scholarly journals Radiação global e difusa diária na região de transição Cerrado-Amazônia brasileira

2021 ◽  
Vol 43 ◽  
pp. e37
Author(s):  
Tamara Zamadei ◽  
Adilson Pacheco de Souza ◽  
Frederico Terra de Almeida ◽  
João Franscisco Escobedo
Keyword(s):  
Solar Radiation ◽  
Aerosol Particles ◽  
Global Radiation ◽  
Diffuse Radiation ◽  
Correction Factors ◽  
Mato Grosso ◽  
Energy Incident ◽  
Biomass Burning Aerosol ◽  
Atmospheric Transmissivity

This study aimed to analyze the seasonal variations in atmospheric transmissivity and solar radiation (global and diffuse) on the horizontal surface in Sinop, Mato Grosso (MT) (11.865°S, 55.485°W, and altitude of 371 m) from 06/02/2011 to 12/31/2014. The values of diffuse radiation were measured using the Melo-Escobedo-Oliveira (MEO) shadow ring, with application of astronomical, geometric, and anisotropic correction factors. The analysis of atmospheric transmissivity was based on the classification of sky cover as cloudy, partly cloudy, partially clear, or clear. The diffuse radiation showed similar behavior to the radiation at the top of the atmosphere, reaching a maximum between October and April (rainy season), while the global radiation displayed higher levels during the dry season (May to September). The average daily global radiation ranged from 22.75±0.61 MJ m−2 d−1 in August to 16.44±1.45 MJ m−2 d−1 in January. In Sinop, cloudy and partly cloudy skies occurred on 45.6% of days and atmospheric transmissivity of global radiation was greater than 55% on 54.6% of days. The variations in diffuse radiation in the region were influenced by cloudiness and the concentration of biomass burning aerosol particles. The diffuse radiation can represent 8.02%–99.12% of the global radiation and 5.33%–29.01% of solar energy incident at the top of the atmosphere.

Diffuse Sky Measurements and Determination of Corrected Shadow Band Multiplication Factors

1983 ◽  
Vol 105 (3) ◽  
pp. 305-310 ◽  
Author(s):  
W. D. Turner ◽  
A. M. Mujahid
Keyword(s):  
Solar Radiation ◽  
Correction Factor ◽  
Global Radiation ◽  
Diffuse Radiation ◽  
Monitoring Station ◽  
Radiation Measurement ◽  
Correction Factors ◽  
Diffuse Solar Radiation ◽  
Variable Factor

A meteorological monitoring station was operated at Blytheville, Arkansas, from April 1978 to April 1980. Direct normal, global, and diffuse sky radiation were monitored. From these data, models have been developed for the prediction of solar radiation, and discussions of several diffuse solar radiation models are included herein. Comparisons are made with these current diffuse models, and the correlation is quite good. In addition, instantaneous shadow band correction factors are presented which will allow a more accurate correction to be applied to the measured diffuse sky reading. The instantaneous correction factors are keyed to the global radiation measurement. Instead of applying a fixed correction factor to the diffuse measurement, regardless of sky condition, a variable factor can be applied. This will solve some of the current errors observed in diffuse measurements, because the current factors overpredict the diffuse radiation on cloudy days and underpredict the diffuse on clear days.

Improved Accuracy Models For Hourly Diffuse Solar Radiation

2005 ◽  
Vol 128 (1) ◽  
pp. 104-117 ◽  
Author(s):  
T. Muneer ◽  
S. Munawwar
Keyword(s):  
Solar Radiation ◽  
Regression Models ◽  
Global Radiation ◽  
Diffuse Radiation ◽  
Evaluation Procedure ◽  
Accuracy Score ◽  
Error Statistics ◽  
Diffuse Solar Radiation ◽  
Energy Applications ◽  
Extensive Evaluation

