Inputs

The ERF executable reads run-time information from an inputs file which you name on the command line. This section describes the inputs which can be specified either in the inputs file or on the command line. A value specified on the command line will override a value specified in the inputs file.

Problem Geometry

List of Parameters

Parameter

Definition

Acceptable Values

Default

geometry.prob_lo

physical location of low corner of the domain

Real

must be set

geometry.prob_hi

physical location of high corner of the domain

Real

must be set

geometry.is_periodic

is the domain periodic in this direction

0 if false, 1 if true

0 0 0

Examples of Usage

  • geometry.prob_lo = 0 0 0 defines the low corner of the domain at (0,0,0) in physical space.

  • geometry.prob_hi = 1.e8 2.e8 2.e8 defines the high corner of the domain at (1.e8,2.e8,2.e8) in physical space.

  • geometry.is_periodic = 0 1 0 says the domain is periodic in the y-direction only.

Domain Boundary Conditions

List of Parameters

Parameter

Definition

Acceptable Values

Default

xlo.type

boundary type of xlo face

must be set if not periodic

xhi.type

boundary type of xhi face

must be set if not periodic

ylo.type

boundary type of ylo face

must be set if not periodic

yhi.type

boundary type of yhi face

must be set if not periodic

zlo.type

boundary type of zlo face

must be set if not periodic

zhi.type

boundary type of zhi face

must be set if not periodic

Resolution

List of Parameters

Parameter

Definition

Acceptable Values

Default

amr.n_cell

number of cells in each direction at the coarsest level

Integer > 0

must be set

amr.max_level

number of levels of refinement above the coarsest level

Integer >= 0

must be set

amr.ref_ratio

ratio of coarse to fine grid spacing between subsequent levels

2 / 3 / 4 (one per level)

2 for all levels

amr.ref_ratio_vect

ratio of coarse to fine grid spacing between subsequent levels

3 integers (one per dir) 2 / 3 / 4

2 for all directions

amr.regrid_int

how often to regrid

Integer > 0 (if negative, no regridding)

-1

amr.regrid_on_restart

should we regrid immediately after restarting

0 or 1

0

amr.iterate_grids

do we iterate on the grids?

True, False

True

Note: if amr.max_level = 0 then you do not need to set amr.ref_ratio or amr.regrid_int.

Examples of Usage

  • amr.n_cell = 32 64 64

    would define the domain to have 32 cells in the x-direction, 64 cells in the y-direction, and 64 cells in the z-direction at the coarsest level.

  • amr.max_level = 2
    would allow a maximum of 2 refined levels in addition to the coarse level. Note that these additional levels will only be created only if the tagging criteria are such that cells are flagged as needing refinement. The number of refined levels in a calculation must be \(\leq\) amr.max_level, but can change in time and need not always be equal to amr.max_level.
  • amr.ref_ratio = 2 3
    would set factor 2 refinement between levels 0 and 1, and factor 3 refinement between levels 1 and 2. Note that you must have at least amr.max_level values of amr.ref_ratio (Additional values may appear in that line and they will be ignored).
  • amr.ref_ratio_vect = 2 4 3
    would set factor {2 in x-dir, 4 in y-dir, 3 in z-dir} refinement between all adjacent levels. Note that you must specify 3 values, one for each coordinate direction.
  • amr.regrid_int = 2 2
    tells the code to regrid every 2 steps. Thus in this example, new level-1 grids will be created every 2 level-0 time steps, and new level-2 grids will be created every 2 level-1 time steps.

Grid Stretching

This automatically activates erf.use_terrain. By default, the problem-specific terrain is initialized to be flat at an elevation of z=0. These inputs are used to automatically generate the staggered z levels used to calculate the grid metric transformation. Alternatively, arbitrary z levels may be specified with the erf.terrain_z_levels parameter, which should vary from 0 (at the surface) to the domain height.

List of Parameters

Parameter

Definition

Acceptable Values

Default

erf.grid_stretching_ratio

scaling factor applied to delta z at each level

Real > 1

0 (no grid stretching)

erf.initial_dz

vertical grid spacing for the cell above the bottom surface

Real > 0

must be set if grid stretching ratio is set

erf.terrain_z_levels

nominal staggered z levels

List of Real

NONE

Notes

  • If both erf.terrain_z_levels and erf.grid_stretching_ratio are specified, the simple grid stretching will be ignored.

