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Edson L Meyer - One of the best experts on this subject based on the ideXlab platform.
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development of energy model based on total Daily Irradiation and maximum ambient temperature
Renewable Energy, 2000Co-Authors: Edson L MeyerAbstract:To predict the energy produced by photovoltaic modules under certain meteorological conditions, an energy model can be used. Existing energy models need parameters that are not always available. In this study, an energy model based on regression analysis of total Daily Irradiation and maximum Daily ambient temperature is developed. This model is able to predict Daily module energy based on these two parameters only. The data used in this study were collected over a 15-month period at the University of Port Elizabeth (UPE), South Africa. The developed model was first compared to two existing energy models using data collected over the month of October 1998. Its validity was then evaluated over the entire 15-month period using seasonal regression coefficients. An application of the model to predict module energy output is illustrated by using data collected at the South African Weather Bureau (SAWB), Port Elizabeth (PE) station. The predicted energy is then compared to the energy measured at UPE. Results obtained show that the developed model is valid and a good predictor of module energy.
Lucien Wald - One of the best experts on this subject based on the ideXlab platform.
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Increasing the accuracy of HelioClim-1 using HelioClim-3
2017Co-Authors: B. Gschwind, Thierry Ranchin, Lucien WaldAbstract:The HelioClim project of MINES ParisTech aims at producing fields of surface solar downward Irradiation (SSI). To that purpose, images of the first generation of the Meteosat series were processed with the Heliosat-2 method to create and update the HelioClim-1 database containing Daily SSI for the period 1985-2005. The HelioClim-1 database (HC1v4) has been validated against measurements performed by pyranometers at ground stations and has been promoted to Data Collection of Open Resources for Everyone (Data-CORE) by the GEOSS (Global Earth Observation System of Systems). The GEOSS Data-CORE is a distributed pool of documented data sets with full, open and unrestricted access. Heliosat-2 was further adapted to processing of images from the second generation of the Meteosat satellites. Since 2004, Meteosat images are acquired at MINES ParisTech every 15 min and routinely processed to update the HelioClim-3 database containing 15 min SSI. Access to the HelioClim databases is given by the SoDa Service (www.soda-pro.com). It was found that HelioClim-3, and especially its version 5 HC3v5, is more accurate than HelioClim-1 when compared to ground measurements. Because HelioClim-1 is widely used, it is tempting to try to improve its accuracy by using HelioClim-3. This communication presents the methods that have been studied and the benefits of the adjusted HelioClim-1 when compared to ground measurements. The methodology is to adjust HC1v4 Daily Irradiation onto HC3v5 Daily Irradiation for the common period Feb 2004-2005 (23 months), then apply the adjustment onto the entire HC1v4 from 1985 to Jan 2004, and then concatenate bias-adjusted HC1 and HC3v5 to yield the time series from 1985 to 2005. The possible improvement in bias and other statistical indicators brought by each method was assessed by comparing the original HC1 and the bias-adjusted HC1 with measurements from ground stations. Six approaches have been investigated: addition of difference in means or modes, ratio of means or modes, affine transform and quantile mapping. Each approach may apply to the clearness indices KT as well, i.e. the HC1 KT is adjusted and then the adjusted Irradiation HC1 is computed by multiplying KT by the Daily Irradiation at the top of atmosphere. This makes a total of 12 methods that have been tested. Seventeen stations having archives of measurements of Daily SSI were used for validation. It was found that no method clearly surpasses the others. However, it was observed that the method ‘quantile mapping’ applied to KT (QM KT) exhibits much better results than the others for all indicators: standard deviation, root mean square error, correlation coefficient and median, except the bias. QM KT improves the bias in 12 stations over 17 (13 for clearness index) and exhibit a slight degradation of the bias in the remaining cases. The fusion of HC1 and HC3v5 is feasible in an easy way that can be turned into operation. In most cases, the adjusted HC1 performs better than HC1 when compared to qualified Daily Irradiation measured in meteorological networks.