Solar energy applications require readily available, site-oriented, and long-term solar data. However, the frequent unavailability of diffuse irradiation, in contrast to its need, has led to the evolution of various regression models to predict it from the more commonly available data. Estimating the diffuse component from global radiation is one such technique. The present work focuses on improvement in the accuracy of the models for predicting horizontal diffuse irradiation using hourly solar radiation database from nine sites across the globe. The influence of sunshine fraction, cloud cover, and air mass on estimation of diffuse radiation is investigated. Inclusion of these along with hourly clearness index, leads to the development of a series of models for each site. Estimated values of hourly diffuse radiation are compared with measured values in terms of error statistics and indicators like, R2, mean bias deviation, root mean square deviation, skewness, and kurtosis. A new method called “the accuracy score system” is devised to assess the effect on accuracy with subsequent addition of each parameter and increase in complexity of equation. After an extensive evaluation procedure, extricate but adequate models are recommended as optimum for each of the nine sites. These models were found to be site dependent but the model types were fairly consistent for neighboring stations or locations with similar climates. Also, this study reveals a significant improvement from the conventional k-kt regression models to the presently proposed models.

scholarly journals Simulation and design of collector array units within large systems

2019 ◽  
Author(s):  
Jianhua Fan ◽  
Zhiyong Tian ◽  
Simon Furbo ◽  
Weiqiang Kong ◽  
Daniel Tschopp
Keyword(s):  
Solar Radiation ◽  
Thermal Performance ◽  
Global Radiation ◽  
Diffuse Radiation ◽  
Solar Heating ◽  
Heating Systems ◽  
Global Irradiance ◽  
Radiation Data ◽  
Large Systems ◽  
Beam Component

Solar radiation data is necessary for the design of solar heating systems and used to estimate the thermal performance of solar heating plants. Compared to global irradiance, the direct beam component shows much more variability in space and time. The global radiation split into beam and diffuse radiation on collector plane is important for the evaluation of the performance of different collector types and collector field designs.

scholarly journals Direct effect of aerosols on solar radiation and gross primary production in boreal and hemiboreal forests

2018 ◽  
Vol 18 (24) ◽  
pp. 17863-17881 ◽  
Author(s):  
Ekaterina Ezhova ◽  
Ilona Ylivinkka ◽  
Joel Kuusk ◽  
Kaupo Komsaare ◽  
Marko Vana ◽  
...  
Keyword(s):  
Solar Radiation ◽  
Primary Production ◽  
Direct Effect ◽  
Gross Primary Production ◽  
Global Radiation ◽  
Diffuse Radiation ◽  
Light Use Efficiency ◽  
Diffuse Fraction ◽  
Aerosol Loading ◽  
Use Efficiency

Abstract. The effect of aerosol loading on solar radiation and the subsequent effect on photosynthesis is a relevant question for estimating climate feedback mechanisms. This effect is quantified in the present study using ground-based measurements from five remote sites in boreal and hemiboreal (coniferous and mixed) forests of Eurasia. The diffuse fraction of global radiation associated with the direct effect of aerosols, i.e. excluding the effect of clouds, increases with an increase in the aerosol loading. The increase in the diffuse fraction of global radiation from approximately 0.11 on days characterized by low aerosol loading to 0.2–0.27 on days with relatively high aerosol loading leads to an increase in gross primary production (GPP) between 6 % and 14 % at all sites. The largest increase in GPP (relative to days with low aerosol loading) is observed for two types of ecosystems: a coniferous forest at high latitudes and a mixed forest at the middle latitudes. For the former ecosystem the change in GPP due to the relatively large increase in the diffuse radiation is compensated for by the moderate increase in the light use efficiency. For the latter ecosystem, the increase in the diffuse radiation is smaller for the same aerosol loading, but the smaller change in GPP due to this relationship between radiation and aerosol loading is compensated for by the higher increase in the light use efficiency. The dependence of GPP on the diffuse fraction of solar radiation has a weakly pronounced maximum related to clouds.

