Evaluation of the influence of two operational fraction of absorbed photosynthetically active radiation (FAPAR) products on terrestrial ecosystem productivity modelling

Abstract. Solar radiation, especially photosynthetically active radiation (PAR), is the main energy source of plant photosynthesis, and the diffuse component can enhance canopy light use efficiency, thus increasing ecosystem productivity. In order to predict the terrestrial ecosystem productivity precisely, we not only need global radiation and PAR as driving variables, but also need to treat diffuse radiation and diffuse PAR explicitly in ecosystem models. Therefore, we generated a series of radiation datasets, including global radiation, diffuse radiation, PAR, and diffuse PAR of China from 1981 to 2010, based on the observations of the China Meteorology Administration (CMA) and the Chinese Ecosystem Research Network (CERN). The dataset should be useful for the analysis of the spatiotemporal variations of solar radiation in China and the impact of diffuse radiation on terrestrial ecosystem productivity based on ecosystem models. The dataset is freely available from Zenodo on the following website: https://zenodo.org/record/1198894#.Wx6–C_MwWo (https://doi.org/10.11922/sciencedb.555, Ren et al., 2018).

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Global radiation, photosynthetically active radiation, and the diffuse components dataset of China, 1981–2010

10.5194/essd-2018-4 ◽

2018 ◽

Author(s):

Xiaoli Ren ◽

Honglin He ◽

Li Zhang ◽

Guirui Yu

Keyword(s):

Solar Radiation ◽

Photosynthetically Active Radiation ◽

Global Radiation ◽

Terrestrial Ecosystem ◽

Diffuse Radiation ◽

Research Network ◽

Ecosystem Productivity ◽

Ecosystem Models ◽

Active Radiation ◽

The Impact

Abstract. Solar radiation, especially photosynthetically active radiation (PAR), is the main energy source of plant photosynthesis; and the diffuse component can enhance canopy light use efficiency, thus increasing ecosystem productivity. In order to predict the terrestrial ecosystem productivity precisely, we not only need global radiation and PAR as driving variables, but also need to treat diffuse radiation and diffuse PAR explicitly in ecosystem models. Therefore, we generated a series of radiation datasets, including global radiation, diffuse radiation, PAR, and diffuse PAR of China from 1981 to 2010, based on the observations of China Meteorology Administration (CMA) and Chinese Ecosystem Research Network (CERN). The dataset should be useful for the analysis of the spatio-temporal variations of solar radiation in China and the impact of diffuse radiation on terrestrial ecosystem productivity based on ecosystem models. The dataset is freely available from the Zenodo at the website of https://zenodo.org/record/1198894 (DOI: 10.11922/sciencedb.555).

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Estimation of Incident Photosynthetically Active Radiation from GOES Visible Imagery

Journal of Applied Meteorology and Climatology ◽

10.1175/2007jamc1475.1 ◽

2008 ◽

Vol 47 (3) ◽

pp. 853-868 ◽

Cited By ~ 43

Author(s):

Tao Zheng ◽

Shunlin Liang ◽

Kaicun Wang

Keyword(s):

Photosynthetically Active Radiation ◽

Terrestrial Ecosystem ◽

New Method ◽

High Temporal Resolution ◽

Atmospheric Conditions ◽

Ecosystem Models ◽

Surface Conditions ◽

Active Radiation ◽

Ground Measurement ◽

Visible Imagery

Abstract Incident photosynthetically active radiation (PAR) is an important parameter for terrestrial ecosystem models. Because of its high temporal resolution, the Geostationary Operational Environmental Satellite (GOES) observations are very suited to catch the diurnal variation of PAR. In this paper, a new method is developed to derive PAR using GOES data. What makes this new method distinct from the existing method is that it does not need external knowledge of atmospheric conditions. The new method retrieves both atmospheric and surface conditions using only at-sensor radiance through interpolation of time series of observations. Validations against ground measurement are carried out at four “FLUXNET” sites. The values of RMSE of estimated and ground-measured instantaneous PAR at the four sites are 130.71, 131.44, 141.16, and 190.22 μmol m−2 s−1, respectively. At the four validation sites, the RMSE as the percentage of estimated mean PAR value are 9.52%, 13.01%, 13.92%, and 24.09%, respectively; the biases are −101.54, 16.56, 11.09, and 53.64 μmol m−2 s−1, respectively. The independence of external atmospheric information enables this method to be applicable to many situations in which external atmospheric information is not available. In addition, topographic impacts on surface PAR are examined at the 1-km resolution at which PAR is retrieved using the GOES visible band data.

