Values Of Diffuse Solar Radiation Research Articles

Prediction of Direct and Diffuse Solar Radiation on Pokhara, Nepal

The measurement of direct and diffuse solar radiation is not easily possible because instruments are quite expensive. The main objective of this study was to predict direct solar radiation (IB) and diffuse solar radiation (ID) on Pokhara (28.186643o N, 83.97518o E, 800 m asl) for a period of one year (2017). Daily data of spectral Aerosol optical depth (AOD) and total ozone column are obtained from NASA website. The maximum value of direct solar radiation and diffuse solar radiation values were found 932.9 ± 65.9 W/m2 in January and 363.0 ± 87.9 W/m2 in February respectively. The minimum value of direct solar radiation and diffuse solar radiation values were found 692.8 ±142.0 W/m2 in April and 107.7 ± 20.4 W/m2 in July respectively. The diffuse solar radiation changes with season. The annual average of direct solar radiation and diffuse solar radiation are found 808.1± 133.7 W/m2 and 220.8 ± 102.8 W/m2 and respectively. The results of this research work will help further identification, impact and analysis of solar radiation in different locations in Nepal with the same geographic conditions.

Estimation of Direct and Diffuse Solar Radiation on Bode, Bhaktapur

The main objective of the study is to estimate direct solar radiation (IB) and diffuse solar radiation (ID) on Bode, Bhaktapur (27.68° N, 85.39° E, 1297 m a. s. l.) for a period of one year (2013). Daily data of Aerosol optical depth (AOD), total ozone column are derived from NASA website. The maximum and minimum monthly average of diffuse solar radiation values were found 318±95 W/m2 in April and 108 ± 20 W/m2 in August respectively. The maximum and minimum monthly average of direct solar radiation values were found 975±74 W/m2 in February and 748 ± 126 W/m2 in March respectively. The annual average of diffuse solar radiation and direct solar radiation are found 216 ± 88 W/m2 and 864 ± 125 W/m2 respectively. Result of this research work is beneficial for the further identification, impact and analysis of direct solar radiation diffuse solar radiation at different places.

Constructing High-Resolution (10 km) Daily Diffuse Solar Radiation Dataset across China during 1982–2020 through Ensemble Model

Diffuse solar radiation is an essential component of surface solar radiation that contributes to carbon sequestration, photovoltaic power generation, and renewable energy production in terrestrial ecosystems. We constructed a 39-year (1982–2020) daily diffuse solar radiation dataset (CHSSDR), using ERA5 and MERRA_2 reanalysis data, with a spatial resolution of 10 km through a developed ensemble model (generalized additive models, GAM). The validation results, with ground-based measurements, showed that GAM had a high and stable performance with the correlation coefficient (R), root-mean-square error (RMSE), and mean absolute error (MAE) for the sample-based cross-validations of 0.88, 19.54 Wm−2, and 14.87 Wm−2, respectively. CHSSDR had the highest consistency with ground-based measurements among the four diffuse solar radiation products (CERES, ERA5, JiEA, and CHSSDR), with the least deviation (MAE = 15.06 Wm−2 and RMSE = 20.22 Wm−2) and highest R value (0.87). The diffuse solar radiation values in China range from 59.13 to 104.65 Wm−2, with a multi-year average value of 79.39 Wm−2 from 1982 to 2020. Generally, low latitude and low altitude regions have larger diffuse solar radiation than high latitude and high altitude regions, and eastern China has less diffuse solar radiation than western China. This dataset would be valuable for analyzing regional climate change, photovoltaic applications, and solar energy resources. The dataset is freely available from figshare.

Prediction of diffuse radiation in solar energy applications: Turkey case study and compare with satellite data

In solar engineering applications, the components of the solar radiation a location must be known to design the systems. Due to the difficulties in the diffuse solar radiation (DSR) measurements, as this component has not been measured in everyplace, the DSR models have been established for various locations over the world. In this study, the models developed to constitute a relation between the monthly mean daily diffuse fraction and diffuse coefficient with clearness index and sunshine fraction in the open literature for Turkey are reviewed. In addition, the comparisons of the DSR values taken from the NASA – Surface meteorology and Solar Energy (NASA-SSE) and computed from the best models for example two cities are carried out. The performances of the models are investigated by various statistical test techniques. These statistical test techniques are root mean square error (RMSE) and mean absolute error (MAE). The statistical comparisons show that the best models give well agreement with the DSR values taken from the NASA-SSE. The difference between the yearly total DSR calculated from the best models and NASA-SSE is approximately 1.94% for Erzurum and 0.57% for Gebze.

