Homogenized Sunshine duration data for the Austrian domain

<p>The measurement of sunshine duration has experienced a number of changes since the operational observation by the national meteorological service ZAMG in Austria. With the automatization of the stations the Campbell-Stokes sunshine recorders were replaced by Haenni Solar 111 instruments and later partly with Meteoservice SD6. While no calibration was/is necessary for Campbell-Stokes and Meteoservice SD6 (using a threshold of 120W/m² as proposed by WMO), calibration was regularly done for the different versions of Haenni (in metadata the name of the company changed multiple times). First inquiries indicated that in the beginning they were calibrated to 200 W/m² and that later on - during one of the service cycles around the year 2000 - the threshold was changed to 50 W/m².</p><p>During the last years, six sun-tracking devices equipped with pyrheliometers have been installed in the Austrian network (ARAD station network - one BSRN site). By using those data the influence of the different sunshine recorder thresholds could be estimated and the meta information on the changes evaluated. For homogenization, ACMANT was used. The use of different choices for reference series have been analyzed and evaluated. Finally, additional to station data, satellite data from the EUMETSAT SARAH dataset from 1983 to 2015 was included in the final homogenization process of those time series.</p><p>The presentation will include information on the stations history, the correction and homogenisation methods explored and evaluated, information on the final homogenization procedure using ACMANT as well as the impact of the homogenization on the&#160; analyses of sunshine duration.</p>