Since 1983 an automatic solar radiation network of 12 stations is operated by SMHI. At all 12 stations direct solar irradiance (Eppley NIP pyrheliometers) and global irradiance (Kipp & Zonen CMlO/CMl 1 pyranometers) are measured continuously. Together with general network information and uncertainty analyses, results of the radiation measurements during 1983 - 1998 are presented in this report.
The resulting quality controlled database consists of yearly, monthly, daily and hourly values of direct (normal) solar and global radiation together with the diffuse sky radiation and sunshine duration, SD. Ed has been calculated from the hourly values of Eh and EK. Observed air temperature (2-m), relative humidity, wind direction and wind speed are available in the hourly radiation database, as well.
Generally, the uncertainty of 6-minute and hourly values of direct and global radiation has been estimated to 3 % and 4 % (at 95 % confidence level), respectively. The precision of annual values has been estimated to 2 % for both quantities.
The solar radiation climate in Sweden varies a lot, both in time and space. The dominating factors influencing the solar radiation climate are the latitudinal location and the prevailing cloud conditions.