Preprints
https://doi.org/10.5194/egusphere-2024-1152
https://doi.org/10.5194/egusphere-2024-1152
21 May 2024
 | 21 May 2024

Impacts of Differing Melt Regimes on Satellite Radar Waveforms and Elevation Retrievals

Alexander Ronan, Robert Hawley, and Jonathan Chipman

Abstract. Geodetic surface mass balance calculations rely on satellite radar altimeters such as CryoSat-2 to understand elevation and volume changes of the Greenland Ice Sheet (GrIS). However, the impact of varying GrIS shallow subsurface stratigraphic conditions on Level 2 CryoSat-2 elevation products is poorly understood. We investigate the reliability of the Offset Center of Gravity (OCOG) and University College London Land-Ice elevation (ULI) retracking algorithms through the analysis of, and comparison with, Level 1B waveform-derived Leading-Edge Width (LeW). We generate a 2010 to 2021 LeW time series using temporal clustering and Bayesian Model averaging and compare with Level 2 OCOG and ULI elevation time series. This workflow is performed at Summit Station, NEEM, and Raven Camp, chosen to represent the upper and lower bounds of the dry-snow zone, and percolation zone respectively. We note that melting event, snowpack recovery, and potentially anomalous snow accumulation and high-speed winds signatures are evident in Summit Station’s LeW time series. We find that Level 1B LeW has a significant inverse relationship with the ULI Level 2 elevations at NEEM and Summit Station, and likely the entire dry snow zone. The ULI Level 2 elevations at Raven Camp, and likely the entire percolation zone, have no clear elevation bias associated with significant melt events. The OCOG retracked elevations showed no significant association with LeW at any site. Future work is needed to understand the impacts of GrIS high-speed wind events and snow accumulation on elevation products, as well as to create retracking algorithms that are more resilient to abrupt changes in the shallow subsurface.

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Journal article(s) based on this preprint

06 Dec 2024
Impacts of differing melt regimes on satellite radar waveforms and elevation retrievals
Alexander C. Ronan, Robert L. Hawley, and Jonathan W. Chipman
The Cryosphere, 18, 5673–5683, https://doi.org/10.5194/tc-18-5673-2024,https://doi.org/10.5194/tc-18-5673-2024, 2024
Short summary
Alexander Ronan, Robert Hawley, and Jonathan Chipman

Interactive discussion

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2024-1152', Anonymous Referee #1, 23 Jun 2024
    • AC1: 'Reply on RC1', Alexander Ronan, 28 Jun 2024
    • AC4: 'Reply on RC1', Alexander Ronan, 15 Jul 2024
  • RC2: 'Comment on egusphere-2024-1152', Anonymous Referee #2, 24 Jun 2024
    • AC2: 'Reply on RC2', Alexander Ronan, 28 Jun 2024
    • AC3: 'Reply on RC2', Alexander Ronan, 15 Jul 2024
  • AC5: 'Comment on egusphere-2024-1152', Alexander Ronan, 15 Jul 2024
    • AC6: 'Reply on AC5', Alexander Ronan, 15 Jul 2024
      • AC7: 'Reply on AC6', Alexander Ronan, 17 Jul 2024

Interactive discussion

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2024-1152', Anonymous Referee #1, 23 Jun 2024
    • AC1: 'Reply on RC1', Alexander Ronan, 28 Jun 2024
    • AC4: 'Reply on RC1', Alexander Ronan, 15 Jul 2024
  • RC2: 'Comment on egusphere-2024-1152', Anonymous Referee #2, 24 Jun 2024
    • AC2: 'Reply on RC2', Alexander Ronan, 28 Jun 2024
    • AC3: 'Reply on RC2', Alexander Ronan, 15 Jul 2024
  • AC5: 'Comment on egusphere-2024-1152', Alexander Ronan, 15 Jul 2024
    • AC6: 'Reply on AC5', Alexander Ronan, 15 Jul 2024
      • AC7: 'Reply on AC6', Alexander Ronan, 17 Jul 2024

Peer review completion

AR: Author's response | RR: Referee report | ED: Editor decision | EF: Editorial file upload
ED: Reconsider after major revisions (further review by editor and referees) (17 Jul 2024) by Masashi Niwano
AR by Alexander Ronan on behalf of the Authors (24 Aug 2024)  Author's response   Author's tracked changes   Manuscript 
ED: Referee Nomination & Report Request started (30 Aug 2024) by Masashi Niwano
RR by Anonymous Referee #1 (10 Sep 2024)
ED: Publish subject to minor revisions (review by editor) (25 Sep 2024) by Masashi Niwano
AR by Alexander Ronan on behalf of the Authors (04 Oct 2024)  Author's response   Author's tracked changes   Manuscript 
ED: Publish as is (11 Oct 2024) by Masashi Niwano
AR by Alexander Ronan on behalf of the Authors (17 Oct 2024)

Journal article(s) based on this preprint

06 Dec 2024
Impacts of differing melt regimes on satellite radar waveforms and elevation retrievals
Alexander C. Ronan, Robert L. Hawley, and Jonathan W. Chipman
The Cryosphere, 18, 5673–5683, https://doi.org/10.5194/tc-18-5673-2024,https://doi.org/10.5194/tc-18-5673-2024, 2024
Short summary
Alexander Ronan, Robert Hawley, and Jonathan Chipman

Data sets

Impacts of Differing Melt Regimes on Satellite Radar Waveforms and Elevation Retrievals: Data & Scripts Alexander Ronan, Robert Hawley, and Jonathan Chipman https://zenodo.org/records/10969275

Model code and software

Impacts of Differing Melt Regimes on Satellite Radar Waveforms and Elevation Retrievals: Data & Scripts Alexander Ronan, Robert Hawley, and Jonathan Chipman https://zenodo.org/records/10969275

Alexander Ronan, Robert Hawley, and Jonathan Chipman

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The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.

Short summary
We generate a 2010–2021 time series of CryoSat-2 waveform shape metrics on the Greenland Ice Sheet, and compare it to CryoSat-2 elevation data, to investigate the reliability of two algorithms used to derive elevations from the SIRAL radar altimeter. Retracked elevations are found to depend on a waveform's leading-edge width in the dry snow zone. The study indicates that retracking algorithms must consider significant climate events and snow conditions when assessing elevation change.