Characterization and Calibration of the AirHARP2 Suite of Instruments

Abstract

AirHARP2 is the aircraft version of the orbital Hyper Angular Rainbow Polarimeter (HARP2) on NASA’s Plankton Aerosol Cloud and ocean Ecosystem (PACE) satellite. In September 2024, AirHARP2 participated in the PACE Postlaunch Airborne eXperiment (PAX). This campaign provides a unique opportunity to validate radiometric and polarimetric measurements and derived science products from the PACE satellite by conducting direct cross-platform comparisons using co-located scenes. AirHARP2 is the polarimeter instrument in the AirHARP2 Suite, which also contains a VNIR imaging spectrometer, UV imaging spectrometer, and a SWIR multi-angle imaging radiometer. The companion instruments in the AirHARP2 suite mirror spectral response of the PACE Ocean Color Instrument (OCI). The full AirHARP2 suite underwent spectral calibration using the Goddard Laser for Absolute Measurement of Radiance (GLAMR) laboratory. GLAMR consists of multiple tunable lasers across the solar spectrum. Radiometric calibration for the AirHARP2 suite was performed using a calibrated integrating sphere. This presentation describes the calibration methods used for the AirHARP2 suite and shows the current state of the calibration.