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A Framework for Consistent Estimation of Leaf Area Index, Fraction of Absorbed Photosynthetically Active Radiation, and Surface Albedo from MODIS Time-Series Data

IEEE Transactions on Geoscience and Remote Sensing ◽

10.1109/tgrs.2014.2370071 ◽

2015 ◽

Vol 53 (6) ◽

pp. 3178-3197 ◽

Cited By ~ 23

Author(s):

Zhiqiang Xiao ◽

Shunlin Liang ◽

Jindi Wang ◽

Donghui Xie ◽

Jinling Song ◽

...

Keyword(s):

Time Series ◽

Leaf Area Index ◽

Photosynthetically Active Radiation ◽

Surface Albedo ◽

Time Series Data ◽

Series Data ◽

Consistent Estimation ◽

Area Index ◽

Active Radiation ◽

Absorbed Photosynthetically Active Radiation

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Upscaling from Instantaneous to Daily Fraction of Absorbed Photosynthetically Active Radiation (FAPAR) for Satellite Products

Remote Sensing ◽

10.3390/rs12132083 ◽

2020 ◽

Vol 12 (13) ◽

pp. 2083

Author(s):

Siyuan Chen ◽

Liangyun Liu ◽

Xue He ◽

Zhigang Liu ◽

Dailiang Peng

Keyword(s):

Zenith Angle ◽

Photosynthetically Active Radiation ◽

Solar Zenith Angle ◽

Field Measurements ◽

Area Index ◽

Active Radiation ◽

Sensing Applications ◽

Typical Satellite ◽

Absorbed Photosynthetically Active Radiation ◽

Local Noon

The fraction of absorbed photosynthetically active radiation (FAPAR) is an essential climate variable (ECV) widely used for various ecological and climate models. However, all the current FAPAR satellite products correspond to instantaneous FAPAR values acquired at the satellite transit time only, which cannot represent the variations in photosynthetic processes over the diurnal period. Most studies have directly used the instantaneous FAPAR as a reasonable approximation of the daily integrated value. However, clearly, FAPAR varies a lot according to the weather conditions and amount of incoming radiation. In this paper, a temporal upscaling method based on the cosine of the solar zenith angle (SZA) at local noon ( c o s ( S Z A n o o n ) ) is proposed for converting instantaneous FAPAR to daily integrated FAPAR. First, the diurnal variations in FAPAR were investigated using PROSAIL (a model of Leaf Optical Properties Spectra (PROSPECT) integrating a canopy radiative transfer model (Scattering from Arbitrarily Inclined Leaves, SAIL)) simulations with different leaf area index (LAI) values corresponding to different latitudes. It was found that the instantaneous black sky FAPAR at 09:30 AM provided a good approximation for the daily integrated black sky FAPAR; this gave the highest correlation (R2 = 0.995) and lowest Root Mean Square Error (RMSE = 0.013) among the instantaneous black sky FAPAR values observed at different times. Secondly, the difference between the instantaneous black sky FAPAR values acquired at different times and the daily integrated black sky FAPAR was analyzed; this could be accurately modelled using the cosine value of solar zenith angle at local noon ( c o s ( S Z A n o o n ) ) for a given vegetation scene. Therefore, a temporal upscaling method for typical satellite products was proposed using a cos(SZA)-based upscaling model. Finally, the proposed cos(SZA)-based upscaling model was validated using both the PROSAIL simulated data and the field measurements. The validated results indicated that the upscaled daily black sky FAPAR was highly consistent with the daily integrated black sky FAPAR, giving very high mean R2 values (0.998, 0.972), low RMSEs (0.007, 0.014), and low rMAEs (0.596%, 1.378%) for the simulations and the field measurements, respectively. Consequently, the cos(SZA)-based method performs well for upscaling the instantaneous black sky FAPAR to its daily value, which is a simple but extremely important approach for satellite remote sensing applications related to FAPAR.

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