Cross-comparison and validation of MODIS AQUA cloud mask by using CLOUDSAT and CALIPSO datasets

This paper presents a cross-comparison of the data acquired by the MODIS, CLOUDSAT and CALIPSO sensors in order to understand the limit of the developed cloud-mask algorithm and to provide a quantitative validation assessment by using exclusively remotely sensed data. The comparison has been carried out by considering both the cloud mask and the intermediate levels such as the brightness temperatures and the reflectance values for different channels from which the cloud mask is derived. The preliminary analysis indicates a general good agreement among the different sources. A main underestimation of cloud cover is present on the sea and especially for high thin clouds. First results indicate that in order to increase the cloud cover accuracy the threshold for the intermediate levels (brightness temperature and reflectance values) may be changed by taking into account also the cloud vertical profiles.