Physics Suites

Beginning with version 4.0, MPAS-Atmosphere introduces a new way of selecting the physics schemes to be used in a simulation. Rather than selecting individual parameterization schemes for different processes (e.g., convection, microphysics, etc.), the preferred method is to select a suite of parameterization schemes that have been tested together. This is done via the namelist option config_physics_suite in the &physics namelist record. Each available suites is described in the sections that follow.

It is possible to override the choice of any individual parameterization scheme through the namelist options described in Appendix B. This is useful, e.g., to disable all parameterizations except for microphysics when running some idealized simulations. See Selecting Individual Physics Parameterizations for details.

mesoscale_reference Suite

The default physics suite in MPAS-Atmosphere is the ‘mesoscale_reference’ suite, which contains the schemes listed in the below table. This suite has been tested for mesoscale resolutions (> 10 km cell spacing), and is not appropriate for convective-scale simulations because the Tiedtke scheme will remove convective instability before resolved-scale motions (convective cells) can respond to it.

The set of parameterization schemes used by the ‘mesoscale_reference’ physics suite

Parameterization	Scheme
Convection	New Tiedtke
Microphysics	WSM6
Land Surface	Noah
Boundary Layer	YSU
Surface Layer	Monin-Obukhov
Radiation (Long-wave)	RRTMG
Radiation (Short-wave)	RRTMG
Cloud Fraction for Radiation	Xu-Randall
Gravity Wave Drag by Orography	YSU

convection_permitting Suite

The ‘convection_permitting’ physics suite is appropriate at spatial resolutions allowing for both explicitly resolved hydrostatic and nonhydrostatic motions. It has been tested for mesh spacings from several hundred kilometers down to 3 km in MPAS. The Grell-Freitas convection scheme transitions from a conventional parameterization of deep convection at hydrostatic scales (cell spacings of several tens of kilometers) to a parameterization of precipitating shallow convection at cell spacings less than 10 km. This is the recommended suite for applications where convection-permitting meshes (dx < 10 km) are employed, including variable-resolution meshes spanning hydrostatic to nonhydrostatic resolutions.

The set of parameterization schemes used by the ‘convection_permitting’ physics suite

Parameterization	Scheme
Convection	Grell-Freitas
Microphysics	Thompson (non-aerosol aware)
Land Surface	Noah
Boundary Layer	MYNN
Surface Layer	MYNN
Radiation (Long-wave)	RRTMG
Radiation (Short-wave)	RRTMG
Cloud Fraction for Radiation	Xu-Randall
Gravity Wave Drag by Orography	YSU

“none” Suite

The only other recognized physics suite in MPAS-Atmosphere is ‘none’, which sets all physics parameterizations to off. This is primarily intended for use with idealized simulations. For example, the idealized supercell test case makes use of the none suite, but with the microphysics scheme explicitly overridden:

config_physics_suite = 'none'
config_microp_scheme = 'kessler'

Selecting Individual Physics Parameterizations

To select or disable an individual physics parameterization, set the appropriate namelist variable to one of its possible options; possible options and their detail are given in the below table. Note that all parameterization options may be set to ‘off’ to disable the parameterization of the associated process.

Possible options for individual physics parameterizations. Namelist variables should be added to the &physics namelist record.

Parameterization	Namelist Variable	Possible Options	Details
Convection	config_convection_scheme	cu_tiedtke cu_ntiedtke cu_kain_fritsch	Tiedtke (WRF 3.8.1) New Tiedtke (WRF 4.5) Modified version of scale-aware Grell-Frietas (WRF 3.6.1) Kain-Fritsch (WRF 3.2.1)
Microphysics	config_microp_scheme	mp_wsm6 mp_thompson mp_kessler	WSM 6-class (WRF 4.5) Thompson non-aerosol aware (WRF 3.8.1) Kessler
Land Surface	config_lsm_scheme	noah	Noah (WRF 4.5)
Boundary Layer	config_pbl_scheme	bl_ysu bl_mynn	YSU (WRF 4.5) MYNN (WRF 3.6.1)
Surface Layer	config_sfclayer_scheme	sf_monin_obukhov sf_mynn	Monin-Obukhov (WRF 4.5) MYNN (WRF 3.6.1)
Radiation (Long-wave)	config_radt_lw_scheme	rrtmg_lw cam_lw	RRTMG (WRF 3.8.1) CAM (WRF 3.3.1)
Radiation (Short-wave)	config_radt_sw_scheme	rrtmg_sw cam_sw	RRTMG (WRF 3.8.1) CAM (WRF 3.3.1)
Cloud Fraction for Radiation	config_radt_cld_scheme	cl_fraction cld_incidence	Xu and Randall (1996) 0/1 cloud fraction depending on qc + qi
Gravity Wave Drag by Orography	config_gwdo_scheme	bl_ysu_gwdo	YSU (WRF 4.5)

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