Formations of Small Satellites to Characterize 3D Cloud Properties: TOM and CloudCT

Clouds have significant impact at global scale on the Earth’s energy balance through albedo as well as on water transport. Therefore, uncertainties in global climate models are significantly affected by our limited knowledge about cloud internal composition, in particular of shallow convective clouds. CloudCT is an ERC Synergy Grant to improve small cloud observations, using a distributed sensor network on small satellites. Crucial for such formations are a high accuracy attitude determination and pointing capacity, as well as self-organizing networked controls to position the satellites for appropriate observations. In the "Telematics earth Observation Mission" TOM 3 Bavarian satellites will test 2021 this advanced small satellite technology in combination with photogrammetric methods for the observation of ash clouds. Here from different perspectives by sensor data fusion 3D images will generated. In CloudCT in 2022 by computed tomography methods the satellite measurements will be combined to derive even the cloud’s internal 3D information. For this objective 10 pico-satellites flying in formation will use multipoint observations of backscattered light from the clouds to reconstruct their interior 3D properties by a computed tomography approach. The basic data processing principles have already been tested by Technion using airborne data. An appropriate test infrastructure based on high precision, high dynamics turntables has been established at ZfT to realize realistic experiments of the in-orbit situation. The new data will provide the input to tune cloud resolving models at Weizmann Institute and to better parametrize their sensitivities in climate models in order to improve longer term climate predictions.