Framework

The e3sm/init component includes a small amount of shared framework code in polaris.e3sm.init.topo. This framework defines supported source-topography resolutions and helper functions used by e3sm/init tasks and by other components that need the same resolution logic.

Supported Resolutions

The supported cubed-sphere resolutions are collected in CUBED_SPHERE_RESOLUTIONS:

3000, the standard high-resolution source-topography product
120, the lower-cost source-topography product for coarse workflows

The supported latitude-longitude resolutions are collected in LAT_LON_RESOLUTIONS:

1.0
0.25
0.125
0.0625
0.03125

Resolution Naming

The helper format_lat_lon_resolution_name() converts a latitude-longitude resolution in degrees into the directory naming convention used throughout Polaris. It formats the resolution with LAT_LON_RESOLUTION_DECIMALS = 5 decimal places and appends _degree.

Examples:

1.0 becomes 1.00000_degree
0.125 becomes 0.12500_degree
0.03125 becomes 0.03125_degree

Cubed-Sphere Resolution Selection

The helper get_cubed_sphere_resolution(low_res) returns either STANDARD_CUBED_SPHERE_RESOLUTION or LOW_RES_CUBED_SPHERE_RESOLUTION.

The helper uses_low_res_cubed_sphere(cell_width) encapsulates the current selection rule for MPAS base meshes. It returns True when cell_width is at least LOW_RES_BASE_MESH_CELL_WIDTH, currently 120.0 km.

This separation keeps shared resolution logic in the component framework rather than in polaris.tasks.e3sm.init, which allows mesh and ocean workflows to reuse the same supported-resolution definitions.