polaris.mesh.spherical.unified.effective_ocean.build_effective_ocean_mask

polaris.mesh.spherical.unified.effective_ocean.build_effective_ocean_mask(candidate_fraction, shared_ocean_mask, ocean_background, lat, lon, resolution, land_blockages=None, passages=None, seed_points=None, grow_threshold=0.35, passage_widen_factor=1.5, passage_widen_factor_high_lat=3.0, passage_widen_latitude_threshold=43.0)[source]

Build the effective ocean mask by emulating the MPAS cull.

Parameters:

  • candidate_fraction (numpy.ndarray) – The candidate-ocean area fraction on the sizing grid (the conservative average of the source ocean mask, the same quantity that becomes ocean_frac on the MPAS mesh), with dimensions (lat, lon)

  • shared_ocean_mask (numpy.ndarray) – The flood-filled ocean mask from the shared coastline products on the same grid

  • ocean_background (numpy.ndarray) – The ocean background cell width in km on the same grid

  • lat (numpy.ndarray) – The latitude coordinate in degrees

  • lon (numpy.ndarray) – The longitude coordinate in degrees

  • resolution (float) – The grid resolution in degrees

  • land_blockages (numpy.ndarray, optional) – A boolean mask of rasterized critical land blockages (removed from the emulated ocean)

  • passages (numpy.ndarray, optional) – A boolean mask of rasterized critical ocean passages (widened and added to the emulated ocean)

  • seed_points (list of tuple, optional) – (lon, lat) seed points in degrees for the flood fill; if None, no flood fill is performed and all mesh-scale ocean is retained

  • grow_threshold (float, optional) – The hysteresis lower bound on the candidate fraction (< 0.5); connected regions above this threshold that touch the strict flood-filled ocean are added, covering cells whose fate at the strict 0.5 threshold depends on the exact MPAS cell tiling

  • passage_widen_factor (float, optional) – The passage swath width in units of the local ocean background cell width

  • passage_widen_factor_high_lat (float, optional) – The passage swath width factor poleward of passage_widen_latitude_threshold (mimicking widen_transect_edge_masks in the MPAS cull)

  • passage_widen_latitude_threshold (float, optional) – The latitude in degrees poleward of which passage_widen_factor_high_lat applies

Returns:

fields (dict of str to numpy.ndarray) – 'effective_ocean_mask': the union of the shared and emulated ocean masks; 'emulated_ocean_mask': the flood-filled, hysteresis-grown mesh-scale ocean mask; 'mesh_scale_fraction': the mesh-scale candidate fraction; 'passages_widened': the widened passage mask