CCPP Framework Meeting Minutes 2021 08 03

Agenda

• Consolidation of MYNN versions
• GNU-10 compatibility
• Update on standard names
• Transition to capgen.py
• Other business

Consolidation of MYNN versions

• Lessons learned (from Laura and Joe)
• Mostly agreement with naming conventions
• Interstitial code for schemes coming from a specific model should be short, for other models likely a bit longer
  • Automating some of these tasks can help reducing the interstitial code
• Structural differences between how MPAS and the UFS use the surface layer scheme
  • Related to land categories (binary mask versus fractional mask versus ...)
  • WRF approach: call scheme once and use lookup tables inside to do the right thing for each grid point
  • UFS approach: call scheme a number of times for different categories, then aggregate fluxes afterwards
  • Preliminary conclusion: there will be schemes with multiple versions of the CCPP interface (wrapper code)
  • This relates to the DDRF proposal on compositing variables for fractional land mask - but this capability is not yet there. What do we do in the meantime?
    • Write interstitials or put it in the wrapper (model dependency)?
    • Single interface to scheme recommended, with interstitial code as needed

GNU-10 compatibility

• GNU 10 much stricter w.r.t. argument mismatches, so far we had to add compiler flags to turn them into warnings (bad)
  • use mpi or include mpif.h don't work w/o these flags; need to use use mpi_f08
  • this turns the MPI communicator into a DDT (no longer an integer), does the framework support this w/o a definition of the DDT?
  • To do: CESM team to explore if use mpi_f08 works in all the supported compilers.

Dictionary of standard names

• Original "rules for standard names" PR https://github.com/ESCOMP/CCPPStandardNames/pull/14 merged last week
• Host model PRs:
  • ccpp-physics: https://github.com/NCAR/ccpp-physics/pull/687 - merged last week
  • UFS/fv3atm: https://github.com/NOAA-EMC/fv3atm/pull/337 - merged last week
  • SCM: https://github.com/NCAR/ccpp-scm/pull/269 - not yet merged
• Update of "rules for standard names" in PR https://github.com/ESCOMP/CCPPStandardNames/pull/16 - merged during the meeting
• Then need to update https://github.com/ESCOMP/CCPPStandardNames/pull/13 and create follow-up PRs for ccpp-physics, fv3atm, scm

Transition to capgen.py

• Dom started to update feature/capgen from main to simplify future work and merge back

Other business

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