debug land albedo regridding

[juliasloan25]

Purpose

see #764 description and thread for details

what we know:

• changing the regridder_type passed to the albedo constructor between InterpolationRegridder and TempestRegridder changes the quality of the plot produced (only tempest is messed up)
• tempest produces an unrealistic plot for both the temporal and static maps,
  • this is true whether we use a space constructed with spacefillingcurve in ClimaCoupler or not

To-do

Content

Plots

• AMIP and slabplanet look the same
• plot looks the same after init and after 1day simulation
• mostly using slabplanet_temporal_map.yml config with h_elem: 16, but tested with AMIP too

Interpolations regridder

Tempest regridder

looks the same with or without spacefillingcurve in ClimaCoupler

Static map

Interpolation regridder

Tempest regridder

---

• I have read and checked the items on the review checklist.

[Sbozzolo]

The problem is in boundary_space somehow. I created a horzspace from scratch from the coupler and it works. What I noticed is that the boundary_space mesh has a different elemorder compared to a fresh horzspace

julia> boundary_space.grid.topology.elemorder
2400-element Vector{CartesianIndex{3}}:
 CartesianIndex(1, 1, 1)
.....

julia> horzspace.grid.topology.elemorder
CartesianIndices((20, 20, 6))

These are not equivalent.

Interestingly,

julia> extrema(parent(good) .- parent(bad))
(0.0, 0.0)

where good and bad are albedo obtained using horzspace or boundary_space respectively.

[juliasloan25]

The problem is in boundary_space somehow. I created a horzspace from scratch from the coupler and it works. What I noticed is that the boundary_space mesh has a different elemorder compared to a fresh horzspace

julia> boundary_space.grid.topology.elemorder
2400-element Vector{CartesianIndex{3}}:
 CartesianIndex(1, 1, 1)
.....

julia> horzspace.grid.topology.elemorder
CartesianIndices((20, 20, 6))

These are not equivalent.

Interestingly,

julia> extrema(parent(good) .- parent(bad))
(0.0, 0.0)

where good and bad are albedo obtained using horzspace or boundary_space respectively.

ClimaAtmos and ClimaCoupler both create spaces using a spacefillingcurve (e.g. here in ClimaCoupler.Regridder), whereas ClimaLand and ClimaUtilities both create spaces without a spacefillingcurve (e.g. here in ClimaUtilities.TempestRegridder). This is why the two spaces have different element orders.

I had to add a TempestRemap GPU workaround in ClimaLand to force the regridding to happen on the CPU (this involves creating a new CPU context and space), and I noticed that if I created the undistributed space with a spacefillingcurve, space_distributed == space_undistributed was not true. This is why ClimaLand (and ClimaUtilities) don't use the spacefillingcurve. We should unify this across all repos, but I'm not sure which approach we should take

[juliasloan25]

resolved - see #764