Journal articles: 'Pyrheliometer'

1

Balenzategui, José Lorenzo, María Molero, José Pedro Silva, Fernando Fabero, José Cuenca, Eduardo Mejuto, and Javier De Lucas. "Uncertainty in the Calibration Transfer of Solar Irradiance Scale: From Absolute Cavity Radiometers to Standard Pyrheliometers." Solar 2, no. 2 (April 2, 2022): 158–85. http://dx.doi.org/10.3390/solar2020010.

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In this work, the method for calculation of uncertainty of pyrheliometers’ responsivity during their outdoor calibration process in the laboratory is exposed. It is applied first for calibration of standard pyrheliometers by comparison to cavity radiometers, and after for calibration of an end-user pyrheliometer against that standard pyrheliometer. The dissemination of the WRR irradiance scale is illustrated in practice and the increasing uncertainty in the traceability chain is quantified. The way of getting traceability to both WRR scale and to SI units in the current situation, where the shift between these radiometric scales is pending to be solved, is also explained. However, the impact of this gap between scales seems to be more important for calibrations of reference Class A pyrheliometers than in the final determination of DNI irradiance, because in this case, the cumulative uncertainty is large enough as to not significantly be affected for the difference. The way to take into account different correction terms in the measurement model function, and how to compute the corresponding uncertainty, is explained too. The influence of temperature of some pyrheliometers during calibration process and the potential impact on the DNI irradiance calculated with these instruments is exemplified.

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IYER, N. V. "A NULL DETECTOR FOR PYRHELIOMETER OBSERVATIONS." MAUSAM 25, no. 3 (February 21, 2022): 503. http://dx.doi.org/10.54302/mausam.v25i3.5265.

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Zhang, Z. M., X. S. Ge, and Y. F. Wang. "A novel pyrheliometer of high accuracy." Solar Energy 39, no. 5 (1987): 371–77. http://dx.doi.org/10.1016/s0038-092x(87)80055-5.

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Cheng, S. X., X. S. Ge, J. A. Li, and H. Q. Feng. "A transient calorimeter pyrheliometer of high accuracy." Solar Energy 45, no. 2 (1990): 79–83. http://dx.doi.org/10.1016/0038-092x(90)90031-7.

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Mujahid, A. M., and A. R. M. Alamoud. "An easily designed and constructed photovoltaic pyrheliometer." Solar & Wind Technology 5, no. 2 (January 1988): 127–30. http://dx.doi.org/10.1016/0741-983x(88)90070-7.

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Dayan, A., A. Olbinsky, and G. Mittelman. "On the Design and Analysis of a Pyrheliometer Comprising a Convex Lens." Journal of Solar Energy Engineering 126, no. 3 (July 19, 2004): 915–20. http://dx.doi.org/10.1115/1.1758724.

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A novel pyrheliometer, based on a solar irradiance concentration method, has been designed, constructed and calibrated. An analytical model of the instrument was developed and incorporated for the design and investigation of the instrument performance. The apparatus contains a small receiver that intercepts and absorbs the solar beam irradiation near the focus of a convex lens, by which the flux is concentrated. The irradiated receiver area is isothermal owing to its small dimensions and high thermal conductivity. Therefore, a single thermo-couple is sufficient to measure the temperature difference between the receiver irradiated area and its surroundings. The solar irradiative flux is evaluated by substituting the recorded temperature difference into, either, a linear experimental calibration chart or into a linear characteristic formula that was derived analytically. The instrument calibration was performed at the Israeli Institute of Standards, using an EPLAB normal incidence pyrheliometer as a reference. The new instrument is inexpensive, simple and portable. Its accuracy is suitable for routine field measurements of direct solar beam irradiation. The analytical model is typical to many solar radiation collection problems and could be considered as useful analytical tool, beyond the specific purpose for which it was developed.

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Mayer, I., and P. G. Holland. "Linearity and temperature compensation tests on a thermopile pyrheliometer." Solar Energy 39, no. 4 (1987): 297–300. http://dx.doi.org/10.1016/s0038-092x(87)80015-4.

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Ferrera Cobos, F., R. X. Valenzuela, L. Ramírez, L. F. Zarzalejo, B. Nouri, S. Wilbert, and G. García. "Assessment of the impact of meteorological conditions on pyrheliometer calibration." Solar Energy 168 (July 2018): 44–59. http://dx.doi.org/10.1016/j.solener.2018.03.046.

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Michalsky, Joseph, Ellsworth G. Dutton, Donald Nelson, James Wendell, Stephen Wilcox, Afshin Andreas, Peter Gotseff, et al. "An Extensive Comparison of Commercial Pyrheliometers under a Wide Range of Routine Observing Conditions." Journal of Atmospheric and Oceanic Technology 28, no. 6 (June 1, 2011): 752–66. http://dx.doi.org/10.1175/2010jtecha1518.1.

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Abstract In the most comprehensive pyrheliometer comparison known to date, 33 instruments were deployed to measure direct normal solar radiation over a 10-month period in Golden, Colorado. The goal was to determine their performance relative to four electrical-substitution cavity radiometers that were calibrated against the World Radiometric Reference (WRR) that is maintained at the World Radiation Center in Davos, Switzerland. Because of intermittent cabling problems with one of the cavity radiometers, the average of three windowed, electrical-substitution cavity radiometers served as the reference irradiance for 29 test instruments during the 10-month study. To keep the size of this work manageable, comparisons are limited to stable sunny conditions, passing clouds, calm and windy conditions, and hot and cold temperatures. Other variables could have been analyzed, or the conditions analyzed could have employed higher resolution. A more complete study should be possible now that the instruments are identified; note that this analysis was performed without any knowledge on the part of the analyst of the instruments’ manufacturers or models. Apart from the windowed cavities that provided the best measurements, two categories of performance emerged during the comparison. All instruments exceeded expectations in that they measured with lower uncertainties than the manufacturers’ own specifications. Operational 95% uncertainties for the three classes of instruments, which include the uncertainties of the open cavities used for calibration, were about 0.5%, 0.8%, and 1.4%. The open cavities that were used for calibration of all pyrheliometers have an estimated 95% uncertainty of 0.4%–0.45%, which includes the conservative estimate of 0.3% uncertainty for the WRR.

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Qiu, Jinhuan, and Xuemei Zong. "A New Method to Retrieve Thin Cloud Optical Thickness from a Ratio of Scattering to Global Solar Irradiance." Journal of the Atmospheric Sciences 71, no. 4 (March 27, 2014): 1521–28. http://dx.doi.org/10.1175/jas-d-13-0139.1.

