Assessment of ocean bottom pressure variations in CMIP6 HighResMIP simulations
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2025-10-01
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Journal Article
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yes
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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 in future pb variance by ∼ 30 %–50 % across deep Arctic basins and the southern South Atlantic. The strengthening appears to be linked to projected changes in high-latitude surface winds and, in the case of the South Atlantic, intensified eddy kinetic energy. 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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published
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21 (5)
Pages / Article No.
2149 - 2167
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Copernicus
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09707 - Soja, Benedikt / Soja, Benedikt