MPAS Version 8.1.0

This release of MPAS introduces several updates and new capabilities for MPAS-Atmosphere, most notably:

• The MYNN Surface Layer and Planetary Boundary Layer (PBL) schemes have been updated. The PBL scheme includes the options needed to run the Eddy Diffusivity Mass Flux (EDMF) scheme.

• A separate driver for the parameterization of surface processes over sea-ice points has been added.

• The build system now tests for the availability of the modern mpi_f08 module in the MPI library. If detected, the mpi_f08 module interface to Fortran MPI routines will be used in favor of the older mpi module interface.

• The atmosphere core now supports the storage and retrieval of time-invariant fields in a separate I/O stream, offering significant disk space savings, especially in cases where large ensembles or cycled simulations are being run. See Section 8.3 of the User's Guide for more details.

• The top-level Makefile provides a new intel build target for the Intel oneAPI Fortran, C, and C++ compiler suite.

• To support real-data simulations on meshes with grid distances approaching 1 km or less, the init_atmosphere core provides an option, config_30s_supersample_factor, for super-sampling of the 30 arc-second terrestrial fields (terrain, land use, soil category, and MODIS FPAR monthly vegetation fraction).

• When compiling, PRECISION=single is now the default, and double-precision builds must be specified with PRECISION=double.

MPAS Version 8.0.2

This bugfix release addresses several issues in the MPAS-Atmosphere model:

• Generalize the mpas_sphere_angle function to provide correct results for non-unit-radius spheres. This generalization fixes problems in remapping static fields to the outermost layer of specified-zone cells in limited-area meshes. (PR #1148)

• Initialize mvd_r and mvd_c before first use in the Thompson microphysics scheme to prevent the potential use of uninitialized memory, which could lead to floating-point exceptions. (PR #1152)

• Correct the units for the grid scale input field to the Thompson cloud fraction scheme. (PR #1153)

Acknowledgements: Thanks are due to Brett Wilt (The Weather Company) for first identifying the bug in the units of dx_p in the call to the Thompson cloud fraction scheme.

MPAS Version 8.0.1

This bugfix release addresses several issues in MPAS-Atmosphere, specifically:

• Fix an OpenMP error in the deallocation of an array (rthdynten) when neither
  the Grell-Freitas nor the Tiedtke/nTiedtke cumulus schemes are used. (PR #1099)

• Fix a compilation issue due to a missing include path for the physics_mmm
  directory when certain Fortran compilers are used. (PR #1096)

• Fix an issue in reading real-valued global attributes from input files with
  SMIOL when the input file is of a different precision than the compiled
  precision of MPAS. (PR #1091)

• Fix a memory leak for the recloud_p, reice_p, and resnow_p arrays in the
  deallocate_microphysics routine. (PR #1090)

• Correct the units and description for the rt_diabatic_tend, pv_vertex,
  pv_edge, and pv_cell variables in the atmosphere core's Registry.xml file. (PRs #1089 and #1092)

MPAS Version 8.0.0

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.

MPAS Version 7.3

This minor release addresses one issue in the MPAS-Atmosphere model.

MPAS-Atmosphere:

• Update the checkout_data_files.sh script to use HTTPS rather than the
  unencrypted Git protocol when obtaining the MPAS-Data repository from
  GitHub.

MPAS Version 7.2

This minor release addresses several issues in the MPAS-Atmosphere model.

MPAS-Atmosphere:

• Correct the use of uninitialized memory in the init_atm_case_squall_line
  routine by initializing the qvb array to zero before its first use.

• Fix a bug in the vertical extrapolation of relative humidity and specific
  humidity to model levels below the lowest first-guess level when first-guess
  levels are given in top-to-bottom order in the input intermediate file.

• Fix reproducibility issues in several fields within the Noah LSM over land-ice
  points when running with different MPI task counts; however, only one of these
  fields -- smstav, the surface moisture availability field -- persists outside
  of the physics driver and is written to MPAS-Atmosphere restart files.

• Correct the units and description attributes for the GWDO fields var2d, con,
  oa1, oa2, oa3, oa4, ol1, ol2, ol3, and ol4 in both the init_atmosphere and
  atmosphere core Registry.xml files.

