Analysis of high resolution MOMS cloud scenes for CLOUDMAP validation

CLOUDMAP applied stereo registration and differential spectroscopy in the A-band of molecular oxygen as new observation methods of clouds, provided by existing or new instruments on polar orbiting satellites with 250 to 1000 m pixel size, comparable to the cloud mean size. Cloud coverage within pixel can only be estimated from spectral effects. High resolution stereoscopic cloud images with 18 m pixel size obtained by the German Modular Opto-electronic Multi-spectral Scanner (MOMS) on the Russian space station MIR over crossing areas with the polar orbiting satellites at small time delays were provided for CLOUDMAP as 3D reference data within the sub-pixel scale of the CLOUDMAP sensors. The main product is an Apparent Stereoscopic Cloud Height (ASCH) with a systematic error resulting from the cloud drift component in the ground track direction of MOMS. Estimates of cloud shadow height and shadow drift were applied to correct for this effect. The cloud data evaluation was based on software of DLR for surface photogrammetry. Cloud to shadow matching was accomplished with radiometric inverted cloud shadow regions. The validation of the applied procedures was based upon the redundancy of the results of different stereo pairs and upon an independent evaluation of the along and cross track components of the cloud and shadow parallaxes.