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What is SIMA?

NCAR advisory panels and Site Visit Teams over the last 3 years have recommended that NCAR unify and integrate the atmospheric modeling efforts that are distributed to the community.

In response to this, NCAR and the community have developed a vision for the next generation of community models for the atmosphere: SIMA, the System for Integrated Modeling of the Atmosphere. The primary goal of the 'SIMA' system is to be able to conduct frontier science simulations in climate, weather and geospace research using the same modeling system.

The initial SIMA vision development arose from the Singletrack project, and featured a large number of NCAR staff and selected community participants. This project ran from January - December 2018 and developed a 'Vision document and Roadmap' that became SIMA. We have started some initial explorations of different options in a 'SIMA version 0' (SIMAv0) using extensions to our existing modeling systems.

SIMA presently has 4 internal NCAR co-leads for Weather (Bill Skamarock), Climate (Andrew Gettelman), Chemistry (Mary Barth), and Geospace (Hanli Liu).

Submit Your Thoughts about SIMA

We invite the community to contribute to defining SIMA. Please let us know what you think by taking the following surveys (each will take about 10 minutes):

SIMA prototype logo

SIMA brings together Weather, Climate, Chemistry and Geospace Community Models at NCAR


SIMAv0 has started exploring unification and harmonization options in our existing systems. This has included the following elements:

  • SIMAv0 Chemistry: develop a new portable and robust infrastructure for building and maintaining chemistry schemes, develop a regionally refined chemical model over the US at 14km
  • SIMAv0 Geospace: extending current dynamical cores up to the thermosphere, and enable coupling to a geomagnetic grid
  • SIMAv0 Polar: A refined mesh configuration of CESM2 with 14km resolution over the Arctic and over Greenland is being developed for community use
  • SIMAv0 Climate: Refined Mesh: A 14km CESM2 mesh for the United States is being developed for the community
  • MPAS in CESMThe non-hydrostatic MPAS dynamical core is being integrated with CESM to enable the explicit simulation of atmospheric convection.  In addition, the Common Community Physics Package (CCPP) is being integrated into CAM/CESM to allow easy access to CCPP compliant physics components, including WRF/MPAS physics.

SIMA Frontier Applications - 3 year targets* Click on image for larger view

SIMA Workshop

NSF is sponsored virtual SIMA workshop in July 2020 to define the SIMA vision and implementation plan. The results of the workshop are available in the SIMA Workshop Vision Document



  File Modified
PNG File SIMA-image.png Dec 17, 2019 by Andrew Gettelman
PNG File SIMA-frontiers.png Dec 17, 2019 by Andrew Gettelman
PDF File SIMA Overview Jan 2020.pdf Dec 17, 2019 by Andrew Gettelman
PDF File SIMA_Workshop_Introduction2.pdf Jun 11, 2020 by Andrew Gettelman
PDF File SIMA Workshop Vision 2020.pdf Oct 06, 2020 by Andrew Gettelman

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