A CLOUD AREA ESTIMATION METHOD FOR GMS IMAGE

摘要

This paper proposes a method that estimates the position of clouds from VIS images (visible), and IR images (infrared) of GMS (Geostationary Meteorological Satellite). In VIS image, some images have incorrect data taken with extremely low brightness. In addition, estimating sunrise and sunset area are impossible because of the changes in the values of brightness with solar irradiance. In order to estimate the position of clouds from sunrise and sunset area, the brightness data of the image is corrected by Cosine law of illumination. Corrected value is calculated based on the solar irradiance of each area. In IR image, the brightness of equatorial area is different from that of Arctic Circle due to the atmospheric temperature. Brightness data of IR image is corrected by the number of the characteristics calculated by Least squares. This method was used to estimate the GMS images in Japan.