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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

Abstract

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
Authors:
AuthorsInstitution or Email of AuthorsAuthor's ORCID iD
Schmidt, KerstenKersten.Schmidt (at) dlr.dehttps://orcid.org/0000-0001-7896-908X
Schwerdt, MarcoMarco.Schwerdt (at) dlr.dehttps://orcid.org/0000-0002-0045-3726
Miranda, NunoEuropean Space Agency/ESRIN, Frascati, ItalyUNSPECIFIED
Reimann, Jensjens.reimann (at) dlr.dehttps://orcid.org/0000-0002-0650-9073
Date:6 March 2020
Journal or Publication Title:Remote Sensing
Refereed publication:Yes
Open Access:Yes
Gold Open Access:Yes
In SCOPUS:Yes
In ISI Web of Science:Yes
Volume:12
DOI :10.3390/rs12050854
Publisher:Multidisciplinary Digital Publishing Institute (MDPI)
ISSN:2072-4292
Status:Published
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:18 Feb 2022 17:38

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