Geometric evaluators#
Evaluators that capture various aspects of the mesh geometry.
SurfaceElevation#
Evaluates the elevation (z-coordinate) and slope magnitude of a mesh.
“evaluator type” = “meshed elevation”
Evaluates the z-coordinate and the magnitude of the slope :math:|\nambla_h z|
meshed-elevation-evaluator-spec
“parent domain name”
[string]SUBSURFACE_DOMAIN Domain name of the parent mesh, which is the 3D version of this domain. Attempts to generate an intelligent default by stripping “surface” from this domain.“dynamic mesh”
[bool]false Lets the evaluator know that the elevation changes in time, and adds the “deformation” dependency.
MY KEYS:
“elevation” DOMAIN-elevation Name the elevation variable. [m]
“slope magnitude” DOMAIN-slope_magnitude Name the elevation variable. [-]
KEYS:
“deformation” optional If “dynamic mesh” == True, this is required to tell when the mesh has been deformed.
Elevation of a Column#
ElevationEvaluatorColumn: evaluates the elevation (z-coordinate) and slope magnitude of a mesh.
Evaluates elevation, slope, and aspect of the “surface_star” mesh of the Arctic Intermediate Scale Model (ISM).
Evaluates the z-coordinate and the magnitude of the slope :math:|\nambla_h
z| Note that this is evaluator is different from both the standard elevation
evaluator, which would take elevation/slope/aspect from the parent 3D mesh, and
from the standard “single cell” column mesh elevation, which can do the same.
Instead, it is a mix of:
elevation is aggregated from the column meshes’ top faces
slope is calculated using a cell-neighbor differencing scheme. Unlike 3D meshes, in the ISM, we deform columns of cells and so do not have faces. Therefore, we use all neighboring cells to compute an average normal for the cell, and use that to compute slope and aspect.
aspect is set to 0. It could easily be calculated using the same normal as the slope algorithm, but is not done currently.
“evaluator type” = “elevation column”
column-elevation-evaluator-spec
“elevation key”
[string]elevation Name the elevation variable. [m]“slope magnitude key”
[string]slope_magnitude Name the elevation variable. [-]“dynamic mesh”
[bool]false Lets the evaluator know that the elevation changes in time, and adds the “deformation” and “base_porosity” dependencies.“parent domain name”
[string]DOMAIN Domain name of the parent mesh, which is the 3D version of this domain. In the columnar meshes the surface elevation and slope are assigned based on the columns and not the base 3D domain.
Example:
<ParameterList name="surface_star-elevation">
<Parameter name="evaluator type" type="string" value="column elevation"/>
</ParameterList>
Depth Evaluator#
Computes depth, positive downward relative to the surface, of mesh cells.
Computes cell depths only.
Note that two algorithms for computing the depth are available:
“cell centroid” uses the cell centroid, as computed by the Mesh, directly.
“mean face centroid” is the default, as the cell centroid can have problems in the case of non-planar faces. Instead, it uses the mean of the above and below face centroids in place of the face centroid, with the implicit assumption that dz is uniform (e.g. this is an extruded mesh).
“evaluator type” = “depth”
depth-evaluator-spec
“algorithm”
[string]mean face centroid Valid is “mean face centroid” and “cell centroid”, see above.