Predictive Polarimetry Atmospherics Closure System (PPACS)

AFRL/VSSS is the lead Air Force group providing the DoD community with physics-based predictive models critical to assessing the utility of EO/IR spectro-polarimetric sensing for aerospace reconnaissance and target cueing. AFRL/VSSS is presently upgrading the government-standard MODTRAN atmospheric radiance code to properly handle polarization. However, there is currently no means of deducing the model inputs to properly represent aerosol composition variability, which strongly impacts target polarized signatures. Even for identical haze visibility levels, the unknown aerosol type can vary the sky degree-of-polarization by a factor of 2. The Predictive Polarimetry Atmospherics Closure System (PPACS) will provide the critical in-field facility for inferring such model inputs for validation against field measurements, the absence of which would otherwise threaten to obstruct development and maturation of spectro-polarimetric predictive models. In Phase 1, we computationally demonstrated the end-to-end feasibility of PPACS against surrogate NASA measurements. In Phase 2, the Aerodyne Research team (ATA, SSI, Dr. Dubovik/UMaryland, Professor Aragon/SFSU) will design, implement, and field demonstrate PPACS, a facility consisting of COTS multiangle radiometer, weather station, the well-regarded aerosol retrieval algorithm of Dubovik, and custom software components that will automatically render the sensor data into a complete set of MODTRAN4-P inputs.