NCAR Imperative 3 | Advance Community Models

We have transitioned much of the CESM infrastructure to the new CIME (Common Infrastructure for Modeling the Earth) paradigm.  CIME separates much of the infrastructure of the model such as coupling, IO and support scripting from the science components of the model.   By doing so, we have engaged collaborators who are using models similar to CESM to share the burden of infrastructure development code among a bigger user and developer community. With CIME, there is greater developer feedback, and more testing, thus improving robustness of the model.

A critical aspect of CIME was to move the CIME source code repository from subversion to git.   The git source code repository has proven to make collaboration and parallel efforts much easier.  We have increased and improved the coverage of both unit testing and system testing.   A database of test results, known problems and outstanding issues is maintained with the git source code repository.   The user community is welcome to review this database, report new problems and even contribute solutions.

The Community Land Model version 5 is complete and includes many new parameterizations and features including hydrology, snow, vegetation processes, urban, nitrogen processes, and land-use processes including agriculture.  CLM5 will be used in upcoming CMIP 6 and CESM2.  CGD scientists are Leads or Co-Leads of the Land-use Model Intercomparison Project (LUMIP) and the Land Surface, Soil Moisture and Snow Intercomparison Project (LS3MIP).  Protocol papers have been published for both MIPs in GMD. LUMIP and CLM5 have been presented at several national meetings.

Chemical mechanisms were expanded to fully represent tropospheric (including a better representation of secondary-organic aerosols), stratospheric (including an explicit representation of volcanic aerosols) and mesospheric chemistries.  These are all being finalized for inclusion in CESM2 and use in CMIP6 simulations.  In addition, it will provide a benchmark against which simplified chemistry mechanisms can be tested.  Simulations of atmospheric composition of relevance to society (tropospheric ozone, stratospheric ozone depletion, air quality) will be more accurate and more physically-based as a result of these efforts.

list of new parameterizations and features for CLM5
Consolidated list of new parameterizations and features for CLM5.