scholarly journals Balanço de Radiação em Ecossistema de Caatinga Preservada Durante um Ano de Seca no Semiárido Pernambucano (Radiation Balance in Caatinga Ecosystem Preserved for a Year Drought in Semiarid Pernambucano)

2015 ◽  
Vol 8 (1) ◽  
pp. 041
Author(s):  
Luciana Sandra Bastos de Souza ◽  
Magna Soelma Beserra de Moura ◽  
Gilberto Chohaku Sediyama ◽  
Thieres George Freire da Silva
Keyword(s):  
Seasonal Variation ◽  
Solar Radiation ◽  
Photosynthetically Active Radiation ◽  
Climatic Conditions ◽  
Semiarid Region ◽  
Radiation Balance ◽  
Net Radiation ◽  
Active Radiation ◽  
Brazilian Semiarid ◽  
Semi Arid

O objetivo deste trabalho foi analisar as variações diárias e sazonais dos componentes do balanço de radiação e da radiação fotossinteticamente ativa para a caatinga preservada durante um ano seco no Semiárido pernambucano. O experimento foi conduzido durante o ano de 2012 em Petrolina, PE, localizado na região do Semiárido brasileiro. Para determinação dos componentes do balanço de radiação foi utilizado um saldo radiômetro modelo CNR1 instalado à 13,3 metros da superfície. Adicionalmente, analisou-se a interação entre a vegetação e a radiação por meio de sensores para o monitoramento da radiação fotossinteticamente ativa acima e em diferentes posições abaixo do dossel da caatinga. Estes dados foram utilizados no cálculo da fração da radiação fotossinteticamente ativa interceptada (fRFAi) e absorvida (fRFAa). Foi observada uma ampla variação sazonal da radiação solar global e do saldo de radiação que atingiram valores médios diários em torno de 23 MJ m-2 dia-1 e 15 MJ m-2 dia-1, respectivamente. Neste caso, observou-se que a magnitude dos valores dos componentes do balanço de radiação foi afetada principalmente em decorrência da nebulosidade e mudanças na vegetação que afetaram principalmente os níveis de emitância da superfície e sua reflexão. No que se refere às frações da radiação fotossinteticamente ativa interceptada e absorvida, observou-se que as mesmas apresentaram valores médios diários ao longo do ano bastante próximos, os quais foram iguais a 0,69 e 0,64, nesta ordem. Estes dados podem ser extremamente úteis para uma melhor compreensão da interação entre a caatinga e a atmosfera sob condições climáticas singulares, e portanto, serem utilizados na formulação de políticas climáticas.   A B S T R A C T The objective of this study was to analyze the daily and seasonal variations of the components of the radiation balance and photosynthetically active radiation for the Caatinga during a dry year in Pernambuco Semi-Arid. The experiment was conducted during the year 2012 in Petrolina, PE, located in the Brazilian semiarid region. To determine the components of the radiation balance we used a balance radiometer CNR1 model installed the 13.3 meters of surface. Additionally, we analyzed the interaction between vegetation and radiation using sensors to monitor the photosynthetically active radiation above and in different positions under the canopy of scrub. These data were used to calculate the fraction of intercepted photosynthetically active radiation (fRFAi) and absorbed (fRFAa). A wide seasonal variation of solar radiation and net radiation was observed that reached daily averages around 23 MJ m-2 d-1 and 15 MJ m-2 d-1, respectively. In this case, it was observed that the magnitude of the component values ​​of the radiation balance was mainly affected due to the cloudiness and changes in vegetation which mainly affected the levels of emittance and reflection surface. With regard to fractions of intercepted and absorbed photosynthetic active radiation, it was observed that they had daily average values ​​over the next years, which were equal to 0.69 and 0.64 in order. This data can be extremely useful for a better understanding of the interaction between the savanna and the atmosphere under natural climatic conditions. Keywords: radiation, net radiation, photosynthetically active radiation, Caatinga, dry.  

scholarly journals Distribuição local e regional de Myracrodruon urundeuva Allemão (Anacardiaceae) no semiárido do nordeste do Brasil (Local and regional distribution of Myracrodruon urundeuva Allemão (Anacardiaceae) in the semi-arid region of northeastern Brazil)

