MPAS Version 8.4.1

This bug fix release addresses several issues in the MPAS-Atmosphere model
and in the MPAS infrastructure. Specific changes include:

• Fix crashes in the atm_srk3 routine when MPAS-A is compiled without defining
  DO_PHYSICS, as is done when the MPAS-A dynamical core is used in, e.g., CAM
  or CAM-SIMA. (PR #1448)

• Limit the saturation vapor pressure, $e_s$, used in the Kessler microphysics to
  a value at or below 99% of the full pressure. Prior to this change, the
  saturation vapor pressure formula in Kessler could produce unphysically large
  values of $e_s$ at very low pressures (high model tops) and cause the model to
  blow up. (PR #1452)

• Fix an issue with multiple occurrences of the same namelist option in the
  specification for the optional active_when attribute for a Registry-defined
  package. With this fix, an active_when attribute may contain logic that uses
  a given namelist option more than once. (PR #1461)

• Fix a bug that occurs when the number of soil layers in Noah-MP is not the
  default (4 layers), resulting in the model not conserving water. (PR #1459)

• Fix broken builds with GEN_F90=true by adding missing include paths to the
  Makefile recipes that are used when MPAS is compiled with GEN_F90=true.
  (PR #1465)

• Switch the allocation of surface arrays to be based on the choice of surface
  layer scheme rather than on the choice of PBL scheme. This change allows
  model simulations that use a surface layer scheme but no PBL scheme to run
  correctly, for example, real-data simulations that use LES options in MPAS-A.
  (PR #1460)

Acknowledgements: Thanks to Marcos Longo (@mpaiao) for identifying issues and
providing fixes in this release.

Checksums for assets:

MPAS-Model-8.4.1.zip SHA-256: 624d6a6783b12f26157497c4f54370f2e675052ebf57916ecdfb3798d206d532
MPAS-Model-8.4.1.tar.gz SHA-256: 772f565c2bd66999492085eff8ffa0b9aa9a2edd1e7f2c0e5d1a8bedc1160861