institute of Geographic Sciences and Natural Resources Research, CAS, Beijing 100101, China
  • 2University of Chinese Academy of Sciences, Beijing 100040, China
  • 3Department of Atmospheric Science, School of Environmental Studies, China University of Geosciences, Wuhan 430074, China

Abstract. Accurate high-resolution actual evapotranspiration (ET) and gross primary production (GPP) information is essential for understanding the large-scale water and carbon dynamics. However, substantial uncertainties exist in the current ET and GPP datasets in China because of insufficient local ground measurements used for model constrain. This study utilizes a water-carbon coupled model, Penman-Monteith-Leuning Version 2 (PML-V2), to estimate 500 m ET and GPP at a daily scale. The parameters of PML-V2 (China) were well-calibrated against observations of 26 eddy covariance flux towers across nine plant functional types in China, indicated by Nash–Sutcliffe Efficiency (NSE) of 0.75 and Root Mean Square Error (RMSE) of 0.69 mm d−1 for daily ET respectively, and NSE of 0.82 and RMSE of 1.71 g C m-2 d−1 for daily GPP. The model estimates get a small bias of 6.28 % and a high NSE of 0.82 against water‐balance annual ET estimates across 10 major river basins in China. Further evaluations suggest that the newly developed product outperforms its global version and other typical products (MOD16A2, SEBAL, GLEAM, MOD17A2H, VPM, and EC-LUE) in estimating both ET and GPP. Moreover, PML-V2 (China) accurately monitors the intra-annual variations in ET and GPP in the croplands with a dual-cropping system. Using the new data showed that, over the last 20 years, the annual GPP and water use efficiency experienced a significant (p < 0.001) increase (8.51 g C m-2 yr-1 and 0.02 g C mm-1 H2O yr-1, respectively), but annual ET showed a non-significant (p > 0.05) increase (0.65 mm yr-1). This indicates that vegetation in China exhibits a huge potential for carbon sequestration with little cost in water resources. The PML-V2 (China) product provides a great opportunity for academic communities and various agencies for scientific studies and applications, freely available at

Shaoyang He et al.

Status: open (until 27 Oct 2022)

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Shaoyang He et al.

Data sets

PML-V2(China): evapotranspiration and gross primary production (2000.02.26-2020.12.31) Yongqiang Zhang, Shaoyang He

Shaoyang He et al.


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Short summary
This study developed a daily, 500 m evapotranspiration and gross primary production product (PML-V2 (China)) using a locally calibrated water-carbon coupled model, PML-V2, which was well-calibrated against observations at 26 flux sites across 9 land cover types. PML-V2 (China) performs satisfactorily in cross-validation and in the plot- and basin-scale evaluations compared to other mainstream products. It Improved intra-annual ET and GPP dynamics, particularly in the cropland ecosystem.