  • The number of input erf.terrain_z_levels must be equal amr.n_cell in the z direction + 1.

Examples of Usage

  • erf.grid_stretching_ratio = 1.025

  • erf.initial_dz = 5.0
    the first cell center would be at z=2.5

Regridding

Overview

The user defines how to tag individual cells at a given level for refinement. This list of tagged cells is sent to a grid generation routine, which uses the Berger-Rigoutsos algorithm to create rectangular grids that contain the tagged cells.

See Mesh Refinement for more details on how to specify regions for refinement.

List of Parameters

Parameter

Definition

Acceptable Values

Default

amr.regrid_file

name of file from which to read the grids

text

no file

amr.grid_eff

grid efficiency at coarse level at which grids are created

Real > 0, < 1

0.7

amr.n_error_buf

radius of additional tagging around already tagged cells

Integer >= 0

1

amr.max_grid_size

maximum size of a grid in any direction

Integer > 0

32

amr.max_grid_size

maximum size

Integer

32

amr.blocking_factor

grid size must be a multiple of this

Integer > 0

2

amr.refine_grid_layout

refine grids more if # of processors \(>\) # of grids

0 if false, 1 if true

1

Notes

  • amr.n_error_buf, amr.max_grid_size and amr.blocking_factor can be read in as a single value which is assigned to every level, or as multiple values, one for each level

  • amr.max_grid_size at every level must be even

  • amr.blocking_factor at every level must be a power of 2

  • the domain size amr.n_cell must be a multiple of amr.blocking_factor at level 0

  • amr.max_grid_size must be a multiple of amr.blocking_factor at every level

Examples of Usage

  • amr.regrid_file = fixed_grids
    In this case the list of grids at each fine level are contained in the file fixed_grids, which will be read during the gridding procedure. These grids must not violate the amr.max_grid_size criterion. The rest of the gridding procedure described below will not occur if amr.regrid_file is set.
  • amr.grid_eff = 0.9
    During the grid creation process, at least 90% of the cells in each grid at the level at which the grid creation occurs must be tagged cells. Note that this is applied at the coarsened level at which the grids are actually made, and before amr.max_grid_size is imposed.
  • amr.max_grid_size = 64
    The final grids will be no longer than 64 cells on a side at every level.
  • amr.max_grid_size = 64 32 16
    The final grids will be no longer than 64 cells on a side at level 0, 32 cells on a side at level 1, and 16 cells on a side at level 2.
  • amr.blocking_factor = 32
    The dimensions of all the final grids will be multiples of 32 at all levels.
  • amr.blocking_factor = 32 16 8
    The dimensions of all the final grids will be multiples of 32 at level 0, multiples of 16 at level 1, and multiples of 8 at level 2.

Gridding and Load Balancing

The ERF gridding and load balancing strategy is based on that in AMReX. See the Gridding section of the AMReX documentation for details.

Simulation Time

List of Parameters

Parameter

Definition

Acceptable Values

Default

max_step

maximum number of level 0 time steps

Integer >= 0

-1

start_time

starting simulation time

Real >= 0

0.0

stop_time

final simulation time

Real >= 0

Very Large

Notes

To control the number of time steps, you can limit by the maximum number of level-0 time steps (max_step), or the final simulation time (stop_time), or both. The code will stop at whichever criterion comes first. Note that if the code reaches stop_time then the final time step will be shortened so as to end exactly at stop_time, not pass it.

Examples of Usage

  • max_step = 1000

  • stop_time = 1.0

will end the calculation when either the simulation time reaches 1.0 or the number of level-0 steps taken equals 1000, whichever comes first.

Time Step

List of Parameters

Parameter

Definition

Acceptable Values

Default

erf.no_substepping

Should we turn off substepping in time?

int (0 or 1)

