For details, please see the v8.2.2 release notes on GitHub .

For details, please see the v8.2.1 release notes on GitHub .

For details, please see the v8.2.0 release notes on GitHub .

For details, please see the v8.1.0 release notes on GitHub .

For details, please see the v8.0.2 release notes on GitHub .

For details, please see the v8.0.1 release notes on GitHub .

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

Changes to the initialization include:

• 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.

Changes to the physics include:

• 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 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.

Changes to the 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.

Changes to infrastructure include:

• 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.

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

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

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

• 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.

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.

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.

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.

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.

This minor release addresses two 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.

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.

This minor release of MPAS affects only the MPAS-Seaice core. There are no changes to MPAS-Atmosphere or to the MPAS software infrastructure.

MPAS v6.0 introduces major changes for the MPAS-Ocean and MPAS-Landice cores, and it contains the first public release of the MPAS-Seaice core. Relative to the MPAS v5.0 release, though, MPAS v6.0 represents a minor increment in capability the MPAS-Atmosphere core.

Noteworthy changes in MPAS-Atmosphere v6.0 include:

• An increase of the default number of layers from 41 to 55 to match the standard experimental set-up used at NCAR.
• The addition of support for the use of GMTED2010 terrain elevation, matching the default terrain dataset used in the WRF model.
  • Set config_topo_data = 'GMTED2010' in the namelist.init_atmosphere file when interpolating static fields.
• Computation of the GWDO sub-grid-scale orography fields in a way that is more consistent with the pre-computed fields used in the WRF model.
• Support for parallel builds of the init_atmosphere and atmosphere cores.
  • Use make -j N ...
• A significant reduction in the size of model initial conditions files.

Changes in the MPAS share infrastructure include:

• Introduction of a new module for logging messages during model execution. Unless any errors are encountered, MPAS cores now write a single log file, named log.<core>.0000.out. In case errors occur, each MPI task will write its own error log file named log.<core>.<task ID>.err.
• Performance enhancements to aggregated halo exchanges used in the Ocean, Land-ice, and Sea-ice cores.
• Minor enhancements to the MPAS "stream manager", including the ability to specify "final_only" for the "input_interval" or "output_interval" of a stream to read/write that stream only at the model stop time.
• Various bug-fixes and other clean-up to ensure that the framework can be used in coupled-model configurations involving more than one MPAS core.

This minor release of MPAS corrects an issue with the initialization of the water vapor mixing ratio field in MPAS-Atmosphere, and it also adds two other fixes that should not affect model results.

The MPAS-Atmosphere initialization program (init_atmosphere_model) had previously assumed that any relative humidity field provided in an intermediate file was specified with respect to liquid water at or above 273.15 K, and with respect to ice below this temperature. However, intermediate files produced by the WPS's ungrib.exe program have the RH field adjusted so that is with respect to liquid water everywhere. With this release, the init_atmosphere core correctly interprets the RH field in producing the initial water vapor mixing ratio field. Note that, when initializing from specific humidity (SPECHUMD) rather than RH, there is no change to results.

Besides the above fix, this release includes two other changes that should have no impact on results:

• The "units" and "description" for scalar tendencies have been corrected in the MPAS-Atmosphere Registry.xml file.
• The sign of the edgeNormalVectors field has been corrected for boundary edges that represent positive normal inflow. Although this change addresses a bug in the code, MPAS-Atmosphere does not have boundary edges, and other MPAS cores either employ no-flux or no-slip conditions along lateral boundaries or arrange such that all boundary edges represent positive outgoing normal velocity.

Thanks very much to The Weather Company for identifying the bug in initializing with relative humidity!

This minor release of MPAS corrects issues when using the PIO 2.x library versions. With the changes in this release, it should be possible to use the latest PIO release from https://github.com/NCAR/ParallelIO/.

When compiling MPAS with a PIO 2.x library version, the USE_PIO2=true option should be added to the MPAS build command.

The PIO 2.x library versions support integrated performance timing with the GPTL library; however, the MPAS infrastructure does not currently provide calls to initialize this library before it is used in PIO. Therefore, it is recommended to add -DPIO_ENABLE_TIMING=OFF to the options in the cmake command used to build PIO.

