Articles | Volume 6, issue 1
Research article
04 Apr 2017
Research article |  | 04 Apr 2017

Radiometric flight results from the HyperSpectral Imager for Climate Science (HySICS)

Greg Kopp, Paul Smith, Chris Belting, Zach Castleman, Ginger Drake, Joey Espejo, Karl Heuerman, James Lanzi, and David Stuchlik

Abstract. Long-term monitoring of the Earth-reflected solar spectrum is necessary for discerning and attributing changes in climate. High radiometric accuracy enables such monitoring over decadal timescales with non-overlapping instruments, and high precision enables trend detection on shorter timescales. The HyperSpectral Imager for Climate Science (HySICS) is a visible and near-infrared spatial/spectral imaging spectrometer intended to ultimately achieve ∼ 0.2 % radiometric accuracies of Earth scenes from space, providing an order-of-magnitude improvement over existing space-based imagers. On-orbit calibrations from measurements of spectral solar irradiances acquired by direct views of the Sun enable radiometric calibrations with superior long-term stability than is currently possible with any manmade spaceflight light source or detector. Solar and lunar observations enable in-flight focal-plane array (FPA) flat-fielding and other instrument calibrations. The HySICS has demonstrated this solar cross-calibration technique for future spaceflight instrumentation via two high-altitude balloon flights. The second of these two flights acquired high-radiometric-accuracy measurements of the ground, clouds, the Earth's limb, and the Moon. Those results and the details of the uncertainty analyses of those flight data are described.

Short summary
Monitoring and attributing changes in Earth climate requires high-radiometric-accuracy spectral measurements of sunlight reflected from the Earth's surface. The HyperSpectral Imager for Climate Science (HySICS) is a new imaging spectrometer intended to ultimately achieve ~ 0.2 % radiometric accuracies, being ~ 10 × better than existing spaceflight instruments. We describe the results from a high-altitude balloon flight demonstrating techniques intended to meet these high-accuracy requirements.