The annual cycle of the probability of sunny days is shown for capitals and selected cities worldwide (click on the marker next to the city to open a small version of the figure. This figure can be enlarged by clicking on the figure). For each selected city the likelihood that a certain day throughout the year is sunny (black line) is shown. For Europe and Africa also the likelihood for a 5-day sunny period (red line) is shown. The date with the highest probability for a sunny day / sunny period is also given. For most cities certain periods with higher / lower probabilities of a sunny day can be identified. Due to the climatological basis of this analysis, individual years will be different to the annual cycles shown here.
In this analysis, a day is defined as a sunny day if the daily surface solar radiation exceeds 80% of the clear-sky surface solar radiation; a 5-day sunny period is defined as five consecutive sunny days. With these definitions and based on more than 3 decades of daily surface solar radiation data the likelihood for a certain day being a sunny day and/or being part of a sunny period has been determined. Sunny period Europe - Filmloop
This analysis is based on the climatological CM SAF SARAH and CLARA * data sets; SARAH stands for Surface Solar Radiation Data Set - Heliosat, and CLARA stands for CM SAF cLouds, Albedo and Radiation dataset from AVHRR data. Both, SARAH and CLARA, are freely available data sets based on high-resolution satellite observations and provide information on the solar radiation at the ground at the daily and monthly time scales (also hourly for SARAH data). The analysis of daily surface solar radiation has been conducted in cooperation with the University of Frankfurt, Institute for Atmospheric and Environmental Sciences, as part of a Master Thesis. The results are available for Europe.
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*The analysis is based on the successor of CLARA-A1, which extends the time series of the data record and is based on improved algorithms. This data record is planned to become available to the users in the second half of 2016.