IEEE JOURNAL OF SELECTED TOPICS IN APPLIED EARTH OBSERVATIONS AND REMOTE SENSING, VOL. 7, NO. 5, MAY 2014 1745 The HelioClim-1 Database of Daily Solar Radiation at Earth Surface: An Example of the Benefits of GEOSS Data-CORE Mireille Lefèvre, Philippe Blanc, Bella Espinar, Benoît Gschwind, Lionel Ménard, Thierry Ranchin, Senior Member, IEEE, Lucien Wald, Laurent Saboret, Claire Thomas, and Etienne Wey Abstract—The HelioClim-1 database contains daily values of the solar radiation reaching the ground. This GEOSS (Global Earth Observation System of Systems) Data Collection of Open Resources for Everyone (Data-CORE) covers Europe, Africa and the Atlantic Ocean, from 1985 to 2005. It is freely accessible at no cost through the SoDa Service (www.soda-is.com). Several assessments of the HelioClim-1 data against measurements made in meteorological networks reveal that the HelioClim-1 database offers a reliable and accurate knowledge of the solar radiation and its daily, seasonal and annual variations over recent years. The HelioClim-1 data may help in qualifying in situ measurements and may supplement them, thus offering 21 years of accurate daily means of surface solar irradiance. Several published works benefited from openness, availability and accuracy of the He- lioClim-1 database in various domains: oceanography, climate, energy production, life cycle analysis, agriculture, forestry, archi- tecture, health and air quality. This demonstration of the benefit of the HelioClim-1 database draws attention to resources open to everyone such as those labeled GEOSS Data-CORE. Index Terms—Africa, agro-meteorology, air quality, archi- tecture, climate, Europe, GEOSS, health, irradiance, meteosat, ocean, solar energy. I. INTRODUCTION T HE surface solar irradiance (SSI) is the power received from the sun over the whole spectrum on a horizontal sur- face at ground level per unit surface [1]. The SSI is an Essential Climate Variable (ECV) as established by the Global Climate Observing System in August 2010 [2]. Knowledge of the SSI and its geographical distribution is of prime importance for sev- eral domains where the SSI plays a major role such as weather, climate, biomass, or energy [3]. Manuscript received May 02, 2013; revised July 23, 2013; accepted September 24, 2013. Date of publication October 17, 2013; date of current version June 13, 2014. This work was supported by the European Union’s Fifth Framework Programme (FP5/1998-2002) under Grant Agreement no. IST-1999-12245 (SoDa project) and by the ADEME (French Agency for Energy) (grant no. 08 05 C 0049, 2008-2010). M. Lefèvre, P. Blanc, B. Espinar, B. Gschwind, L. Ménard, T. Ranchin, and L. Wald are with MINES ParisTech, Center Observation, Impacts, Energy, 06904 Sophia Antipolis cedex, France (e-mail: lucien.wald@ mines-paristech.fr). L. Saboret, C. Thomas, and E. Wey are with Transvalor Innovations, 06904 Sophia Antipolis cedex, France. Color versions of one or more of the figures in this paper are available online at http://ieeexplore.ieee.org. Digital Object Identifier 10.1109/JSTARS.2013.2283791 Accurate assessments of the SSI can now be drawn from satellite data and several studies demonstrate the superiority of the use of satellite data over interpolation methods applied to sparse measurements performed within a radiometric network [4], [5]. Stations measuring the SSI on the long-term are rare and satellites are an accurate way to supplement them [6]. Sev- eral databases have been developed that contain hourly or daily means of the SSI. The HelioClim-1 database, hereafter abbrevi- ated in HC-1, is one of them. In this paper, brief introductions to the HelioClim Project and the GEOSS (Global Earth Observation System of Systems) Data-CORE (Data Collection of Open Resources for Everyone) are followed by a description of the HC-1 database and how it has been constructed. The HC-1 database is available for ev- eryone and provides data of known quality. Several examples of use of HC-1 data in various domains have been found in scien- tific journals. These case studies are briefly mentioned to illus- trate the benefit of the HC-1 database in science. This paper aims at attracting attention to resources open to everyone such as the HC-1 database and at demonstrating through case studies how such freely supplied data on solar radiation support research, development and business in various domains. II. THE HELIOCLIM PROJECT The HelioClim Project is an ambitious initiative of MINES ParisTech launched in 1997 after preliminary works in the 1980s [7], [8] to increase knowledge on the SSI and to offer SSI values for any site, any instant over a large geographical area and long period of time, to a wide audience [3]. The project comprises several databases that cover Europe, Africa and the Atlantic Ocean. The HC-1 database offers daily means of the SSI for the period 1985–2005. It has been created from archives of images of the Meteosat First Generation. The Meteosat series of satellites are geostationary and pro- vide synoptic views of Europe, Africa and Atlantic Ocean for meteorological purposes. Initiated by the European Space Agency, the program is currently operated by Eumetsat, a European agency comprising the national weather offices. Images taken in the visible band (Fig. 1) and other bands clearly depict clouds and more generally the optical state of the atmosphere. Several operational programs are currently pro- cessing Meteosat images, or have processed them, in order to assess the SSI and create and update databases. 1939-1404 © 2013 IEEE. Translations and content mining are permitted for academic research only. Personal use is also permitted, but republication/ redistribution requires IEEE permission. See http://www.ieee.org/publications_standards/publications/rights/index.html for more information.