Search results for "Monthly average"
showing 4 items of 4 documents
Instantaneous hourly and daily radiation on tilted surfaces
1991
A simple model to evaluate the irradiance incident on tilted surfaces of various orientations is proposed in this paper. It is based on the knowledge of the monthly daily average values of global and diffuse radiation on horizontal surfaces and their distributions over a period of a day. These distributions are approximated by a modified Gaussian expression with two parameters, which take into account the morning-to-afternoon asymmetries. Integrating the irradiance over a period of an hour or a day, values of monthly hourly average and daily on variously oriented surfaces have been calculated for the locations of Barcelona, Genoa, and Montreal. The calculated values are generally in good ag…
Diffuse UV erythemal radiation experimental values
2007
[1] Measurements of diffuse UV erythemal radiation (UVER) using a shadowband have been corrected using the models proposed by Drummond (1956), LeBaron et al. (1990), and Batlles et al. (1995). Two different methods were used to validate these models: intercomparison with an Optronic OL754 spectroradiometer and comparison with the values simulated by two radiative transfer codes, SMARTS and SBDART. For this comparison only clear days have been used. The corrected experimental values were analyzed in order to study the average values of the diffuse UVER fraction in relation to the clearness index kt. These varied between 62%, for kt close to 0.8, and 93% for kt of 0.2–0.3. Finally, a study of…
An atmospheric model for computing direct and diffuse solar radiation
1979
Abstract This paper proposes an atmospheric model, which extends the computation of the direct radiation given by Cole's model to the cloudy sky and shows a method to calculate the diffuse radiation. Therefore the monthly average values of the global radiation incident on a horizontal surface at Palermo are computed by this method. These values are compared with the experimental data provided by the Istituto di Idraulica Agraria, Universita di Palermo and generally exhibit a mean deviation not more than 10 per cent. The deviations become lower than 8 per cent taking into account the effect of the underlying surface albedo. In order to better verify the validity of the proposed method, it sh…
An atmospheric model applied to some actinometric stations of Sicily
1980
Abstract In this paper the application of an atmospheric model proposed by S. Barbaro et al. in a previous work for computing the direct and diffuse solar radiation is extended to some actinometric stations in Sicily, namely Gela, Messina, Pantelleria, Trapani and Ustica. The comparison of the monthly average values of the global radiation computed by this method with the experimental data shows a good agreement, that confirms the encouraging results obtained for Palermo in the previous work. This further test of the validity of the proposed model allows this one may be used with good reliability to predict the radiation on locations lacking in actinometric instruments. Finally, the influen…