A43A-0260
Progress in Photoelastic Modulator-Based Spectropolarimetric Imaging of Aerosols and Clouds
Thursday, 17 December 2015
Poster Hall (Moscone South)
David J Diner1, Christine Lavella Bradley2, Michael A Bull1, Russell A Chipman2, Anthony B Davis1, Michael J Garay3, Veljko M Jovanovic3, Olga Kalashnikova1, Meredith Kupinski2, Brian E Rheingans1, Felix C Seidel1, Gerard van Harten3, Feng Xu3 and MSPI Team, (1)NASA Jet Propulsion Laboratory, Pasadena, CA, United States, (2)University of Arizona, Tucson, AZ, United States, (3)Jet Propulsion Laboratory, Pasadena, CA, United States
Abstract:
JPL's Multiangle SpectroPolarimetric Imager (MSPI) development effort is aimed at advancing our understanding of the climate and air quality impacts of airborne particles. Three photoelastic modulator (PEM)-based cameras have been built with the aim of acquiring high-accuracy multispectral images of intensity and linear polarization. The ground-based and airborne GroundMSPI and AirMSPI acquire multiangle images in the ultraviolet, visible, and near infrared, and measure polarization at 470, 660, and 865 nm. AirMSPI-2 extends the approach into the shortwave infrared, adding polarization channels at 1620 and 2185 nm. MSPI observations are being used to develop data processing algorithms for retrieval of aerosol and cloud properties. Data include ground-based imagery to validate assumptions used to characterize surface bidirectional reflectance factors (BRFs), namely, spectral invariance in the angular shape of the BRFs and absolute magnitude of the polarized BRF (pBRF). GroundMSPI measurements show that many surfaces satisfy these conditions, providing valuable constraints on the multivariate aerosol-surface retrieval problem. Algorithms for retrieval of aerosol optical and microphysical properties are being applied to AirMSPI data acquired during several airborne field campaigns, including PODEX and SEAC4RS. We explore the information content of different combinations of view angles, spectral bands, and polarimetric channels by using subsets of AirMSPI observations coincident with ground-based or airborne validation datasets, enabling direct association of particular measurement capabilities with retrieval accuracies and sensitivities. In preparation for the ORACLES Earth Venture Suborbital field campaign to be conducted off the west coast of Africa in 2016, retrievals of aerosols above stratocumulus clouds using constraints on cloud reflectance through polarimetric observations of the backscatter glory and supernumerary bows are also being tested and refined.
