Spectroradiometric and Stray light characterization of the Pushbroom Imager for Cloud and Aerosol Research and Development (PICARD) Airborne Imager

The PICARD (Pushbroom Imager for Cloud and Aerosol Research and Development) instrument, developed by the NASA Ames Research Center in partnership with Brandywine Photonics, LLC, is an airborne imager consisting of dual Offner spectrometers and an all-reflective telescope with a 50° full field-of-view (FOV). The instrument operates over a wavelength range of 400 – 2400 nm in more than 200 bands. PICARD has already flown multiple engineering flights on NASA ER-2 high altitude aircraft, the most recent during 2023 Western Diversity Time Series (WDTS) spring campaign where near co-incident measurements with spaceborne sensors such as MODIS and VIIRS were obtained including those over railroad valley (RRV) calibration site.  In addition, PICARD has recently flown during the 2024 Plankton, Aerosol, Cloud, Ocean Ecosystem Postlaunch Airborne eXperiment (PACE-PAX) field campaign to gather data for the validation of the recently launched PACE mission. A recent analysis comparing PICARD measurements with RadCalNet dataset from RRV revealed excellent agreement for most of the bands except in the UV and blue region, where PICARD generally under reported. To better characterize these bands and improve this under reporting, detailed PICARD spectroradiometric characterization measurements were collected at Goddard Laser for Absolute Measurement of Radiance (GLAMR) laboratory at Goddard Space Flight Center (GSFC) in February 2024. The initial analysis of this characterization suggested that this under-report during flight is due to a stray light sensitivity inherent in the low signal-to-noise (SNR) bands of array spectroradiometers. Correcting for the GLAMR measured stray light reconciles the under report. In addition, poor SNR bands in SWIR atmospheric absorptions are recovered when corrected for stray light. In this presentation, we will share findings from our recent PICARD spectroradiometric characterization over GLAMR including updated results comparing PICARD flight radiances with RadCalNet at RRV.