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Comparison of several databases of downward solar Daily Irradiation data at ocean surface with PIRATA measurements
European geosciences union general assembly, 2017Co-Authors: Mélodie Trolliet, Lucien WaldAbstract:The solar radiation impinging at sea surface is an essential variable in climate system. There are several means to assess the Daily Irradiation at surface, such as pyranometers aboard ship or on buoys, meteorological re-analyses and satellite-derived databases. Among the latter, assessments made from the series of geostationary Meteosat satellites offer synoptic views of the tropical and equatorial Atlantic Ocean every 15 min with a spatial resolution of approximately 5 km. Such Meteosat-derived databases are fairly recent and the quality of the estimates of the Daily Irradiation must be established. Efforts have been made for the land masses and must be repeated for the Atlantic Ocean. The Prediction and Research Moored Array in the Tropical Atlantic (PIRATA) network of moorings in the Tropical Atlantic Ocean is considered as a reference for oceanographic data. It consists in 17 long-term Autonomous Temperature Line Acquisition System (ATLAS) buoys equipped with sensors to measure near-surface meteorological and subsurface oceanic parameters, including downward solar Irradiation. Corrected downward solar Daily Irradiation from PIRATA were downloaded from the NOAA web site and were compared to several databases: CAMS RAD, HelioClim-1, HelioClim-3 v4 and HelioClim-3 v5. CAMS-RAD, the CAMS radiation service, combines products of the Copernicus Atmosphere Monitoring Service (CAMS) on gaseous content and aerosols in the atmosphere together with cloud optical properties deduced every 15 min from Meteosat imagery to supply estimates of the solar Irradiation. Part of this service is the McClear clear sky model that provides estimates of the solar Irradiation that should be observed in cloud-free conditions. The second and third databases are HelioClim-1 and HelioClim-3 v4 that are derived from Meteosat images using the Heliosat-2 method and the ESRA clear sky model, based on the Linke turbidity factor. HelioClim-3 v5 is the fourth database and differs from v4 by the partial use of McClear and CAMS products. HelioClim-1 covers the period 1985-2005, while the others start in 2004 and are updated Daily. Deviations between PIRATA measurements and estimates were computed and summarized by usual statistics. Biases and root mean square errors differ from one database to the other. As a whole, the correlation coefficients are large, meaning that each database reproduces the day-to-day changes in Irradiation well. These good results will support the development of a satellite-derived database of Daily Irradiation created by MINES ParisTech within the HelioClim project. The size of the cells will be 0.25°. HelioClim-1 and HelioClim-3v5 will be combined yielding a period coverage of 32 years, from 1985 to 2016, thus allowing analyses of long term variability of downward shortwave solar radiation over the Atlantic Ocean.
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Validation of HelioClim-3 version 4, HelioClim-3 version 5 and MACC-RAD using 14 BSRN stations
2015Co-Authors: Claire Thomas, Lucien Wald, Etienne Wey, Philippe Blanc, Mireille LefèvreAbstract:This communication presents the results of a comparison of three satellite-derived databases covering Africa, Europe, Middle East and part of South America, against corresponding 15 min Irradiations of very high quality measured by fourteen Baseline Surface Radiation Network (BSRN) stations. The three databases are accessible via the SoDa Service website, and are the two latest versions of HelioClim-3: versions 4 (HC3v4) and 5 (HC3v5), and the MACC-RAD database. The comparison was performed for durations of 15 min, 1 h, 1 day and 1 month for both the global Irradiation received on a horizontal surface (GHI) and the direct Irradiation received on a plane normal to sun rays (DNI). It is found that the three satellite-derived radiation databases exhibit satisfactory performances. For most of the fourteen locations, HC3v5 surpasses HC3v4 and MACC-RAD, with a bias ranging from-4 to 5% for the GHI and for all tested duration. The correlation coefficient is large for all databases and most often greater than 0.92 for 15 min and 0.98 for Daily Irradiation for GHI. The RMSE is fairly constant for all locations for 15 min and is approximately 20 kWh m-2 –slightly greater for MACC-RAD.-For Daily Irradiation, it ranges between 300 and 400 kWh m-2 for HC3v5, 300 and 500 kWh m-2 for HC3v4, and 400 and 550 kWh m-2 for MACC-RAD. Bias for the DNI is larger in absolute values than for GHI for all databases:-12 to 10% for HC3v5. The correlation coefficient is most often greater than 0.68 for 15 min and 0.84 for Daily Irradiation. The RMSE for 15 min ranges between 46 and 60 kWh m-2 for HC3v5, 46 and 63 kWh m-2 for HC3v4, and 48 and 66 kWh m-2 for MACC-RAD. For Daily Irradiation, it ranges between 1100 and 1600 kWh m-2 for HC3v5, between 1300 and 1700 kWh m-2 for HC3v4, and between 1000 and 1850 kWh m-2 for MACC-RAD. The MACC-RAD resource show promises provided the model for cloud properties is improved.