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Abstract Three kinds of “visible” cloud optical thickness τ—matching shortwave direct, global, and scattering solar irradiances (Ids, Igs and Iss)—are defined, which are marked as τd, τg, and τs, respectively. It is found from radiation calculations that a ratio of Iss to Igs in the small-τ case has a unique characteristic: strong sensitivity to τ but weak sensitivity to the cloud scattering phase function. On the basis of this characteristic, a method to retrieve Iss-equivalent τs from the ratio is proposed. This method is validated by way of simulation and application tests, in which the Discrete Ordinate Radiative Transfer model (DISORT) is used to calculate irradiances. As shown in simulations with τ < 2, there may be unrealistically negative or grossly overestimated τ values from Igs, owing to the difference between τs and τd, while the new method can lead to a very good agreement of τs retrieval with its input. Furthermore, this method is used to retrieve small τ from the pyrheliometer and pyranometer measurements in Lhasa during 2006. It is found that τ retrieved from Igs was often negative because of cloud inhomogeneity, while the application of the new method resulted in stable yet reasonable τs values. The Iss calculations using 1293 sets of τs retrievals fit well into the Iss determinations from pyrheliometer and pyranometer measurements with an annual-mean deviation of 0.18%, but the deviation was raised to 46.4% when using τg retrievals.

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Kmito, A. A. "Development and Investigation of Cooled-cavity Precision Pyrheliometer Receiver PCC-3." Metrologia 28, no. 3 (January 1, 1991): 169–71. http://dx.doi.org/10.1088/0026-1394/28/3/012.

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Horseman, A. M., T. Richardson, A. T. Boardman, W. Tych, R. Timmis, and A. R. MacKenzie. "Systematic and rapid extraction of direct downwelling irradiance estimates from Campbell-Stokes sunshine recorder archives." Atmospheric Measurement Techniques Discussions 5, no. 6 (December 5, 2012): 8729–57. http://dx.doi.org/10.5194/amtd-5-8729-2012.

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Abstract. An improved, semi-automatic method for analysing the cards from the widely used Campbell-Stokes sunshine recorder is described. We show how the application of inexpensive commercial equipment and practices can simply and robustly build an archive of high-quality card images and manipulate them into a form suitable for easy further analysis. Rectified and registered digital images are produced, with the card's midday marker in the middle of the longest side, and with a temporal scaling of 150 px h−1. The method improves on previous, mostly manual, analyses by simplifying and automating steps into a process capable of handling thousands of cards in a practical time-scale. A prototype method of extraction of data from this archive is then tested by comparison with records from a co-located pyrheliometer at a resolution of the order of minutes. The comparison demonstrates that the Campbell-Stokes recorder archive contains a time series of downwelling solar-irradiance-related data with similar characteristics to that of benchmark pyrheliometer data from the baseline solar radiation network. A universal transfer function for card burn to direct downwelling short-wave radiation is still some way off and is the subject of ongoing research. Until such time as a universal transfer function is available, specific functions for extracting data in particular circumstances offer a useful way forward. The new image-capture method offers a practical way to exploit the worldwide sets of long-term Campbell-Stokes recorder data to create a time series of solar irradiance and atmospheric aerosol loading metrics reaching back over 100 yr from the present day.

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Horseman, A. M., T. Richardson, A. T. Boardman, W. Tych, R. Timmis, and A. R. MacKenzie. "Calibrated digital images of Campbell–Stokes recorder card archives for direct solar irradiance studies." Atmospheric Measurement Techniques 6, no. 5 (May 23, 2013): 1371–79. http://dx.doi.org/10.5194/amt-6-1371-2013.

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Abstract. A systematic, semi-automatic method for imaging the cards from the widely used Campbell–Stokes sunshine recorder is described. We show how the application of inexpensive commercial equipment and practices can simply and robustly build an archive of high-quality card images and manipulate them into a form suitable for easy further analysis. Rectified and registered digital images are produced, with the card's midday marker in the middle of the longest side, and with a temporal scaling of 150 pixels per hour. The method improves on previous, mostly manual, analyses by simplifying and automating steps into a process capable of handling thousands of cards in a practical timescale. A prototype method of extraction of data from this archive is then tested by comparison with records from a co-located pyrheliometer at a resolution of the order of minutes. The comparison demonstrates that the Campbell–Stokes recorder archive contains a time series of downwelling solar-irradiance-related data with similar characteristics to that of benchmark pyrheliometer data from the Baseline Surface Radiation Network. A universal transfer function for card burn to direct downwelling short-wave radiation is still some way off and is the subject of ongoing research. Until such time as a universal transfer function is available, specific functions for extracting data in particular circumstances offer a useful way forward. The new image-capture method offers a practical way to exploit the worldwide sets of long-term Campbell–Stokes recorder data to create a time series of solar irradiance and atmospheric aerosol loading metrics reaching back over 100 yr from the present day.

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14

Curtiss, Peter. "An Analysis of Methods for Deriving the Constituent Insolation Components From Multipyranometer Array Measurements." Journal of Solar Energy Engineering 115, no. 1 (February 1, 1993): 11–21. http://dx.doi.org/10.1115/1.2930018.

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A multipyranometer array (MPA) is a static platform of solar sensors designed to “untangle” the beam, diffuse and reflected portions of the total solar radiation. Over the past four years, a series of weather stations located throughout Colorado has used MPA’s to record insolation. This paper compares the beam radiation derived from an MPA with that measured by a nearby tracking pyrheliometer. Three different diffuse sky models as well as uniform and specular foreground reflectance models are used in the analysis. The ability of each model to predict the actual beam radiation is tabulated. Finally, two novel methods for deriving the beam component without the use of sky models are presented, along with a comparison with the conventional models.

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Harting, E. "A simple pyrheliometer substitute for prediction of power input to tilting concentrator arrays." Solar Energy 34, no. 2 (1985): 195–97. http://dx.doi.org/10.1016/0038-092x(85)90180-x.

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Patrick, Heather J., Thomas A. Germer, Clarence J. Zarobila, Catherine C. Cooksey, and Howard W. Yoon. "Optical reflectance of pyrheliometer absorption cavities: progress toward SI-traceable measurements of solar irradiance." Applied Optics 55, no. 23 (August 8, 2016): 6346. http://dx.doi.org/10.1364/ao.55.006346.

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Carballar, Alejandro, Roberto Rodríguez-Garrido, Manuel Jerez, Jonathan Vera, and Joaquín Granado. "Measuring DNI with a New Radiometer Based on an Optical Fiber and Photodiode." Sensors 24, no. 11 (June 6, 2024): 3674. http://dx.doi.org/10.3390/s24113674.

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A new cost-effective radiometer has been designed, built, and tested to measure direct normal solar irradiance (DNI). The proposed instrument for solar irradiance measurement is based on an optical fiber as the light beam collector, a semiconductor photodiode to measure the optical power, and a calibration algorithm to convert the optical power into solar irradiance. The proposed radiometer offers the advantage of separating the measurement point, where the optical fiber collects the solar irradiation, from the place where the optical power is measured. A calibration factor is mandatory because the semiconductor photodiode is only spectrally responsive to a limited part of the spectral irradiance. Experimental tests have been conducted under different conditions to evaluate the performance of the proposed device. The measurements confirm that the proposed instrument performs similarly to the expensive high-accuracy pyrheliometer used as a reference.

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Aparicio, A. J. P., M. Antón, M. C. Gallego, A. Sanchez-Lorenzo, and J. M. Vaquero. "Re-evaluation of trends in atmospheric column transparency from pyrheliometer measurements in Madrid (1910–1929)." Atmospheric Research 217 (March 2019): 165–71. http://dx.doi.org/10.1016/j.atmosres.2018.11.003.

