NDSL is a middleware for climate and weather modelling developped conjointment by NOAA and NASA. The middleware brings together GT4Py (the cartesian flavor), an ETH CSCS's stencil DSL, and DaCE, an ETH SPCL's data flow framework, both developped for high-performance and portability. On top of those pillars, NDSL deploys a series of optimized APIs for common operations (Halo exchange, domain decomposition, MPI...) and a set of bespoke optimizations for the models targeted by the middleware.

Historically NDSL was developed to port the FV3 dynamical core on the cube-sphere. Therefore, the middleware ships with ready-to-execute specilization for models based on cube-sphere grid and FV-based model in particular.

NDSL submodules gt4py and dace to point to vetted versions, use git clone --recurse-submodule.

NDSL is NOT available on pypi. Installation of the package has to be local, via pip install ./NDSL (-e supported). The packages has a few options:

• ndsl[test]: installs the test packages (based on pytest)
• ndsl[develop]: installs tools for development and tests.

Tests are available via:

• pytest -x test: running CPU serial tests (GPU as well if cupy is installed)
• mpirun -np 6 pytest -x test/mpi: running CPU parallel tests (GPU as well if cupy is installed)