Photosynthetically active radiation

In the broad sense, photosynthetically active radiation (PAR) is the part of electromagnetic radiation that can be used as the source of energy for photosynthesis by green plants. Technically, it is defined as radiation in the spectral range from 400 to 700 nm [ −2 s −1), since photosynthesis is a quantum process, or in terms of photosynthetic radiant flux density (PAR irradiance, W m −2), more suitable for energy balance studies. A fundamental term in the quantification of light used by plants in the photosynthesis process is the fraction of absorbed photosynthetically active radiation (fAPAR) calculated as the ratio of absorbed to total incident PAR in a vegetation canopy. This variable is widely used in vegetation functioning models at a range of spatial scales from the plant to the globe as an indicator of the amount of energy... Photosynthetically active radiation (PAR): The part of electromagnetic radiation that can be used as the source of energy for photosynthesis by green plants, measured as PAR irradiance or PPFD. PAR waveband: Spectral region for electromagnetic radiation defined by the wavelength limits of 400–700 nm. PAR irradiance: Radiant flux density, or the radiative energy received by unit surface area in unit time, carried by photons in the PAR waveband. Photosynthetic photon flux density (PPFD): The number of photons with wavelengths in the PAR waveband passing through unit surface area in unit time; synonymous to PAR quantum flux. Photosynthetic action...

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: A spatial radiation dataset of China from 1981 to 2010, including global radiation, diffuse radiation, photosynthetically active radiation (PAR), and diffuse PAR, is generated and shared based on several estimation models and observations of the China Meteorology Administration and the Chinese Ecosystem Research Network. This is an integral and consistent radiation dataset for ecological modeling and the analysis of the effects of diffuse radiation on terrestrial ecosystem prod...