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WIDMALM, SVEN. "QUANTIFYING SUNSHINE: KNUT ANGSTROM AND THE STANDARDISATION OF PYRHELIOMETRY1." Nuncius 17, no. 2 (2002): 653–71. http://dx.doi.org/10.1163/182539102x00162.

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Abstracttitle SUMMARY /title The paper describes and analyses the work of Knut Angstrom, physics professor at Uppsala University from 1896 to 1910. Angstrom's research focussed mainly on radiation measurement. His magnum opus was the so-called electric compensating pyrheliometer, a device for measuring the heat content of radiation, for instance to study the energy distribution in spectra. The instrument was launched as a finished product around 1900, rapidly enjoying a widespread use, and thus elevating the Uppsala department to the status of standards institution, i.e. an institution setting and upholding technical norms in a well defined scientific area. This status was acknowledged in 1905, when the International Union for Co-Operation in Solar Research assigned the Uppsala department the task of controlling standardisation in this area of solar research. The paper analyses Angstrom's technoscientific style in its institutional setting, showing in particular how it facilitated the creation of a scientific community of solar researchers, with Uppsala as its administrative centre.

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Taşçıoğlu, Ayşegül, Onur Taşkın, and Ali Vardar. "A Power Case Study for Monocrystalline and Polycrystalline Solar Panels in Bursa City, Turkey." International Journal of Photoenergy 2016 (2016): 1–7. http://dx.doi.org/10.1155/2016/7324138.

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It was intended to reveal the time dependent power generation under different loads for two different solar panels under the conditions of Bursa province in between August 19 and 25, 2014. The testing sets include solar panels, inverter, multimeter, accumulator, regulator, pyranometer, pyrheliometer, temperature sensor, and datalogger. The efficiency of monocrystalline and polycrystalline solar panels was calculated depending on the climatic data’s measurements. As the result of the study, the average performances of monocrystalline and polycrystalline panels are 42.06 and 39.80 Wh, respectively. It was seen that 87.14 W instantaneous power could be obtained from monocrystalline solar panel and that 80.17 W instantaneous power could be obtained from polycrystalline solar panel under maximum total radiation (1001.13 W/m2). Within this frame, it was determined that monocrystalline solar panel is able to operate more efficiently under the conditions of Bursa compared to polycrystalline solar panel. When the multivariate correlations coefficients were examined statistically, a significant relationship in positive direction was detected between total and direct radiation and ambient temperature on energy generation from monocrystalline and polycrystalline panel.

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Antuña-Marrero, Juan Carlos, Victoria Cachorro Revilla, Frank García Parrado, Ángel de Frutos Baraja, Albeth Rodríguez Vega, David Mateos, René Estevan Arredondo, and Carlos Toledano. "Comparison of aerosol optical depth from satellite (MODIS), sun photometer and broadband pyrheliometer ground-based observations in Cuba." Atmospheric Measurement Techniques 11, no. 4 (April 20, 2018): 2279–93. http://dx.doi.org/10.5194/amt-11-2279-2018.

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Abstract. In the present study, we report the first comparison between the aerosol optical depth (AOD) and Ångström exponent (AE) of the Moderate Resolution Imaging Spectroradiometer (MODIS) instruments on the Terra (AODt) and Aqua (AODa) satellites and those measured using a sun photometer (AODSP) at Camagüey, Cuba, for the period 2008 to 2014. The comparison of Terra and Aqua data includes AOD derived with both deep blue (DB) and dark target (DT) algorithms from MODIS Collection 6. Combined Terra and Aqua (AODta) data were also considered. Assuming an interval of ±30 min around the overpass time and an area of 25 km around the sun photometer site, two coincidence criteria were considered: individual pairs of observations and both spatial and temporal mean values, which we call collocated daily means. The usual statistics (root mean square error, RMSE; mean absolute error, MAE; median bias, BIAS), together with linear regression analysis, are used for this comparison. Results show very similar values for both coincidence criteria: the DT algorithm generally displays better statistics and higher homogeneity than the DB algorithm in the behaviour of AODt, AODa, AODta compared to AODSP. For collocated daily means, (a) RMSEs of 0.060 and 0.062 were obtained for Terra and Aqua with the DT algorithm and 0.084 and 0.065 for the DB algorithm, (b) MAE follows the same patterns, (c) BIAS for both Terra and Aqua presents positive and negative values but its absolute values are lower for the DT algorithm; (d) combined AODta data also give lower values of these three statistical indicators for the DT algorithm; (e) both algorithms present good correlations for comparing AODt, AODa, AODta vs. AODSP, with a slight overestimation of satellite data compared to AODSP, (f). The DT algorithm yields better figures with slopes of 0.96 (Terra), 0.96 (Aqua) and 0.96 (Terra + Aqua) compared to the DB algorithm (1.07, 0.90, 0.99), which displays greater variability. Multi-annual monthly means of AODta establish a first climatology that is more comparable to that given by the sun photometer and their statistical evaluation reveals better agreement with AODSP for the DT algorithm. Results of the AE comparison showed similar results to those reported in the literature concerning the two algorithms' capacity for retrieval. A comparison between broadband aerosol optical depth (BAOD), derived from broadband pyrheliometer observations at the Camagüey site and three other meteorological stations in Cuba, and AOD observations from MODIS on board Terra and Aqua show a poor correlation with slopes below 0.4 for both algorithms. Aqua (Terra) showed RMSE values of 0.073 (0.080) and 0.088 (0.087) for the DB and DT algorithms. As expected, RMSE values are higher than those from the MODIS–sun photometer comparison, but within the same order of magnitude. Results from the BAOD derived from solar radiation measurements demonstrate its reliability in describing climatological AOD series estimates.

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Möllenkamp, Jana, Thomas Beikircher, and Andreas Häberle. "Recalibration of SPN1 pyranometers against pyrheliometer and its relevance for the evaluation of concentrating solar process heat plants." Solar Energy 197 (February 2020): 344–58. http://dx.doi.org/10.1016/j.solener.2019.12.055.

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Antón, M., J. M. Vaquero, and A. J. P. Aparicio. "The controversial early brightening in the first half of 20th century: A contribution from pyrheliometer measurements in Madrid (Spain)." Global and Planetary Change 115 (April 2014): 71–75. http://dx.doi.org/10.1016/j.gloplacha.2014.01.013.

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Raptis, Ioannis-Panagiotis, Stelios Kazadzis, Ilias Fountoulakis, Kyriakoula Papachristopoulou, Dimitra Kouklaki, Basil E. Psiloglou, Andreas Kazantzidis, Charilaos Benetatos, Nikolaos Papadimitriou, and Kostas Eleftheratos. "Evaluation of the Solar Energy Nowcasting System (SENSE) during a 12-Months Intensive Measurement Campaign in Athens, Greece." Energies 16, no. 14 (July 14, 2023): 5361. http://dx.doi.org/10.3390/en16145361.