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Improving HelioClim-3 estimates of surface solar irradiance using the McClear clear-sky model and recent advances in atmosphere composition
Atmospheric Measurement Techniques, 2014Co-Authors: B. Gschwind, Mireille Lefèvre, Lucien WaldAbstract:Abstract. The HelioClim-3 database (HC3v3) provides records of surface solar Irradiation every 15 min, estimated by processing images from the geostationary meteorological Meteosat satellites using climatological data sets of the atmospheric Linke turbidity factor. This technical note proposes a method to improve a posteriori HC3v3 by combining it with data records of the Irradiation under clear skies from the new McClear clear-sky model, whose inputs are the advanced global aerosol property forecasts and physically consistent total column content in water vapour and ozone produced by the MACC (Monitoring Atmosphere Composition and Climate) projects. The method is validated by comparison with a series of ground measurements for 15 min and 1 h for 6 stations and for Daily Irradiation for 23 stations. The correlation coefficient is large, greater than respectively 0.92, 0.94, and 0.97, for 15 min, 1 h and Daily Irradiation. The bias ranges from −4 to 4% of the mean observed Irradiation for most sites. The relative root mean square difference (RMSD) varies between 14 and 38% for 15 min, 12 and 33% for 1 h Irradiation, and 6 and 20% for Daily Irradiation. As a rule of thumb, the farther from the nadir of the Meteosat satellite located at latitude 0° and longitude 0°, and the greater the occurrence of fragmented cloud cover, the greater the relative RMSD. The method improves HC3v3 in most cases, and with no degradation in the others. A systematic correction of HC3v3 with McClear is recommended.
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Integration of Meteosat-derived data and digital terrain model into a GIS for local atlases of solar radiation
2004Co-Authors: Sylvain Cros, Lucien Wald, Rachid Chriqi, Michel Albuisson, A. Dahman Saidi, M. BennounaAbstract:Solar radiation at ground level is a necessary input for several applications as potential solar energy assessment, agronomic or meteorological related studies. Images from meteorological geostationnary satellite, once properly processed, can provide solar radiation maps. Several solar atlases with a wide geographical coverage have been built by this process. These maps are more accurate than those made from interpolations of ground measurements. Nevertheless, their spatial resolution - about 10 km over mid-latitude in the best cases - are not sufficient for taking into account spatial variability of the Irradiation due to the orographic effects in a local scale. Among these atlases, HelioClim is a GIS providing Daily Irradiation maps over Europe, Africa and Atlantic Ocean from 1985 up to now. It was developed from a processing on Meteosat images needing a digital terrain model (DTM) as input. HelioClim use the TerrainBase DTM, its spatial resolution is about 1 km. Irradiation maps produced by HelioClim have a spatial resolution of 10 km in our latitudes. In our work, we integrate a digital terrain model (DTM) of very high resolution (10 m) covering the Ouneine valley (Morocco) with HelioClim outputs into a GIS and we derive solar radiation maps. Spatial resolution of these maps is the same as the DTM. We built 12 maps of monthly mean of Daily global Irradiation for each month of a year. These monthly means have been computed from Daily Irradiation between 1997 and 2002. We made comparisons between these maps and ground measurements. We found a relative root mean square error (RMSE) of 7.5 % for July and 5 % for January. HelioClim using TerrainBase presents for monthly mean of Daily Irradiation a relative RMSE of 10 % for January and 13 % for July. Integration of HelioClim and a high resolution DTM into a GIS permits to produce accurate solar Irradiation maps. Spatial variability of terrain elevation is better taken into account. Such GIS are convenient tools for mapping solar Irradiation in mountainous area.
Beatriz Martínez - One of the best experts on this subject based on the ideXlab platform.
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Validation of Daily global solar Irradiation images from MSG over Spain
Renewable Energy, 2013Co-Authors: Alvaro Moreno, María Amparo Gilabert, Fernando Camacho, Beatriz MartínezAbstract:Daily Irradiation images over Spain – area that embraces a highly heterogeneous landscape, climatic conditions and relief – are calculated from the down-welling surface short-wave radiation flux (DSSF) product derived from the MSG SEVIRI images. Their analysis and validation is carried out using two different station networks along the year 2008. The first network covers the peninsular Spain and Balearic islands. A denser one, covering the Catalonian territory and including many stations located in rugged terrain, is found useful to assess the elevation correction to be applied to the images. The statistics from the validation using the first network shows a relative mean bias of about 1%, a relative mean absolute difference of 6%, and a mean absolute difference of 1.0MJm−2. The analysis of the second database shows that the elevation correction reduces the relative mean bias, for rugged terrains and for clear sky data, from 5% to 0.5%, whereas for the complete sampling the mean absolute difference of the derived Daily Irradiation images is 1.3MJm−2. A downscaling of the DSSF product is also carried out, and a methodology to obtain topographically-corrected Daily Irradiation images, based on merging the DSSF with a digital elevation model, is proposed. These images satisfactorily map the surface solar radiation at 1-km spatial resolution even in rugged terrains.
