SPEX airborne On-ground and In-flight Performance During the ImPACT-PM and ACEPOL Field Campaigns

SPEX airborne is a multi-angle spectropolarimeter payload, that has been developed in the Netherlands for observing and characterizing aerosols from NASA's high-altitude research aircraft ER-2. SPEX airborne provides autonomously snapshot measurements of spectral radiance and degree of linear polarization from 400-770 nm over a 7° swath and in nine fixed viewing angles spanning a range of 112°. SPEX airborne uses the spectral polarization modulation technique to extract 30 highly accurate polarimetric measurements and hyperspectral radiance measurements at 2.5 nm resolution per observed ground pixel. SPEX airborne had its maiden flight on the ER-2 in February 2016 and co-flew with AirMSPI during ImPACT-PM campaign, which was organised by Jet Propulsion Laboratory in July 2016. During the oncoming ACEPOL campaign in October 2017, SPEX airborne will co-fly with AirMSPI, RSP (NASA GISS) and AirHARP (UMBC) as well as the Cloud Physics Lidar (GSFC) and High Spectral Resolution Lidar (HSRL-2, NASA Langley) with the aim of performing polarimeter cross-calibration and simultaneous observation of aerosols and clouds by the suite of multi-angle polarimeters and lidars. In this presentation, we will present the on-ground calibration and in-flight performance of SPEX airborne. We will show results of the polarimetric calibration with JPL's polarization state generator, discuss the calibration processing approach, and demonstrate a polarimetric accuracy of 0.002. The in-flight performance is addressed using a radiometric and polarimetric intercomparison of SPEX airborne and AirMSPI data gathered simultaneously over several scenes during the Impact-PM field campaign. Aerosol retrieval results over land and ocean scenes will be presented and compared with AERONET observations in Fresno, Bakersfield, El Segundo and SeaPrism. We will conclude with preliminary results from the ACEPOL campaign and give an outlook on further exploitation of SPEX airborne data gathered during this campaign.