Photosynthetically Active Radiation: Measurement and Modeling

Mõttus, Matti; Sulev, Madis; Baret, Frédéric; Lopez-Lozano, Raoul; Reinart, Anu

doi:10.1007/978-1-4419-0851-3_451

Cited by 29 publications

(16 citation statements)

References 118 publications

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“…Yet, measuring the fPAR of an understory is not an easy task due to low vegetation and constantly fluctuating light conditions under the tree canopy (e.g. Mõttus et al 2012;Liu et al 2013). As an alternative to measuring fPAR with a spectroradiometer, the fPAR of the understory may be approximated using fractional cover estimates of different plant species (Pickett-Heaps et al 2014).…”

Section: Estimation Of Fparmentioning

confidence: 99%

“…This is partly due to the large number of PAR sensors needed to reach accurate estimates of canopy reflectance in heterogeneous coniferous forests (e.g. Mõttus et al 2012), and partly due to the scarcity of towers which may be used for setting up the instruments. For these reasons, values derived from literature or measured from a flux tower (e.g.…”

Section: Estimation Of Fparmentioning

confidence: 99%

“…Satellite based fPAR is commonly defined as instantaneous fPAR assuming only direct radiation, yet the ground reference fPAR is calculated as a sum of direct and diffuse radiation components (Olofsson and Eklundh 2007;D'Odorico et al 2014). Validation of satellite based fPAR products have focused on comparing different satellite based fPAR products, because measuring ground reference fPAR is difficult and requires data collection over several days (Mõttus et al 2012). In addition, the development of the algorithms for estimating fPAR in boreal forests is hindered by the lack of ground reference fPAR data (McCallum et al 2010;Camacho et al 2013;D'Odorico et al 2014).…”

Section: Remote Sensing Of Lai and Fparmentioning

confidence: 99%

“…Sensor systems can be divided into hemispherical (integrate over the hemisphere) or directional (measurements with a narrow FOV) instruments (e.g. Mõttus et al 2012). Hemispherical sensors systems (AccuPAR, SunScan, SunFleck, and quantum sensors) have been more popular in measuring PAR, because they allow better spatial sampling compared to directional sensor systems.…”

Section: Measurements Of Fparmentioning

confidence: 99%

“…Measuring fPAR requires a large number of sensors and is time-consuming, because of its spatial and temporal dynamics, and thus, modeling fPAR may be preferred (Liang et al 2012;Mõttus et al 2012). Still, acquiring all the parameters needed for modeling fPAR in heterogeneous environments (e.g.…”

Section: Modeling Forest Canopy Fparmentioning

confidence: 99%

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Estimation of leaf area index and the fraction of absorbed photosynthetically active radiation in a boreal forest

Majasalmi¹

2015

Diss. For.

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The aim of this dissertation is to assess the accuracy of different ground reference methods used to validate satellite based leaf area index (LAI) and the fraction of absorbed photosynthetically active radiation (fPAR) products. LAI and fPAR are strongly linked, although they principally and practically measure different properties: LAI quantifies the areal interphase between soil and atmosphere, whereas fPAR quantifies the energy available for photosynthesis. Until now, the development of remote sensing based methods to estimate LAI and fPAR in a boreal forest has been hindered by the scarcity of ground data, which is required to validate and develop existing algorithms. The aim of the first part of this dissertation was to assess the impacts of different methodological approaches to estimate LAI in boreal forests, and to validate satellite based LAI products. Results showed that the accuracy of ground based LAI estimates is sensitive to both the retrieval methods and sampling scheme used to collect the optical LAI data. The satellite based measurements of LAI demonstrated a large temporal variability in LAI. The second part of the dissertation focused on measuring and modeling fPAR in a boreal forest. A new scheme for measuring and modeling ground reference fPAR based on photon recollision probability was presented in this dissertation. Ground reference fPAR is usually estimated only for the forest canopy layer. This study is among the first ones to validate the new global satellite based fPAR product called GEOV1 using data of both the forest canopy and understory layers from boreal forests. Results showed that satellite based fPAR products may correspond better with the total fPAR, instead of only the forest canopy fPAR as has often been presumed.

