Seasonal CO2 Cycle at the Martian Poles Revealed by Sounding Radar

Abstract Seasonal CO2 frost accumulates and ablates at the Martian poles during night and day, respectively. We report the first robust measurements of polar seasonal change in SHAllow RADar (SHARAD) data, based on calibration of the 16‐year data set. At each pole, radar surface echo power varies an...

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Main Authors: Erica R. Jawin, Bruce A. Campbell, Cyril Grima
Format: Article
Language:English
Published: Wiley 2025-07-01
Series:Geophysical Research Letters
Subjects:
Online Access:https://doi.org/10.1029/2025GL116047
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author Erica R. Jawin
Bruce A. Campbell
Cyril Grima
author_facet Erica R. Jawin
Bruce A. Campbell
Cyril Grima
author_sort Erica R. Jawin
collection DOAJ
description Abstract Seasonal CO2 frost accumulates and ablates at the Martian poles during night and day, respectively. We report the first robust measurements of polar seasonal change in SHAllow RADar (SHARAD) data, based on calibration of the 16‐year data set. At each pole, radar surface echo power varies annually by ∼3–4 dB (increase of 2–2.5 times in power) with a distinct temporal signal, where power decreases during the night and increases during daytime, although spatial heterogeneities exist. Power variations are restricted to the surface reflection. The timing and magnitude of radar power variations are largely consistent with the deposition and removal of CO2 frost, despite predicted seasonal frost layers being thinner than a SHARAD range cell. Radar power variations largely agree with previous analyses. This study represents the first documentation of the full seasonal CO2 frost cycle at both Martian poles using radar sounder data.
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spelling doaj-art-58975fb924074cdcb13efe3ea432d2502025-08-20T03:31:52ZengWileyGeophysical Research Letters0094-82761944-80072025-07-015214n/an/a10.1029/2025GL116047Seasonal CO2 Cycle at the Martian Poles Revealed by Sounding RadarErica R. Jawin0Bruce A. Campbell1Cyril Grima2National Air and Space Museum Smithsonian Institution Washington DC USANational Air and Space Museum Smithsonian Institution Washington DC USAInstitute for Geophysics University of Texas Austin TX USAAbstract Seasonal CO2 frost accumulates and ablates at the Martian poles during night and day, respectively. We report the first robust measurements of polar seasonal change in SHAllow RADar (SHARAD) data, based on calibration of the 16‐year data set. At each pole, radar surface echo power varies annually by ∼3–4 dB (increase of 2–2.5 times in power) with a distinct temporal signal, where power decreases during the night and increases during daytime, although spatial heterogeneities exist. Power variations are restricted to the surface reflection. The timing and magnitude of radar power variations are largely consistent with the deposition and removal of CO2 frost, despite predicted seasonal frost layers being thinner than a SHARAD range cell. Radar power variations largely agree with previous analyses. This study represents the first documentation of the full seasonal CO2 frost cycle at both Martian poles using radar sounder data.https://doi.org/10.1029/2025GL116047MarsradarMartian polesseasonal CO2 cycle
spellingShingle Erica R. Jawin
Bruce A. Campbell
Cyril Grima
Seasonal CO2 Cycle at the Martian Poles Revealed by Sounding Radar
Geophysical Research Letters
Mars
radar
Martian poles
seasonal CO2 cycle
title Seasonal CO2 Cycle at the Martian Poles Revealed by Sounding Radar
title_full Seasonal CO2 Cycle at the Martian Poles Revealed by Sounding Radar
title_fullStr Seasonal CO2 Cycle at the Martian Poles Revealed by Sounding Radar
title_full_unstemmed Seasonal CO2 Cycle at the Martian Poles Revealed by Sounding Radar
title_short Seasonal CO2 Cycle at the Martian Poles Revealed by Sounding Radar
title_sort seasonal co2 cycle at the martian poles revealed by sounding radar
topic Mars
radar
Martian poles
seasonal CO2 cycle
url https://doi.org/10.1029/2025GL116047
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AT bruceacampbell seasonalco2cycleatthemartianpolesrevealedbysoundingradar
AT cyrilgrima seasonalco2cycleatthemartianpolesrevealedbysoundingradar