0

erf.cfl

CFL number for hydro

Real > 0 and <= 1

0.8

erf.fixed_dt

set level 0 dt as this value regardless of cfl or other settings

Real > 0

unused if not set

erf.fixed_fast_dt

set fast dt as this value

Real > 0

only relevant if use_native_mri is true

erf.fixed_mri_dt_ratio

set fast dt as slow dt / this ratio

even int > 0

only relevant if no_substepping is 0

erf.init_shrink

factor by which to shrink the initial dt

Real > 0 and <= 1

1.0

erf.change_max

factor by which dt can grow in subsequent steps

Real >= 1

1.1

Notes

  • The time step controls work somewhat differently depending on whether one is using acoustic substepping in time; this is determined by the value of no_substepping.
  • If erf.no_substepping = 1 there is only one time step to be calculated, and fixed_fast_dt and fixed_mri_dt_ratio are not used.
    • If erf.fixed_dt is also specified, the timestep will be set to fixed_dt.
    • If erf.fixed_dt is not specified, the timestep will be computed using the CFL condition for compressible flow. If erf.cfl is specified, that CFL value will be used. If not, the default value will be used.
  • If erf.no_substepping = 0 we must determine both the slow and fast timesteps.
    • If erf.fixed_dt is specified, the slow timestep will be set to fixed_dt.
    • If erf.fixed_dt is not set, the slow timestep will be computed using the CFL condition for incompressible flow. If erf.cfl is specified, that CFL value will be used. If not, the default value will be used.
    • There are several consistency checks before the fast timestep is computed. Specifically, if any of the following are true the code will abort while reading the inputs.
      • If erf.fixed_mri_dt_ratio is specified but is not an even positive integer
      • If erf.fixed_dt and erf.fast_fixed_dt are specified and the ratio of fixed_dt to fast_fixed_dt is not an even positive integer
      • If erf.fixed_dt and erf.fast_fixed_dt and erf.fixed_mri_dt_ratio are all specified but are inconsitent
    • Once the slow timestep is set and the inputs are allowed per the above criteria, the fast timestep is computed in one of several ways:
      • If erf.fixed_fast_dt is specified, the fast timestep will be set to fixed_fast_dt.
      • If erf.fixed_mri_dt_ratio is specified and erf.fixed_fast_dt is not specified, the fast timestep will be the slow timestep divided by fixed_mri_dt_ratio.
      • If neither erf.fixed_mri_dt_ratio nor erf.fixed_fast_dt is specified, then the fast timestep will be computed using the CFL condition for compressible flow, then adjusted (reduced if necessary) as above so that the ratio of slow timestep to fine timestep is an even integer. If erf.cfl is specified, that CFL value will be used. If not, the default value will be used.

Examples of Usage of Additional Parameters

  • erf.init_shrink = 0.01
    sets the initial slow time step to 1% of what it would be otherwise. Note that if erf.init_shrink \(\neq 1\) and fixed_dt is specified, then the first time step will in fact be erf.init_shrink * erf.fixed_dt.
  • erf.change_max = 1.1
    allows the slow time step to increase by no more than 10% in this case. Note that the time step can shrink by any factor; this only controls the extent to which it can grow.

Restart Capability

See Checkpoint / Restart for how to control the checkpoint/restart capability.

PlotFiles

See Plotfiles for how to control the types and frequency of plotfile generation.

Screen Output

List of Parameters

Parameter

Definition

Acceptable Values

Default

amr.v

verbosity of Amr.cpp

0 or 1

0

erf.v

verbosity of ERF.cpp

0 or 1

0

erf.sum_interval

if \(> 0,\) how often (in level-0 time steps) to compute and print integral quantities

Integer

-1

Examples of Usage

  • erf.sum_interval = 2
    if erf.sum_interval \(> 0\) then the code computes and prints certain integral quantities, such as total mass, momentum and energy in the domain every erf.sum_interval level-0 steps. In this example the code will print these quantities every two coarse time steps. The print statements have the form
    TIME= 1.91717746 MASS= 1.792410279e+34
    for example. If this line is commented out then it will not compute and print these quantities.

Diagnostic Outputs

If erf.v is set then one or more additional output files may be requested. These include (1) a surface time history file, (2) a history of mean profiles, (3) a history of vertical flux profiles (i.e., variances and covariances), and (4) a history of modeled subgrid stresses. The number of specified output filenames dictates the level of output. E.g., specifying 3 filenames will give outputs (1), (2), and (3). Data files are only written if erf.profile_int > 0. This output functionality has not been implemented for terrain.