2019 ◽  
Vol 12 (3) ◽  
pp. 944
Author(s):  
Carlos Antônio Belarmino Alves ◽  
João Everthon Da Silva Ribeiro ◽  
Natan Medeiros Guerra ◽  
Ramon Santos Souza ◽  
Mariana Muniz Nunes ◽  
...  
Keyword(s):  
Photosynthetically Active Radiation ◽  
Regional Distribution ◽  
Northeastern Brazil ◽  
Semiarid Region ◽  
Radiation Balance ◽  
Net Radiation ◽  
Active Radiation ◽  
Brazilian Semiarid ◽  
Semi Arid Region ◽  
Semi Arid

Uma das vegetações que tem sido utilizada pelas populações tradicionais ao longo do tempo, e investigada por especialistas é a do semiárido. Muitos estudos realizados nessa região são direcionados para espécies de usos madeireiro e medicinal. Nesta pesquisa, realizou-se uma análise pontual da distribuição local de Myracrodruon urundeuva Allemão, com base em informações coletadas em comunidades rurais de seis municípios do estado da Paraíba. Foram registrados 1.559 indivíduos de M. urundeuva em 144 horas de turnê guiada. Percebeu-se que que as populações desta espécie tendem a formar aglomerados, estando alguns localizados próximos as residências, o que pode ser explicado pela utilização medicinal das cascas para diversas enfermidades. Os dados abordados neste estudo refletem as características ambientais de cada área estudada, indicando para cada região a melhor forma de manejo para as populações locais desta espécie.  A B S T R A C TThe objective of this study was to analyze the daily and seasonal variations of the components of the radiation balance -and photosynthetically active radiation for the Caatinga during a dry year in Pernambuco Semi-Arid. The experiment was conducted during the year 2012 in Petrolina, PE, located in the Brazilian semiarid region. To determine the components of the radiation balance we used a balance radiometer CNR1 model installed the 13.3 meters of surface. Additionally, we analyzed the interaction between vegetation and radiation using sensors to monitor the photosynthetically active radiation above and in different positions under the canopy of scrub. These data were used to calculate the fraction of intercepted photosynthetically active radiation (fRFAi) and absorbed (fRFAa). A wide seasonal variation of solar radiation and net radiation was observed that reached daily averages around 23 MJ m-2 d-1 and 15 MJ m-2 d-1, respectively. In this case, it was observed that the magnitude of the component values of the radiation balance was mainly affected due to the cloudiness and changes in vegetation which mainly affected the levels of emittance and reflection surface. With regard to fractions of intercepted and absorbed photosynthetic active radiation, it was observed that they had daily average values over the next years, which were equal to 0.69 and 0.64 in order. This data can be extremely useful for a better understanding of the interaction between the savanna and the atmosphere under natural climatic conditions.Keywords: radiation, net radiation, photosynthetically active radiation, Caatinga, dry.

scholarly journals Microclimate under different shading screens in greenhouses cultivated with bromeliads

2012 ◽  
Vol 16 (8) ◽  
pp. 858-863 ◽  
Author(s):  
Ester Holcman ◽  
Paulo C. Sentelhas
Keyword(s):  
Relative Humidity ◽  
Solar Radiation ◽  
Air Temperature ◽  
Photosynthetically Active Radiation ◽  
External Condition ◽  
Low Density Polyethylene ◽  
Low Density ◽  
Net Radiation ◽  
Active Radiation ◽  
Incoming Solar Radiation

This study had as its objective the evaluation of the influence of shading screens of different colors on the different microclimate variables in a greenhouse covered with transparent low-density polyethylene (LDPE). The experiment was conducted with five treatments: thermo-reflective screen (T1); a control - without screen (T2); red screen (T3); blue screen (T4); and black screen (T5), all of them with 70% of shading. An automatic micrometeorological station was installed in each treatment, measuring air temperature (T), relative humidity (RH), incoming solar radiation (Rg), photosynthetically active radiation (PAR) and net radiation (Rn) continuously. The control (T2) and red screen (T3) treatments promoted the highest solar radiation transmissivity, respectively 56.3 and 27%. The black screen (T5) had the lowest solar radiation transmissivity (10.4%). For PAR and Rn the same tendency was observed. The highest temperature was observed under blue screen (T4) treatment, which was 1.3 °C higher than external condition. Blue screen (T4) treatment also presented the highest relative humidity difference between inside and outside conditions.

