Abstract
The methods for estimation of hourly global solar radiation using the other climatic elements as predictor varibles are discussed in this paper. For this investigaion, mainly data measured at Kagoshima Meteorological Station during a year of 1975 were used. Hourly cloud cover and cloud type were chosen first in chapter 2 as predictor variables. It was concluded, however, that they were not effective estimation indices. The duration of sunshine over a long period is known to be correlated strongly with the global solar radiation of the corresponding period. In chapter 3 the question of whether the same relation also exists in hourly data was examined. The following results were obtained : The hourly global solar radiation can be represented by a linear function of the hourly extra-terrestrial insolation when the hourly duration of sunshine is given. And more effective relation between them can be obtained if hourly climatic information about the weather condition, the cloud cover or the vapor pressure as well as the duration of sunshine are available. From these conclusions, several equations for the estimation of hourly global solar radiation using these climatic elements were proposed. However, it is possible that the relationship of the global solar radiation data to the sunshine data measured in Kagoshima does not correlate to the relationship of global solar radiation data to sunshine data measured at other meteorological stations. This problem was considerd in chapter 4, and a method for the generalization of the formulae obtained in chapter 3 to the entire Japanese islands was proposed. In chapter 5, estimated values from the formulae were compared with the measured values.
