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Coherent Backscatter Enhancement in Bistatic Ku- and X-Band Radar Observations of Dry Snow

Stefko, Marcel and Leinss, Silvan and Frey, Othmar and Hajnsek, Irena (2022) Coherent Backscatter Enhancement in Bistatic Ku- and X-Band Radar Observations of Dry Snow. The Cryosphere, 16 (7), pp. 2859-2879. Copernicus Publications. doi: 10.5194/tc-16-2859-2022. ISSN 1994-0416.

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Official URL: https://tc.copernicus.org/articles/16/2859/2022/


The coherent backscatter opposition effect (CBOE) enhances the backscatter intensity of electromagnetic waves by up to a factor of 2 in a very narrow cone around the direct return direction when multiple scattering occurs in a weakly absorbing, disordered medium. So far, this effect has not been investigated in terrestrial snow in the microwave spectrum. It has also received little attention in scattering models. We present the first characterization of the CBOE in dry snow using ground-based and spaceborne bistatic radar systems. For a seasonal snowpack in the Ku-band (17.2 GHz), we found backscatter enhancement of 50 %-60 % (+1.8-2.0 dB) at a zero bistatic angle and a peak half-width at half-maximum (HWHM) of 0.25°. In the X-band (9.65 GHz), we found backscatter enhancement of at least 35 % (+1.3 dB) and an estimated HWHM of 0.12° in the accumulation areas of glaciers in the Jungfrau-Aletsch region, Switzerland. Sampling of the peak shape at different bistatic angles allows estimating the scattering and absorption mean free paths, 3T and 3A. In the VV polarization, we obtained 3T = 0.4 ± 0.1 m and 3A = 19 ± 12 m at the Ku-band and 3T = 2.1 ± 0.4 m and 3A = 21.8 ± 2.7 m at the X-band, assuming an optically thick medium. The HH polarization yielded similar results. The observed backscatter enhancement is thus significant enough to require consideration in backscatter models describing monostatic and bistatic radar experiments. Enhanced backscattering beyond the Earth, on the surface of solar system bodies, has been interpreted as being caused by the presence of water ice. In agreement with this interpretation, our results confirm the presence of the CBOE at X- and Ku-band frequencies in terrestrial snow.

Item URL in elib:https://elib.dlr.de/187571/
Document Type:Article
Title:Coherent Backscatter Enhancement in Bistatic Ku- and X-Band Radar Observations of Dry Snow
AuthorsInstitution or Email of AuthorsAuthor's ORCID iDORCID Put Code
Leinss, SilvanUniversité Savoie Mont BlancUNSPECIFIEDUNSPECIFIED
Date:19 July 2022
Journal or Publication Title:The Cryosphere
Refereed publication:Yes
Open Access:Yes
Gold Open Access:Yes
In ISI Web of Science:Yes
Page Range:pp. 2859-2879
Publisher:Copernicus Publications
Series Name:Creative Commons Attribution 4.0 License
Keywords:Coherent backscatter, bistatic Ku-band, X-band, radar observations, dry snow, CBOE, glaciers, Jungfau-Aletsch region
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 - Polarimetric SAR Interferometry HR
Location: Oberpfaffenhofen
Institutes and Institutions:Microwaves and Radar Institute > Radar Concepts
Deposited By: Radzuweit, Sibylle
Deposited On:20 Jul 2022 10:26
Last Modified:20 Jul 2022 10:31

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