Relationship between net radiation and solar radiation for semi-arid shrub-land

2003 ◽  
Vol 116 (3-4) ◽  
pp. 221-227 ◽  
Author(s):  
I Alados ◽  
I Foyo-Moreno ◽  
F.J Olmo ◽  
L Alados-Arboledas
Keyword(s):  
Solar Radiation ◽  
Net Radiation ◽  
Semi Arid

scholarly journals Radiación fotosintéticamente activa evaluada en la ciudad de Zacatecas

2020 ◽  
pp. 1-11
Author(s):  
Mónica Montserrat Escobedo-Sánchez ◽  
Ricardo Conejo-Flores ◽  
Sergio Miguel Durón-Torres ◽  
Juan Manuel García-González
Keyword(s):  
Decision Making ◽  
Solar Radiation ◽  
Production Planning ◽  
Photosynthetically Active Radiation ◽  
Detailed Knowledge ◽  
Active Radiation ◽  
Incident Solar Radiation ◽  
Daily Average ◽  
Life On Earth

The present investigation is related to one of the most important processes for the development of life on Earth; photosynthesis, an essential process in the cycle and development of living beings, centered on solar radiation that is useful for plants to carry out this process, Photosynthetically Active Radiation (PAR). The objective of this work is to generate information on the PAR through a database to collaborate in the decision-making of farmers in the area. For this purpose, a quantum sensor installed in building 6 of the UAZ Siglo XXI Campus was used. According to Abal (2013), in agricultural and production planning, it is especially important to have a detailed knowledge of incident solar radiation on the earth's surface (Abal and Durañona, 2013). When collecting, treating and analyzing the data, it was found that the daily average PAR is 819.52 μmol of photons m-2 s-1 (179.47 W m-2), if only the sunny hours are taken into account. It can be concluded that according to the PAR received in the evaluation region and the type of nutrients in the soil, other crop alternatives to those traditionally used can be sought.

scholarly journals A Photovoltaic Greenhouse with Passive Variation in Shading by Fixed Horizontal PV Panels

Energies ◽  
2019 ◽  
Vol 12 (17) ◽  
pp. 3269 ◽  
Author(s):  
Simona Moretti ◽  
Alvaro Marucci
Keyword(s):  
Solar Radiation ◽  
Photosynthetically Active Radiation ◽  
Natural Variation ◽  
Elevation Angle ◽  
Fixed Position ◽  
Mathematical Relationship ◽  
Photovoltaic Panels ◽  
Active Radiation ◽  
Autumn And Winter ◽  
Interesting Solution

The traditional shading systems that greenhouses use cause some of the solar radiation that is reflected or absorbed to be lost and, therefore, not used by the plants under cultivation. An interesting solution to these problems is to position photovoltaic (PV) panels on the roofs of greenhouses. All of the photovoltaic greenhouses that have been realized in Mediterranean areas are characterized by a fixed position of the PV panels and excessive shading, especially in autumn and winter. The purpose of this study is to describe a prototype of a photovoltaic greenhouse with both fixed and horizontal PV panels that exploit the natural variation in the elevation angle of the sun’s rays during the year to allow for “passive” variation in shading. The considerable variation in the elevation angle of the sun’s rays (from 24.4° to 71.1°) results in a high variation in shading (from 39.4% to 72.6%), with the highest values in the summer months and the lowest values in the winter months. This trend is favorable for meeting the photosynthetically active radiation (PAR) needs of greenhouse plants. If the plants under cultivation require more solar energy, it is necessary to increase the distance between the panels. We implement a specific mathematical relationship to define the precise distance to be assigned to the photovoltaic panels on the roof pitch.

scholarly journals Drivers of inter-annual variability in Net Ecosystem Exchange in a semi-arid savanna ecosystem, South Africa

2009 ◽  
Vol 6 (2) ◽  
pp. 251-266 ◽  
Author(s):  
S. A. Archibald ◽  
A. Kirton ◽  
M. R. van der Merwe ◽  
R. J. Scholes ◽  
C. A. Williams ◽  
...  
Keyword(s):  
South Africa ◽  
Eddy Covariance ◽  
Photosynthetically Active Radiation ◽  
Ecosystem Respiration ◽  
Net Ecosystem Exchange ◽  
Ann Model ◽  
Rainfall Events ◽  
Active Radiation ◽  
Annual Variability ◽  
Semi Arid