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mapping Daily global solar Irradiation over spain a comparative study of selected approaches
Solar Energy, 2011Co-Authors: Alvaro Moreno, María Amparo Gilabert, Beatriz MartínezAbstract:Abstract Three methods to estimate the Daily global solar Irradiation are compared: the Bristow–Campbell (BC), Artificial Neural Network (ANN) and Kernel Ridge Regression (KRR). BC is an empirical approach based on air maximum and minimum temperature. ANN and KRR are non-linear approaches that use temperature and precipitation data (which have been selected as the best combination of input data from a gamma test). The experimental dataset includes 4 years (2005–2008) of Daily Irradiation collected at 40 stations and temperature and precipitation data collected at 400 stations over Spain. Results show that the ANN method produces the best global solar Irradiation estimates, with a mean absolute error 2.33 MJ m −2 day −1 . Daily maps of solar Irradiation over Spain at 1-km spatial resolution are produced by applying the ANN method to temperature and precipitation maps generated from ordinary kriging.
L Martin - One of the best experts on this subject based on the ideXlab platform.
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analysis of different comparison parameters applied to solar radiation data from satellite and german radiometric stations
Solar Energy, 2009Co-Authors: Bella Espinar, Jesús Polo, Lourdes Ramirez, Anja Drews, Hans Georg Beyer, L F Zarzalejo, L MartinAbstract:Abstract In this paper new comparison parameters are defined for assessing statistical similarity between two data sets. The new parameters are based on the commonly used Kolmogorov–Smirnov test. They allow quantifying differences between the cumulative distribution functions of each data series. These parameters are applied to global horizontal Daily Irradiation values from pyranometric measurements and satellite data. The test data from 38 stations distributed throughout Germany cover the time from 1995 until 2003. The results affirm that the new parameters contribute valuable information to the comparison of data sets complementing those that are found with the mean bias and root mean squared differences.
Alvaro Moreno - One of the best experts on this subject based on the ideXlab platform.
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Validation of Daily global solar Irradiation images from MSG over Spain
Renewable Energy, 2013Co-Authors: Alvaro Moreno, María Amparo Gilabert, Fernando Camacho, Beatriz MartínezAbstract:Daily Irradiation images over Spain – area that embraces a highly heterogeneous landscape, climatic conditions and relief – are calculated from the down-welling surface short-wave radiation flux (DSSF) product derived from the MSG SEVIRI images. Their analysis and validation is carried out using two different station networks along the year 2008. The first network covers the peninsular Spain and Balearic islands. A denser one, covering the Catalonian territory and including many stations located in rugged terrain, is found useful to assess the elevation correction to be applied to the images. The statistics from the validation using the first network shows a relative mean bias of about 1%, a relative mean absolute difference of 6%, and a mean absolute difference of 1.0MJm−2. The analysis of the second database shows that the elevation correction reduces the relative mean bias, for rugged terrains and for clear sky data, from 5% to 0.5%, whereas for the complete sampling the mean absolute difference of the derived Daily Irradiation images is 1.3MJm−2. A downscaling of the DSSF product is also carried out, and a methodology to obtain topographically-corrected Daily Irradiation images, based on merging the DSSF with a digital elevation model, is proposed. These images satisfactorily map the surface solar radiation at 1-km spatial resolution even in rugged terrains.
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mapping Daily global solar Irradiation over spain a comparative study of selected approaches
Solar Energy, 2011Co-Authors: Alvaro Moreno, María Amparo Gilabert, Beatriz MartínezAbstract:Abstract Three methods to estimate the Daily global solar Irradiation are compared: the Bristow–Campbell (BC), Artificial Neural Network (ANN) and Kernel Ridge Regression (KRR). BC is an empirical approach based on air maximum and minimum temperature. ANN and KRR are non-linear approaches that use temperature and precipitation data (which have been selected as the best combination of input data from a gamma test). The experimental dataset includes 4 years (2005–2008) of Daily Irradiation collected at 40 stations and temperature and precipitation data collected at 400 stations over Spain. Results show that the ANN method produces the best global solar Irradiation estimates, with a mean absolute error 2.33 MJ m −2 day −1 . Daily maps of solar Irradiation over Spain at 1-km spatial resolution are produced by applying the ANN method to temperature and precipitation maps generated from ordinary kriging.