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Energy nowcasting is a valuable asset in managing energy loads and having real-time information on solar irradiation availability. In this study, we evaluate the spectrally integrated outputs of the SENSE system for solar irradiance nowcasting for the period of the ASPIRE (atmospheric parameters affecting spectral solar irradiance and solar energy) campaign (December 2020–December 2021) held in Athens, Greece. For the needs of the campaign, several ground-based instruments were operating, including two pyranometers, a pyrheliometer, a cloud camera, a CIMEL sunphotometer, and a precision spectral radiometer (PSR). Global horizontal irradiance (GHI) estimations were more accurate than direct normal irradiance (DNI). SENSE estimations are provided every 15 min, but when comparing bigger time intervals (hours-days), the statistics improved. A dedicated assessment of the SENSE’s inputs is performed in respect to ground-based retrievals, considering cloud conditions (from a sky imager), AOD, and precipitable water vapor from AERONET. The factor that established the larger errors was the visibility of the solar disc, which cannot be defined by the available sources of model inputs. Additionally, there were discrepancies between the satellite estimation of the clouds and the ground picture, which caused deviations in results. AOD differences affected more the DNI.

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Abreu, Edgar F. M., Paulo Canhoto, and Maria João Costa. "Prediction of Circumsolar Irradiance and Its Impact on CSP Systems under Clear Skies." Energies 16, no. 24 (December 7, 2023): 7950. http://dx.doi.org/10.3390/en16247950.

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In this work, a model to estimate circumsolar normal irradiance (CSNI) for several half-opening angles under clear skies was developed. This approach used a look-up table to determine the model parameters and estimate CSNI for half-opening angles between 0.5° and 5°. To develop and validate the proposed model, data from five locations worldwide were used. It was found that the proposed model performs better at the locations under study than the models available in the literature, with relative mean bias error ranging from −13.94% to 0.70%. The impact of CSNI for these different half-opening angles on concentrating solar power (CSP) systems was also studied. It was found that neglecting CSNI could lead to up to a 7% difference between the direct normal irradiance (DNI) measured by a field pyrheliometer and the DNI that is captured by CSP systems. Additionally, a case study for parabolic trough concentrators was performed as a way to estimate the impact of higher circumsolar ratios (CSR) on the decrease of the intercept factor for these systems. It was also concluded that if parabolic trough designers aim to reduce the impact of CSNI variation on the intercept factor, then parabolic troughs with higher rim angles are preferred.

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Saputro, R. D., D. Handoko, Q. A. Hidayah, H. A. Nugraha, A. Sail, and I. S. Lukito. "The comparison of indoor and outdoor pyranometer calibration method in Jakarta." IOP Conference Series: Earth and Environmental Science 1167, no. 1 (May 1, 2023): 012004. http://dx.doi.org/10.1088/1755-1315/1167/1/012004.

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Abstract The increasing energy crisis motivated people to develop renewable energy, one of the promising renewable energies is solar energy. Considering that Indonesia has the potential for sunlight throughout the year, this country should be able to take full advantage of this solar radiation energy. To discover potential area in Indonesia, good and calibrated equipment are needed such as pyranometer, pyrheliometer etc. The objective of this study is to compare developed method of outdoor and indoor pyranometer calibration responsivity. There are 4 pyranometer calibration methods, one of them is called Continuous Sun and Shade Method (CoSSM). However, this method has never been carried out before, so it is going to be developed by the Agency for Meteorology, Climatology, and Geophysics (BMKG) Indonesia. The CoSSM method utilizes two standard components consist of direct and diffuse irradiance to obtain new responsivity values from calibrated global radiation sensor or so called Unit Under Test (UUT). This experiment used 4 UUT and carried out for 12 days. The new responsivity values then compared with the responsivity value that had been obtained from BMKG indoor calibration accredited by National Accreditation Committee (KAN). The results obtained from calibration process provided the highest percentage difference of 6.2% and the smallest 0.2%. This shows that outdoor calibration in cloudy and polluted conditions in Jakarta still give quite good result.

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Pashiardis, Stelios, Alexandros Pelengaris, and Soteris A. Kalogirou. "Comparison of Sunshine Duration Measurements between the Campbell–Stokes Sunshine Recorder and Three Automatic Sensors at Three Locations in Cyprus." Applied Sciences 13, no. 22 (November 16, 2023): 12393. http://dx.doi.org/10.3390/app132212393.

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This paper compares the daily sunshine duration (SD) measured by the Campbell–Stokes sunshine recorder (CS) with three automatic instruments (Kipp & Zonen pyranometers (CM6 B), pyrheliometer (CHP1) and CSD3 sunshine recorders). The comparisons are essential, since recently, automatic sunshine duration sensors have been replacing the manual measurements, affecting, therefore, the continuity of the CS time series. The comparisons were applied to the daily SD data of three synoptic stations (Larnaca A/P, Pafos A/P and Athalassa) where parallel measurements of manual and automatic instruments are carried out during the periods 2009–2012 and 2012–2015. The CSD3 measurements were obtained from two automatic weather stations (AWSs) which are close to the synoptic station of Larnaca A/P. The comparisons referred to the daily and monthly sums of sunshine duration, as well as to their statistical distributions and their relationships. The daily differences in the pairs of sunshine recorders installed at the same location are mostly within the range of −1.0 to +1.0 h. At Larnaca, in the period 2009–2012, the pyranometric method’s (Gl) values were higher than the CS in the summer months. Pafos and Athalassa showed higher values of CS compared to Gl and the pyrheliometric method (Pr), respectively, almost throughout the year. Generally, the annual average daily differences between the different pairs range between 0.3 and 0.5 h. Regression equations were determined allowing the estimation of daily SD under different sky conditions. The coefficient of determination (R2) reached the values of 0.91 and 0.96 under ‘all sky’ conditions, and between 0.80 and 0.91 under ‘clear’ sky conditions at the three locations.

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Overen, Ochuko Kelvin, Edson Leroy Meyer, and Golden Makaka. "Indoor Daylighting and Thermal Response of a Passive Solar Building to Selective Components of Solar Radiation." Buildings 11, no. 1 (January 19, 2021): 34. http://dx.doi.org/10.3390/buildings11010034.

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Solar radiation provides the most significant natural energy in buildings for space heating and daylighting. Due to atmospheric interference, solar radiation received at the Earth’s surface consists of direct beam and diffuse radiation, where diffuse can be further broken down into longwave and visible radiation. Although each of these components co-occurs, their influence on the indoor visual and thermal conditions of a building differ. This study aims to analyze the influence of the various components of solar radiation on the indoor thermal and daylighting of a passive solar building. Thus, a pyrheliometer, pyranometer, shaded-pyranometer, and pyrgeometer mounted on a SOLYS 2 (Kipp & Zonen, Delft, Netherlands) dual Axis sun tracker, were used to monitor direct, global horizontal, diffuse and downward longwave radiation, respectively. The seasonal indoor air temperature and relative humidity were measured using an HMP 60 temperature relative humidity probe. A Li-210R photometric sensor was used to monitor the indoor illuminance. The summer and winter indoor air temperature, as well as relative humidity, were found to be influenced by diffuse horizontal and global horizontal irradiance, respectively. In summer, the indoor air temperature response to diffuse horizontal irradiance was 0.7 °C/ħW/m2 and 1.1 °C/ħW/m2 to global horizontal irradiance in winter, where ħ is 99.9 W/m2. The indoor daylighting which was found to be above the minimum office visual task recommendation in most countries, but within the useful daylight illuminance range was dominated by direct normal irradiance. A response of 260 lux/ħW/m2 was observed. The findings of the study support the strategic locating of the windows in passive solar design. However, the results show that north-facing clerestory windows without shading device could lead to visual discomfort.

