Advanced radiometry measurements and Earth science applications with the Airborne Prism Experiment (APEX)

作者：Schaepman Michael E; Jehle Michael; Hueni Andreas; D' Odorico Petra; Damm Alexander; Weyerrnann Jurg; Schneider Fabian D; Laurent Valerie; Popp Christoph; Seidel Felix C; Lenhard Karim; Gege Peter; Kuechler Christoph; Brazile Jason; Kohler Peter; De Vos Lieve; Meuleman Koen; Meynart Roland; Schlaepfer Daniel; Kneubuhler Mathias; Itten Klaus I

来源：Remote Sensing of Environment, 2015, 158: 207-219.

DOI：10.1016/j.rse.2014.11.014

• Imaging spectroscopy
• Earth observation
• APEX
• Calibration
• Processing
• Validation
• Earth science applications

We present the Airborne Prism Experiment (APEX), its calibration and subsequent radiometric measurements as well as Earth science applications derived from this data. APEX is a dispersive pushbroom imaging spectrometer covering the solar reflected wavelength range between 372 and 2540 nm with nominal 312 (max. 532) spectral bands. APEX is calibrated using a combination of laboratory, in-flight and vicarious calibration approaches. These are complemented by using a forward and inverse radiative transfer modeling approach, suitable to further validate APEX data. We establish traceability of APEX radiances to a primary calibration standard, including uncertainty analysis. We also discuss the instrument simulation process ranging from initial specifications to performance validation. In a second part, we present Earth science applications using APEX. They include geometric and atmospheric compensated as well as reflectance anisotropy minimized Level 2 data. Further, we discuss retrieval of aerosol optical depth as well as vertical column density of NOx, a radiance data-based coupled canopy atmosphere model, and finally measuring sun-induced chlorophyll fluorescence (Fs) and infer plant pigment content. The results report on all APEX specifications including validation. APEX radiances are traceable to a primary standard with <4% uncertainty and with an average SNR of >625 for all spectral bands. Radiance based vicarious calibration is traceable to a secondary standard with <= 65% uncertainty. Except for inferring plant pigment content, all applications are validated using in-situ measurement approaches and modeling. Even relatively broad APEX bands (FWHM of 6 nm at 760 nm) can assess Fs with modeling agreements as high as R-2 = 0.87 (relative RMSE = 27.76%). We conclude on the use of high resolution imaging spectrometers and suggest further development of imaging spectrometers supporting science grade spectroscopy measurements.

• 出版日期2015-3-1