Dorota Matuszko

A comparison of sunshine duration records from the Campbell-Stokes sunshine recorder and CSD3 sunshine duration sensor

The purpose of this paper is to compare daily sunshine duration data measured using a Campbell-Stokes sunshine recorder (CS) and a CSD3 sunshine duration sensor (AUTO) as well as to attempt to explain discrepancies between the two data sets. The paper is based on heliographic data and cloudiness observations for 2007–2012. All the data come from the research station of the Jagiellonian University located in Krakow, Poland. Both instruments tend to produce similar sunshine duration data; however, the electronic sensor tends to show more sunshine duration than the CS. The difference may amount to several hours a day, especially on days with maximum solar radiation. The CSD3 sensor is twice as sensitive as the CS and reacts quickly to solar radiation. This is especially true for the first hour following sunrise, the last hour before sunset and when the Sun’s disc becomes visible for short periods of time due to changes in cloudiness. However, there are days when the CSD3 registers less sunshine duration (up to an hour) than the CS. This happens with Cumulus clouds in the sky, which tend to pass the Sun’s disc very quickly. The CSD3 sensor does not register sunshine in the presence of thick Altostratus and Cirrostratus clouds due to the relative lack of direct radiation. The sunshine recorder, on the other hand, registers this low level of sunshine.

Multi-Annual Variability of Cloudiness and Sunshine Duration in Cracow Between 1826 and 2005

The study presents the characteristics of the multi-annual variability of cloudiness and sunshine duration in Cracow. It draws on the results of cloudiness observations carried out at fixed times of day (1863–2005) and measurements of sunshine duration (1884–2005). In addition, the mean monthly and annual values of cloudiness have been reconstructed on the basis of the number of clear and overcast days for the 1826–1862 period and sunshine duration for the years 1826–1883. The application of segmentation of data series allowed for the identification of various periods of cloudiness, sunshine duration and the cyclonicity index. The basic statistical characteristics have been calculated. Individual features of the variability of cloudiness and sunshine duration have been determined. Moreover, the study indicates the influence of the changeability of local conditions on the variability of cloudiness and sunshine duration. An attempt to explain the reasons for the multi-annual variability of these elements has been undertaken.

Long‐term course of cloud genera frequency in Cracow (1906–2000)

The studies on the contemporary climate fluctuations seldom analyze the multi-annual qualitative changes of cloudiness, although many authors emphasize the necessity of undertaking nephological research which is indispensable to know, model, and monitor the climate. There are hypotheses that in various regions of the world an increase of frequency of occurrence of certain cloud genera (Ci, Ac, Sc, Cu, and Cb) and a decrease of frequency of other genera (Cc, Cs, Ns, St, and fog) takes place.