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Eerme, K., U. Veismann, and S. Lätt. "Proxy-based reconstruction of erythemal UV doses over Estonia for 1955–2004." Annales Geophysicae 24, no. 7 (August 9, 2006): 1767–82. http://dx.doi.org/10.5194/angeo-24-1767-2006.

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Abstract. A proxy-based reconstruction of the erythemally-weighted UV doses for 1955-2004 has been performed for the Tartu-Tõravere Meteorological Station (58°16' N, 26°28' E, 70 m a.s.l.) site. The pyrheliometer-measured daily sum of direct irradiance on partly cloudy and clear days, and the pyranometer-measured daily sum of global irradiance on overcast days were used as the cloudiness influence related proxies. The TOMS ozone data have been used for detecting the daily deviations from the climatic value (averaged annual cycle). In 1998–2004, the biases between the measured and reconstructed daily doses in 55.5% of the cases were within ±10% and in 83.5% of the cases within ±20%, on average. In the summer half-year these amounts were 62% and 88%, respectively. In most years the results for longer intervals did not differ significantly, if no correction was made for the daily deviations of total ozone from its climatic value. The annual and summer half-yearly erythemal doses (contributing, on average, 89% of the annual value) agreed within ±2%, except for the years after major volcanic eruptions and one extremely fine weather year (2002). Using the daily relative sunshine duration as a proxy without detailed correction for atmospheric turbidity results in biases of 2–4% in the summer half-yearly dose in the years after major volcanic eruptions and a few other years of high atmospheric turbidity. The year-to-year variations of the summer half-yearly erythemal dose in 1955–2004 were found to be within 92–111% relative to their average value. Exclusion of eight extreme years reduces this range for the remaining to 95–105.5%. Due to the quasi-periodic alternation of wet and dry periods, the interval of cloudy summers 1976–1993 regularly manifests summer half-yearly erythemal dose values lower than the 1955–2004 average. Since 1996/1997 midwinters have been darker than on average.

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Cheng, S. X., H. P. Hu, and L. Chen. "Two simple and novel pyrheliometers." Solar Energy 61, no. 3 (September 1997): 203–10. http://dx.doi.org/10.1016/s0038-092x(97)00052-2.

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Foukal, P. V., C. C. Hoyt, and P. J. Miller. "Cryogenic Radiometers for Remote Sensing and Pyrheliometry." Metrologia 28, no. 3 (January 1, 1991): 255–59. http://dx.doi.org/10.1088/0026-1394/28/3/030.

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Räisänen, Petri, and Anders V. Lindfors. "On the Computation of Apparent Direct Solar Radiation." Journal of the Atmospheric Sciences 76, no. 9 (August 23, 2019): 2761–80. http://dx.doi.org/10.1175/jas-d-19-0030.1.

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Abstract Near-forward-scattered radiation coming from the vicinity of the sun’s direction impacts the interpretation of measurements of direct solar radiation by pyrheliometers and sun photometers, and it is also relevant for concentrating solar technology applications. Here, a Monte Carlo radiative transfer model is employed to study the apparent direct solar transmittance t(α), that is, the transmittance measured by an instrument that receives the radiation within a half-field-of-view (half-FOV) angle α from the center of the solar disk, for various ice cloud, water cloud, and aerosol cases. The contribution of scattered radiation to t(α) increases with increasing particle size, and it also depends strongly on ice crystal morphology. The Monte Carlo calculations are compared with a simple approach, in which t(α) is estimated through Beer’s law, using a scaled optical depth that excludes the part of the phase function corresponding to scattering angles smaller than α. Overall, this optical depth scaling approach works very well, although with some degradation of the performance for ice clouds for very small half-FOV angles (α < 0.5°–1°), and in optically thick cases. The errors can be reduced by fine-tuning the optical depth scaling factors based on the Monte Carlo results. Parameterizations are provided for computing the optical depth scaling factors for water clouds, ice clouds, aerosols, and for completeness, Rayleigh scattering to allow for a simple calculation of t(α). It is also shown that the optical depth scaling used in delta-two-stream approximations is inappropriate for simulating the direct solar radiation received by pyrheliometers.

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WIDMALM, SVEN. "QUANTIFYING SUNSHINE: KNUT ANGSTROM AND THE STANDARDISATION OF PYRHELIOMETRY¹." Nuncius 17, no. 2 (January 1, 2002): 653–71. http://dx.doi.org/10.1163/221058702x00166.

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Zahid, Muhammad Aleem, Ganesh T. Chavan, Young Hyun Cho, and Junsin Yi. "Optimal Tilt Angle For Getting Maximum Energy Produced By Pv Panel By Utilizing Clear Sky And Array Performance Models." Light & Engineering, no. 05-2020 (October 2020): 61–67. http://dx.doi.org/10.33383/2020-011.

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In this paper, we analysed and implement clear sky and array performance models to achieve maximum electrical energy produced from the photovoltaic (PV) panel. The selected models just not only include location dependent parameters but also include environmental factors such as Linke Turbidity (include aerosols, absorption due to assorted gases, Rayleigh scattering), cloud cover, albedo, perceptible water vapour. 250 W PV panel was used as a reference to check the output electrical energy in a given location by inputting the latitude and longitude of a location. It is concluded that 27° facing south is the optimized tilt angle for every locations having latitude at north direction and longitude at east direction. By taking the example of location Nagpur India (21.14° N, 79.08° E), a difference of only 0.35 % is reported when comparing the computed electrical energy with actual electrical energy that have been acquired by using pyranometers, pyrheliometers and illuminance meters installed by the National Renewable Energy Laboratory (NREL). So, a good approximation of electrical energy can be computed by combining clear sky and array performance models.

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VASHISTHA, R. D., R. MADAN, and S. K. SRIVASTAV. "Spectral (direct) solar irradiance at Pune." MAUSAM 49, no. 4 (December 16, 2021): 487–92. http://dx.doi.org/10.54302/mausam.v49i4.3660.

