The MODIS Airborne Simulator (MAS) Level-2 Cloud Data product (MASL2CLD) consists of cloud optical and physical parameters. These parameters are derived using remotely sensed infrared and near infrared solar reflected radiances. Multispectral images of the reflectance and brightness temperature at 10 wavelengths between 0.66 and 13.98nm were used to derive the probability of clear sky (or cloud), cloud thermodynamic phase, and the optical thickness and effective radius of liquid water and ice clouds.MASL2CLD product files are stored in Hierarchical Data Format (HDF-EOS). All gridded cloud parameters are stored as Scientific Data Sets (SDS) within the file.For more information and for a list of MAS campaign flights visit ladsweb at:https://ladsweb.modaps.eosdis.nasa.gov/missions-and-measurements/mas/