Probability of cloud-free observation conditions across Great Britain estimated using MODIS cloud mask

Cloud cover is a major constraint on applications using optical remote sensing, particularly in temperate regions such as Great Britain (GB). This research explores the potential of the Moderate Resolution Imaging Spectroradiometer (MODIS) cloud mask product to calculate cloud probability across GB. MODIS 1km cloud mask data for 2005 were downloaded and processed to map cloud-free probabilities. The results indicate an average yearly cloud-free probability of 21.3%, with maximum and minimum monthly mean probabilities of 33.3% and 12.9% in November and March, respectively. Temporal and spatial variations in cloud-free frequencies are apparent. Northern and western regions are generally cloudier than those in the south. The results of this research indicate that cloud probabilities can be identified at a relatively high spatial resolution.