Achieving 0.1% radiometric uncertainty in the solar bands using FTS

Abstract

We report on the feasibility and advantages of an improved radiometric calibration concept for hyperspectral, Earthviewing, remote sensors operating in the solar bands (250 nm -3000 nm). An absolute radiometric measurement uncertainty of 0.1% relative to 100% Earth albedo appears feasible with this new system concept. This is an order of magnitude finer than conventional calibration methods that rely on solar illuminated diffusers, direct solar irradiance, lunar irradiance, bulb driven integrating spheres, reference detectors, Earth landmarks, or inter-satellite comparison.The improvement is accomplished by combining the unique properties of an uncooled, broadband active cavity radiometer; a multi-wavelength LED-driven integrating sphere; a laser-driven plasma white light source; and a UV/VIS/NIR Fourier Transform Spectrometer. The calibrated radiance product is spectrally resolved and tied directly to an International System of Units (SI). Performance remains naturally immune to the optical and electrical degradation characteristics common with prior calibration methods.