Abstract. Inter-annual variability in primary production and ecosystem respiration was explored using eddy-covariance data at a semi-arid savanna site in the Kruger Park, South Africa. New methods of extrapolating night-time respiration to the entire day and filling gaps in eddy-covariance data in semi-arid systems were developed. Net ecosystem exchange (NEE) in these systems occurs as pulses associated with rainfall events, a pattern not well-represented in current standard gap-filling procedures developed primarily for temperate flux sites. They furthermore do not take into account the decrease in respiration at high soil temperatures. An artificial neural network (ANN) model incorporating these features predicted measured fluxes accurately (MAE 0.42 gC/m2/day), and was able to represent the seasonal patterns of photosynthesis and respiration at the site. The amount of green leaf area (indexed using satellite-derived estimates of fractional interception of photosynthetically active radiation fAPAR), and the timing and magnitude of rainfall events, were the two most important predictors used in the ANN model. These drivers were also identified by multiple linear regressions (MLR), with strong interactive effects. The annual integral of the filled NEE data was found to range from −138 to +155 g C/m2/y over the 5 year eddy covariance measurement period. When applied to a 25 year time series of meteorological data, the ANN model predicts an annual mean NEE of 75(±105) g C/m2/y. The main correlates of this inter-annual variability were found to be variation in the amount of absorbed photosynthetically active radiation (APAR), length of the growing season, and number of days in the year when moisture was available in the soil.

A Generalized Relationship between Photosynthetically Active Radiation and Solar Radiation 1

1984 ◽  
Vol 76 (6) ◽  
pp. 939-945 ◽  
Author(s):  
D. W. Meek ◽  
J. L. Hatfield ◽  
T. A. Howell ◽  
S. B. Idso ◽  
R. J. Reginato
Keyword(s):  
Solar Radiation ◽  
Photosynthetically Active Radiation ◽  
Active Radiation

Light interception and canopy radiation balance of staghorn sumac (Rhus typhina)

2008 ◽  
Vol 38 (6) ◽  
pp. 1695-1700
Author(s):  
Peter M. Lafleur ◽  
Andrew G. Farnsworth
Keyword(s):  
Leaf Area Index ◽  
Leaf Area ◽  
Photosynthetically Active Radiation ◽  
Solar Zenith Angle ◽  
Radiation Balance ◽  
Area Index ◽  
Mean Values ◽  
Active Radiation ◽  
Rhus Typhina ◽  
Flux Incident

We measured interaction of photosynthetically active radiation (PAR) at a staghorn sumac ( Rhus typhina L.) canopy near Peterborough, Ontario, during summer 2006. Measurements included above-canopy and below-canopy incoming and reflected PAR fluxes and leaf area index (LAI). The ratio of down-welling PAR below the canopy to the flux incident at the top of the canopy (τ) and proportion of incident PAR absorbed by the canopy (fPAR), were calculated. While the canopy was leafless, the sumac stems absorb 10%–20% of incident PAR. LAI increased rapidly during the month of June, and correspondingly τ decreased rapidly while fPAR increased rapidly. Mean values of τ and fPAR at maximum LAI were 0.38±0.09 (SD) and 0.60 ±0.04, respectively. Neither variable showed a relationship with solar zenith angle. We present a simple idealized model of PAR interaction with sumac. Although only one stand was studied, we hypothesize that these results may be more widely applicable to other mature sumac stands.

scholarly journals Light Use Efficiency of Aboveground Biomass Production of Norway Spruce Stands

2017 ◽  
Vol 65 (1) ◽  
pp. 9-16
Author(s):  
Michal Bellan ◽  
Irena Marková ◽  
Andrii Zaika ◽  
Jan Krejza
Keyword(s):  
Norway Spruce ◽  
Aboveground Biomass ◽  
Photosynthetically Active Radiation ◽  
Climatic Conditions ◽  
Light Use Efficiency ◽  
Active Radiation ◽  
Spruce Stands ◽  
Use Efficiency ◽  
Study Sites ◽  
Radiation Use

Light use efficiency (LUE or photosynthetically active radiation use efficiency) in production of young spruce stands aboveground biomass was determined at the study sites Rájec (the Drahanská vrchovina Highland) and Bílý Kříž (the Moravian‑Silesian Beskids Mountains) in 2014 and 2015. The LUE value obtained for the investigated spruce stands were in the range of 0.45 – 0.65 g DW MJ–1. The different LUE values were determined for highland and mountain spruce stand. The differences were caused by growth and climatic conditions and by the amount of assimilatory apparatus (LAI).

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