Measurements of sunshine duration by automatic sensors and their effects on the homogeneity of long-term series in the Czech Republic

• Published in: Climate research 2019-01, Vol.78 (1), p.83-101
• Main Authors: Valík, Adam, Brázdil, Rudolf, Zahradníček, Pavel, Tolasz, Radim, Možný, Martin, Řezníčková, Ladislava
• Format: Article
• Language: English
• ISSN: 0936-577X; 1616-1572
• DOI: 10.3354/CR01564

For many decades, meteorological stations in the Czech Republic used the Campbell- Stokes (CS) sunshine recorder to measure sunshine duration. However, automatic devices have progressively replaced it since the mid-1990s, first with the Vaisala DSU12 sensor and then with the SD4, SD5 and SD6 sensors produced by Meteoservis. The technical specifications and modes of function of these instruments differ from those of their predecessors and therefore integration of their results into standard sunshine duration series may give rise to significant break-points. In this contribution, we used statistics to analyse differences in sunshine duration totals derived from measurements taken by the CS sunshine recorder and those employing automatic sensors at daily, monthly and annual levels from meteorological stations located at Doksany, Churáňov, Kocelovice, Kostelní Myslová and Prague-Karlov in the Czech Republic. These differences were also evaluated from the point of view of daily cloudiness. Finally, series combining measurements by the CS recorder with those from automatic sensors and series measured by only the CS sunshine recorder were created, homogenised and analysed in terms of long-term fluctuations and annual variations.