This paper reports accurate measurements of the radiation characteristics and optical properties of Nannochloropsis oculata in the photosynthetically active radiation (PAR) region. These marine microalgae were grown in 2 cm thick culture bottles with vented caps exposed, on one side, to either white fluorescent light bulbs or red LEDs emitting at 630 nm. The illuminance varied from 2000 to 10,0...

[1] We describe a method that retrieves surface photosynthetically active radiation (PAR) and its direct and diffuse components from the Surface and Atmospheric Radiation Budget (SARB) product of Clouds and the Earth’s Radiant Energy System (CERES). The shortwave spectrum in the SARB Edition 2 is calculated in 15 bands, 4 of which are used to develop the PAR, in conjunction with the look-up tab...

This paper reviews the several methods available for estimating the fAPAR, both at local and large scale. The fAPAR definition is first discussed with regards to the directionality of the incident radiation. Then, the several techniques to estimate fAPAR from local ground measurements are reviewed with emphasis on the sampling strategy. We then describe methodologies to upscale fAPAR measuremen...

A two band Enhanced Vegetation Index (EVI2) without the blue band reflectance has recently been developed as a proxy for the phenology, quantity, and activity of vegetation. We compared the ability of EVI2 and the more commonly used Normalized Difference Vegetation Index (NDVI) to resolve differences in surface greenness and Leaf Area Index (LAI) among three sites located along a burn severity ...

The quantum yield of photosystem II, determined by chlorophyll fluorescence and the quantum yield of CO2 uptake, determined from gas exchange, are two physiologically important measurements in clarifying the response to environmental stress. Both measurements, however, require an accurate assessment of leaf light absorption in the photosynthetically active radiation wavelength range (400–700 nm...

Because the leaf area index (LAI) is an essential parameter for understanding structure and growth status of plant canopies, nondestructive continuous estimation methods have been required. Recently, LAI method using ratio near-infrared radiation (NIR; 700–1000 nm) to photosynthetically active (PAR; 400–700 (NIR in /PAR ) transmitted through a canopy has proposed. However, because previous stud...

This report describes a system for integrating photosynthetically active radiation (PAR) using fi beroptics. Many photoelectric sensors or 1-m-long line sensors that integrate individual interception points for spatial averaging were replaced with fi beroptics, which integrate interception points. Depending on the positioning of optical fi bers and the amount of fi bers terminated at a PAR sens...

Solar-induced chlorophyll fluorescence (SIF), which can be used as a novel proxy for estimating gross primary production (GPP), can be effectively retrieved using ground-based, airborne and satellite measurements. Absorbed photosynthetically active radiation (APAR) is the key bridge linking SIF and GPP. Remotely sensed SIF at the canopy level (SIFcanopy) is only a part of the total SIF emission...

Biomass burning activities emit high concentrations of aerosol particles to the atmosphere. Such particles can interact with solar radiation, decreasing the amount of light reaching the surface and increasing the fraction of diffuse radiation through scattering processes, and thus has implications for photosynthesis within plant canopies. This work reports results from photosynthetically active...

The fraction of photosynthetically active radiation (FPAR) absorbed by vegetation – a key parameter in crop biomass and yields as well as net primary productivity models – is critical to guiding crop management activities. However, accurate and reliable estimation of FPAR is often hindered by a paucity of good field-based spectral data, especially for corn crops. Here, we investigate the relati...