CCPP Updates for the SRW App v2.1.0 Release

Here is what’s new in CCPP Physics for the UFS SRW v2.1.0 public release. These changes are expected to improve the performance of the RRFS_v1beta, HRRR, and WoFS_v0 suites.

RRFS_v1beta, HRRR, and WoFS Suites:

  • Added the ability to configure the MYNN-EDMF PBL scheme to function at closure level 2.5, 2.6 (current default), or 3.0 closure and included a partial-condensation scheme.

  • Reverted to Tian-Kuang lateral entrainment, which reduces a high relative humidity bias found in some HRRR cases.

  • Reduced the entrainment rate for momentum.

  • Removed the first-order form of the Chaboureau and Bechtold (CB2002) stratiform cloud fraction calculation—it now only uses a higher form of CB.

  • Changed CB to use absolute temperature instead of “liquid” temperature (CB2002).

  • Added variable sm3d—a stability function for momentum.

MYNN Surface Layer Scheme:
  • Moved four internal parameters to namelist options:

    • isftcflux: flag for thermal roughness lengths over water in MYNN-SFCLAY

    • iz0tlnd: flag for thermal roughness lengths over land in MYNN-SFCLAY

    • sfclay_compute_flux: flag for computing surface scalar fluxes in MYNN-SFCLAY

    • sfclay_compute_diag: flag for computing surface diagnostics in MYNN-SFCLAY

Subgrid Scale Clouds Interstitial Scheme:
  • Separated frozen subgrid clouds into snow and ice categories.

  • Added CB2005 as a new cloud fraction option.

  • Removed cloud fraction calculations for the MYNN-EDMF scheme, since cloud fraction is already defined in the subgrid scale cloud scheme used by MYNN-EDMF.

HRRR Suite:

RUC Land Surface Model:
  • In the computation of soil resistance to evaporation, the soil moisture field capacity factor changed from 0.7 to 1. This change will reduce direct evaporation from bare soil.

GSL Drag Suite:
  • Removed limits on the standard deviation of small-scale topography used by the small-scale GWD and turbulent orographic form drag (TOFD) schemes; removed the height limitation of the TOFD scheme.

Removed the “sfc_nst” scheme from the suite to avert a cooling SST trend that had a negative impact on surface variables in the coastal regions.

RRFS_v1beta Suite:

Noah-MP Land Surface Model:
  • Added a connection with the MYNN surface layer scheme via namelist option opt_sfc=4.

GFS_v16 Suite:

GFS saSAS Deep Convection and saMF Shallow Cumulus Schemes:
  • Added a new prognostic updraft area fraction closure in saSAS and saMF (Bengtsson et al., 2022). It is controlled via namelist option progsima (set to false by default) and an updated field table including sigmab.