PARAMETERIZATION OF SHORT-WAVE SOLAR IRRADIANCE FOR GLACIOLOGICAL APPLICATIONS

2021 ◽  
pp. 5-20
Author(s):  
O.O. RYBAK ◽  
◽  
R. SATYLKANOV ◽  
E.A. RYBAK ◽  
A.S. GUBANOV ◽  
...  
Keyword(s):  
Solar Irradiance ◽  
Global Radiation ◽  
Thermal Conditions ◽  
Diffuse Radiation ◽  
Short Wave ◽  
Tien Shan ◽  
Atmospheric Composition ◽  
Shortwave Radiation ◽  
Mountain Glaciers ◽  
Atmospheric Transmissivity

Solar irradiance is the most important factor which determines the thermal conditions of mountain glaciers. We use trigonometric formulae to calculate direct solar radiation incoming on any arbitrary oriented surface under the condition of absence of the atmosphere. Shading effect from the surrounding relief can also be evaluated rather precisely. Nevertheless, in order to obtain correct results, it is necessary to take into account atmospheric transmissivity, diffuse radiation, and influence of cloudiness. The paper presents a model for calculation of shortwave radiation, utilizing up-to-date data on the atmospheric composition and schemes for parameterization of the atmospheric transmissivity, which have never been implemented in glaciological applications before. Validation of the model was carried out using observational data on the global radiation on two weather stations established on Karabatkak glacier (Inner Tien Shan).

scholarly journals Monthly average daily diffuse solar radiation in Poland within the period 2005–2015

2018 ◽  
Vol 23 ◽  
pp. 00020
Author(s):  
Małgorzata Kleniewska ◽  
Dorota Mitrowska ◽  
Bogdan H. Chojnicki
Keyword(s):  
Solar Radiation ◽  
Linear Relationship ◽  
Global Radiation ◽  
Diffuse Radiation ◽  
Diffuse Fraction ◽  
Diffuse Solar Radiation ◽  
Monthly Average

In this paper an 11-year series of daily values of diffuse solar radiation registered at 8 actinometric stations in Poland was used to describe the characteristics of diffuse radiation and diffuse fraction of global radiation for the area of Poland. Based on the monthly average daily diffuse, global and extraterrestrial solar radiation a linear relationship between these elements was determined. The obtained equation enables the calculation of the monthly average daily diffuse solar radiation for Poland and the application of its values to further climatology studies.

scholarly journals Global radiation, photosynthetically active radiation, and the diffuse component dataset of China, 1981–2010

2018 ◽  
Vol 10 (3) ◽  
pp. 1217-1226 ◽  
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 ◽  
Diffuse Component ◽  
Ecosystem Productivity ◽  
Ecosystem Models ◽  
Active Radiation

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).

scholarly journals Annual evolution of global, direct and diffuse radiation and fractions in tilted surfaces

2012 ◽  
Vol 32 (2) ◽  
pp. 247-260
Author(s):  
Adilson P. de Souza ◽  
João F. Escobedo ◽  
Alexandre Dal Pai ◽  
Eduardo N. Gomes
Keyword(s):  
Solar Radiation ◽  
Cloud Cover ◽  
Diffuse Radiation ◽  
Incident Radiation ◽  
Sao Paulo ◽  
Horizontal Surface ◽  
Direct Radiation ◽  
Incident Solar Radiation ◽  
Cover Ratio ◽  
Atmospheric Transmissivity

It was evaluated the annual evolution of global, direct and diffuse components of incident solar radiation on tilted surfaces to 12.85, 22.85 and 32.85º, facing north, in Botucatu, state of São Paulo, Brazil. The radiometric fractions were obtained for each component of the radiation in the aforementioned surfaces, through the ratio with the global and top of the atmosphere radiations. Seasonality was evaluated based on monthly averages of daily values. The measures occurred between 04/1998 and 07/2001 at 22.85º; 08/2001 and 02/2003 at 12.85º; and from 03/2003 to 12/2007 at 32.85º, with concomitant measures in the horizontal surface (reference). The levels of global and direct radiation on tilted surfaces were lower in summer and higher in the equinoxes when compared with the horizontal. The diffuse radiation on tilted surfaces was lower in most months, with losses of up to 65%. A trend of increasing differences occurred between horizontal and tilted surfaces with the increase of the angle in all the components and fractions of incident radiation. The annual evolution of rainfall and cloud cover ratio directly affected the atmospheric transmissivity of direct and diffuse components in the region.

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