Testing Air–Sea Equilibration Timescales: Resolution Dependence and Advancing Modelling Tools to Constrain Marine CDR Effectiveness
Yinghuan Xie
Most Marine Carbon Dioxide Removal (mCDR) methods rely on creating a deficit in seawater CO2 concentrations and partial pressure (pCO2), quantified as a deficit in dissolved inorganic carbon (DIC). This DIC deficit drives atmospheric CO2 uptake or reduces CO2 outgassing.
The success of mCDR depends on efficient air-sea CO2 equilibration before the DIC deficit becomes isolated from the atmosphere through water mass subduction. Since equilibration spans vast ocean regions, in situ measurements are impractical, making numerical modeling essential.
This study utilizes the ACCESS-OM2 model at three resolutions (0.1°, 0.25°, and 1°) to investigate how equilibration timescales vary with resolution, ranging from noneddying to eddy-rich. Inter-model comparisons with CESM2 and ECCO indicate that model resolution has limited impact in the tropics but a stronger influence in polar regions. Furthermore, intra-model differences (due to resolution) are smaller than inter-model differences.
To improve accessibility, we introduce a computationally inexpensive virtual particle tracking method. This innovative approach offers a low-cost alternative to traditional, HPC-dependent ocean modeling, enabling easier testing of air-sea equilibration timescales,particularly for non-specialists.
These findings advance model-based assessments of air-sea CO2 equilibration timescales and provide a practical, accessible tool for enhancing mCDR effectiveness.
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