Abstract
This study shows the methods for estimating the irradiation by using the GMS images The brightness values of clouds were forecasted as a basis study of estimatihg the irradiation. In the first place, we have developed the method for deriving drift vector of clouds from the images and forecasting brightness at certain pixels. The drift vector stands for movement direction and speed of clouds are calculated with the correlation function that calculate with GMS cloud images. This time, the brightness values forecasted from one hour later to five hours later were calculated with the data from January 3 to March 10 in 1997. The root-mean-square error, RMSE was 7.37% for an hour later estimate. The RMSE was much the same as this model errors. This result may indicate that the spatial resolution of the images is not enough to detect clouds movement for an hour, statistically. Another RMSE were 12.9% for two hours later estimate, 13.6% for three hours later estimate, 13.8% for four hours later estimate and 13.9% five hours later estimate. When the weather is not changeable, estimated values were not affected by the size of area which the correlation function was calculated in. The method of estimating the brightness methods we have developed is available for forecasting irradiation for a few hour later. If the weather changes rapidly, would calculate estimated values by size to calculate correlation coefficient adapted to the weather.
