single_column

The single column tests in polaris.tasks.ocean.single_column exercise the vertical dynamics of the ocean model only. The test cases are:

Testing the vertical mixing library, CVMix, under surface forcing
Testing the Ideal Age tracer under surface forcing
Testing the Coriolis term by quantifying the inertial frequency
Testing the Ekman solution under wind forcing

Here, we describe the tests and their shared framework.

framework

The shared config options for the single_column tests are described in single column in the User’s Guide.

Additionally, the tests share a forward.yaml file with a few common model config options related to the initial state, coriolis forcing, run duration and surface forcing, as well as defining mesh, input, restart, and output, streams.

init

The class polaris.tasks.ocean.single_column.init.Init defines a step for setting up the initial state for each test case.

4×4 planar hex mesh is generated for this task using mpas_tools.planar_hex.make_planar_hex_mesh(). The number of cells in each dimension can be modified with config options single_column:nx, single_column:ny. By default, the mesh is 960 m in horizontal resolution and is not intended to resolve any lateral gradients. The horizontal resolution can be modified with config option single_column:resolution

A vertical grid is generated, with 100 layers of 4 m thickness each by default.

The initial temperature and salinity field are computed with variability in the vertical dimension only. The config options that determine these profiles are located in section single_column and include:

Option	Description
`surface_temperature`, `surface_salinity`	Initial surface values
`temperature_gradient_mixed_layer`, `salinity_gradient_mixed_layer`	Gradients within the mixed layer
`temperature_difference_across_mixed_layer`, `salinity_difference_across_mixed_layer`	Profile discontinuity across the mixed layer
`temperature_gradient_interior`, `salinity_gradient_interior`	Interior (below mixed layer) gradients
`mixed_layer_depth_temperature`, `mixed_layer_depth_salinity`	Mixed layer depths (typically ~40 m)

For cases with ideal age tracers, an initial profile for the ideal age tracer is also constructed and is equal to zero seconds throughout the column.

A forcing netCDF file is also created based on the config options given in the single_column_forcing section. A subset of those options are:

Option	Description
`temperature_piston_velocity`, `salinity_piston_velocity`	Surface restoring rates
`temperature_surface_restoring_value`, `salinity_surface_restoring_value`	Target surface values
`temperature_interior_restoring_rate`, `salinity_interior_restoring_rate`	Interior restoring rates
`latent_heat_flux`, `sensible_heat_flux`, `shortwave_heat_flux`	Surface heat flux components
`evaporation_flux`, `rain_flux`	Surface freshwater fluxes
`wind_stress_zonal`, `wind_stress_meridional`	Wind stress values

forward

The class polaris.tasks.ocean.single_column.forward.Forward defines a step for running MPAS-Ocean from the initial condition produced in the init step. The ocean model is run.

viz

The class polaris.tasks.ocean.single_column.viz.Viz produces figures comparing the initial and final profiles of temperature and salinity.

cvmix

The polaris.tasks.ocean.single_column.cvmix.CVMix test performs a 10-day run on 1 cores. Then, validation of temperature, salinity, layerThickness and normalVelocity are performed against a baseline if one is provided when calling polaris setup.

ekman

The polaris.tasks.ocean.single_column.cvmix.CVMix test performs a 5-day run on 1 cores. Then, validation of temperature, salinity, layerThickness and normalVelocity are performed against a baseline if one is provided when calling polaris setup.

ideal age

The polaris.tasks.ocean.single_column.cvmix.IdealAge test performs the same 10-day run on 1 cores as the polaris.tasks.ocean.single_column.cvmix.CVMix test, but with a single ideal age tracer included. An additional forward.yaml file is included in the ideal age tracer test case for enabeling on the ideal age tracers and ideal age surface forcing, as well as for defining idealAgeTracers streams. Validation of temperature, salinity, and idealAgeTracers are performed against a baseline if one is provided when calling polaris setup.

inertial

The polaris.tasks.ocean.single_column.inertial.Inertial test performs a 10-day run on 1 cores. Then, validation of temperature, salinity, layerThickness and normalVelocity are performed against a baseline if one is provided when calling polaris setup. Then, the analysis step is run, and the viz step is optionally run.

analysis

The polaris.tasks.ocean.single_column.inertial.analysis.Analysis compares the inertial frequency with its theoretical value and induces a failure if the frequency is more than a given fractional difference from theory, as determined by the config option single_column_inertial:period_tolerance_fraction.