Pace split

[FlorianDeconinck]

Pace will be split alongside three axis and recomposed from them.

• ndsl: middleware part
• PyFV3: the Python/DSL version of FV3
• PySHiELD: the Python/DSL version of physics parametrization

Pace remains a model, bringing the three parts above as submodules and dealing with driver & bespoke init.

⚠ Due to the breath of the refactor - a coding freeze is required⚠

Branch/PR wise, a freeze will be enacted then the following pattern will be implemented.

main (freeze) |----|----|----|---|--------|--- main (resume dev)
               \   /    \   /    \       /     
	       ndsl     pyfv3    pySHiELD

In-between each merge, a full fresh install of Pace + running a C12 for 1 timesteps will insure functionality.

We will document here all changes. Post refactor, we expect some movement of code from and to the new repository but that should be minimal.

Out of scope for this issue.

• makefile workflow
• docker image
• github CI hooks
• docs

DoD: Pace relies on ndsl, pyFV3 and pySHiELD.

Cross-post: NOAA-GFDL#53

[FlorianDeconinck]

ndsl

• tracer_variables: need an API in ndsl and calls in the model. Stays in ndsl for now, API needed.
• halo and origin in gt4py_utils: those should have an API with reasonable defaults.

physics

• update_dwind_phys.py, update_atmos_state.py and fv_update_phys.py lives in Physics but should be part of a broader plug & play Physics API that know how to interface with the Dynamical Core.

[FlorianDeconinck]

ndsl

• examples/mpi are the examples from util

[FlorianDeconinck]

ndsl

• There's a C12 data bundle for testing restart in tests/main/data on Pace

[FlorianDeconinck]

ndsl

• Clean up the __init__.py of the package or subdirectory to only publicize the correct API. Or do away entirely with the concept.
• utils:
  • Halo updates are now bundled in utils.halo
  • Comms, partition & MPI are bundled utils.comm

Todo:

• Reconnect utils tests to github workflow

[FlorianDeconinck]

ndsl

• utils:
  • remove _corners, _capture_streams, _xarray, nudging, time
  • move util._timing in performance

Todo:

• PACE_LOGLEVEL: NDSL_LOGLEVEL
• restart should move to Pace and/or pyFV3

[FlorianDeconinck]

ndsl

• Do we keep the __init__.py has a method of public API (reduce the import on top of the files) or keep the full import structure (less cross imports)

[FlorianDeconinck]

ndsl

• pre-commit setup

[FlorianDeconinck]

Porting errors to fix

• ndsl.grid.eta depends on pyFV3 for ETA calculation.
• ndsl.stencils.c2l_ord depends on pyFV3, requires DycoreState

Breakage due to refactor

• docs is broken and need rewire
• Makefile are broken in all new repositories
• docker are broken in all new repositories

[FlorianDeconinck]

todo

• makes issues
• x-post to NOAA
• set up working branches and secure main

[FlorianDeconinck]

New repositories:
ndsl
pyFV3
pySHiELD