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https://doi.org/10.5194/egusphere-2025-775
https://doi.org/10.5194/egusphere-2025-775
26 Feb 2025
 | 26 Feb 2025

Assessment of Ocean Bottom Pressure Variations in CMIP6 HighResMIP Simulations

Le Liu, Michael Schindelegger, Lara Börger, Judith Foth, and Junyang Gou

Abstract. Ocean bottom pressure (pb) variations from high-resolution climate model simulations under the CMIP6 (Coupled Model Intercomparison Project Phase 6) HighResMIP protocol are potentially useful for oceanographic and space-geodetic research, but the overall signal content and accuracy of these pb estimates have hitherto not been assessed. Here we compute monthly pb fields from five CMIP6 HighResMIP models at 1/4° grid spacing over both historical and future time spans and compare these data, in terms of temporal variance, against observation-based pb estimates from a 1/4° downscaled GRACE (Gravity Recovery and Climate Experiment) product and 23 bottom pressure recorders, mostly in the Pacific. The model results are qualitatively and quantitatively similar to the GRACE-based pb variances, featuring—aside from eddy imprints—elevated amplitudes on continental shelves and in major abyssal plains of the Southern Ocean. Modeled pb variance in these regions is ∼10–80 % higher and thus overestimated compared to GRACE, whereas underestimation relative to GRACE and the bottom pressure recorders prevails in more quiescent deep-ocean regions. We also form variance ratios of detrended pb signals over 2030–2049 under a high-emission scenario relative to 1980–1999 for three selected models and find statistically significant increases of future pb variance by ∼30–50 % across the Arctic and in eddy-rich regions of the South Atlantic. The strengthening is consistent with projected changes in high-latitude surface winds and, in the case of the South Atlantic, intensified Agulhas leakage. The study thus points to possibly new pathways for relating observed pb variability from (future) satellite gravimetry missions to anthropogenic climate change.

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Journal article(s) based on this preprint

01 Oct 2025
Assessment of ocean bottom pressure variations in CMIP6 HighResMIP simulations
Le Liu, Michael Schindelegger, Lara Börger, Judith Foth, and Junyang Gou
Ocean Sci., 21, 2149–2167, https://doi.org/10.5194/os-21-2149-2025,https://doi.org/10.5194/os-21-2149-2025, 2025
Short summary
Le Liu, Michael Schindelegger, Lara Börger, Judith Foth, and Junyang Gou

Interactive discussion

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2025-775', Christopher Piecuch, 03 Apr 2025
    • AC1: 'Reply on RC1', Le Liu, 28 May 2025
  • RC2: 'Comment on egusphere-2025-775', Anonymous Referee #2, 01 May 2025
    • AC2: 'Reply on RC2', Le Liu, 28 May 2025

Interactive discussion

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2025-775', Christopher Piecuch, 03 Apr 2025
    • AC1: 'Reply on RC1', Le Liu, 28 May 2025
  • RC2: 'Comment on egusphere-2025-775', Anonymous Referee #2, 01 May 2025
    • AC2: 'Reply on RC2', Le Liu, 28 May 2025

Peer review completion

AR: Author's response | RR: Referee report | ED: Editor decision | EF: Editorial file upload
AR by Le Liu on behalf of the Authors (03 Jul 2025)  Author's response   Author's tracked changes   Manuscript 
ED: Publish subject to technical corrections (08 Jul 2025) by John M. Huthnance
AR by Le Liu on behalf of the Authors (09 Jul 2025)  Manuscript 

Journal article(s) based on this preprint

01 Oct 2025
Assessment of ocean bottom pressure variations in CMIP6 HighResMIP simulations
Le Liu, Michael Schindelegger, Lara Börger, Judith Foth, and Junyang Gou
Ocean Sci., 21, 2149–2167, https://doi.org/10.5194/os-21-2149-2025,https://doi.org/10.5194/os-21-2149-2025, 2025
Short summary
Le Liu, Michael Schindelegger, Lara Börger, Judith Foth, and Junyang Gou
Le Liu, Michael Schindelegger, Lara Börger, Judith Foth, and Junyang Gou

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Short summary
As seawater is moved about by the different types of ocean flow, the pressure at the ocean bottom changes with time and location. We show that such bottom pressure variations are represented reasonably well by high-resolution climate models and that in some regions, like the Arctic Ocean, the intensity of the pressure fluctuations will likely increase under global warming. These insights are useful for the design of future satellite missions that will track mass variations in the Earth system.
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