add default get_field methods

NEWS.md

@@ -6,6 +6,12 @@ ClimaCoupler.jl Release Notes
 
 ### ClimaCoupler features
 
+#### Add default `get_field` methods for surface models PR[#1210](https://github.com/CliMA/ClimaCoupler.jl/pull/1210)
+Add default methods for `get_field` methods that are commonly
+not extended for surface models. These return reasonable default
+values, and can be extended by surface models that won't use the
+defaults (e.g. the full land model).
+
 #### Add coupler fields based on simulation type PR[#1207](https://github.com/CliMA/ClimaCoupler.jl/pull/1207)
 Previously, the coupler fields were hardcoded to be the same for all
 simulations, independent of what components were included. Now, each

docs/src/interfacer.md

@@ -118,23 +118,22 @@ extrapolated to the surface, with units of [kg m^-3].
 ### SurfaceModelSimulation - required functions
 Analogously to the `AtmosModelSimulation`, a `SurfaceModelSimulation`
 requires additional functions to those required for a general `ComponentModelSimulation`.
-- `get_field(::SurfaceModelSimulation. ::Val{property})`: This getter
+- `get_field(::SurfaceModelSimulation, ::Val{property})`: This getter
 function returns the value of the field property for the simulation at
 the current time. For a `SurfaceModelSimulation`, it must be extended
 for the following properties:
 
 | Coupler name      | Description | Units |
 |-------------------|-------------|-------|
 | `area_fraction`     | fraction of the simulation grid surface area this model covers | |
-| `beta`              | factor that scales evaporation based on its estimated level of saturation | |
 | `roughness_buoyancy` | aerodynamic roughness length for buoyancy | m |
 | `roughness_momentum` | aerodynamic roughness length for momentum | m |
 | `surface_direct albedo`    | bulk direct surface albedo | |
 | `surface_diffuse albedo`    | bulk diffuse surface albedo | |
 | `surface_humidity`  | surface humidity | kg kg^-1 |
 | `surface_temperature` | surface temperature | K |
 
-- `update_field!(::SurfaceModelSimulation. ::Val{property}, field)`:
+- `update_field!(::SurfaceModelSimulation, ::Val{property}, field)`:
 A function to update the value of property in the component model
 simulation, using the values in `field` passed from the coupler
 This update should be done in place. If this function
@@ -157,6 +156,18 @@ following properties:
 | `surface_diffuse_albedo`    | bulk diffuse surface albedo; needed if calculated externally of the surface model (e.g. ocean albedo from the atmospheric state) | |
 