List of Parameters

Parameter

Definition

Acceptable Values

Default

erf.datalog

Output filename(s)

Up to four strings

NONE

erf.profile_int

Interval (number) of steps between ouputs

Integer

-1

erf.interp_profiles_to_cc

Interpolate all outputs to cell centers

Boolean

true

By default, all profiles are planar-averaged quantities \(\langle\cdot\rangle\) interpolated to cell centers. Setting erf.interp_profiles_to_cc = false will keep vertically staggered quantities on z faces (quantities already at cell centers or on x/y faces will remain at those locations). Note that all output quantities–whether cell-centered or face-centered–will be output on the staggered grid. The user should discard the highest z level (corresponding to the z-dir amr.n_cell + 1) for cell-centered quantities. Staggered quantities are indicated below.

The requested output files have the following columns:

  • Surface time history

    1. Time (s)

    2. Friction velocity, \(u_*\) (m/s)

    3. Surface-layer potential temperature scale, \(\theta_*\) (K)

    4. Obukhov length, \(L\) (m)

  • Mean flow profiles

    1. Time (s)

    2. Height (m)

    3. X-velocity, \(\langle u \rangle\) (m/s)

    4. Y-velocity, \(\langle v \rangle\) (m/s)

    5. Z-velocity, \(\langle w \rangle\) (m/s) – staggered

    6. Dry air density, \(\langle \rho \rangle\) (kg/m3)

    7. Total (moist) potential temperature, \(\langle \theta \rangle\) (K)

    8. Turbulent kinetic energy (TKE), \(\langle k \rangle\) (m2/s2) for the subgrid model

  • Vertical flux profiles

    1. Time (s)

    2. Height (m)

    3. X-velocity variance, \(\langle u^\prime u^\prime \rangle\) (m2/s2)

    4. X,Y-velocity covariance, \(\langle u^\prime v^\prime \rangle\) (m2/s2)

    5. X,Z-velocity covariance, \(\langle u^\prime w^\prime \rangle\) (m2/s2) – staggered

    6. Y-velocity variance, \(\langle v^\prime v^\prime \rangle\) (m2/s2)

    7. Y,Z-velocity covariance, \(\langle v^\prime w^\prime \rangle\) (m2/s2) – staggered

    8. Z-velocity variance, \(\langle w^\prime w^\prime \rangle\) (m2/s2) – staggered

    9. X-direction heat flux, \(\langle u^\prime \theta^\prime \rangle\) (K m/s)

    10. Y-direction heat flux, \(\langle v^\prime \theta^\prime \rangle\) (K m/s)

    11. Z-direction heat flux, \(\langle w^\prime \theta^\prime \rangle\) (K m/s) – staggered

    12. Temperature variance, \(\langle \theta^\prime \theta^\prime \rangle\) (K m/s)

    13. X-direction turbulent transport of TKE, \(\langle u_i^\prime u_i^\prime u^\prime \rangle\) (m3/s3) – Note: \(u_i u_i = uu + vv + ww\)

