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Radiometric Comparison within the Sentinel-1 SAR Constellation over a Wide Backscatter Range

Schmidt, Kersten and Schwerdt, Marco and Miranda, Nuno and Reimann, Jens (2020) Radiometric Comparison within the Sentinel-1 SAR Constellation over a Wide Backscatter Range. Remote Sensing, 12 (5). Multidisciplinary Digital Publishing Institute (MDPI). doi: 10.3390/rs12050854. ISSN 2072-4292.

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Official URL: https://www.mdpi.com/2072-4292/12/5/854


Radiometric calibration adjusts the measured pixel intensity to a physical property, the radar cross section (RCS). After calibration, this relationship is defined over the entire backscatter range: from low image power (near noise) up to high reflections (below saturation). Based on a proper radiometric calibration, the measured radar backscatter for the Sentinel-1 synthetic aperture radar (SAR) satellite constellation is validated over a wide backscatter range using different target types. Therefore, the RCS derived from point targets and radar brightness from distributed targets are compared between Sentinel-1A (S-1A) and Sentinel-1B (S-1B) acquisitions over the same observation area for regions where a stable target backscatter is expected for a certain period of time. Low differences (in the order of 0.3 dB) are found between S-1A and S-1B for high and medium backscatter derived from point targets or rainforest regions, but higher differences for low backscattering regions like ice areas and lakes. For comparing radar brightness containing low backscatter targets, an accurate derived noise level has to be taken into account. In addition to the measured lower noise equivalent beta zero (NEBZ) level, higher transmit power was detected for S-1B compared to S-1A. The higher antenna gain of S-1B leads finally to a higher sensitivity for low backscattering areas of S-1B compared to S-1A and explains the found differences.

Item URL in elib:https://elib.dlr.de/134555/
Document Type:Article
Title:Radiometric Comparison within the Sentinel-1 SAR Constellation over a Wide Backscatter Range
AuthorsInstitution or Email of AuthorsAuthor's ORCID iDORCID Put Code
Schmidt, KerstenUNSPECIFIEDhttps://orcid.org/0000-0001-7896-908XUNSPECIFIED
Schwerdt, MarcoUNSPECIFIEDhttps://orcid.org/0000-0002-0045-3726UNSPECIFIED
Miranda, NunoEuropean Space Agency/ESRIN, Frascati, ItalyUNSPECIFIEDUNSPECIFIED
Reimann, JensUNSPECIFIEDhttps://orcid.org/0000-0002-0650-9073UNSPECIFIED
Date:6 March 2020
Journal or Publication Title:Remote Sensing
Refereed publication:Yes
Open Access:Yes
Gold Open Access:Yes
In ISI Web of Science:Yes
Publisher:Multidisciplinary Digital Publishing Institute (MDPI)
Keywords:synthetic aperture radar (SAR); Sentinel-1; SAR system constellation; radar backscatter; radiometric accuracy; radiometric noise; NESZ; SAR system calibration
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Space
HGF - Program Themes:Earth Observation
DLR - Research area:Raumfahrt
DLR - Program:R EO - Earth Observation
DLR - Research theme (Project):R - SAR missions
Location: Oberpfaffenhofen
Institutes and Institutions:Microwaves and Radar Institute > Spaceborne SAR Systems
Deposited By: Schmidt, Dr. Kersten
Deposited On:31 Mar 2020 11:38
Last Modified:25 Oct 2023 08:29

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