 ### SurfaceModelSimulation - optional functions
+- `get_field(::SurfaceModelSimulation, ::Val{property})`:
+For some quantities, default `get_field` functions are provided, which may be
+overwritten or used as-is. These currently include the following:
+
+| Coupler name      | Description | Units | Default value |
+|-------------------|-------------|-------|---------------|
+| `beta` | factor that scales evaporation based on its estimated level of saturation | | 1 |
+| `emissivity` | measure of how much energy a surface radiates | | 1 |
+| `height_disp` | displacement height relative to the surface | m | 0 |
+| `energy` | globally integrated energy | J | `nothing` |
+| `water` | globally integrated water | kg | `nothing` |
+
 - `update_turbulent_fluxes!(::ComponentModelSimulation, fields::NamedTuple)`:
 This function updates the turbulent fluxes of the component model simulation
 at this point in horizontal space. The values are updated using the energy
@@ -176,13 +187,11 @@ the cache variables specified as:
 ```
 get_field(sim::AbstractSurfaceStub, ::Val{:area_fraction}) = sim.cache.area_fraction
 get_field(sim::AbstractSurfaceStub, ::Val{:beta}) = sim.cache.beta
-get_field(sim::AbstractSurfaceStub, ::Val{:energy}) = nothing
 get_field(sim::AbstractSurfaceStub, ::Val{:roughness_buoyancy}) = sim.cache.z0b
 get_field(sim::AbstractSurfaceStub, ::Val{:roughness_momentum}) = sim.cache.z0m
 get_field(sim::AbstractSurfaceStub, ::Union{Val{:surface_direct_albedo}, Val{:surface_diffuse_albedo}}) = sim.cache.α
 get_field(sim::AbstractSurfaceStub, ::Val{:surface_humidity}) = TD.q_vap_saturation_generic.(sim.cache.thermo_params, sim.cache.T_sfc, sim.cache.ρ_sfc, sim.cache.phase)
 get_field(sim::AbstractSurfaceStub, ::Val{:surface_temperature}) = sim.cache.T_sfc
-get_field(sim::AbstractSurfaceStub, ::Val{:water}) = nothing
 ```
 and with the corresponding `update_field!` functions
 ```

experiments/ClimaEarth/components/ocean/eisenman_seaice.jl

@@ -93,7 +93,6 @@ end
 
 # extensions required by Interfacer
 Interfacer.get_field(sim::EisenmanIceSimulation, ::Val{:area_fraction}) = sim.integrator.p.area_fraction
-Interfacer.get_field(sim::EisenmanIceSimulation, ::Val{:beta}) = convert(eltype(sim.integrator.u), 1.0)
 Interfacer.get_field(sim::EisenmanIceSimulation, ::Val{:roughness_buoyancy}) =
     @. sim.integrator.p.params.p_i.z0b * (sim.integrator.p.ice_area_fraction) +
        sim.integrator.p.params.p_o.z0b .* (1 - sim.integrator.p.ice_area_fraction)
@@ -105,7 +104,6 @@ Interfacer.get_field(sim::EisenmanIceSimulation, ::Union{Val{:surface_direct_alb
        sim.integrator.p.params.p_o.α .* (1 - sim.integrator.p.ice_area_fraction)
 Interfacer.get_field(sim::EisenmanIceSimulation, ::Val{:surface_humidity}) = sim.integrator.u.q_sfc
 Interfacer.get_field(sim::EisenmanIceSimulation, ::Val{:surface_temperature}) = sim.integrator.u.T_sfc
-Interfacer.get_field(sim::EisenmanIceSimulation, ::Val{:water}) = nothing
 
 """
     Interfacer.get_field(sim::EisenmanIceSimulation, ::Val{:energy})

experiments/ClimaEarth/components/ocean/prescr_seaice.jl

@@ -155,14 +155,12 @@ end
 
 # extensions required by Interfacer
 Interfacer.get_field(sim::PrescribedIceSimulation, ::Val{:area_fraction}) = sim.integrator.p.area_fraction
-Interfacer.get_field(sim::PrescribedIceSimulation, ::Val{:beta}) = convert(eltype(sim.integrator.u), 1.0)
 Interfacer.get_field(sim::PrescribedIceSimulation, ::Val{:roughness_buoyancy}) = sim.integrator.p.params.z0b
 Interfacer.get_field(sim::PrescribedIceSimulation, ::Val{:roughness_momentum}) = sim.integrator.p.params.z0m
 Interfacer.get_field(sim::PrescribedIceSimulation, ::Union{Val{:surface_direct_albedo}, Val{:surface_diffuse_albedo}}) =
     sim.integrator.p.params.α
 Interfacer.get_field(sim::PrescribedIceSimulation, ::Val{:surface_humidity}) = sim.integrator.p.q_sfc
 Interfacer.get_field(sim::PrescribedIceSimulation, ::Val{:surface_temperature}) = sim.integrator.u.T_sfc