    14. Y-direction turbulent transport of TKE, \(\langle u_i^\prime u_i^\prime v^\prime \rangle\) (m3/s3)

    15. Z-direction turbulent transport of TKE, \(\langle u_i^\prime u_i^\prime w^\prime \rangle\) (m3/s3) – staggered

    16. X-direction pressure transport of TKE, \(\langle p^\prime u^\prime \rangle\) (m3/s3)

    17. Y-direction pressure transport of TKE, \(\langle p^\prime v^\prime \rangle\) (m3/s3)

    18. Z-direction pressure transport of TKE, \(\langle p^\prime w^\prime \rangle\) (m3/s3) – staggered

  • Modeled subgrid-scale (SGS) profiles

    1. SGS stress tensor component, \(\tau_{11}\) (m2/s2)

    2. SGS stress tensor component, \(\tau_{12}\) (m2/s2)

    3. SGS stress tensor component, \(\tau_{13}\) (m2/s2) – staggered

    4. SGS stress tensor component, \(\tau_{22}\) (m2/s2)

    5. SGS stress tensor component, \(\tau_{23}\) (m2/s2) – staggered

    6. SGS stress tensor component, \(\tau_{33}\) (m2/s2)

    7. SGS heat flux, \(\tau_{\theta w}\) (K m/s)

    8. SGS turbulence dissipation, \(\epsilon\) (m2/s3)

Advection Schemes

List of Parameters

Parameter

Definition

Acceptable Values

Default

erf.dycore_horiz_adv_type

Horizontal advection type for dycore vars

see below

Upwind_3rd

erf.dycore_vert_adv_type

Vertical advection type for dycore vars

see below

Upwind_3rd

erf.dryscal_horiz_adv_type

Horizontal advection type for dry scalars

see below

Upwind_3rd

erf.dryscal_vert_adv_type

Vertical advection type for dry scalars

see below

Upwind_3rd

erf.moistscal_horiz_adv_type

Horizontal advection type for moist scalars

see below

WENO3

erf.moistscal_vert_adv_type

Vertical advection type for moist scalars

see below

WENO3

erf.use_efficient_advection

Use efficient advection scheme for scalars

true/false

false

The allowed advection types for the dycore variables are “Centered_2nd”, “Upwind_3rd”, “Blended_3rd4th”, “Centered_4th”, “Upwind_5th”, “Blended_5th6th”, and “Centered_6th”.

The allowed advection types for the dry and moist scalars are “Centered_2nd”, “Upwind_3rd”, “Blended_3rd4th”, “Centered_4th”, “Upwind_5th”, “Blended_5th6th”, “Centered_6th” and in addition, “WENO3”, “WENOZ3”, “WENOMZQ3”, “WENO5”, and “WENOZ5.”

Note: if using WENO schemes, the horizontal and vertical advection types must be set to the same string.

The efficient advection schemes for dry and moist scalars exploit the substages of the time advancing RK3 scheme by using lower order schemes in the first two substages and the solver’s choice of scheme in the final stage. Based on CPU-only runtimes on Perlmutter for the scalar advection routine, the approximate computational savings for the scalar advection schemes are as follows when using efficient advection option: roughly 30% for Centered_4th and Centered_6th, 35% for Upwind_5th, roughly 45% for WENO5 and WENOZ5, and roughly 60% for Upwind_3rd, WENO3, WENOZ3, and WENOMZQ3.

Diffusive Physics

List of Parameters

Parameter

Definition

Acceptable Values

Default

erf.alpha_T

Diffusion coeff. for temperature

Real

0.0

erf.alpha_C

Diffusion coeff. for scalar

Real

0.0

erf.rho0_trans

Reference density to compute const. rho*Alpha

Real

1.0

erf.les_type

Using an LES model, and if so, which type?

“None”, “Smagorinsky”, “Deardorff”

“None”

erf.molec_diff_type

Using molecular viscosity and diffusivity?

“None”, “Constant”, or “ConstantAlpha”

“None”

erf.dynamicViscosity

Viscous coeff. if DNS

Real

0.0

erf.Cs

Constant Smagorinsky coeff.

Real

0.0

erf.Pr_t

Turbulent Prandtl Number

Real

1.0

erf.Sc_t

Turbulent Schmidt Number

Real

1.0

erf.use_NumDiff

Use 6th order numerical diffusion

“True”, “False”

“False”

erf.NumDiffCoeff

Coefficient for 6th order numerical diffusion

Real [0.0, 1.0]

0.0

Note: in the equations for the evolution of momentum, potential temperature and advected scalars, the diffusion coefficients are written as \(\mu\), \(\rho \alpha_T\) and \(\rho \alpha_C\), respectively.

If we set erf.molec_diff_type to Constant, then

  • erf.dynamicViscosity is used as the value of \(\mu\) in the momentum equation, and

  • erf.alpha_T is multiplied by erf.rho0_trans to form the coefficient for potential temperature, and

  • erf.alpha_C is multiplied by erf.rho0_trans to form the coefficient for an advected scalar.

If we set erf.molec_diff_type to ConstantAlpha, then

  • the dynamic viscosity in the momentum equation is assumed to have the form \(\mu = \rho \alpha_M\) where \(\alpha_M\) is a momentum diffusivity constant with units of kinematic viscosity, calculated as erf.dynamicViscosity divided by erf.rho0_trans; this diffusivity is multiplied by the instantaneous local density \(\rho\) to form the coefficient in the momentum equation; and

  • erf.alpha_T is multiplied by the instantaneous local density \(\rho\) to form the coefficient for potential temperature, and

  • erf.alpha_C is multiplied by the instantaneous local density \(\rho\) to form the coefficient for an advected scalar.

