Surface Radiation Measurements at the Koldewey Ground Station (Arctica)

The pyranometers and pyrgeometers are ventilated with slightly preheated air to minimize hoar frost problems and zero offsets during cloudless and windless conditions. The instruments were maintained continuously several times per day throughout the year. After one year of operation they are re-calibrated at the German Weather Bureau according the World Radiometric Reference (WRR).

At AWI, the radiation measurements - averaged over 5 minutes - are archived together with the data from the mast measurements, daily upper air soundings and routine synoptic surface observations in a relational database (SYBASE). Additionally some derived quantities (Iqbal 1983) such as the solar elevation, extraterrestrial solar insolation, astronomical sunshine duration are available. In order to obtain daily averaged radiation data, each day was subdivided into eight 3-hourly intervals (0-3, 3-6, ..., 21-24 UTC).

For each 3-hourly interval an average was derived irrespective of the number of measurements. This procedure was chosen in order to minimize problems resulting from missing values. If one or more 3-hourly averages were missing, no daily average was calculated.

Data are accessible via Web network by means of the AWI-Home-Page, 'awi-bremerhaven.de', and can be obtained from AWI after prior consultation.