Imagers for Spaceborne Cloud Tomography

Spaceborne observations serve as input to models and retrieval algorithms of various atmospheric properties. Specifically, we seek 3-D volumetric scattering tomography of clouds. Toward this, cloud fields are to be imaged simultaneously from multiple directions. The CloudCT project aims to demonstrate this by the formation of ten nanosatellites. Based on this data, scattering tomography will seek the 3-D volumetric distribution of cloud microphysical properties. We present constraints and fundamental considerations for spaceborne formation-based cloud tomography. We quantitatively compare visible (VIS) polarized imagers, VIS unpolarized imagers, and short-wave infrared unpolarized imagers. Each possibility is considered using a large eddy simulation of clouds. We study tomographic quality in the presence of sensor and photon noise, calibration errors, and stray light. We find that a polarized imager of a red waveband is preferable.