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Radiometric Accuracy and Stability of Sentinel-1A Determined using Point Targets

Schmidt, Kersten and Tous Ramon, Núria and Schwerdt, Marco (2018) Radiometric Accuracy and Stability of Sentinel-1A Determined using Point Targets. International Journal of Microwave and Wireless Technologies. Cambidge University Press. DOI: 10.1017/S1759078718000016 ISSN 1759-0787

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Official URL: https://www.cambridge.org/core/journals/international-journal-of-microwave-and-wireless-technologies/article/radiometric-accuracy-and-stability-of-sentinel1a-determined-using-point-targets/3E32B48BC0FD1B43B280DF9405DA4387

Abstract

Sentinel-1A is a space-borne SAR system developed in the frame of the Copernicus Program. The German Aerospace Center supported the radiometric and polarimetric calibration of Sentinel-1A by the analysis of point target responses of several acquisitions considering different modes, beams and polarization channels. An elevation dependent bias, which had not been properly predicted by the used antenna model, was found for all investigated modes. Offsets of up to 2 dB were determined during the SAR instrument calibration phase, in particular for low and high elevation angles. Therefore, in order to correct these elevation biases, a radiometric refinement was carried out by ESA in November 2015. After that, Sentinel-1A radiometric accuracy and long-term stability were analysed over a period of 1.5 years. For this period, the absolute calibration factor and the channel imbalance were determined for the main imaging mode. Moreover, a slight drift of the derived calibration factor was observed starting from July 2016. At the same time an anomaly was detected in the front-end affecting several transmit and receive modules in one tile. The radiometric behaviour of Sentinel-1A should therefore be monitored for a longer period of time, especially to detect potential degradation effects of the SAR instrument.

Item URL in elib:https://elib.dlr.de/115839/
Document Type:Article
Title:Radiometric Accuracy and Stability of Sentinel-1A Determined using Point Targets
Authors:
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Schmidt, KerstenKersten.Schmidt (at) dlr.dehttps://orcid.org/0000-0001-7896-908X
Tous Ramon, NúriaNuria.TousRamon (at) dlr.dehttps://orcid.org/0000-0002-0450-0438
Schwerdt, MarcoMarco.Schwerdt (at) dlr.dehttps://orcid.org/0000-0002-0045-3726
Date:9 March 2018
Journal or Publication Title:International Journal of Microwave and Wireless Technologies
Refereed publication:Yes
Open Access:Yes
Gold Open Access:No
In SCOPUS:Yes
In ISI Web of Science:Yes
DOI :10.1017/S1759078718000016
Publisher:Cambidge University Press
ISSN:1759-0787
Status:Published
Keywords:SAR System calibration. Sentinel-1, radiometric accuracy and stability, radiometric calibration, channel imbalance, Long term System monitoring
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 - SAR-Missions
Location: Oberpfaffenhofen
Institutes and Institutions:Microwaves and Radar Institute > Spaceborne SAR Systems
Deposited By: Schmidt, Dr. Kersten
Deposited On:22 Nov 2017 11:13
Last Modified:06 Sep 2019 15:20

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