A NIST-Traceable Lab-to-Sky Spectral and Radiometric Calibration for NASA’s High-Altitude Airborne Hyperspectral Pushbroom Imager for Cloud and Aerosol Research and Development (PICARD)

Abstract

The Pushbroom Imager for Cloud and Aerosol Research and Development (PICARD) visible through shortwave infrared imaging spectrometer was developed to carry a calibration laboratory environment to high altitudes, while also providing high- dy-namic- range bright cloud-top radiance measurements across a field of view just under 50 degrees. The in-flight performance of this new spectroradiometer was validated in comparison to multiple reference data sources and targets using imagery collected aboard NASA’s ER-2 high-altitude aircraft during the Western Diversity Time Series (WDTS) airborne science campaign in April 2023 and the September 2024 Plankton, Aerosol, Cloud, and ocean Ecosystem (PACE) Postlaunch Airborne eXperiment (PACE-PAX), both operating out of southern California. PICARD measurements from flights over Railroad Valley Playa, Nevada, USA, were compared to high-resolution radiance spectra of the dry lakebed provided by the Radiometric Calibration Network (RadCalNet) Working Group. Direct comparison to satellite cloud radiometry was en-abled by the ER-2 flying in coordination with simultaneous overpasses of the Terra, Aqua, and NOAA-20 Earth-observing satellites during WDTS and with the PACE ob-servatory during PACE-PAX. To account for large spectral differences between incan-descent laboratory sources and solar illumination, PICARD calibration relies on meas-urements using the Goddard Laser for Absolute Measurements of Radiance (GLAMR) to characterize and minimize spectral stray light from the instrument’s twin Offner grating spectrometers. Good agreement in comparison to reference measurements demonstrates PICARD’s ability to provide imagery for environmental science or for testing new sensor designs and retrieval algorithms for cloud and aerosol research with verified laboratory calibrations at high altitudes.

Authors

• Gary D Hoffmann Bay Area Environmental Research Institute
• Thomas Ellis Bay Area Environmental Research Institute
• Haiping Su Bay Area Environmental Research Institute
• Alok Shrestha Bay Area Environmental Research Institute
• Julia A Barsi Goddard Space Flight Center
• Roseanne Dominguez Bay Area Environmental Research Institute
• Eric Fraim Bay Area Environmental Research Institute
• James Jacobson Bay Area Environmental Research Institute
• Steven Platnick Goddard Space Flight Center
• G Thomas Arnold Science Systems and Applications (United States)
• Kerry Meyer Goddard Space Flight Center
• Jessica L McCarty Ames Research Center

Keywords

• intersensor comparison
• validation
• calibration
• PACE-PAX
• GLAMR
• PICARD
• SWIR
• VNIR
• remote sensing
• stray light
• hyperspectral imagery
• imaging spectroscopy