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Direct Solar Irradiation (DSI) measurements are made with pyrheliometers. When used with selected filters, the spectral distribution can be worked out. Measurements at Pune indicate that large scale attenuation takes place in blue-green region of solar spectrum likely due to aerosol particles injected by industrial advancement over the region. consequent rapid urbanisation and resultant changed land-use patterns. Values show evidences on the role played by moisture field on the transmission characteristics of the Pune skies. The afternoon irradiances are seen to be generally higher than the forenoon values. However, IR and yellow-orange wavelengths have higher irradiances in the forenoons during the pre-monsoon months and occasionally even in March. Over a year 774 Wm-2 of irradiance can be expected on any cloudless occasion around noon time, the individual spectral values vary depending on the actual sky and atmospheric conditions. From the comparative study of the irradiances in the different spectral regions, inferences could be drawn on the changes that take place in the size distribution of aerosol particles during a day.

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Nouri, Bijan, Stefan Wilbert, Pascal Kuhn, Natalie Hanrieder, Marion Schroedter-Homscheidt, Andreas Kazantzidis, Luis Zarzalejo, et al. "Real-Time Uncertainty Specification of All Sky Imager Derived Irradiance Nowcasts." Remote Sensing 11, no. 9 (May 5, 2019): 1059. http://dx.doi.org/10.3390/rs11091059.

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The incoming downward shortwave solar irradiance is harvested to an increasing extent by solar power plants. However, the variable nature of this energy source poses an operational challenge for solar power plants and electrical grids. Intra hour solar irradiance nowcasts with a high temporal and spatial resolution could be used to tackle this challenge. All sky imager (ASI) based nowcasting systems fulfill the requirements in terms of temporal and spatial resolution. However, ASI nowcasts can only be used if the required accuracies for applications in solar power plants and electrical grids are fulfilled. Scalar error metrics, such as mean absolute deviation, root mean square deviation, and skill score are commonly used to estimate the accuracy of nowcasting systems. However, these overall error metrics represented by a single number per metric are neither suitable to determine the real time accuracy of a nowcasting system in the actual weather situation, nor suitable to describe any spatially resolved nowcast accuracy. The performance of ASI-based nowcasting systems is strongly related to the prevailing weather conditions. Depending on weather conditions, large discrepancies between the overall and current system uncertainties are conceivable. Furthermore, the nowcast accuracy varies strongly within the irradiance map as higher errors may occur at transient zones close to cloud shadow edges. In this paper, we present a novel approach for the spatially resolved real-time uncertainty specification of ASI-based nowcasting systems. The current irradiance conditions are classified in one of eight distinct temporal direct normal irradiance (DNI) variability classes. For each class and lead-time, an upper and lower uncertainty value is derived from historical data, which describes a coverage probability of 68.3%. This database of uncertainty values is based on deviations of the irradiance maps, compared to three reference pyrheliometers in Tabernas, Andalucia over two years (2016 and 2017). Increased uncertainties due to transient effects are considered by detecting transient zones close to cloud shadow edges within the DNI map. The width of the transient zones is estimated by the current average cloud height, cloud speed, lead-time, and Sun position. The final spatially resolved uncertainties are validated with three reference pyrheliometers, using a data set consisting of the entire year 2018. Furthermore, we developed a procedure based on the DNI temporal variability classes to estimate the expected average uncertainties of the nowcasting system at any geographical location. The novel method can also be applied for global tilted or horizontal irradiance and is assumed to improve the applicability of the ASI nowcasts.

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MANI, ANNA, and OOMMEN CHACKO. "Measurements of Solar Radiation and Atmospheric Turbidity with Angstrom Pyrheliometers at Poona and Delhi during the I.G. Y." MAUSAM 14, no. 3 (March 4, 2022): 270–82. http://dx.doi.org/10.54302/mausam.v14i3.4862.

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Marzo, Aitor, Jesús Ballestrín, Joaquín Alonso-Montesinos, Pablo Ferrada, Jesús Polo, Gabriel López, and Javier Barbero. "Field Quality Control of Spectral Solar Irradiance Measurements by Comparison with Broadband Measurements." Sustainability 13, no. 19 (September 24, 2021): 10585. http://dx.doi.org/10.3390/su131910585.

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Measurement of solar spectral irradiance is required in an increasingly wide variety of technical applications, such as atmospheric studies, health, and solar energy, among others. The solar spectral irradiance at ground level has a strong dependence on many atmospheric parameters. In addition, spectroradiometer optics and detectors have high sensitivity. Because of this, it is necessary to compare with a reference instrumentation or light source to verify the quality of measurements. A simple and realistic test for validating solar spectral irradiance measurements is presented in this study. This methodology is applicable for a specific spectral range inside the broadband range from 280 to 4000 nm under cloudless sky conditions. The method compares solar spectral irradiance measurements with both predictions of clear-sky solar spectral irradiance and measurements of broadband instruments such as pyrheliometers. For the spectral estimation, a free atmospheric transmittance simulation code with the air mass calculation as the mean parameter was used. The spectral direct normal irradiance (Gbλ) measurements of two different spectroradiometers were tested at Plataforma Solar de Almería, Spain. The results are presented in this article. Although only Gbλ measurements were considered in this study, the same methodology can be applied to the other solar irradiance components.

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Foukal, Peter. "Solar Irradiance Variability and Luminosity Changes." Highlights of Astronomy 10 (1995): 294–95. http://dx.doi.org/10.1017/s1539299600011242.

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This review presents a discussion of radiometrie measurements of solar total irradiance variation, ΔS, on time scales of days, to the 15-year extent of present measurements. It does not cover variations in spectral irradiance, particularly the relatively large solar UV and EUV flux variations of great importance in studies of trends in stratospheric ozone, and of upper atmospheric heating variations.Analysis of the pyrheliometry of ΔS carried out from the Solar Maximum Mission, Nimbus-7 and ERB S satellites has shown that a) the sun brightens by 0.05 - 0.1% around activity maximum and; b) it dims by up to approximately 0.2% when large sunspot groups cross the disc. Empirical models of ΔS based on areas and photometric contrasts of sunspots, and on proxies of facular area, are remarkably successful in matching the observed record of ΔS, on time scales between days and the full 15- year record available since 1978. These models indicate that the opposite contributions of sunspots and faculae in active regions roughly balance over time scales of years, and the net solar brightening observed around peak activity is caused by increased emission from the photospheric magnetic network.

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DÖÖRRIES, MATTHIAS. "In the public eye: Volcanology and climate change studies in the 20th century." Historical Studies in the Physical and Biological Sciences 37, no. 1 (September 1, 2006): 87–125. http://dx.doi.org/10.1525/hsps.2006.37.1.87.

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ABSTRACT Three factors furthered the emergence of the field of volcanism and climate change in the 20th century: trigger events in the form of major volcanic eruptions, which attracted scientific and public attention (Katmai [1912], Agung [1963], Mount St. Helens [1980], El Chichóón [1982], Pinatubo [1991]); the availability of long-term global data obtained by instruments including pyrheliometers, sondes, computers, and satellites, which allowed generalizations and theoretical considerations; and major scientific and public debates that assigned an important place to the theme. No one of these factors alone would have been sufficient; the new object of research emerged only from a specific but not necessarily simultaneous combination of arbitrary events in nature, standardized measurements of global reach, and public demand. The latter comprised many aspects, beginning with the debate around the cause of the ice ages, mutating into an environmental discussion of man-made climate change covering a spectrum of apocalyptic scenarios that pointed up the fragility of human existence on earth, including the possible impact of atmospheric H-bomb tests during the 1950s and 1960s, the environmental and human consequences of a nuclear war between the USSR and the United States, and anthropogenic climate change. Existing historical representations of the research field have so far been written exclusively by scientists themselves. This paper critically examines these accounts while placing the research on the field of volcanism and climate change within its larger social and political history.