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Section: Estimation Of Fparmentioning

confidence: 99%

Section: Estimation Of Fparmentioning

confidence: 99%

Section: Remote Sensing Of Lai and Fparmentioning

confidence: 99%

Section: Measurements Of Fparmentioning

confidence: 99%

Section: Modeling Forest Canopy Fparmentioning

confidence: 99%

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Estimation of leaf area index and the fraction of absorbed photosynthetically active radiation in a boreal forest

Majasalmi¹

2015

Diss. For.

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Enhancement of microalgae growth using magnetic artificial cilia

Verburg

Schaap

Zhang

et al. 2021

Biotech & Bioengineering

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Microalgae have shown great potential as a source of biofuels, food, and other bioproducts. More recently, microfluidic devices have been employed in microalgae-related studies. However, at small fluid volumes, the options for controlling flow conditions are more limited and mixing becomes largely reliant on diffusion. In this study, we fabricated magnetic artificial cilia (MAC) and implemented them in millimeter scale culture wells and conducted growth experiments with Scenedesmus subspicatus while actuating the MAC in a rotating magnetic field to create flow and mixing. In addition, surface of MAC was made hydrophilic using plasma treatment and its effect on growth was compared with untreated, hydrophobic MAC. The experiments showed that the growth was enhanced by ten and two times with hydrophobic and hydrophilic MAC, respectively, compared with control groups which contain no MAC. This technique can be used to investigate mixing and flow in small sample volumes, and the enhancement in growth can be beneficial for the throughput of screening studies. Moreover, the methods used for creating and controlling MAC can be easily adopted in labs without microfabrication infrastructures, and they can be mastered by people with little prior experience in microfluidics.

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Optimal Photovoltaic Array Layout of Agrivoltaic Systems Based on Vertical Bifacial Photovoltaic Modules

Arena,

Aneli,

Gagliano

et al. 2023

Solar RRL

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An agrivoltaic (APV) plant is a complex system, where solar photovoltaic (PV) energy generation is concomitant with agricultural production. The performances associated with these activities could be antagonistic as the presence of PV installation might reduce the favorable conditions for agriculture and vice versa. In this context, vertical bifacial PV (AbPV) farms could represent a fascinating perspective to optimize the land’s dual‐use request. This means finding geometrical configurations for the AbPV plant to produce the same energy as ground‐mounted PV farms, not hinder agricultural activities, and limit the Photosynthetically Active Radiation (PAR) deficit. This study evaluates the performances of a vertical bifacial APV plant, located in the southeast of Sicily, as a function of the PV modules’ plan allocation (i.e. orientation and array density). The analyses developed through numerical simulations using two software tools, SAM and PVsyst, compare the relative capabilities of monofacial and vertical bifacial farms in terms of acceptable PAR debit, and energy yield as a function of the array density. The land equivalent ratios (LER) of vertical AbPVs from a maximum values of 1.93 (p/h = 2.5) and a minimum of 1.56 (p/h = 5.0) for crops which have low sensitive response to the drop of solar radiation, while from 1.71 and 1.42 for crops which have higher sensitive response to the drop of solar radiation.This article is protected by copyright. All rights reserved.

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Photosynthetically Active Radiation: Measurement and Modeling

Cited by 29 publications

References 118 publications

Estimation of leaf area index and the fraction of absorbed photosynthetically active radiation in a boreal forest

Estimation of leaf area index and the fraction of absorbed photosynthetically active radiation in a boreal forest

Enhancement of microalgae growth using magnetic artificial cilia

Optimal Photovoltaic Array Layout of Agrivoltaic Systems Based on Vertical Bifacial Photovoltaic Modules

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