Assessment of spectra of solar radiation during the partial solar eclipse of 21 June 2020 at, Tanta, Egypt

ABSTRACT The main objective of this study is to obtain vartiation of solar spectrum during the recent solar eclipse in the range 350-1100nm. The net results are studying the spectral composition of global solar radiation which are collective of the direct and diffuse solar radiation values do not similar to the computation result (45% covering of the solar disk). The maximum absorption energy in the atmosphere is at range 820–900nm. The depression in the solar enenrgy is 0.11 (W.m-2.nm-1). The ultraviolet band is suffering low depression with respect to another bands but not given any risks on the human life as common. That the change in meteorological parameter related to variability in the solar spectrum that shift the short wave before 600 nmto long wave around 1000 nm. The most extreme drop in the solar spectrum lies in the interval which consists of the normal peak of the solar spectrum from 500 - 600nm. The percentage of radiant energy reaching the earth through 350-1100nm at the maximum of the solar eclipse was 54%. Consequently, the rate of depresion in energy is equal to 46%, which is very strange compared to the normal flow rate of 44%. During the eclipse, the maximum solar energy at the maximum eclipse are at 480nm (13.07 W.m-2.nm-1) and 630nm (13.17 W.m-2.nm-1). At the wavelength 580nm rpresents the absorbition of O2 , andthe absorbtion of H2O at 680, 730, 780 and the maximum absorbtion energy by the H2O is at 830nm (low enegy transimmted at 0.31 W.m-2.nm-1).

On the use of BRL model for daily and hourly solar radiation components assessment in a semiarid climate

Solar radiation components assessment is a highly required activity for solar energy applications. Despite their importance, diffuse and direct solar radiation components are not available in many locations in the world. This is specifically the case in the studied region due to high fiscal demands and technical limitations. In the present work, our main objective is to estimate the two components using global solar radiation components as the only measured input parameter. Machine learning (ML) techniques seem to be a good solution of such an estimation problem but the main issue of ML techniques is the need of long historical data of both desired outputs, direct and diffuse, to build the optimum model in the training phase. However, in the present study, we adopt the use of the Boland–Ridley–Lauret (BRL) model to deal with the problem of estimation of the direct and diffuse components from the global radiation. The adjusted BRL model was applied on two time scales, daily and hourly components. It was found that the estimated direct and diffuse solar radiation values by the adjusted BRL model are in favorable agreement with the measured data.

Estimated long-term variability of direct and diffuse solar radiation in North China during 1959–2016

The long-term variability of direct and diffuse solar radiation at the surface remains unknown for many areas of the world due to the lack of measurements. In this study, two methods, an empirical model and a neural network, are used to estimate annual direct and diffuse solar radiation in North China for the 1959–2016 period. Results reveal that the two methods have a good performance in estimating direct solar radiation (R2 = 0.49–0.95), and the estimation accuracy of diffuse solar radiation can be improved by incorporating the influence of aerosols (R2 = 0.29–0.79). Generally, total and direct solar radiations have significantly decreased with the declining trend in sunshine duration since 1959 (p < 0.01). However, diffuse solar radiation shows a significant (p < 0.01) increasing tendency over the period of 1959–2016. The proportions of direct and diffuse solar radiation are almost equal from 1982 onward. Influenced by the atmospheric aerosols, two periods with large diffuse solar radiation values have been observed from 1959 to 1989 and from 2004 to 2016. Over the period of 2000–2016, sunshine duration and aerosols can explain 89 and 85% of direct and diffuse solar radiation variations, where aerosol concentration accounts for about 63% of changes in diffuse solar radiation. This study characterizes the long-term variability of direct and diffuse solar radiation in North China since 1959 and highlights the significance of aerosols to diffuse solar radiation from 2000 to 2016.

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

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.