• Add code that had inadvertently been omitted for computing dtheta_dt_mp, the
  potential temperature heating rate from microphysics. Prior to this change,
  the dtheta_dt_mp field would always contain a constant zero value when written
  to model output files.

• Correct a check on the availability of the dtheta_dt_mix variable when
  computing depv_dt_mix in the PV diagnostics module.

• Correct the parallel computation of iLev_DT (and other fields that depend on
  it, including u_pv, v_pv, theta_pv, vort_pv, depv_dt_diab_pv, and
  depv_dt_fric_pv) in the PV diagnostics module.

MPAS Version 7.1

This minor release addresses several issues in the MPAS-Atmosphere model and
initialization, and it corrects several minor compilation issues.

MPAS-Atmosphere:

• In calculating moist air density in the real-data initialization case, virtual
  temperature, rather than temperature, should be used.

• An out-of-bounds array access in the GWDO scheme when running with multiple
  OpenMP threads has been corrected.

• A check has been added in the init_atmosphere core to ensure that the
  intermediate file interval and the 'surface' stream output interval are
  consistent.

• A non-standard BOZ-literal constant has been corrected in the
  module_ra_cam_support.F file. The non-standard constant lead to build
  failures, particularly with newer versions of the GNU compilers.

General software:

• The logic to add PIO libraries to the definition of LIBS in the top-level
  Makefile has been updated to accommodate newer versions (approx. 2.5.2 or
  later) of the PIO library; without the fix to the Makefile, builds would
  fail with the message

  Checking for a usable PIO library...
  ************ ERROR ************
  Failed to compile a PIO test program
  Please ensure the PIO environment variable is set to the PIO installation directory
  ************ ERROR ************

• Various options for the 'gfortran' build target have been cleaned up.

• Occasional parallel build failures related to a race condition in the ezxml
  library compilation have been addressed.

MPAS Version 7.0

This major release of MPAS introduces significant new features in the MPAS-Atmosphere model as well as minor fixes and clean-up to the software infrastructure.

Atmosphere

Significant new features or changes to MPAS-Atmosphere v7.0 include:

• The capability to perform limited-area simulations on the surface of the sphere.
• An update to the physics schemes in the 'mesoscale_reference' suite to match the scheme versions in the Weather Research and Forecasting (WRF) model v4.0.3; the WSM6 scheme matches WRF v4.1.
• The addition of two new upper absorbing layer formulations.
• An initial relative humidity field that is computed w.r.t. ice for temperatures below freezing, consistent with the computation used for the model output files.
• A fix for the communication of effective radii between the WSM6 and RRTMG schemes when config_microp_re=true.
• The ability to specify an explicit list of model level heights when constructing the vertical coordinate surfaces in the init_atmosphere core.
• A change to the default sources of data for terrain height and land use category to GMTED2010 and MODIS 20-class, respectively.
• Added MODIS-based sources for monthly albedo, monthly vegetation fraction, and maximum snow albedo; these MODIS datasets are now the default.

IMPORTANT NOTE: The updated physics schemes require new look-up tables, in particular, for the Noah land-surface model. 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.

Infrastructure

Changes to the shared MPAS infrastructure include:

• A new build target, llvm, to enable building MPAS with the clang and flang compilers.
• Updates to the xlf build target to support building on Linux/POWER systems with the XL compilers.
• Various minor fixes and clean-up.

MPAS Version 6.3

This minor release addresses two minor issues in MPAS-Atmosphere.

1. The default setting for config_o3climatology was previously 'false',
   which caused the model to use a single seasonal ozone profile everywhere
   in the model domain when the RRTMG radiation schemes was used. The default
   is now 'true', which causes the model to use the same monthly ozone
   climatology for RRTMG as is used by the CAM radiation schemes.

2. Model simulations using a non-integer timestep would result in 'xtime'
   variables in model output files that were incorrect, which caused problems
   when trying to restart the model at the correct time. The xtime variable
   is now correct when the valid time of output files has no fractional
   seconds.

MPAS Version 6.2

This minor release addresses two issues in the MPAS infrastructure with how character strings are read from netCDF files via PIO, and it adds the 'recursive' attribute to the mpas_log_write routine to avoid errors raised by several newer compilers when critical errors are written.