gpuwm-hex (GPU-native variable-resolution atmospheric model core)
Copyright 2026 ArWen contributors

Licensed under the Apache License, Version 2.0. Vendored components and
upstream works from which this distribution derives retain their own
licenses and notices, reproduced below.

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MPAS-Atmosphere (LANL / UCAR)

gpuwm-hex reimplements the dynamical core of MPAS-Atmosphere (Model for
Prediction Across Scales) version 8.4.1 for CUDA devices, with pinned
source-line citations. MPAS-Atmosphere is developed by the Los Alamos
National Laboratory and the University Corporation for Atmospheric
Research / National Center for Atmospheric Research, and is distributed
under the BSD-3-Clause terms reproduced at the end of this section. Those
terms govern the MPAS-derived portions of this distribution and travel
with every copy of it.

That license separately requires that derivative works be clearly marked
so as not to be confused with the version available from LANS and UCAR.
This is that marking:

  - The distribution, the command and the namespace are named gpuwm-hex.
    The MPAS name is used only to state what this software derives from
    and what it is measured against.
  - Neither LANS, UCAR, NCAR nor their contributors endorse this
    software.
  - Results from gpuwm-hex are not results from MPAS-Atmosphere. Where
    the two are known to differ, the differences are measured, and the
    quantities are stated in README.md.

The cumulus scheme is a different generation from the reference:
gpuwm-hex carries the 2018 Grell-Freitas formulation, MPAS-A v8.4.1
carries the 2013 ensemble fork. They differ in closure membership, in the
rain conversion coefficient and its temperature dependence, and in
whether shallow convection precipitates. Three further differences are
measured and declared as divergences, judged against observations: an
upper-band potential-temperature drift, a convective rainfall deficit,
and a downstream condensate surplus.

Two of the MPAS-derived operators carry a further upstream lineage, which
MPAS-Model distributes inside its own tree under the terms reproduced
below. The orographic gravity-wave-drag operator in
src/mpas_port/cuda_gwdo_v841.py is a reimplementation of MPAS-Model's
physics_wrf/module_bl_gwdo.F, which is WRF-derived, and of
physics_mmm/bl_gwdo.F90, the Kim/YSU orographic gravity-wave-drag and
flow-blocking scheme from NCAR/MMM. Those files are cited by path and line
in the module that reimplements them. No source from either upstream is
copied into this distribution; the citations record what the CUDA operator
was written against.

MPAS-Atmosphere license text, retained in full:

Copyright (c) 2013-2019,  Los Alamos National Security, LLC (LANS) (Ocean: LA-CC-13-047;
Land Ice: LA-CC-13-117) and the University Corporation for Atmospheric Research (UCAR).

All rights reserved. 

LANS is the operator of the Los Alamos National Laboratory under Contract No.
DE-AC52-06NA25396 with the U.S. Department of Energy.  UCAR manages the National
Center for Atmospheric Research under Cooperative Agreement ATM-0753581 with the
National Science Foundation.  The U.S. Government has rights to use, reproduce,
and distribute this software.  NO WARRANTY, EXPRESS OR IMPLIED IS OFFERED BY
LANS, UCAR OR THE GOVERNMENT AND NONE OF THEM ASSUME ANY LIABILITY FOR THE USE
OF THIS SOFTWARE.  If software is modified to produce derivative works, such
modified software should be clearly marked, so as not to confuse it with the
version available from LANS and UCAR.

Additionally, redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:

1) Redistributions of source code must retain the above copyright notice, this
list of conditions and the following disclaimer.

2) Redistributions in binary form must reproduce the above copyright notice,
this list of conditions and the following disclaimer in the documentation and/or
other materials provided with the distribution.

3) None of the names of LANS, UCAR or the names of its contributors, if any, may
be used to endorse or promote products derived from this software without
specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

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ArWen (Python package "gpuwm")

Every physics column in the forecast lane runs through ArWen's
column-batch seam. ArWen is a separate distribution under the Apache
License, Version 2.0, with its own NOTICE covering the WRF-, RRTMG- and
RRTMGP-derived assets its physics carries. It is not vendored here; it is
declared as a dependency and installed from its own distribution.

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Data services (not redistributed)

Meshes, static geographical fields and initial conditions are staged by
the user from their providers. None of those datasets are redistributed
by this project; their terms are between the user and the provider.