PBL Scheme

List of Parameters

Parameter

Definition

Acceptable Values

Default

erf.pbl_type

Name of PBL Scheme to be used

“None”, “MYNN2.5”

“None”

erf.pbl_A1

MYNN Constant A1

Real

1.18

erf.pbl_A2

MYNN Constant A2

Real

0.665

erf.pbl_B1

MYNN Constant B1

Real

24.0

erf.pbl_B2

MYNN Constant B2

Real

15.0

erf.pbl_C1

MYNN Constant C1

Real

0.137

erf.pbl_C2

MYNN Constant C1

Real

0.75

erf.pbl_C3

MYNN Constant C3

Real

0.352

erf.pbl_C4

MYNN Constant C4

Real

0.0

erf.pbl_C5

MYNN Constant C5

Real

0.2

erf.advect_QKE

Include advection terms in QKE eqn

bool

1

erf.diffuse_QKE_3D

Include horizontal turb. diffusion terms in QKE eqn.

bool

0

Note that the MYNN2.5 scheme must be used in conjunction with a MOST boundary condition at the surface (Zlo) boundary.

If the PBL scheme is activated, it determines the turbulent diffusivity in the vertical direction. If an LES model is also specified, it determines only the horizontal turbulent diffusivity.

Right now, the QKE equation is solved if and only if the MYNN2.5 PBL model is selected. In that transport equation, it is optional to advect QKE, and to apply LES diffusive transport for QKE in the horizontal directions (the vertical component is always computed as part of the PBL scheme).

Forcing Terms

List of Parameters

Parameter

Definition

Acceptable Values

Default

erf.abl_driver_type

Type of external forcing term

None, PressureGradient GeostrophicWind

None

erf.abl_pressure_grad

Pressure gradient forcing term (only if abl.driver_type = PressureGradient)

3 Reals

(0.,0.,0.)

erf.abl_geo_wind

Geostrophic forcing term (only if abl.driver_type = GeostrophicWind)

3 Reals

(0.,0.,0.)

erf.use_gravity

Include gravity in momentum update? If true, there is buoyancy

true / false

false

erf.use_coriolis

Include Coriolis forcing

true / false

false

erf.use_rayleigh_damping

Include explicit Rayleigh damping

true / false

false

In addition, custom forcings or tendencies may be defined on a problem-specific basis. This affords additional flexibility in defining the RHS source term as a function of time and/or height. Implementation entails modifying problem source code inside the Exec directory and overriding the update_*_sources() function(s).

Parameter

Definition

Acceptable Values

Default

erf.custom_forcing_uses_primitive_vars

User-defined source terms set the tendency of primitive variables instead of conserved quantities (rho*prim_var)

true or false

false

erf.add_custom_rhotheta_forcing

Apply the user-defined temperature source term

true or false

false

Initialization

ERF can be initialized in different ways. These are listed below:

  • Custom initialization:

    Several problems under Exec are initialized in a custom manner. The state and velocity components are specific to the problem. These problems are meant for demonstration and do not include any terrain or map scale factors.

  • Initialization using a NetCDF file:

    Problems in ERF can be initialized using a NetCDF file containing the mesoscale data. The state and velocity components of the ERF domain are ingested from the mesoscale data. This is a more realistic problem with real atmospheric data used for initialization. The typical filename used for initialization is wrfinput_d01, which is the outcome of running ideal.exe or real.exe of the WPS/WRF system. These problems are run with both terrain and map scale factors.

  • Initialization using an input_sounding file:

    Problems in ERF can be initialized using an input_sounding file containing the vertical profile. This file has the same format as used by ideal.exe executable in WRF. Using this option for initialization, running ideal.exe and reading from the resulting wrfinput_d01 file are not needed. This option is used for initializing ERF domain to a horizontally homogeneous mesoscale state and does not include terrain or map scale factors.

In addition, there is a run-time option to project the initial velocity field to make it divergence-free. To take advantage of this option, the code must be built with USE_POISSON_SOLVE = TRUE in the GNUmakefile if using gmake, or with -DERF_ENABLE_POISSON_SOLVE:BOOL=ON in the cmake.sh file if using cmake.

List of Parameters

Parameter

Definition

Acceptable Values

Default

erf.init_type

Initialization type

“custom”, “ideal”, “real”,

“input_sounding”

custom

erf.input_sounding_file

Path to WRF-style input sounding file

String

“input_sounding”

erf.init_sounding_ideal

Perform initialization like WRF’s ideal.exe

true or false

false

erf.use_real_bcs

If init_type is real or metgrid, do we want to use these bcs?

true or false

true if if init_type is real or metgrid; else false

erf.nc_init_file

NetCDF file with initial mesoscale data

String

NONE

erf.nc_bdy_file

NetCDF file with mesoscale data at lateral boundaries

String

NONE

erf.project_initial_velocity

project initial velocity?

