Running WRF with Thompson Aerosol-aware Microphysics

The following information is specific to WRFV3.9+. If using an older version of WRF, see `Running WRF with Thompson Aerosol-aware Microphysics Prior to V3.9`_


Thompson Aerosol-aware Microphysics : namelist option mp_physics=28 in the &physics record.

use_aero_icbc = .false.

When the namelist variable use_aero_icbc is set to false, the Thompson and Eidhammer 2014 scheme assumes all model horizontal grid points have the same vertical profiles of water nucleating aerosols (CCN, also known as number of water-friendly aerosols, NWFA) and ice nucleating aerosols (IN, also known as number of ice-friendly aerosols, NIFA). These profiles are controlled by parameter settings of variables at the top of phys/module_mp_thompson.F:

  • naCCN0 (300 per cubic centimeter) is the near-surface value of CCN.

  • naCCN1 (50 per cubic centimeter) is the free tropospheric value of CCN.

  • A set of similar variables are used for IN.

The vertical profile is terrain height-dependent, designed to fit the Continental U.S., where the near-surface value exists within an idealized boundary layer of approximately 200 to 1000 meters, depending on starting elevation. It was designed to not follow height above ground, nor height above sea level because the boundary-layer height is not the same at the top of high-elevation mountains as it is at lower, flatter elevations. In effect, the formulation tries to account for a very thin idealized boundary layer height of tens of meters in high terrain (above 2500 meters), but closer to 1000 meters for grid points near sea level. An exponential decay of aerosol number from the higher numerical value in the boundary layer to the lower free tropospheric number is used to complete the vertical profile. These settings are taken into account once at model initial time (inside subroutine thompson_init), regardless of land versus water, or other potential geographic information.

During model integration, the NWFA and NIFA variables are advected and diffused exactly as other scalars (e.g., cloud ice number concentration), and a zero-gradient lateral boundary condition also follows the other scalars. A fake surface aerosol emissions/flux/tendency is computed as a 2D field (computed in subroutine thompson_init and held in the variable nwfa2d), based on horizontal grid spacing and starting aerosol number concentration for the NWFA variable. No surface emission tendency is applied for NIFA as of this writing (April 2014). The 2D tendency field is added each time step to the first model vertical level NWFA value.


use_aero_icbc = .true.

When the namelist variable, use_aero_icbc is true, the Thompson and Eidhammer 2014 scheme uses an auxiliary aerosol climatology file incorporated through the WPS program. Aerosol number concentrations were derived from multi-year (2001-2007) global model simulations (Colarco 2010) in which particles and their precursors are emitted by natural and anthropogenic sources and are explicitly modeled with multiple size bins for multiple species of aerosols by the Goddard Chemistry Aerosol Radiation and Transport (GOCART) model (Ginoux et al. 2001). The aerosol input data used included mass mixing ratios of sulfates, sea salts, organic carbon, dust, and black carbon from the 7-year simulation with 0.5-degree longitude by 1.25-degree latitude spacing. These data were transformed into the simplified aerosol treatment by accumulating dust mass larger than 0.5 microns into the ice nucleating, non-hygroscopic mineral dust mode, NIFA, and combining all other species besides black carbon as an internally-mixed cloud droplet nucleating, hygroscopic CCN mode, NWFA. Input mass mixing ratio data were converted to final number concentrations by assuming log-normal distributions with characteristic diameters and geometric standard deviations taken from Chin et al. (2002; Table 2). The aerosol climatology data must reside on the same set of vertical (pressure) levels as the input meteorological data; therefore separate files exist for GFS, AWIP, and ERA data.

If using the NCAR Derecho HPC, the files are available in /glade/work/wrfhelp/WPS_files, named

  • QNWFA_QNIFA_Monthly_AWIP

  • QNWFA_QNIFA_Monthly_ERA, and

  • QNWFA_QNIFA_Monthly_GFS


Alternatively, they can be downloaded.






To run this, place the file that coordinates with the input data type (e.g., QNWFA_QNIFA_Monthly_GFS, for GFS input data) inside the WPS directory. Before running metgrid.exe, add the following line in the &metgrid namelist record in the namelist.wps file:

constants_name = 'QNWFA_QNIFA_Monthly_datatype'

where datatype is either AWIP, ERA, or GFS. Then run metgrid.exe, and proceed to run real.exe and wrf.exe


Questions/concerns can be directed to Greg Thompson (gthompsn AT ucar dot edu) or Trude Eidhammer (trude AT ucar dot edu).