GSB 7.1 Standardlösung

Global Climatology of Sunny Days based on SARAH and CLARA

The CM SAF extended its climatology of sunny days to the global scale. Basis are the CM SAF datasets SARAH and CLARA, which offer more than three decades of homogeneous, high resolved surface radiation data with high accuracy. SARAH stands for Surface Solar Radiation Data Set – Heliosat and is basing on data of the geostationary satellite Meteosat. CLARA stands for CM SAF cLouds, Albedo and Radiation dataset from AVHRR and provides global information based on data from polar orbiting satellites Both datasets are well suited for climatological analyses and are provided by the CM SAF free of charge (

The analysis of the so-called “sunny days” was started in cooperation with the Goethe University Frankfurt. A “sunny day” is defined by the fact that the mean daily global radiation corresponds to at least 80 % of the maximum possible solar insolation. A “sunny period” is characterized by five consecutive “sunny days”. Basing on SARAH and CLARA solar radiation data the possibility of each day of a year for being a “sunny day” or belonging to a “sunny period” was determined.

The results of this analysis are display via an interactive map on the CM SAF webpage ( Here the “sunny days” probability of global capitals and additional selected cities can be easily derived (see example in Fig. 1). Please get in touch with us if you would like to receive this information for other places:

Sunny Days Kigali Sunny Days Kigali Fig. 1 The possibility of sunny days for Kigali, Rwanda Source: CM SAF

SK / June2016

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