Coherent backscatter enhancement in bistatic Ku- and X-band radar observations of dry snow

Stefko, Marcel; Leinss, Silvan; Frey, Othmar; Hajnsek, Irena

doi:https://doi.org/10.5194/tc-16-2859-2022

Articles | Volume 16, issue 7

https://doi.org/10.5194/tc-16-2859-2022

© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

https://doi.org/10.5194/tc-16-2859-2022

© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 16, issue 7

Research article

|

19 Jul 2022

Research article |

| 19 Jul 2022

Coherent backscatter enhancement in bistatic Ku- and X-band radar observations of dry snow

Marcel Stefko, Silvan Leinss, Othmar Frey, and Irena Hajnsek

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Final revised paper (published on 19 Jul 2022)
Supplement to the final revised paper
Preprint (discussion started on 21 Dec 2021)
Supplement to the preprint

Interactive discussion

Status: closed

RC1:
'Comment on tc-2021-358', Henning Loewe, 31 Jan 2022

see attachement

Citation: https://doi.org/10.5194/tc-2021-358-RC1
- AC1: 'Reply on RC1', Marcel Stefko, 30 Mar 2022
  
  Please see attached file.
  
  Citation: https://doi.org/10.5194/tc-2021-358-AC1
RC2:
'Comment on tc-2021-358', Anonymous Referee #2, 27 Feb 2022
Coherent Backscattering enhancement for volume scattering and rough surface scattering have been known for a long time. The experiments for volume scattering were first observed in Kuga and Ishimaru ( JOSA 1984), and for rough surface by Phu etal, Radio Science (1994)

The enhancement has a maximum of 3dB which is significant for remote sensing applications. The validations have been exclusively from laboratory optical and microwave experiments where accurate bistatic measurements can be made within a fraction of a degree from the backscattering direction. However, it has largely been neglected in applications in microwave remote sensing of snow because of the difficulty of bistatics measurements to within a fraction of a degree from the backscattering direction

The authors in this experiment have made a good effort in measuring accurate bistatic measurements with Ku band for ground measurements and Tandem X of X band for satellites. The paper is a good step towards experiment validation of CBOE in remote sensing applications and the possible inclusion in modeling X band and Ku band volume scattering in snow. I have a few minor comments

For Ku bad for volume scattering of snow, cross polarizations are usually strong. In laboratory experiments cross polarization enhancement are more conspicuous than co-polarization for both volume scattering (Kuga etal JOSA A, 1985) and surface scattering ( Johnson etal IEEE Transactions on Antennas and Propagation 1994) . What are the reasons for non-observations in this paper. How about deeper snow?

The optical thickness can indicate the order of multiple scattering. Please discuss the optical thicknesses tau in the measurements at X band and Ku band

For X band at Tandem X, the soil surface below the snow have significant contributions. What is the magnitude of surface scattering of the snow/soil interface below the snow layer?

Will there be coherent backscattering due to rough soil surface below the snow at X band?
Citation: https://doi.org/10.5194/tc-2021-358-RC2
- AC2: 'Reply on RC2', Marcel Stefko, 30 Mar 2022
  
  Please see attached file.
  
  Citation: https://doi.org/10.5194/tc-2021-358-AC2

Peer review completion

AR: Author's response | RR: Referee report | ED: Editor decision | EF: Editorial file upload

ED: Publish subject to revisions (further review by editor and referees) (18 Apr 2022) by Carrie Vuyovich

AR by Marcel Stefko on behalf of the Authors (29 Apr 2022) Author's response Author's tracked changes Manuscript

ED: Referee Nomination & Report Request started (23 May 2022) by Carrie Vuyovich

RR by Henning Löwe (31 May 2022)

ED: Publish as is (09 Jun 2022) by Carrie Vuyovich

AR by Marcel Stefko on behalf of the Authors (15 Jun 2022) Manuscript

Short summary

The coherent backscatter opposition effect can enhance the intensity of radar backscatter from dry snow by up to a factor of 2. Despite widespread use of radar backscatter data by snow scientists, this effect has received notably little attention. For the first time, we characterize this effect for the Earth's snow cover with bistatic radar experiments from ground and from space. We are also able to retrieve scattering and absorbing lengths of snow at Ku- and X-band frequencies.