## 3 Simulation Conditions  
Figure 1 shows the target area of the present simulations near the southeastern coast of Korea, where one of the candidate sites for CO\({}_{2}\) ocean geological storage is located. The data for inland and seafloor topographies were obtained from the Global 30 Arc-Second Elevation Dataset (GTOPO30) of the United States Geological Survey's Earth Resources Observation and Science Center and the JODC-Expert Grid Data for Geography-500m (J-EGG500) of the Japan Oceanographic Data Center, respectively. Grid systems for the mesoscale domain were generated using the preprocessor of the MEC model with these data. The dimensions of the computational domain were approximately  
Figure 3 shows the initial conditions of T, S, and DCO2 obtained from the data of the Array for Real-time Geostrophic Oceanography project by the National Institute of Meteorological Sciences of Korea ([[http://argo.nims.go.kr](http://argo.nims.go.kr)]([http://argo.nims.go.kr](http://argo.nims.go.kr))).  
To calculate the fluxes of temperature and salinity at the free surface, climate data, which were the temporal average of observed data by the National Aeronautics and Space Administration (NASA, [[https://power.larc.nasa.gov/data-access-viewer/](https://power.larc.nasa.gov/data-access-viewer/)]([https://power.larc.nasa.gov/data-access-viewer/](https://power.larc.nasa.gov/data-access-viewer/))), were used, as depicted in Table 3.  
The leakage rate and initial diameter of the CO2 bubble were selected as the main parameters. The assumed leakage rates for the present study were 3800, 50,000, and 100,000 t/y, based on the study of [PERSON] et al. [11], where two cases for the leakage rate were studied: an extreme case, 94,600 t/y, which assumed that a large fault accidentally connected the CO2 reservoir and the seafloor; and a reasonable case, 3800 t/y, based on the seepage rate of an existing enhanced oil recovery (EOR) site [22]. The initial diameters of the CO2 bubble were set to 5, 10, and 20 mm. The simulation cases and leakage are listed and illustrated in Table 4 and Figure 4, respectively.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Tidal Components** & **Period (h)** & **Amplitude (m)** & **Phase (\({}^{\circ}\))** \\ \hline M2 & 12.42 & 0.0689 & 356.07 \\ O1 & 25.82 & 0.0522 & 182.96 \\ K1 & 23.93 & 0.0476 & 220.93 \\ S2 & 12.00 & 0.0386 & 102.91 \\ \hline \hline \end{tabular}
\end{table}
Table 2: Tidal components used for open boundary conditions.  
Figure 3: Initial conditions of (**a**) temperature, (**b**) salinity, and (**c**) DCO2.  
Quantitative criteria are needed to assess the environmental impact when CO\({}_{2}\) leakage occurs. [PERSON] et al. [23] elucidated that the biological impacts of CO\({}_{2}\) in the ocean should not be related solely to pH, but also to the partial pressure of CO\({}_{2}\) (pCO\({}_{2}\)). [PERSON] and [PERSON] [24] collected LC50 and LT50 data against pCO\({}_{2}\) for various marine species and proposed that the change in pCO\({}_{2}\) (\(\Delta\)pCO\({}_{2}\)) of 5000 ppm is the no-observed effect concentration (NOEC) and that 500 ppm is the predicted no-effect concentration (PNEC). Although these values have not been authorized, we refer to them as tentative standards in this study.