Summary
First release of version 2 of the Energy Exascale Earthy System Model contains the following changes from v1.0
EAM
The atmosphere component remains EAM. Major changes since version 1 include: all column-physics parameterizations are computed on a separate grid that has approximately half the number of points of the dynamics grid, a new nonhydrostatic dynamical core (running in hydrostatic mode) with semi-Lagrangian tracer transport, CLUBB has been changed from v1 to v2,
ELM
The land component is still ELM. Major changes since version 1 include: …
General MPAS improvements
MPAS still provides the components for ocean, sea-ice and land-ice.
Stand-alone testing suites are available in a new version of COMPASS (https://github.com/MPAS-Dev/compass ) using standardized python libraries and numerous new test cases.
Automated and improved generation of variable-resolution unstructured meshes and coastlines using jigsaw (https://github.com/dengwirda/jigsaw ) and COMPASS.
MPAS-Ocean
Redi isopycnal mixing has been updated, tested, and tuned in combination with the Gent-McWilliams parameterization.
A new semi-implicit barotropic solver has been introduced as an option.
There have been a number of performance improvements, including an initial GPU port of several portions of the model using OpenACC directives.
Ability to have inactive top cells below ice shelves.
Tracking and verification of flux budgets with coupler
Improvements in code simplicity and readability include transplanting MPAS code directly into E3SM repository, direct access to mesh and config variables, and excluding init mode in forward runs.
Addition of tidal forcing, wetting and drying for shorelines, internal wave drag, GOTM vertical mixing library, and sediment transport (all not yet fully validated).
MPAS-seaice
The sea-ice component remains MPAS-seaice. Major changes since version 1 include:…
MPAS-Albany-landice
The land-ice component remains MPAS-Albany-landice and is a static ice sheet. Major changes since version 1 include preparation for using an active ice sheet such as:
MALI code was moved from a submodule to instead exist directly within the E3SM repository.
An ice shelf damage evolution scheme was added, but is not yet coupled to calving or advection.
A von Mises tensile stress calving schemes was implemented and the calving algorithm was rewritten to eliminate a number of bugs.
The grounded marine terminus ocean melting scheme from ISMIP6-Greenland was implemented.
The option to use a regularized Coulomb basal friction law and a general power law basal friction law were added.
The sub-ice-shelf melting scheme from ISMIP6-Antarctica was added.
The prescribed mask-calving forcing scheme from ISMIP6-Antarctica was added.
Coupler/Configurations
All components allow regional refinement of their meshes and an example of refinement in and around North America is provided.