Topography generation

ACCESS-OM3 Topography Workflow

Introduction

The supported ACCESS-OM3 configurations now use a topography based on the GEBCO2024 global topography dataset. This dataset maintains a high resolution of 15 arc-seconds (i.e., 1/240 deg = ~460m at the equator and finer zonally near the poles).

Bathymetry Tools

The workflow described below uses bathymetry-tools to perform specific tasks, such as removing seas or generating the land/sea mask. Instructions to install bathymetry-tools can be found here.

General Workflow

The general workflow for generating the OM3 topography and corresponding land/sea masks is as follows:

1. Interpolate GEBCO2024 data onto the model grid.
2. Adjust C-grid connectivity using the deseas algorithm to ensure marginal seas with 1-cell-wide outlets (e.g., Gibraltar) remain connected to the ocean.
3. Remove T cells that are smaller than the given threshold.
4. Fill cells with a sea area fraction smaller than 0.5.
5. Apply manual topography edits using editTopo.py.
6. Remove isolated seas.
7. Apply minimum and maximum allowed ocean depths.
8. Generate the land/sea mask from the topography.
9. Generate additional necessary model input files, such as ESMF meshes and runoff remapping weights.

This workflow assumes that a horizontal super-grid has already been created and that the model uses a C-grid. Some manual editing may still be necessary to refine the topography.

For a complete workflow and instructions on generating OM3 topography, refer to the make_OM3_025deg_topo repository.