Integer

1

Notes

If erf.init_type = ideal, the problem is initialized with mesoscale data contained in a NetCDF file, provided via erf.nc_init_file. The mesoscale data are horizontally homogeneous, i.e., there is variation only in the vertical direction.

If erf.init_type = real, the problem is initialized with mesoscale data contained in a NetCDF file, provided via erf.nc_init_file. The mesoscale data are realistic with variation in all three directions. In addition, the lateral boundary conditions must be supplied in a NetCDF files specified by erf.nc_bdy_file = wrfbdy_d01

If erf.init_type = input_sounding, a WRF-style input sounding is read from erf.input_sounding_file. This text file includes any set of levels that goes at least up to the model top height. The first line includes the surface pressure [hPa], potential temperature [K], and water vapor mixing ratio [g/kg]. Each subsequent line has five input values: height [m above sea level], dry potential temperature [K], vapor mixing ratio [g/kg], x-direction wind component [m/s], and y-direction wind component [m/s]. Please pay attention to the units of pressure and mixing ratio. If erf.init_sounding_ideal = true, then moist and dry conditions throughout the air column are determined by integrating the hydrostatic equation from the surface.

If erf.init_type = custom or erf.init_type = input_sounding, erf.nc_init_file and erf.nc_bdy_file do not need to be set.

Setting erf.project_initial_velocity = 1 will have no effect if the code is not built with ERF_USE_POISSON_SOLVE defined.

Map Scale Factors

Map scale factors are always present in the evolution equations, but the values default to one unless specified in the initialization when erf.init_type = real.

There is an option to test the map scale factors by setting erf.test_mapfactor = true; this arbitrarily sets the map factors to 0.5 in order to test the implementation.

Terrain

ERF allows the use to specify whether terrain-fitted coordinates should be used by setting erf.use_terrain (default false). If terrain-fitted coordinates are chosen, they are defined to be static (default) or moving by setting erf.terrain_type. If using terrain, the user also has the option to specify one of three methods for defining how the terrain-fitted coordinates given the topography:

  • Basic Terrain Following (BTF):

    The influence of the terrain decreases linearly with height.

  • Smoothed Terrain Following (STF):

    Small-scale terrain structures are progressively smoothed out of the coordinate system as height increases.

  • Sullivan Terrain Following (name TBD):

    The influence of the terrain decreases with the cube of height.

List of Parameters

Parameter

Definition

Acceptable Values

Default

erf.use_terrain

use terrain-fitted coordinates?

true / false

false

erf.terrain_type

static or moving?

Static / Moving

Static

erf.terrain_smoothing

specify terrain following

0, 1, 2

0

Examples of Usage

  • erf.terrain_smoothing = 0

    BTF is used when generating the terrain following coordinate.

  • erf.terrain_smoothing = 1

    STF is used when generating the terrain following coordinate.

  • erf.terrain_smoothing = 2

    Sullivan TF is used when generating the terrain following coordinate.

Moisture

ERF has several different moisture models. The following run-time options control how the full moisture model is used.

List of Parameters

Parameter

Definition

Acceptable Values

Default

erf.moisture_model

Name of moisture model

“SAM”, “Kessler”, “FastEddy”

“Null”

erf.do_cloud

use basic moisture model

true / false

true

erf.do_precip

include precipitation in treatment of moisture

true / false

true

Runtime Error Checking

Through AMReX functionality, ERF supports options to raise errors when NaNs, division by zero, and overflow errors are detected. These checks are activated at runtime using the input parameters below.

Note

When running on Macs using the Apple-Clang compilers with optimization (DEBUG = FALSE in the GNUmakefile), these checks may lead to false positives due to optimizations performed by the compiler and the flags should be turned off. It is still possible to run with these error checks with Apple-Clang debug builds.

List of Parameters

Parameter

Definition

Acceptable Values

Default

amrex.fpe_trap_invalid

Raise errors for NaNs

0 / 1

0

amrex.fpe_trap_zero

Raise errors for divide by zero

0 / 1

0

amrex.fpe_trap_overflow

Raise errors for overflow

0 / 1

0