CCPP Updates for the SRW App v2.2.0 Release

Here is what’s new in CCPP Physics for the UFS SRW v2.2.0 public release.

General Updates

  • Added RAP suite (FV3_RAP) as a new supported suite (documentation here)

  • Added the Community Land Model (CLM) lake model in the HRRR suite (FV3_HRRR)

Thompson Microphysics Scheme

  • Reduced ice generation supersaturation requirement from 0.25 to 0.15 to generate more ice at the upper levels and reduce the outgoing longwave radiation bias

  • Divided cloud number concentration into two parts (over land and others). Reduced number concentration over ocean to a smaller number (50/L) from its previous default (100/L). Both changes were made to reduce excessive surface downward shortwave radiative flux off coastal regions including the Southeast Pacific

  • Implemented small fixes to the minimum size of snow and collision constants

Note

The above improvements were tested with the non-aerosol option, so results with the aerosol-aware Thompson (used in the SRW App) may vary.

NoahMP Land Surface Model

  • Option for using the unified frozen precipitation fraction in NoahMP.

  • Diagnostic 2-meter temperature and humidity now based on vegetation and bare-ground tiles (new namelist option iopt_diag)

  • Bug fixes for GFS-based thermal roughness length scheme

  • New soil color dataset introduced to improve soil albedo to reduce the large warm bias found in the Sahel desert

  • Wet leaf contribution factor is included

  • Leaf-area index now depends on momentum roughness length

RUC Land Surface Model

  • Initialization of land and ice emissivity and albedo with consideration of partial snow cover

  • Initialization of water vapor mixing ratio over land ice

  • Initialization of fractions of soil and vegetation types in a grid cell

  • Changes in the computation of a flag for sea ice: set to true only if flag_cice=.false (atmosphere uncoupled from the sea ice model).

  • Separate variables for sea ice, for example: snowfallac is replaced with snowfallac_ice

  • Solar angle dependence of albedo for snow-free land

  • Coefficient in soil resistance formulation (Sakaguchi and Zeng, 2009) raised from 0.7 to 1.0 to increase soil resistance to evaporation

  • Computation of snow cover fraction and snow thermal conductivity updated

GFS Scale-Aware TKE-EDMF PBL and Cumulus Schemes

  • Parameterization to represent environmental wind shear effect added to reduce excessively high hurricane intensity

  • Entrainment rates enhanced proportionally to the sub-cloud or PBL-mean TKE when TKE is larger than a threshold value

  • Entrainment rate is increased as a function of vegetation fraction and surface roughness length to enhance underestimated CAPE

MYNN-EDMF PBL Scheme

  • Small increase of buoyancy length scale in convective environments

  • Patch for ensuring non-zero cloud fractions for all grid cells where cloud mixing ratio is greater than 1e-6 or ice mixing ratio is greater than 1e-9

Subgrid-Scale (SGS) Clouds Scheme

  • Bug fix for cloud condensate input into RRTMG radiation

  • New code section for use with SAS convection scheme

  • Cloud fraction now computed as a mix between the area-dependent form and the modified Chaboureau and Bechtold (2005) form

  • Adjusted limit for the boundary flux functions

MYNN Surface-layer Scheme

  • Reintroduced friction velocity averaging over water to reduce noise in 10-m winds in the hurricane regime

Grell-Freitas Scale and Aerosol Aware Convection Scheme

  • Update for aerosol-awareness (experimental)

  • Scale-awareness turned off when explicit microphysics is not active anywhere in the column

  • Convection is completely suppressed at grid points where the MYNN PBL scheme produces shallow convection

  • Radar reflectivity considers mass flux PDF as well as whether scale-awareness is turned on at the grid point in question

Unified Gravity Wave Physics Scheme

  • Optional diagnostic for tendencies computed. They can be switched on by setting the following namelist variables to “.true.”: ldiag3d and ldiag_ugwp

Attention

The improvements in Thompson cloud microphysics, NoahMP land surface model, GFS TKE-EDMF and cumulus schemes were tested in the UFS global configuration, so results in the UFS limited-area configuration (SRW) may vary.