Spatially transferable regional model for half-hourly values of diffuse solar radiation for general sky conditions based on perceptron artificial neural networks

We describe a procedure to build an artificial neural network model of half-hourly values of diffuse solar radiation at the surface that can be repeated for other locations in a region. The model was developed for the location of the Portorož Airport (Slovenia) using data gathered by a standard automatic meteorological station and diffuse solar radiation measured over one year. The model was constructed based on a perceptron artificial neural network, which is a universal approximator for highly nonlinear systems. To date, models of this type have been restricted to a single chosen location. An inland location at Maribor was tested as a benchmark for comparison. It is shown that the Portorož model can be directly transferable without significant quality loss to the inland location of Maribor Airport, which has a different climate. Comparison to the Maribor benchmark model gives a correlation ranging from the initial value of 0.9030 to 0.9004, RMSE increases from 40.5 to 43.7 Wm−2, coefficient of variation of the RMSE increases from 38% to 41%; values for the initial location of Portorož are 0.9453, 28.7 Wm−2, 26.4%. To the best of our knowledge, this report describes the first such regional model that is spatially transferable.

Estimation and Comparison of Diffuse Solar Radiation over Iraq

Using sunshine duration, extraterrestrial radiation and global radiation are used as input parameters in four mathematical models. The daily average diffuse solar radiation in various (16) locations in Iraq have been estimated by using a thirty years solar radiation data within the period from (1961 – 1991). These locations had chosen randomly to cover the most geographic regions of Iraq. The maximum values of diffuse solar radiation are appeared in the summer season which is in range (2 - 9 MJ. m -2 day -1) for (4 models), while the minimum values for solar radiation were in months January and December . These four models are compared between them to estimate the diffuse radiation values for different studied locations over Iraq.

Modeling of Diffuse Solar Radiation and Impact of Complex Terrain over Pakistan Using RS/GIS

Diffuse solar radiation is subject to the combined influence of ground and sky factors, such as topography, geography of the area and cloud cover. This study attempts to quantify the impacts of topography, sky factors and the cloud cover on the distribution of diffuse solar radiation over Pakistan. Distributed modeling approach by considering anisotropy scattering mechanism was adopted. Digital elevation model and observed data are used to derive average monthly diffuse solar radiation values over the rugged terrains of Pakistan. Extraterrestrial solar radiation model, sky view factor model (openness model) and digital elevation model (DEM) are applied to investigate the impacts of ground factors, while diffuse solar radiation model for horizontal surface was considered for sky factors. Furthermore, corrected MODIS cloud fraction data are incorporated using GIS plat form. Results show that the highest amount of diffused solar radiation occurs during the monsoon months along the eastern side of the River Indus, when the sky is covered by clouds of various heights and densities. The variation due to topography is evident in mountainous areas, particularly in the North Pakistan and over the Baluchistan Plateau.

Correlation model of hourly diffuse solar radiation based on ASHRAE model: a study case in India

Measurements of diffuse and global solar radiation carried out from January 2001 to December 2005 at Ahmedabad, Mumbai, Calcutta, Chennai and Pune cities of India, representing varying weather conditions of the entire country, have been used to develop the correlation model for the estimating hourly values of diffuse solar radiation on horizontal surface. The comparisons of the present estimated hourly diffuse solar radiation for different locations have been made with theoretical models of American Society of Heating Refrigeration and Air-conditioning Engineers (ASHRAE) (1999), Parishwad et al. (1997) and Erbs et al. (1982) along with the measured data. It is observed that in comparison to other models, new proposed model (modified ASHRAE model) estimates better hourly diffuse solar radiation for all Indian stations. For further validation and to observe the accuracy of present model over others, the root mean square error (RMSE), mean bias error (MBE) and t-static test have also been carried out.

The role of clouds in improving the regression model for hourly values of diffuse solar radiation

The study introduces a new regression model developed to estimate the hourly values of diffuse solar radiation at the surface. The model is based on the clearness index and diffuse fraction relationship, and includes the effects of cloud (cloudiness and cloud type), traditional meteorological variables (air temperature, relative humidity and atmospheric pressure observed at the surface) and air pollution (concentration of particulate matter observed at the surface). The new model is capable of predicting hourly values of diffuse solar radiation better than the previously developed ones ( R 2 = 0.93 and RMSE = 0.085). A simple version with a large applicability is proposed that takes into consideration cloud effects only (cloudiness and cloud height) and shows a R 2 = 0.92.

