Quality assessment of HelioClim-3 versus ground stations - Generalities

Last update: Jan. 2016

    Introduction - BSRN - Belgium - Brazil INMET - Brazil INPE

Independant validation performed by P. Ineichen, University of Geneva - February 2016: Long term HelioClim-3 global, beam and diffuse irradiance validation

Please find in this page our validation results comparing to HelioClim-3 (versions 4 and 5) and in-situ measurements:
  • BSRN: 14 Baseline Surface Radiation Network (BSRN) stations spread in the Meteosat 2nd generation coverage, 1 min values
  • Belgium: 8 stations from the Belgian Royal Meteorological Institute (RMI), hourly values
  • Brazil INMET: 31 stations from the Instituto Nacional de Meteorologia (INMET), hourly values
  • Brazil INPE: 11 stations from the Instituto Nacional de Pesquisas Espaciais (INPE), 1 min values
  • Oman and UAE: 5 stations - poster , article coming soon
Access the HelioClim-3 data over Feb. 2004-2005 (for free)
Access the HelioClim-3 data over Feb. 2004-onwards until D-1 (for pay)

Validation protocol: http://www.soda-pro.com/help/general/validation-protocol

Statistic indices: http://www.soda-pro.com/help/general/statistics

Additional comments:

  • Diffused component measured with a pyranometer and a shadow band: If you need to handle the measurements of the Diffuse Horizontal component acquired by a pyranometer and a shadow-band, the values will likely be underestimated. This is due to the fact that the band is occulting a part of the sky and thus a part of diffuse that should be collected by the sensor.
    Here at MINES ParisTech/Transvalor, we decided to apply the correction of Muneer-Zhang (Muneer T, Zhang X. A new method for correcting shadow band diffuse irradiance data. J Sol Energy Eng 2002;124:34e43) which sligthly increase the values for the diffuse component.
  • Measurements with a pyrheliometer: the pyheliometers have a larger half opening angle than the satellite-based estimations (HelioClim-3, MACC-RAD...) which obeys by construction to the definition given by the community of the radiative transfer models where the sun is more punctual. This has a very limited influence in clear sky conditions, but in overcast conditions, the contribution of the circumsolar  irradiance to the pyrheliometer measurements may exceed 50% due to specific effects of clouds, especially that of cirrus clouds. No correction is presently brought to the HelioClim-3 or MACC-RAD outputs.