single column

description

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 Ekman solution under wind forcing
Testing the Ideal Age tracer under surface forcing
Testing the Coriolis term by quantifying the inertial frequency
Testing K-profile parameterization (KPP) boundary-layer regimes under wind, cooling, evaporation, Langmuir enhancement and sea ice; see KPP regimes.
Comparing Omega’s penetrating-shortwave-radiation scheme against surface-absorbed shortwave heating
Comparing penetrating-shortwave-radiation schemes across Jerlov water types

suppported models

All but the ideal age task support MPAS-Ocean and Omega, whereas the ideal age task supports MPAS-Ocean only. The shortwave_pen task supports both models. MPAS-Ocean uses its two-band Jerlov scheme, while Omega runs both an equivalent configuration and a three-band Manizza configuration.

mesh

The mesh is planar and spans the minimum number of cells (16 for MPAS-Ocean). The config options lx and ly are given arbitrarily small values of 1 m in order to ensure that the minimum number of cells is chosen.

By virtue of testing the vertical dynamics, these tests should be insensitive to the horizontal resolution. As such, only 960 m horizontal resolution is currently supported.

vertical grid

Currently, these tests feature a very fine vertical resolution of 4 m with 100 vertical levels.

config options

# Options related to the vertical grid
[vertical_grid]

# the type of vertical grid
grid_type = uniform

# Number of vertical levels
vert_levels = 100

# Depth of the bottom of the ocean
bottom_depth = 400.0

# The type of vertical coordinate (e.g. z-level, z-star)
coord_type = z-star

# Whether to use "partial" or "full", or "None" to not alter the topography
partial_cell_type = None

# The minimum fraction of a layer for partial cells
min_pc_fraction = 0.1

initial conditions

The initial conditions are either stably stratified or uniform. See each task below.

forcing

Default values of no forcing are given here, which are then overwritten by the config options for various test cases. The rates for surface restoring are also given here, but are only used when the namelist options in forward.yaml turn surface restoring on.

# config options for forcing single column testcases
[single_column_forcing]

# Piston velocity to control rate of restoring toward temperature_surface_restoring_value
temperature_piston_velocity = 4.0e-6

# Piston velocity to control rate of restoring toward salinity_surface_restoring_value
salinity_piston_velocity = 4.0e-6

# Temperature to restore towards when surface restoring is turned on
temperature_surface_restoring_value = ${single_column:surface_temperature}

# Salinity to restore towards when surface restoring is turned on
salinity_surface_restoring_value = ${single_column:surface_salinity}

# Rate at which temperature is restored toward the initial condition
temperature_interior_restoring_rate = 1.0e-6

# Rate at which salinity is restored toward the initial condition
salinity_interior_restoring_rate = 1.0e-6

# Net latent heat flux applied when bulk forcing is used. Positive values indicate a net
# input of heat to ocean
latent_heat_flux = 0.0

# Net sensible heat flux applied when bulk forcing is used. Positive values indicate a
# net input of heat to ocean
sensible_heat_flux = 0.0

# Net solar shortwave heat flux applied when bulk forcing is used. Positive values
# indicate a net input of heat to ocean
shortwave_heat_flux = 0.0

# Net surface evaporation when bulk forcing is used. Positive values indicate a net
# input of water to ocean
evaporation_flux = 0.0

# Net surface rain flux when bulk forcing is used. Positive values indicate a net input
# of water to ocean
rain_flux = 0.0

# Net surface river runoff flux when bulk forcing is used. Positive values indicate a net
#flux of water to ocean
river_runoff_flux = 0.0

# Net surface subglacial runoff flux when bulk forcing is used. Positive values indicate a net
#flux of water to ocean
subglacial_runoff_flux = 0.0

# Net surface ice runoff flux when bulk forcing is used. Positive values indicate a net
#flux of water to ocean
ice_runoff_flux = 0.0

# Net iceberg freshwater flux when bulk forcing is used. Positive values indicate a net
#flux of water to ocean
iceberg_flux = 0.0

# Zonal surface wind stress over the domain
wind_stress_zonal = 0.0

# Meridional surface wind stress over the domain
wind_stress_meridional = 0.0

config options

# config options for single column testcases
[single_column]

# size of the domain (typically the minimum allowed size of 4x4 cells)
nx = 4
ny = 4

# resolution in km
resolution = 960.0

# Surface temperature
surface_temperature = 20.0

# Temperature gradient in the mixed layer in degC/m
temperature_gradient_mixed_layer = 0.0

# The temperature below the mixed layer
temperature_difference_across_mixed_layer = 0.0

# Temperature gradient below the mixed layer
temperature_gradient_interior = 0.0

# Depth of the temperature mixed layer
mixed_layer_depth_temperature =  0.0

# Surface salinity
surface_salinity = 35.0

# Salinity gradient in the mixed layer in PSU/m
salinity_gradient_mixed_layer = 0.0

# The salinity below the mixed layer
salinity_difference_across_mixed_layer = 0.0

# Salinity gradient below the mixed layer
salinity_gradient_interior = 0.0

# Depth of the salinity mixed layer
mixed_layer_depth_salinity = 0.0

# coriolis parameter
coriolis_parameter = 1.0e-4

See mesh section for a description of lx and ly and initial conditions section for a description of the remaining config options.

time step and run duration

The time step is given as 10 min and the barotropic time step is 30s in forward.yaml. The run duration is given in the forward.yaml file for each test case. Both can be changed after set-up by modifying the namelist file.

cores

Both default and minimum number of cores are hard-coded as 1 given that the domain is only 16 cells.

vmix stable

description

The vmix_stable test runs a series of forward steps with different namelist paramters to test out different vertical mixing options under stable stratification. The analysis step then compares the boundary layer depth for the forward step without Coriolis with the analytic solution from equation 35 of Van Roekel et al. (2018) https://doi.org/10.1029/2018MS001336

The temperature and salinity profiles after 10 days are shown here:

Parameter	Value
`NearIrFraction`	`rfac`
`NearIrCoeff`	`1 / depth1`
`RedFraction + BlueFraction`	`1 - rfac`
`Kred = Kblue`	`1 / depth2`

single column

description

suppported models

mesh

vertical grid

config options

initial conditions

forcing

config options

time step and run duration

cores

vmix stable

description

mesh

vertical grid

initial conditions

forcing

time step and run duration

config options

cores

ekman

description

mesh

vertical grid

initial conditions

forcing

time step and run duration

config options

cores

ideal age

description

mesh

vertical grid

initial conditions

forcing

time step and run duration

config options

cores

inertial

description

mesh

vertical grid

initial conditions

forcing

time step and run duration

config options

cores

KPP regimes

description

supported models

mesh

vertical grid

initial conditions

forcing

time step and run duration

config options

cores

output and interpretation

kpp_wind

kpp_convection_cooling

kpp_combined

kpp_non_local_flux_suppression

kpp_langmuir

kpp_sea_ice

kpp_convection_evaporation

kpp_cooling_with_mixedlayer

kpp_strong_convection_cooling

thermo

description

mesh

vertical grid

initial conditions

forcing

time step and run duration

config options

cores

shortwave_pen

description

mesh

vertical grid