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Elias, Thierry, Nicolas Ferlay, Gabriel Chesnoiu, Isabelle Chiapello, and Mustapha Moulana. "Regional validation of the solar irradiance tool SolaRes in clear-sky conditions, with a focus on the aerosol module." Atmospheric Measurement Techniques 17, no. 13 (July 8, 2024): 4041–63. http://dx.doi.org/10.5194/amt-17-4041-2024.

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Abstract. The Solar Resource estimate (SolaRes) tool based on the Speed-up Monte Carlo Advanced Radiative Transfer code using GPU (SMART-G) has the ambition to fulfil both research and industrial applications by providing accurate, precise, and high-time-resolution simulations of the solar resource. We investigate the capacity of SolaRes to reproduce the radiation field, relying on 2 years of ground-based measurements by pyrheliometers and pyranometers acquired in northern France (Lille and Palaiseau). Our main objective is to provide, as a first step in clear-sky conditions, a thorough regional validation of SolaRes, allowing us to investigate aerosol impacts on solar resource. We perform comparisons between SolaRes-simulated and clear-sky-measured global horizontal irradiance (GHI), direct normal irradiance (DNI), diffuse horizontal irradiance (DifHI), and global and diffuse irradiance on a tilted plane (GTI, DifTI), and we even consider the circumsolar contributions. Using spectral aerosol optical thickness (AOT) data sets as input, which are delivered by the AErosol RObotic NETwork (AERONET) and the Copernicus Atmosphere Monitoring Service (CAMS), we examine the influence of aerosol input data sets in SolaRes on the comparison scores. Two aerosol models are mixed to compute aerosol optical properties. We also perform a sensitivity study on the aerosol parametrisation and investigate the influence of applying more or less strict cloud-screening methods to derive ground-based proof data sets of clear-sky moments. SolaRes is validated with the (relative) root mean square difference (RMSD) in GHI as low as 1 % and a negligible mean bias difference (MBD). The impact of the cloud-screening method in GHI is 0.5 % of RMSD and 0.3 % of MBD. SolaRes also estimates the circumsolar contribution, which improves MBD in DNI and DifHI by 1 % and 4 %, respectively, and RMSD by ∼ 0.5 %. MBD in DNI is around −1 % and RMSD around 2 %, and MBD in DifHI is 2 % and RMSD around 9 %. RMSD and MBD in both DNI and DifHI are larger than in GHI because they are more sensitive to the aerosol and surface properties. DifTI measured on a vertical plane facing south is simulated by SolaRes with an RMSD of 8 %, comparable to that obtained for DifHI. Our results suggest a strong influence of reflection by not only ground surface but also surrounding buildings. The sensitivity studies on the aerosol parameterisation show that the spectral AOT contains enough information for high performance in DNI simulations, with low influence of the choice of the aerosol models on the RMSD. However, choosing a model with smaller aerosol single scattering albedo significantly decreases SolaRes DifHI and GHI. The best combination in Lille and Palaiseau consists of continental clean mixed with desert dust. Also, complementary information on angular scattering and aerosol absorption provided by the AERONET-inverted model further improves simulated clear-sky GHI by reducing RMSD by ∼ 0.5 % and MBD by ∼ 0.8 %. Eventually, the choice of the data source has a significant influence. Indeed, using CAMS AOT instead of AERONET AOT increases the RMSD in GHI by ∼ 1 % and MBD by ∼ 0.4 % and RMSD in DNI by 5 %. The RMSD in GHI remains slightly smaller than state-of-the-art methods.

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Gnos, Michael, Brenton Greska, and Anjaneyulu Krothapalli. "On the Development of a Low Cost Pyrheliometer." Journal of Solar Energy Engineering 133, no. 3 (August 1, 2011). http://dx.doi.org/10.1115/1.4004266.

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A low cost pyrheliometer, based on a thermoelectric sensor, was developed at the Energy and Sustainability Center at the Florida State University. In addition, an inexpensive double-axis tracking device, capable of autonomous operation, enables the pyrheliometer to operate as a stand-alone system. Widely available off-the-shelf components were used and compromises in accuracy and time responsiveness were made in order to keep the cost low. The obtained data was compared with an Eppley Normal Incidence Pyrheliometer (NIP) using model ST-1 solar tracker. Steady state values of irradiance were measured with an accuracy better than ±2%. Transient measurements are time delayed by a thermal lag of about 2 min, which leads to a high error for instantaneous measured values. However, the integrated irradiance over the course of any given day yields irradiation values with accuracy better than ±2%, even on days when the sun and clouds quickly alternate. Based on a manufacturing cost analysis, the prototype pyrheliometer system is anticipated to cost an order of magnitude less than commercially available products if mass-produced.

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Røed, Ellen Johanne. "Skyvelære (While Attempting to Balance)." Nordic Journal of Art and Research 2, no. 2 (December 17, 2013). http://dx.doi.org/10.7577/information.v2i2.738.

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The video Skyvelære (While Attempting to Balance) portrays the 11th International Pyrheliometer Comparison Event (IPC-XI). Here, metrologists representing 45 different countries, accomplished the meticulous calibration of their Pyrheliometers, an instrument for measuring the energy emitted form the sun. Realized by artist Ellen Røed as part of her fellowship in artistic research at Bergen National Academy of Art and Design, it constitutes a reflection on the production of knowledge. Composed of the words sliding and knowing, the norwegian term Skyvelære means caliper, a device which, by means of a set edge and a variable slide operated by the thumb, can be used to measure distance and depth in great detail. In the video, the production and use of units and set reference points are presented as a social project in which people relate to the world collectively. The video was part of the final result of Røeds fellowship project that was presented as a solo exhibition in 2013. Here, the video was presented as a projection with surround sound. In this number of In Formation the video is presented as an individual piece of video art, accompagnied with a text.

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Bi, Ziqiang, Guanying Chu, Xinyu Pan, Jichong Guo, Minming Gu, and Jianmin Ban. "A solar irradiance estimation technique via curve fitting based on dual-mode Jaya optimization." Frontiers in Energy Research 11 (June 8, 2023). http://dx.doi.org/10.3389/fenrg.2023.1173739.

