UGWP Physics Package

How to use the UGWP physics package in MPAS

The Unified Gravity Wave Physics (UGWP) scheme is adapted from the CCPP library. A description of the scheme can be found in a NOAA Tech Note.

NOTE: In the documentation below, the string xxxx is a wildcard place holder for the designation of your mesh, e.g., x1.10242 for the 240km uniform global mesh, or hrrrv5_mpas for a regional mesh.

I. Creating static orographic data file for your mesh — xxxx.ugwp_oro_data.nc

1. Make sure you have the file xxxx.grid.nc in your directory. This file contains the necessary cell lat/lon and cell area data.

2. Configure the streams.init_atmosphere file as follows:

<immutable_stream name="input"
                  type="input"
                  filename_template="xxxx.grid.nc"
                  input_interval="initial_only" />

<immutable_stream name="output"
                  type="output"
                  filename_template="xxxx.static.nc"
                  packages="initial_conds"
                  output_interval="initial_only" />

<immutable_stream name="ugwp_oro_data"
                  type="output"
                  filename_template="xxxx.ugwp_oro_data.nc"
                  output_interval="initial_only"
                  packages="gwd_gsl_stage_out" />

Note that the execution of init_atmosphere_model in step 5 creates the xxxx.static.nc file as well as the xxxx.ugwp_oro_data.nc. If you already have the xxxx.static.nc file, save it somewhere and replace the newly created static file with it if desired.

3. In the namelist.init_atmosphere file, you'll need:

&preproc_stages
    config_static_interp = true
    config_native_gwd_static = false
    config_native_gwd_gsl_static = true

4. Link or download the required static data to your 'WPS_GEOG' directory. For those outside of NOAA, these are available from NSF NCAR's MPAS website. They can also be found as attachments to releases within this repository. If you are working on the NOAA RDHPCS Ursa or Hera machines, link the following two directories under your ‘WPS_GEOG’ directory:

/scratch3/BMC/wrfruc/Clark.Evans/mpas_static/topo_ugwp_2.5m
/scratch3/BMC/wrfruc/Clark.Evans/mpas_static/topo_ugwp_30s

5. Run init_atmosphere_model. Check that the file xxxx.ugwp_oro_data.nc file was created.

II. Running the atmosphere model with the UGWP physics package.

1. Make sure you have the xxxx.ugwp_oro_data.nc file in your run direcotry.

2. Include the following lines in your streams.atmosphere file:

<immutable_stream name="ugwp_oro_data_in"
                  type="input"
                  filename_template="xxxx.ugwp_oro_data.nc"
                  input_interval="initial_only" 
                  packages="ugwp_orog_stream" />

3. In the namelist.atmosphere file, include the following line in the &physics section of the namelist:

config_gwdo_scheme = 'bl_ugwp_gwdo'

4. Running optional non-stationary gravity wave drag (NGW) scheme: For global runs with a model top height exceeding ~50km, you may want to run the non-stationary gravity wave drag scheme. By default it is turned off, but it can be activated by setting &physics namelist option:

config_ngw_scheme = true

The optional &physics namelist option 'config_knob_ugwp_tauamp' is a "tuning" knob that determines the strength of the parameterized non-stationary gravity wave momentum flux (Pa) emitted at the launch level of 250hPa. It is mesh-size-dependent. The recommended settings are as follows:

• 3-km mesh — 0.13e-3 Pa
• 13-km mesh — 0.5e-3
• 26-km mesh — 0.8e-3
• 52-km mesh — 1.5e-3
• 100-km mesh — 3.e-3
• 200-km mesh — 6.e-3

Note: You will also need to copy the file 'src/core_atmosphere/physics/physics_wrf/files/ugwp_limb_tau.nc' into your run directory.

5. Run atmosphere_model.

 

_{Initial instructions provided by Mike Toy, NOAA GSL}