The following steps may be used as a rough guide to obtaining and installing the latest PIO code:

 
  git clone git@github.com:NCAR/ParallelIO.git
  cd ParallelIO
  export PIOSRC=`pwd`
  cd ..
  mkdir build
  cd build
  export CC=mpicc
  export FC=mpif90
  cmake -DNetCDF_C_PATH=$NETCDF -DNetCDF_Fortran_PATH=$NETCDF -DPnetCDF_PATH=$PNETCDF \
        -DCMAKE_INSTALL_PREFIX=/somewhere/writable/pio2 -DPIO_ENABLE_TIMING=OFF $PIOSRC
  make
  make install
  

• Re-engineering of the 3-d divergence damping mechanism to improve model stability in some variable-resolution simulations
• Making the upper gravity-wave absorbing layer scale aware, which is necessary to effectively damp vertically propagating waves in the coarse part of variable-resolution meshes
• A fix for patches of high 2-m theta sometimes found in simulations with the MYNN surface layer scheme (part of the 'convection_permitting' suite)
• A new initialization option to extrapolate temperature below the first-guess surface with a lapse rate, needed for usable initialization in some cases
• A fix for an issue in which writing 'mslp', but not an isobaric temperature field, to an output stream lead to garbage for MSLP field
• Changes to fix compilation issues on macOS case-insensitive filesystems with GEN_F90=true
• Changes to properly handle the ECMWF 100-289 cm soil layer
• A fix for initializing with hybrid-level first-guess data that provides a 3-d 'PRESSURE' field
• A fix for compiling on BlueGene systems
• Fixes for various memory issues, mostly related to the expanded use of 'packages' in the v5.0 release

• A new physics suite, 'convection_permitting', that is suitable for applications where convection-permitting meshes (dx < 10 km) are employed, including variable-resolution meshes spanning hydrostatic to nonhydrostatic resolutions
• Updates to the versions of existing physics schemes
• A new vertical level distribution (selected by default when running init_atmosphere_model) that has been used in several MPAS-Atmosphere real-time experiments, including the prediction of tropical cyclones
• The ability to initialize the water vapor mixing ratio directly from specific humidity rather than relative humidity
• An option to compute sub-grid-scale orography statistics for use by the GWDO scheme directly on the native MPAS mesh from the 30-arc-second topography used for the model terrain field
• The use of "packages" to save memory by selectively allocating fields based on run-time choices of physics suite or schemes
• Substantial performance optimizations to the dynamical solver (with contributions from Thomas Henderson (then at NOAA), Robert Sinkovits (SDSC), John Dennis (NCAR), and Ryan Cabell (NCAR))
• The ability to obtain bit-identical results for any MPI task count (though this may require the addition of compiler flags, e.g., '-fp-model precise' for the ifort compiler)
• An experimental hybrid-parallel capability to allow execution with MPI and OpenMP; note that this ability does not currently offer a performance advantage and is being released for further development by collaborators
• Complete documentation for all namelist options and fields in the Registry file; units and description for all fields are also written as variable attributes to all model output files
• The introduction of a new framework for including diagnostics modules in MPAS-Atmosphere
• New diagnostics: Ertel PV diagnostics (thanks to Nick Szapiro (OU)), and convective diagnostics including CAPE and CIN
• The ability to write soundings for a specified list of locations at any specified interval during model integration
• For data assimilation, an Incremental Analysis Update (IAU) module to reduce initial noise by adding analysis increments over a time window (thanks to Soyoung Ha (NCAR))

• A simplified method for building single-precision executables: simply add PRECISION=single to the compilation command-line
• Minor performance improvements, e.g., in halo communication
• Fixes to allow the infrastructure to correctly handle large meshes (>10^7 cells)
• OpenMP threading of memory initialization, buffer copying, etc.
• Minor cleanup and bug fixes throughout

• A new split dynamics-transport integration scheme has been introduced, allowing scalar transport to take place on a longer timestep than the other dynamics. Real-data testing indicates that the new scheme offers greater model stability. This scheme, selected by default, is controlled by the new namelist options config_split_dynamics_transport, which controls whether the new option is used, and config_dynamics_split_steps, which sets number of dynamics sub-cycles in a timestep.
• The concept of physics suites has been introduced, allowing groups of physics parameterizations that have been tested together to be selected with a single namelist option; this is an alternative to individually specifying parameterization schemes. By default, MPAS-Atmosphere uses the 'mesoscale_reference' suite, described in Section 6.1 of the Users' Guide.
• Improved support for initializing with model-level datasets, in particular, ERA-Interim model level data.
• Scale-adaptive coordinate surface smoothing.

• A new optional keyword, io_type, has been implemented in the XML stream configuration files, allowing the file format and library to be selected on a per-stream basis. More details are available in Section 5.2 of the Users' Guide.
• In the MPAS 3.x releases, fields and global attributes showed up in output files in random order; now, the order of the file contents is based on the order that fields and namelist options were declared in the Registry.xml file of a core.
• A few minor improvements have been made to enable MPAS-Atmosphere to run more reliably in single-precision and at high-resolution, especially on large MPI task counts.