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Solar irradiance is a crucial environmental parameter for optimal control of photovoltaic (PV) systems. However, precise measurements of the solar irradiance are difficult since the irradiation sensors (i.e., pyranometer or pyrheliometer) are expensive and hard to calibrate. This paper proposes a cost-effective and accurate method for estimating the solar irradiance with a PV module via curve fitting. A dual-mode Jaya (DM-Jaya) optimization algorithm is introduced to extract the real-time value of solar irradiance from the measured PV characteristics data by using two search strategies. The step sizes of a random walk are taken from even and Lévy distribution distributions in different searching phases. Compared with the traditional irradiance sensors, the proposed estimator does not require additional circuit and obtains relatively lower error rates. A comparative study of seven population-based optimization algorithms for the optimal design of the estimator is presented. These algorithms include particle swarm optimization (PSO), cuckoo search (CS), Jaya, simulated annealing (SA), genetic algorithm (GA), supply-demand-based optimization (SDO), and the proposed DM-Jaya algorithm. Simulations and experimental results reveal that DM-Jaya outperforms the other optimization algorithms in terms of the estimation speed and accuracy.

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BALENZATEGUI, Jose Lorenzo, javier de Lucas, José Cuenca, Ana Gonzalez Leiton, María Molero, Fernando Fabero, José Pedro Silva, et al. "Characterization of absolute cavity radiometers for traceability to SI of solar irradiance." Measurement Science and Technology, July 27, 2022. http://dx.doi.org/10.1088/1361-6501/ac849d.

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Abstract Solar-type Cavity Radiometers are instruments of the highest metrological level for measuring solar Direct Normal Irradiance. To ensure their traceability and performance, they are periodically compared to the World Group of Standards, which realises the World Radiometric Reference (WRR), in the International Pyrheliometer Comparisons (IPC). Additionally, they can be characterized in an absolute way, with direct traceability to SI units and with their measurement uncertainty calculated. This paper describes the different techniques and procedures applied for the characterization and calibration of solar cavity radiometers, with the main results obtained to date in the case of an Automatic Hickey-Frieden (AHF) radiometer. Voltmeters, resistors, temperature sensors and the area of the precision apertures have been calibrated, while the effective absorptance, temperature coefficients, optical scattering and non-equivalence factor have been evaluated. The temperature dependence of the electrical current in the cavity heater has also been analysed. The resulting corrections obtained for the AHF by characterization are compatible with the WRR factors obtained by this instrument in the past IPCs. An uncertainty of 0.42 % (k = 1) has been obtained, and this paper discusses further improvements that may be able to reduce this figure to the desired expanded uncertainty of U = 0.1 % (k = 2).

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Love, N. D., R. N. Parthasarathy, and S. R. Gollahalli. "Rapid Characterization of Radiation and Pollutant Emissions of Biodiesel and Hydrocarbon Liquid Fuels." Journal of Energy Resources Technology 131, no. 1 (February 6, 2009). http://dx.doi.org/10.1115/1.3068345.

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As a result of decreasing petroleum supplies, new fuel sources, such as transesterified biofeedstock based oils and their blends with petroleum diesel fuels, have emerged with potential to partially replace conventional diesel and gasoline fuels. Although these fuels have shown some promising results in engine studies, their basic combustion properties have not been well documented. Also, research is underway to develop new fuels from other sources or by altering their molecular structure to be fungible with conventional fuels. Thus, there is a need for tests to characterize the combustion and emission properties of these new liquids, which are available only in small quantities at the research and development stage. This paper deals with a technique that meets those goals. The fuel was prevaporized and mixed with air and burnt in a tubular burner (9.5 mm inner diameter) at atmospheric pressure under laminar conditions. A pilot methane/air flame was used as the ignition source. The test conditions were so chosen that the measured properties could be attributed primarily to the fuel chemical structure. Several liquid fuels were tested, including commercially available petroleum-based No. 2 diesel fuel, canola methyl ester (CME B100) biodiesel, kerosene, methanol, toluene, and selected alkanes. The radiative heat flux from the flames was measured using a wide-angle pyrheliometer; the emissions from the flames were sampled to measure the concentration of CO, CO2, and NO. The measured radiant heat fraction values and the emission indices of NO and CO of both petroleum-derived and biofuels agreed well with those found in literature; thus, the feasibility of this method to rapidly characterize the combustion and emission properties of new liquids, such as biofuels, is demonstrated.

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Jumrusprasert, Pattanapong. "A Conversion Efficiency Determination of High Efficiency Solar Cells with Parabolic Dish Concentrating System." Current Alternative Energy 04 (August 18, 2020). http://dx.doi.org/10.2174/2405463104999200818092254.

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Aims: Field test for the conversion efficiency determination of high concentrating solar cells with parabolic dish concentrating system in a tropical location. Background: Typical solar cell system using in a tropical location is a fixed panel via commercial grade mono crystalline, poly crystalline or amorphous solar panels. They have low conversion efficiency so they need wide area to enhance the electrical energy. The consequence is low yielding in terms of economics and unpopular used in urban zone. Objective: To test for the conversion efficiency determination of high concentrating solar cells with parabolic dish concentrating system in a tropical location. Method: The research was conducted at the top of Nakhon Ratchasima Rajabhat University(NRRU) Science Center Building, Nakhon Ratchasima, Thailand. The four multi junction solar cells were connected together to receive the reflecting concentrated sunlight from the parabolic dish. I also determined the conversion efficiency of the 160 watts peak mono crystalline solar cell panel for a comparing purpose. Multi junction solar cells with parabolic dish concentrating and cooling systems, solar cell panel, pyrheliometer, pyranometer and light sensor were set up on the dual axes sun tracker. Data were gathered every 5 minutes all day from January 2018 to February 2019 for all 3 seasons via the automatic data logging system. Result: The results had presented that the average conversion efficiency of high concentrating solar cell module with parabolic dish concentrating system for 100x and of the 160 watts peak mono crystalline solar cell panel were 15.18% and 9.46% respectively, with the percentage difference of 56.45%. While, the average output powers per unit area per year of multi junction solar cells with concentrating system and mono crystalline solar cell panel were 98,544.92watt/m2 and 664.37watt/m2 respectively, with the ratio of 148.33. Conclusion: It is clearly seen that, in terms of conversion efficiency and output power per unit area per year, the multi junction solar cells with parabolic dish concentrating system has more advantage than the typical mono crystalline solar cell panel. Other: Especially for economical aspect, the utilization of parabolic dish concentrating system with MJ solar cells can reduce the land investment cost and also encourage of solar cell utilization not only in rural but also in urban for the tropical climate countries.

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Исазаде, Намиг. "УСОВЕРШЕСТВЕННАЯ МЕТОДИКА ДЛЯ ИЗМЕРЕНИЯ ПРЯМОЙ НОРМАЛЬНОЙ СОЛНЕЧНОЙ РАДИАЦИИ." Caucasus-Economic and Social Analysis Journal of Southern Caucasus, July 5, 2019, 111. http://dx.doi.org/10.36962/32052919111.

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In the article the new method for calibration of pyrheliometers on direct normal solar radiation is suggested. The proposed method provides for non-dependence of the calibration result on optical thickness of pure atmosphere integrated on whole spectrum, which makes it possible to increase the accuracy of measurements.

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Russell, P. B. "Sunlight transmission through desert dust and marine aerosols: Diffuse light corrections to Sun photometry and pyrheliometry." Journal of Geophysical Research 109, no. D8 (2004). http://dx.doi.org/10.1029/2003jd004292.

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Journal articles on the topic 'Pyrheliometer'

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