Diffuse solar radiation estimation models for Turkey’s big cities

A reasonably accurate knowledge of the availability of the solar resource at any place is required by solar engineers, architects, agriculturists, and hydrologists in many applications of solar energy such as solar furnaces, concentrating collectors, and interior illumination of buildings. For this purpose, in the past, various empirical models (or correlations) have been developed in order to estimate the solar radiation around the world. This study deals with diffuse solar radiation estimation models along with statistical test methods used to statistically evaluate their performance. Models used to predict monthly average daily values of diffuse solar radiation are classified in four groups as follows: (i) From the diffuse fraction or cloudness index, function of the clearness index, (ii) From the diffuse fraction or cloudness index, function of the relative sunshine duration or sunshine fraction, (iii) From the diffuse coefficient, function of the clearness index, and (iv) From the diffuse coefficient, function of the relative sunshine duration or sunshine fraction. Empirical correlations are also developed to establish a relationship between the monthly average daily diffuse fraction or cloudness index ( K d) and monthly average daily diffuse coefficient ( K dd) with the monthly average daily clearness index ( K T) and monthly average daily sunshine fraction ( S/ S o) for the three big cities by population in Turkey (Istanbul, Ankara and Izmir). Although the global solar radiation on a horizontal surface and sunshine duration has been measured by the Turkish State Meteorological Service (STMS) over all country since 1964, the diffuse solar radiation has not been measured. The eight new models for estimating the monthly average daily diffuse solar radiation on a horizontal surface in three big cites are validated, and thus, the most accurate model is selected for guiding future projects. The new models are then compared with the 32 models available in the literature in terms of the widely used statistical indicators, namely; the relative percentage error ( E), coefficient of determination ( R 2), the mean percentage error (MPE), the mean absolute percentage error (MAPE), the sum of the squares of relative errors (SSRE), the relative standard error (RSE), the mean bias error (MBE), the root mean square error (RMSE), and the t-statistic ( t-stat) method combining the last two errors. It may be concluded that the new models predict the values of cloudness index ( K d) and diffuse coefficient ( K dd) as a function of clearness index ( K T) and sunshine fraction ( S/ S o) for three big cities in Turkey better than other available models, while all the models tested appear to be location independent models for diffuse radiation predictions, at least for three big cities in Turkey. It is also expected that the models reviewed and developed will be beneficial to everyone involved or interested in the design and study of solar energy.

Performance of empirical correlations for predicting monthly mean daily diffuse solar radiation values at Kampala, Uganda

Existing literature lacks information on formulation and performance assessment of diffuse solar radiation models in the Eastern African region yet this region has a high potential for the utilization of solar energy. The objective of this paper is to assess the performance of seventeen diffuse solar irradiation empirical correlations, at Kampala, Uganda. The best performing correlations were determined using the ranking method. The normalized absolute mean bias error and root mean square error were computed and utilized in the ranking process. The results indicated that the correlations relating diffuse transmittance \((\bar{H}_d/\bar{H}_0)\) with relative sunshine duration \((\bar{S}/\bar{S}_0)\) are more reliable for diffuse solar radiation predictions at least in the Uganda environment. These models are expressed in terms of first, second and third order polynomials of the relative sunshine duration and are particularly recommended for their simplicity and worldwide applicability.

A deterministic method to characterize canopy radiative transfer properties

AbstractInvestigations of snowcover dynamics beneath vegetation canopies require either measured or estimated solar and thermal radiation values at the snow surface. A deterministic method is presented that uses portable arrays of pyranometers and pyrgeometers to quantify the amount of incoming radiation at the snow surface. Example solar and thermal radiation datasets are presented from boreal deciduous, boreal coniferous and temperate coniferous forest stands. The data indicate that the canopies transmitted 33% (4–8 March), 15% (6–10 February), and 3% (22–24 September) of the above‐canopy radiation. In the boreal deciduous and temperate conifer stands, thermal radiation is increased by 25% and 34% respectively. Thermal gains partially offset solar reduction, such that incoming all‐wave radiation is decreased by 22% and 25% respectively for each of these stands. When recorded at a high temporal resolution, array data can estimate below‐canopy diffuse solar radiation values for estimation techniques that treat direct and diffuse transmission independently. We provide examples of how radiometer array data are used to derive simple canopy radiation transmissivity parameters for global, beam and diffuse radiation. Radiometer arrays also provide data for detailed investigations to assess within‐stand radiation variability, or to investigate radiation variations across land cover discontinuities, to advance our understanding of snowcover energetics in complex environments. Copyright © 2004 John Wiley &amp; Sons, Ltd.

