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An approach for spaceborne aperture synthesis radiometer calibration

Peichl, Markus and Wittmann, Volker (2007) An approach for spaceborne aperture synthesis radiometer calibration. In: International Geoscience and Remote Sensing Symposium 2007. IGARSS 2007, 2007-07-23 - 2007-07-27, Barcelona, Spain.

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Abstract

This paper outlines an approach which was developed and investigated for the SMOS spaceborne imaging radiometer to be launched end of 2007. SMOS is an L-band Y-shaped aperture synthesis radiometer intended for global measurements of soil moisture and ocean salinity. Since the directly measured quantities are correlation values in the spatial frequency domain, a calibration procedure has to transform them to brightness temperatures, which are the typical radiometer output signals and specified as the SMOS level-1 data products. Furthermore, the imperfect system response has to be corrected, for which some on-board implemented hardware tools are available. However, those are only able to correct part of the errors and, typically, the residual imperfections are more expensive to eliminate. Finally the map of correlation values has to be converted to an image in the spatial domain in order to assign the determined geophysical data to their corresponding geographical location. The here proposed image reconstruction and calibration approach is based on the in-space measurements of well-known calibration targets like point sources in a low-power background as it could be provided by the Moon and the deep space. The use of multiple scenes, where the point-source is located on different positions within the usable field of view, allows the determination of a G matrix describing the whole imperfect system. Once determined, the matrix can be used to compute efficiently the corrected and calibrated brightness temperature map of the actually observed scene. Simulation results for various realistic conditions in order to assess the performance of the approach are shown and discussed.

Document Type:Conference or Workshop Item (Speech)
Title:An approach for spaceborne aperture synthesis radiometer calibration
Authors:
AuthorsInstitution or Email of Authors
Peichl, MarkusUNSPECIFIED
Wittmann, Volker(retired)
Date:25 July 2007
Journal or Publication Title:International Geoscience and Remote Sensing Symposium 2007
Refereed publication:No
In SCOPUS:No
In ISI Web of Science:No
Editors:
EditorsEmail
IEEE, UNSPECIFIED
Status:Published
Keywords:Radiometry, aperture synthesis, image reconstruction, G matrix
Event Title:IGARSS 2007
Event Location:Barcelona, Spain
Event Type:international Conference
Event Dates:2007-07-23 - 2007-07-27
Organizer:UPC
HGF - Research field:Aeronautics, Space and Transport (old)
HGF - Program:Space (old)
HGF - Program Themes:W EO - Erdbeobachtung
DLR - Research area:Space
DLR - Program:W EO - Erdbeobachtung
DLR - Research theme (Project):W - Projekt sicherheitsrelevante Erdbeobachtung (old)
Location: Oberpfaffenhofen
Institutes and Institutions:Microwaves and Radar Institute > Reconnaissance and Security
Deposited By: Dr.-Ing. Markus Peichl
Deposited On:19 Jul 2007
Last Modified:06 May 2011 10:17

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