-Interfacer.get_field(sim::PrescribedIceSimulation, ::Val{:water}) = nothing
 
 """
     Interfacer.get_field(sim::PrescribedIceSimulation, ::Val{:energy})

experiments/ClimaEarth/components/ocean/slab_ocean.jl

@@ -108,14 +108,12 @@ end
 
 # extensions required by Interfacer
 Interfacer.get_field(sim::SlabOceanSimulation, ::Val{:area_fraction}) = sim.integrator.p.area_fraction
-Interfacer.get_field(sim::SlabOceanSimulation, ::Val{:beta}) = convert(eltype(sim.integrator.u), 1.0)
 Interfacer.get_field(sim::SlabOceanSimulation, ::Val{:roughness_buoyancy}) = sim.integrator.p.params.z0b
 Interfacer.get_field(sim::SlabOceanSimulation, ::Val{:roughness_momentum}) = sim.integrator.p.params.z0m
 Interfacer.get_field(sim::SlabOceanSimulation, ::Val{:surface_direct_albedo}) = sim.integrator.p.α_direct
 Interfacer.get_field(sim::SlabOceanSimulation, ::Val{:surface_diffuse_albedo}) = sim.integrator.p.α_diffuse
 Interfacer.get_field(sim::SlabOceanSimulation, ::Val{:surface_humidity}) = sim.integrator.p.q_sfc
 Interfacer.get_field(sim::SlabOceanSimulation, ::Val{:surface_temperature}) = sim.integrator.u.T_sfc
-Interfacer.get_field(sim::SlabOceanSimulation, ::Val{:water}) = nothing
 
 """
     Interfacer.get_field(sim::SlabOceanSimulation, ::Val{:energy})

src/Interfacer.jl

@@ -155,7 +155,6 @@ an atmosphere component model.
 get_field(
     sim::AtmosModelSimulation,
     val::Union{
-        Val{:energy},
         Val{:height_int},
         Val{:height_sfc},
         Val{:liquid_precipitation},
@@ -166,7 +165,6 @@ get_field(
         Val{:turbulent_moisture_flux},
         Val{:thermo_state_int},
         Val{:uv_int},
-        Val{:water},
     },
 ) = get_field_error(sim, val)
 
@@ -181,7 +179,6 @@ get_field(
     sim::SurfaceModelSimulation,
     val::Union{
         Val{:area_fraction},
-        Val{:beta},
         Val{:roughness_buoyancy},
         Val{:roughness_momentum},
         Val{:surface_direct_albedo},
@@ -200,6 +197,13 @@ get_field(sim::ComponentModelSimulation, val::Val) = get_field_error(sim, val)
 
 get_field_error(sim, val::Val{X}) where {X} = error("undefined field `$X` for " * name(sim))
 
+# Set default values for fields that are not defined in all component models
+get_field(sim::ComponentModelSimulation, ::Val{:beta}) = convert(eltype(sim.integrator.u), 1.0)
+get_field(sim::ComponentModelSimulation, ::Val{:emissivity}) = convert(eltype(sim.integrator.u), 1.0)
+get_field(sim::ComponentModelSimulation, ::Val{:height_disp}) = convert(eltype(sim.integrator.u), 0.0)
+get_field(::ComponentModelSimulation, ::Val{:energy}) = nothing
+get_field(::ComponentModelSimulation, ::Val{:water}) = nothing
+
 """
     update_field!(::AtmosModelSimulation, ::Val, _...)
 

src/surface_stub.jl

@@ -43,7 +43,6 @@ get_field(sim::AbstractSurfaceStub, ::Val{:surface_diffuse_albedo}) = sim.cache.
 get_field(sim::AbstractSurfaceStub, ::Val{:surface_humidity}) =
     TD.q_vap_saturation_generic.(sim.cache.thermo_params, sim.cache.T_sfc, sim.cache.ρ_sfc, sim.cache.phase)
 get_field(sim::AbstractSurfaceStub, ::Val{:surface_temperature}) = sim.cache.T_sfc
-get_field(sim::AbstractSurfaceStub, ::Val{:water}) = nothing
 
 """
     update_field!(sim::AbstractSurfaceStub, ::Val{:area_fraction}, field::CC.Fields.Field)

test/interfacer_tests.jl

@@ -133,7 +133,6 @@ end
     # Test that get_field gives correct warnings for unextended fields
     for value in (
         :area_fraction,
-        :beta,
         :roughness_buoyancy,
         :roughness_momentum,
         :surface_direct_albedo,
@@ -156,7 +155,6 @@ end
 
     # Test that get_field gives correct warnings for unextended fields
     for value in (
-        :energy,
         :height_int,
         :height_sfc,
         :liquid_precipitation,
@@ -167,7 +165,6 @@ end
         :turbulent_moisture_flux,
         :thermo_state_int,
         :uv_int,
-        :water,
     )
         val = Val(value)
         @test_throws ErrorException("undefined field `$value` for " * Interfacer.name(sim)) Interfacer.get_field(