No abstract

No abstract

No abstract

A statistical analysis and inter-comparison of the broadband ultraviolet-B (UVB) radiation at two sites in Cyprus representing two different climate regimes of the island (Athalassa-inland plain vs Larnaca-coastal location) covering the period January 2013-December 2015 is presented. Mean annual and mean monthly daily totals of the UVB irradiation and their frequency distribution at both sites are computed and discussed. Daily maximum of hourly average irradiance values occur in July, 2.09 W m -2 , and minimum, 0.47 W m -2 , in December at solar noon at Athalassa. The respective values at Larnaca are slightly higher (2.48 W m -2 and 0.67 W m -2 , respectively). UVB daily values follow the pattern of the solar altitude angle; the total accumulated UVB irradiation along a mean year reaches 10.27 MJ m -2 at Athalassa and 13.49 MJ m -2 ; maximum stability of UVB takes place at midday hours during the summer. Large fluctuations of the daily UVB irradiation are observed in the spring months and November, which are mainly due to unstable meteorological conditions during the transition from cold to warm weather and vice versa. During summer the daily UVB radiation exceeds the value of 70 kJ m -2 at Larnaca and 55 kJ m -2 at Athalassa, while during the winter season the lowest is about 5 kJ m -2 at both stations. The UVB potential and extraterrestrial irradiation has also been calculated in order to estimate the attenuation of UVB radiation through the atmosphere. During summer the UVB transmittance is higher than in winter with a maximum value of 9% in July and a minimum of about 4% in December. Statistical relationships between UVB and other radiation components (UVA and global radiation) were established.

In this work, hourly measurements of global solar irradiances obtained from pyranometers and sunshine duration data using either Kipp & Zonen CSD3 automatic sensors or Campbell–Stokes sunshine recorders were assessed through an extensive quality control procedure and statistical analysis on the measured and derived solar parameters for all the actinometric stations installed in various locations over the island of Cyprus, covering mainly the period 2019–2021. This information is useful for engineers concerning the solar energy capture systems and energy efficiency who can therefore take knowledge of the local radiation levels. Monthly mean hourly values of global radiation and sunshine duration are calculated and shown through isoline diagrams. During June or July, daily global irradiations ranged between 25 MJ/m2 and 30 MJ/m2, with the lowest occurring in the mountainous locations. On the other hand, in January or December, they ranged between 6.5 MJ/m2 and 10.5 MJ/m2. The total annual number of hours of sunshine duration ranged between 2500 and 3500, with the lowest values recorded at the mountainous sites. The clearness index and relative sunshine duration were used for the classification of the weather conditions over the island. Furthermore, the interrelationships between the said indices were used for the estimation of global radiation. This work has specifically contributed to the characterization and analysis of hourly and daily solar global radiation. Furthermore, the measurements on the ground level could be compared with satellite observations in order to improve the geographical distribution of global radiation, especially in areas where no measurements exist. The analysis could be also extended for the other shortwave radiation components (Direct, Diffuse and Photosynthetic Active Radiation (PAR)) in order to assess the solar radiation regime over the island.