Derivation of Cloud Index from Geostationary Satellites and Application to the Production of Solar Irradiance and Daylight Illuminance Data

Abstract

SummaryWe investigate in the present paper the relationship between satellite count, global irradiance and other solar and illumination resource components, bringing a particular attention to low solar elevation situations (below 20 ) which are very important in northern latitudes. Our investigation is based on data from two geostationary satellites, METEO-SAT and GOES, backed by ground measurements in Switzerland and the northeastern USA.The study of different clear sky normalizations lead to the conclusion that a linear correlation between the global clearness index and the irradiance (like the heliosat method) would be inaccurate for low solar elevations, and therefore for high latitude regions. We developed a model that directly relates an elevation dependent clearness index to the could index. This methodology presents a definite advantage because it can be generalized to address the clearness index of other solar radiation components, besides global irradiance, such as direct irradiance, diffuse illuminance, etc.The correlations described in this paper were developed on the data from Geneva (in the frame of the EC program`S atellight'') and evaluated on two other independent data sets (Albany, USA and Lausanne, Switzerland). Their precisions, on a hourly basis, are respectively 30%, 40% and 60% for the global, diffuse and beam components) (90, 55 and 95 W/m 2 ). The use of independent data for the derivation and the validation of the models shows that those can be used in a wide range of locations, even if the applicability has to be assessed for very different climates.

Surface solar irradiance from SCIAMACHY measurements: algorithm and validation

“…Indeed, the evaluated RMSD values of FRESCO SSI versus BSRN data are in the same order of magnitude as those found from the comparison of SSI derived from Meteosat using Heliosat or Heliosat-like methods with ground-based measurements (e.g. Ineichen and Perez, 1999;Zelenka et al, 1999;Dagestad, 2004;Lorenz, 2007). This demonstrates the performance of the FRESCO SSI algorithm concerning its precision.…”

“…These data sets have been extensively validated against ground-based solar radiation measurements (Perez et al, 2001;Meyer et al, 2003;Rigollier et al, 2004). The relative standard deviation between hourly mean surface solar irradiances derived using the Heliosat algorithms and ground-based measurements is typically 20-25 % (Ineichen and Perez, 1999;Zelenka et al, 1999;Dagestad, 2004;Lorenz, 2007). It is now well established that the surface solar irradiances derived from satellite measurements can be more accurate than those found by interpolation using ground-based measurements which are more than 30 km apart (Perez et al, 1997;Zelenka et al, 1999).…”

Assured Solar Energy Hot-Spots over Indian Landmass Detected through Remote Sensing Observations from Geostationary Meteorological Satellite

“…The extraterrestrial solar radiation reaching the top of the atmosphere (Rs 0 ) was computed using standard astronomical formulae that require day number in a year, time in a day, latitude and longitude 15 . This is also termed as potential insolation.…”

Satellite-Based Actual Evapotranspiration over Drying Semiarid Terrain in West Africa

“…Newer methods are described, for example, in Stuhlmann et al (1989), Hammer et al (2003), Ineichen and Perez (1999), and Rigollier et al (2001). All of these methods relate the reflected sunlight measured by the Meteosat VIS channel covering the range of 0.45-1.0 m to the incoming solar radiation at the surface of the earth.…”