A Model for the Estimation of Global Solar Radiation Using Fuzzy Random Variables

Abstract

Abstract In this paper, the concept of fuzzy random variables is applied for the estimation of global solar radiation on a surface at ground level. The cloudiness index is defined as the fraction of extraterrestrial radiation that reaches the earth's surface when the sky above the location of interest is obscured by the cloud cover. The cloud cover at the location of interest during the jth time interval of a day is assumed to follow the fuzzy random phenomenon. The cloudiness index, therefore, is considered as a fuzzy random variable that accounts for the cloud cover at the location of interest during the jth time interval of a day. This variable is assumed to depend on four other fuzzy random variables that, respectively, account for the cloud cover corresponding to the 1) type of cloud group, 2) climatic region, 3) season with most of the precipitation, and 4) type of precipitation at the location of interest during the jth time interval. The method is applied to estimate the monthly mean daily global ...