Imaging Spectropolarimetric Sensor for Airborne and Ground Based Retrieval of Aerosol Properties

Aerodyne Research will develop, demonstrate and market HySPAR, the HyperSpectral Polarimeter for Aerosol Retrievals. Our HySPAR commercial market will comprise both product sales (selling copies of the sensor) and R&D-level aerosol field measurement services. HySPAR employs snapshot multi-angle (passive optical) spectropolarimetry to retrieve atmospheric aerosol macro and microphysical properties. It will be made suitable for both uplooking ground-based measurements, as well as downlooking airborne measurements. In Phase I, we performed a preliminary design for a HySPAR sensor suitable for both airborne and ground-based applications. The design is compact and offers the advantages of single snapshot spectro-polarimetry over a 120 degree field-of-view with no moving parts. The simplicity of the design should allow a cost effective implementation even if built in small quantities (>10 units). We performed experiments with our prototype sensor and two co-located sensors, an Aerosol Mass Spectrometer, and a robotic sunphotometer belonging to NASA's AERONET network, yielding good correlation. Using NASA/GISS forward atmospheric modeling codes, we ascertained that the spectral variability of polarized albedos is compatible with our straightforward Stokes inversion method which we demonstrated on sky radiance data measured using our prototype sensor. The Phase I objectives were achieved in entirety and clearly warrant Phase II continuation.