CAM Development


This page is intended to be a summary of the Atmosphere Model Working Group (AMWG) activities in developing the CESM Community Atmosphere Model (CAM)

The current version of the Community Atmosphere Model is CAM6, view here

The path to CAM6 & CESM2

High Horizontal Resolution

We expect that global climate models in the next decade will run routinely at horizontal resolutions of 25 km or lower. High-resolution simulations targets simulations of tropical cyclones, improvement in important regional and mesoscale circulation, etc...

Increased Vertical Resolution

Higher vertical resolution improves the ability to represent certain aspect of physics or dynamics better (QBO, sudden stratospheric warmings, etc...

  • Increased Vertical resolution simulations
  • 46-level model
  • Richter et al. (2014) On the Simulation of the Quasi-Biennial Oscillation in the Community Atmosphere Model, Version 5, Accepted in JAMES, doi: 10.1002/2013JD021122. [Paper]
  • Richter et al. (2014) Effects of Vertical Resolution and Non-Orographic Gravity Wave Drag On the Simulated Climate in the Community Atmosphere Model, Version5 , Submitted to JAMES [Paper]
  • Richter (2013) Higher vertical resolution in CAM. Do we need it ? CESM Workshop, Breckenridge, 17 - 20 June 2013. [Talk]
  • Summary of Potentially level dependent physics
  • Figure of the vertical levels high & low

Cloud Physics

There are several Community development activities related to the improvement of the cloud physics (CLUBB, UNICON, deep convection activities)


Implement a multi-variate PDF based moist turbulence and cloud macrophysics scheme based on the Cloud Layers Unified By Binormals (CLUBB) into CAM.

  • CLUBB Simulations
  • Bogenschutz et al. (2014) Recent progress and developments with CAM-CLUBB. AMWG Meeting, Boulder, 10-12 February 2014 [Talk]
  • Bogenschutz et al. (2013) A unified cloud/convection scheme for CAM: Concept and preliminary results. CESM Workshop, Breckenridge, 17 - 20 June 2013. [Talk]
  • Bogenschutz et al. (2013) Higher-order turbulence closure and it's impact on climate simulations in the Community Atmosphere Model. J. Climate, 26, 9655-9676, doi:10.1175/JCLI-D-13-00075.1. [Paper]
  • Bogenschutz et al. (2012) Unified parameterization of the planetary boundary layer and shallow convection with a higher-order turbulence closure in the Community Atmosphere Model. Geo. Sci. Model Dev., 5, 1407-1423, doi:10.5194/gmd-5-1407-2012 [Paper]


A unified convection scheme for CAM that unifies treatment of deep and shallow convection.

  • UNICON Simulations
  • Park (2014) A Unified Convection Scheme, UNICON. Part I. Formulation. Journal of the Atmospheric Sciences, doi:10.1175/JAS-D-13-0233.1. [Paper]
  • Park (2014) A Unified Convection Scheme, UNICON. Part II. Simulation. Journal of the Atmospheric Sciences, doi:10.1175/JAS-D-13-0234.1. [Paper]
  • Park (2014) An update on the CAM Unified Convection Scheme (UNICON), 10-12 February 2014 [Paper]
  • Park (2013) Scale-adaptive physics parameterization. CESM Workshop, Breckenridge, 17 - 20 June 2013 [Paper]

Deep Convection

Modifications of the Zhang McFarlane scheme for short-term tuning of CAM5 high resolution simulations.


Next generation of MG microphysics. Includes prognostic precipitation, mixed phase ice nucleation and convective microphysics.

MG2 Microphysics

  • MG2 Simulations
  • Gettelman et al (2014) Advanced Two-Moment Microphysics for Global Models. Part I: Off line tests and comparisons with other schemes. Accepted for publication in J. Climate, [Preprint]
  • Gettelman et al (2014) Advanced Two-Moment Microphysics for Global Models. Part II: Global model solutions and Aerosol-Cloud Interactions. Accepted for publication in J. Climate [Preprint]

New Ice Nucleation

Mixed-phase cloud ice nucleation + Refinement of ice nucleation treatment in cirrus clouds

  • Ice Nucleation Simulation
  • Wang el al (2014) Impact of heterogeneous ice nucleation by natural dust and soot based on a probability density function of contact angle model with the Community Atmospheric Model version 5, Atmos. Chem. Phys. Discuss, 14, 7141-7186, doi:10.5194/acpd-14-7141-2014 [Paper]
  • English et al (2014): Contributions of clouds, surface albedos, and mixed-phase ice nucleation schemes to Arctic radiation biases in CAM5. J. Climate, doi:10.1175/JCLI-D-13-00608.1 [Paper]
  • Shi et al. (2014): Effects of preexisting ice crystals on cirrus clouds and comparison between different ice nucleation parameterizations with the Community Atmosphere Model (CAM5), Submitted to Atmos. Chem. Phys. Discuss Manuscript]

Gravity Wave Drag (GWD) & Turbulent Mountain Stress (TMS)

Development targets Gravity Wave Drag (GWD) and Turbulent Mountain Stress (TMS) schemes.

MAM Development

Development targets are MAM4 and prescribed MAM. MAM4 includes a primary carbon mode and improves the simulation of black carbon at high-latitudes.

Energy Formulation In CAM

An error in the energy formulation in CAM is identified and corrected.

Ocean Spunup Simulations

We look at spinup issue with the Spectral Element dycore.

  • Ocean Spunup Simulations
  • Cecile Hannay, Rich Neale, Joe Tribbia, Keith Lindsay and Gokhan Danabasoglu (2014), Coupled Simulations with CAM5.3. Ocean Spinup in CESM: Is it dycore dependant ? Atmosphere Model Working Group (AMWG) Meeting, Boulder, 10-12 February, 2014 [Talk]

Spectral Coupled Simulation

CAM5-CLM4.5 Coupled Simulation

CAM Development Timelines

Bug Reporting