Skip to content

MPAS Version 8.0.0

Compare
Choose a tag to compare
@mgduda mgduda released this 16 Jun 21:03
· 334 commits to master since this release

This major release of MPAS introduces significant new features in the
MPAS-Atmosphere model and its supporting software infrastructure.

Initialization:

  • Enable parallel remapping of static fields with arbitrary graph partition
    files; special CVT partition files are no longer required.

  • Reset the default for the lower air-temperature extrapolation
    (config_extrap_airtemp) from 'linear' to 'lapse-rate' in the namelist. This
    applies to initialization and to lateral boundary condition generation for
    MPAS-A.

  • Set the condition for the lower extrapolation of the horizontal velocity
    such that it returns the lowest analysis level value instead of a linear
    extrapolation when the requested level is below the analysis level.

  • Create a new init case (13) for creating 3-d CAM-MPAS grids.

Physics:

  • Update the Noah land surface scheme to the WRF 4.5 release.

  • Update the MM5 surface layer scheme to the WRF 4.5 release.

  • Implemented the CCPP-compliant version of:

    • the revised MM5 surface layer scheme;
    • the parameterization of the gravity-wave drag over orography;
    • the YSU Planetary Boundary Layer scheme;
    • the scale-aware nTiedtke parameterization of convection; and
    • the WSM6 cloud microphysics parameterization.
  • Correct the initialization of the maximum snow albedo over sea ice points
    (now set to 0.75 instead of 0).

  • Fix the option that defines the surface albedo over sea ice points. The
    default option is now set to zero and the default value for the surface
    albedo over sea ice points is set to 0.65.

  • In the dynamics, rework the computation of the advective tendency of
    potential temperature needed as forcing in the nTiedtke and Grell-Freitas
    parameterizations of deep convection. The advective tendency of potential
    temperature is now computed the same way for the nTiedtke and Grell-Freitas
    convection schemes.

    IMPORTANT NOTE: The updated Noah scheme requires new look-up tables.
    The checkout_data_files.sh script that is run at build time should correctly
    update these tables, but tables in other run directories will need to be
    manually updated.

Dynamics:

  • Modify the regional MPAS-A relaxation-zone filters to increase the
    robustness of regional MPAS-A simulations, including access to specific
    relaxation-zone filter parameters through the namelist. The defaults for
    regional relaxation-zone filtering for the horizontal momentum have been
    changed from the previous release.

  • Generalize the 2nd-order horizontal mixing used in the upper wave absorbing
    region in MPAS-A, including access to the configuration parameters through
    the namelist.

  • The pressure-level height diagnostic is now interpolated using ln(p) for
    increased accuracy. This significantly reduces the diagnostics height bias
    in the previous version.

  • Change the vertical interpolation weights for projecting cell-centered
    variables to w levels to be the vertically integrated average. Previously
    the weights represented a linear interpolation in z. These weights are
    computed in the initialization code and used in both the initialization and
    integration.

  • Eliminate the need to specify a horizontal length scale in namelists
    (config_len_disp). New mesh files supply this length scale, which is read by
    the model at start-up.

  • Include changes to the initialization and to MPAS-A such that this release
    can be directly used in CESM/CAM.

Infrastructure:

  • Introduce a new I/O layer, the Simple MPAS I/O Layer. SMIOL provides a
    subset of the parallel I/O functionality of PIO, but with a simplified
    design that minimizes external dependencies to just the Parallel-NetCDF
    library. When the $PIO environment variable is not set at compile time,
    SMIOL will be used in MPAS.

  • Refactor halo communication to make use of a new group (aggregated) halo
    exchange module. The new mpas_halo module is designed to be amenable to
    GPU-direct communication of halos with OpenACC. In this release, however,
    OpenACC directives have not yet been added.