MPAS Version 5.0

This major release of MPAS introduces new capabilities, options, and enhancements to MPAS-Atmosphere, as well as many small improvements in the MPAS framework.

Significant changes to MPAS-Atmosphere include:

• 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))

Updates and improvements to the MPAS framework include:

• 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