Improve CAM_SE hyperdiff robustness and update cases

that use ClimaHyperdiffusion to be consistent

Author: Julians42

config/default_configs/default_config.yml

@@ -29,10 +29,10 @@ z_max:
   value: 30000.0
 vorticity_hyperdiffusion_coefficient:
   help: "Hyperdiffusion coefficient for vorticity (m s-1)"
-  value: 1.5
+  value: 0.1857
 scalar_hyperdiffusion_coefficient:
   help: "Hyperdiffusion coefficient for scalar (m s-1)"
-  value: 1.5
+  value: 0.929738
 # Topography
 topography:
   help: "Define the surface elevation profile [`NoWarp` (default), `Earth`, `DCMIP200`, `Hughes2023`, `Agnesi`, `Schar`, `Cosine2D`, `Cosine3D`]"
@@ -152,7 +152,7 @@ vert_diff:
   help: "Vertical diffusion [`false` (default), `VerticalDiffusion`, `true` (defaults to `VerticalDiffusion`), `DecayWithHeightDiffusion`]"
   value: false
 hyperdiff:
-  help: "Hyperdiffusion [`ClimaHyperdiffusion` (or `true`), `CAM_SE` (default), `none` (or `false`)]"
+  help: "Hyperdiffusion. Use `CAM_SE` for sensible default values and ClimaHyperdiffusion for user control. [`CAM_SE` (default), `ClimaHyperdiffusion` (or `true`), `none` (or `false`)]"
   value: "CAM_SE"
 smagorinsky_lilly:
   help: "Smagorinsky-Lilly diffusive closure [`false` (default), `true`]"
@@ -177,7 +177,7 @@ moist:
   value: "dry"
 divergence_damping_factor:
   help: "Divergence damping factor"
-  value: 1.0
+  value: 5.0
 rayleigh_sponge:
   help: "Rayleigh sponge [`true`, `false` (default)]"
   value: false

config/model_configs/baroclinic_wave_topography_dcmip_rs.yml

@@ -6,6 +6,9 @@ initial_condition: "DryBaroclinicWave"
 t_end: "6days"
 dt: "200secs"
 hyperdiff: "ClimaHyperdiffusion"
+vorticity_hyperdiffusion_coefficient: 1.5
+scalar_hyperdiffusion_coefficient: 1.5
+divergence_damping_factor: 1.0
 disable_surface_flux_tendency: true
 netcdf_output_at_levels: false
 diagnostics:

src/solver/model_getters.jl

@@ -66,17 +66,27 @@ function get_hyperdiffusion_model(parsed_args, ::Type{FT}) where {FT}
             ν₄_scalar_coeff,
             divergence_damping_factor,
         )
-    elseif hyperdiff_name in ("CAM_SE",)
+    elseif hyperdiff_name == "CAM_SE"
         # To match hyperviscosity coefficients in:
         #    https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2017MS001257
         #    for equation A18 and A19
         # Need to scale by (1.1e5 / (sqrt(4 * pi / 6) * 6.371e6 / (3*30)) )^3  ≈ 1.238
-        @info "Using CAM_SE hyperdiffusion. vorticity_hyperdiffusion_coefficient, \
-               scalar_hyperdiffusion_coefficient and divergence_damping_factor in the config \
-               will be ignored."
+        # These are re-scaled by the grid resolution in function ν₄(hyperdiff, Y)
         ν₄_vorticity_coeff = FT(0.150 * 1.238)
         ν₄_scalar_coeff = FT(0.751 * 1.238)
         divergence_damping_factor = FT(5)
+        # Ensure the user isn't trying to set the values manually from the config as CAM_SE defines a set of hyperdiffusion coefficients
+        coeff_pairs = [
+            (ν₄_vorticity_coeff, "vorticity_hyperdiffusion_coefficient"),
+            (ν₄_scalar_coeff, "scalar_hyperdiffusion_coefficient"),
+            (divergence_damping_factor, "divergence_damping_factor"),
+        ]
+
+        for (cam_coef, config_coef) in coeff_pairs
+            # check to machine precision
+            config_val = FT(parsed_args[config_coef])
+            @assert isapprox(cam_coef, config_val, atol = 1e-8) "CAM_SE hyperdiffusion overwrites $config_coef, use hyperdiff: ClimaHyperdiffusion to set this value manually in the config instead."
+        end
         return ClimaHyperdiffusion(;
             ν₄_vorticity_coeff,
             ν₄_scalar_coeff,

test/solver/model_getters.jl

@@ -4,22 +4,24 @@ import ClimaAtmos as CA
 
 @testset "Hyperdiffusion config" begin
     @info "CAM_SE (Special case of ClimaHyperdiffusion)"
+
+    # Test that CAM_SE uses the correct hardcoded coefficients
+    # These match the values from https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2017MS001257
     config = CA.AtmosConfig(
         Dict(
             "hyperdiff" => "CAM_SE",
-            "vorticity_hyperdiffusion_coefficient" => 0.2,
-            "scalar_hyperdiffusion_coefficient" => 99.0,
-            "divergence_damping_factor" => 99.0,
+            "vorticity_hyperdiffusion_coefficient" => 0.1857,
+            "scalar_hyperdiffusion_coefficient" => 0.929738,
+            "divergence_damping_factor" => 5.0,
         ),
-        job_id = "model3",
+        job_id = "test_hyperdiff_cam_se_args",
     )
+
     parsed_args = config.parsed_args
     FT = eltype(config)
     hyperdiff_model = CA.get_hyperdiffusion_model(parsed_args, FT)
-    # Coefficients are currently hardcoded in the CAM_SE type!!!
-    # Regardless of user specified coeffs above, the CAM_SE selection
-    # should override these coefficients to match values in
-    # https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2017MS001257
+
+    # Test that CAM_SE returns the correct coefficient values
     cam_se_ν₄_vort = FT(0.150 * 1.238)
     cam_se_ν₄_scalar = FT(0.751 * 1.238)
     cam_se_ν₄_dd = FT(5)
@@ -28,12 +30,28 @@ import ClimaAtmos as CA
     @test hyperdiff_model.ν₄_scalar_coeff == cam_se_ν₄_scalar
     @test hyperdiff_model.divergence_damping_factor == cam_se_ν₄_dd
 
+    @info "Test CAM_SE coefficient validation"
+    # Test that CAM_SE throws an error when user tries to set different coefficients
+    config_wrong = CA.AtmosConfig(
+        Dict(
+            "hyperdiff" => "CAM_SE",
+            "vorticity_hyperdiffusion_coefficient" => 0.18571, # deliberately wrong value
+            "scalar_hyperdiffusion_coefficient" => 0.929738,
+            "divergence_damping_factor" => 5.0,
+        ),
+        job_id = "test_hyperdiff_cam_se_wrong_args",
+    )
+    @test_throws AssertionError CA.AtmosSimulation(config_wrong)
+
     @info "Test unrecognized Hyperdiffusion scheme"
-    config = CA.AtmosConfig(
+    config_unknown = CA.AtmosConfig(
         Dict("hyperdiff" => "UnknownHyperdiffusion"),
-        job_id = "model4",
+        job_id = "test_unknown_hyperdiff",
+    )
+    parsed_args_unknown = config_unknown.parsed_args
+    FT = eltype(config_unknown)
+    @test_throws ErrorException CA.get_hyperdiffusion_model(
+        parsed_args_unknown,
+        FT,
     )
-    parsed_args = config.parsed_args
-    FT = eltype(config)
-    @test_throws ErrorException CA.get_hyperdiffusion_model(parsed_args, FT)
 end