抄録
Sharpness of the satellite composite image is degraded by the period composite process associated with clouds and sensor zenith angles. In order to evaluate the image quality degradation by the period composite process, the period composites of band 1 of the corrected reflectance (CREFL) were created for the period of 1, 5, 10, and 30 days and for the spatial resolution of 250 m with a minimum pixel value among observations. The Modulation Transfer Function (MTF) of each MODIS period composite image are calculated by the method of edge-spectra ratio, where the Hanning Window is applied to the spatial pattern before the Fourier transformation. As a result, i) the 30 days period composite image was determined by the 5 days period composite image, ii) it was found that the 5 days period composite image should be combined with the cloud-free images and without the spatially deteriorated images in the end of scan angles in order to minimize the deterioration of image quality.