• Fix an issue in the timekeeping library when comparing time intervals with different numbers of years or months
• Fix a memory leak when setting times in the time manager
• Add improved error messages when attempting to read from non-existent files
• Correctly catch error conditions produced by open() when opening XML files
• Fix bug in merging var_struct and var_array elements in Registry.xml files
• Set the s_d variable within time manager to avoid potential division by zero
• Remove an extra if-test to handle r0a field destruction in pools
• Avoid allocating memory for inactive package variables
• Fix for directory creation for streams when directories are nested within non-writable directories
• Permit input streams to have the same filename template
• Update infrastructure bootstrapping process to properly handle stream attributes
• Fix an issue with interval division when resetting alarms

This bug was only present in v3.0, and not in earlier releases of MPAS-Atmosphere.

• Support for soil moisture and soil temperature from ERA-I levels (0-7, 7-28, 28-100, and 100-25 cm);
• a significant reduction in the print statements written to the log files;
• a reduction in the set of fields written to the default model history files; and
• miscellaneous minor bugfixes.

• As a significant step in preparing the MPAS framework for support of multiple MPAS cores being compiled together in the same executable, the internal storage of fields and namelist options has been rewritten; this change principally affects model developers who need to access fields inside the MPAS code.
• To enable full run-time control over file input and output, a new I/O layer has been developed for MPAS. In past releases of MPAS, control over input, restart, and history files took place in the namelist file. Now, all configuration of model input, restart, and history files makes use of separate XML configuration files. A new chapter (Chapter 5) has been added to the MPAS-Atmosphere Users' Guide to describe the use of this new I/O system.

• The double-precision RRTMG long-wave table, RRTMG_LW_DATA.DBL, was inconsistent with the version of the RRTMG code that was included in MPAS-Atmosphere. The RRTMG_LW_DATA.DBL has been updated in the MPAS-Data repository, and the source code includes changes in the data checkout script to download the latest version of all WRF physics tables from this repository.
• In two places in the MPAS-Atmosphere solver, the upwinding coefficient for the 3rd-order advection scheme, config_coef_3rd_order, was incorrectly declared as an integer rather than a real. The bug affects the diagnosis of the covariant vertical velocity omega, resulting in the use of a fourth-order diagnosis as opposed to the third-order diagnosis consistent with the horizontal transport.

• the option to run the RRTMG long-wave and short-wave radiation codes with climatologically varying ozone profiles
• improved interpolation of surface update fields (sea-surface temperatures and fractional seaice)
• the ability to run MPAS-A in single-precision. This capability has received very limited testing, and the MPAS-A group would be interested in receiving any feedback based on user experiences with this feature. For information on building and running MPAS-A for single-precision execution, please see this page.
• other minor corrections to code, including:
  • logic changes to compute simulated radar reflectivity and other diagnostic fields at the proper time in high-frequency diagnostic files
  • fix for the lower bound of a loop in the computation of horizontal advection of w when config_w_adv_order=3 (no impact on results); thanks to Bill Gustafson Jr. and Matus Martini of PNNL
  • turning off the inclusion of moisture by default in the initialization for the Jablonowski and Williamson test case

• We have not tested the model for deep-atmosphere configurations; our model top has typically been set at 30 km in real-data simulations.
  
• The current physics suite, taken from the WRF-NRCM configuration with a few additional options, had not been developed for coarse meshes [dx ~ O(100 km)].  We have observed a number of MPAS-A failures related to physics on coarse meshes for long-term integrations with surface updates.
• We have only used GFS, CFSR, and NNRP data for initialization of full-physics real-world cases. Real case initializations using other data, like ERA-Interim data, are currently being tested.
  
• We have only limited post-processing capabilities at present, particularly with respect to visualization.
• While we have begun testing methods for interpolating the MPAS output to latitude-longitude meshes (which would greatly expand our post-processing capabilities), these packages are not available in this release.  We expect to make them available in the near future.
  
• MPAS must be run under MPI because MPAS uses PIO.  We understand that there would be some utility to having a serial build, and this capability may appear in a later release.
  
• MPAS does not currently support running MPAS-Atmosphere coupled to MPAS-Ocean.  We anticipate that most coupled-model work using MPAS-A will occur in CESM.  We are, however, open to working with others exploring coupling with other modeling systems.
  
• MPAS-A and MPAS-O are standalone models; this release does not contain the CESM configurations for MPAS-A or MPAS-O, both of which are currently under development.
• Data assimilation using the Data Assimilation Research Testbed (DART) with MPAS-A is under development.  This capability is not available in this release.