Global numerical ocean model for stratification effects on tides

Global configuration of the MITgcm (Massachusetts Institute of Technology general circulation model) that allows users to reproduce selected results of the following study:

Opel. L., Schindelegger, M., Ray, R.D. (2024), A likely role for stratification in long-term changes of the global ocean tides, Communications Earth and Environment, submitted.

Contents: See README.txt

Specifications of the MITgcm setup:

• Global domain on LLC1080 (latitude-longitude-polar-cap grid, with 1080 points along one-quarter of the Earth’s circumference at the equator)
• z-coordinates, 59 vertical layers (6 m near the surface, 484 m at the deepest level)
• Equilibrium tidal forcing of four primary constituents (M₂, S₂, K₁, O₁) and the corresponding self-attraction and loading (SAL) tide
• 40-day integrations can be run with background stratification of a particular year (1993 to 2020)
• Input files provided: Background potential temperature and salinity (3D) for the year 2006, model bathymetry, equilibrium tide and SAL as pressure forcing
• Provenance of stratification data: GLORYS12 Version 1 (https://marine.copernicus.eu/access-data, product identifier GLOBAL_MULTIYEAR_PHY_001_030)

Additional content:

• Script to interpolate GLORYS data to model grid (both horizontally and vertically)
• Script to harmonically analyze hourly surface elevation output
• barotropic_M2_trends_1993_2020.nc: Barotropic M₂ amplitude, in-phase, and quadrature trends over 1993–2020 due to stratification changes (STR, modeled with the MITgcm on LLC1080) and sea level rise (SLR, from a barotropic model)
• baroclinic_M2_trends_1993_2020.nc: Baroclinic M₂ amplitude, in-phase, and quadrature trends over 1993–2020 due to stratification changes
• potential_energy_anomaly_trends_1993_2020.nc: Potential energy anomaly trends over 1993–2020 (trends deduced from GLORYS12 Version 1, https://doi.org/10.48670/moi-00021)
• M2_total_RMS_variability_1993_2020.nc: Total RMS variability of the M₂ tide over 1993–2020
• M2_trends_1993_2020_budget.xlsx: Table underlying Figure 7 in Opel et al. (2024), A likely role for stratification in long-term changes of the global ocean tides, Communications Earth and Environment

Contact: L.Opel (opel@igg.uni-bonn.de)