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

Schaepman, Michael E. and Jehle, Michael and Hueni, Andreas and D'Odorico, Petra and Damm, Alexander and Weyermann, Jörg and Schneider, Fabian Daniel and Laurent, Valérie and Popp, Christoph and Seidel, Felix and Lenhard, Karim and Gege, Peter and Küchler, Christoph and Brazile, Jason and Kohler, Peter and De Vos, Lieve and Meuleman, Koen and Meynart, Roland and Schläpfer, Daniel and Kneubühler, Mathias and Itten, K. I. (2015) Advanced radiometry measurements and Earth science applications with the Airborne Prism Experiment (APEX). Remote Sensing of Environment, 158, pp. 207-219. Elsevier. DOI: 10.1016/j.rse.2014.11.014 ISSN 0034-4257

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Official URL: http://www.sciencedirect.com/science/article/pii/S0034425714004568


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 ≤ 6.5% 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 R2 = 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.

Item URL in elib:https://elib.dlr.de/92452/
Document Type:Article
Title:Advanced radiometry measurements and Earth science applications with the Airborne Prism Experiment (APEX)
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Schaepman, Michael E.michael.schaepman (at) geo.uzh.chUNSPECIFIED
Jehle, MichaelRSL Uni ZürichUNSPECIFIED
Hueni, Andreasahueni (at) geo.uzh.chUNSPECIFIED
D'Odorico, PetraRSL Uni ZürichUNSPECIFIED
Damm, AlexanderRSL Uni ZürichUNSPECIFIED
Weyermann, JörgRSL Uni ZürichUNSPECIFIED
Schneider, Fabian DanielRSL Uni ZürichUNSPECIFIED
Laurent, ValérieRSL Uni ZürichUNSPECIFIED
Popp, ChristophNMNH, Smithsonian InstitutionUNSPECIFIED
Seidel, FelixJPL, CalTechUNSPECIFIED
Lenhard, Karimkarim.lenhard (at) dlr.deUNSPECIFIED
Gege, Peterpeter.gege (at) dlr.deUNSPECIFIED
Küchler, ChristophRUAG SchweizUNSPECIFIED
Brazile, JasonNetcetera AGUNSPECIFIED
Kohler, PeterNetcetera AGUNSPECIFIED
De Vos, LieveOIP Sensor SystemsUNSPECIFIED
Schläpfer, DanielReSe ApplicationsUNSPECIFIED
Kneubühler, MathiasRSL Uni ZürichUNSPECIFIED
Itten, K. I.Uni Zürich, Dept. of Geography, Remote Sensing Laboratories, RSL, Zurich (CH)UNSPECIFIED
Date:1 March 2015
Journal or Publication Title:Remote Sensing of Environment
Refereed publication:Yes
Open Access:No
Gold Open Access:No
In ISI Web of Science:Yes
DOI :10.1016/j.rse.2014.11.014
Page Range:pp. 207-219
Bauer, MarvinUniversity of Minnesota, St. Paul, Minnesota, USA
Keywords:Imaging spectroscopy; Earth observation; APEX; Calibration; Processing; Validation; Earth science applications, CHB
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Space
HGF - Program Themes:Earth Observation
DLR - Research area:Raumfahrt
DLR - Program:R EO - Erdbeobachtung
DLR - Research theme (Project):R - Vorhaben Spektrometrische Verfahren und Konzepte der Fernerkundung (old)
Location: Oberpfaffenhofen
Institutes and Institutions:Remote Sensing Technology Institute > Experimental Methods
Deposited By: Lenhard, Karim
Deposited On:09 Dec 2014 10:10
Last Modified:04 Aug 2016 16:46

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