A New Shadow-Ring Device for Measuring Diffuse Solar Radiation at the Surface

A new shadow-ring device for measuring diffuse solar radiation at the surface is presented. In this device the seasonal variation of shadow is followed by moving the detector horizontally. This unique characteristic facilitates its application for long and continuous periods of time. The blocking effect caused by the ring and other related geometric properties are formulated considering the diffuse solar radiation isotropic. The correction factor, shadow size, and ring-detector distance are derived as a function of radius and width of the ring, sun position, and local latitude. The largest blocking occurs during summer, when the ring-detector distance and the shadow width are the smallest, and it is compensated by a smaller blocking effect in the winter period. The performance of the new device is verified comparing daily values of diffuse solar radiation measured simultaneously with a similar device from Kipp & Zonen, Inc. The results show a very good agreement (within 2.5%) between both devices. The new device was also able to reproduce the radiometric properties of the local atmosphere based on 3-yrlong measurements of direct solar radiation using a pyrheliometer. The new device can be applied to estimate daily values of diffuse solar radiation at the surface in the range of 30 8N‐308S with results comparable to other similar apparatuses.

Correlation models of diffuse solar-radiation applied to the city of São Paulo, Brazil

Measurements of global and diffuse solar-radiation, at the Earth's surface, carried out from May 1994 to June 1999 in São Paulo City, Brazil, were used to develop correlation models to estimate hourly, daily and monthly values of diffuse solar-radiation on horizontal surfaces. The polynomials derived by linear regression fitting were able to model satisfactorily the daily and monthly values of diffuse radiation. The comparison with models derived for other places demonstrates some differences related mainly to altitude effects.

On the annual and monthly mean diurnal variations of diffuse solar radiation at a meteorological station in west Africa

In addition to global solar radiationE ↓ g , the hourly diffuse componentE ↓ d incident on a horizontal surface has been measured from February 1993 to January 1995 at a meteorological station in tropical West Africa. The measured diffuse solar irradiance data was corrected for shadow band effects. The monthly mean diurnal variations of diffuse solar irradiance obtained for identical months in the two years have been compared and found to be generally consistent. The corresponding monthly mean hourly values ofE ↓ d for identical months in 1993 and 1994 agreed to within 9% while yielding correlation coefficients greater than 0.960. In addition, the monthly mean daily totals ofE ↓ d for identical months were found to agree mostly to within 6% and showed virtually the same annual variations in both years. The monthly mean daily total values of diffuse solar radiation for most months in the two years ranged between 7.94 MJm−2d−1 and 10.50 MJm−2d−1. The monthly mean of daily hourly maximum values ofE ↓ d obtained for identical months in the two years have been discussed in relation to the dominant atmospheric conditions during these months. The results been presented here have been compared with those of some investigators within and outside the Africa region.

Measurements and predictions of solar radiation incident on horizontal surfaces at Santa Fe, Argentina (31° 39′S, 60° 43′W)

Measurements and predictions of solar radiation during a period of 10 years on horizontal surfaces at Santa Fe (31° 39′ S, 60° 43′ W), Argentina, reported as average daily global radiation for each month, are presented. Data are compared to those obtained with a previously published and verified model for computing solar radiation on horizontal planes at the earth's surface for cloudless sky days. Measurements show an important reduction of global radiation with respect to the cloudless sky model predictions for all months of the year. Conversely, averaged daily diffuse solar radiation calculated with Page's formula shows a small increment with respect to the predicted diffuse solar radiation for cloudless sky conditions. When direct solar radiation data, calculated from global and diffuse solar radiation values, are compared to theoretical prediction, a significant decrease is observed. This trend is similar to that obtained for global solar radiation.