Announcements:

Updated, 7 February 2013: Based on preliminary tests, some suggestions for using CM1 on yellowstone have been made available. Please contact George Bryan with any questions or suggestions about using CM1 on yellowstone. Thanks.

5 January 2012: A bug was uncovered in CM1 (cm1r15 and earlier versions) that affects simulations using terrain (terrain_flag = .true.) that have vertically stretched grids (stretch_z = 1). (If you are not using terrain, this bug does not affect you.) Further details are available in the Known problems and fixes page.

What is CM1?

In scientific terms: CM1 is a three-dimensional, non-hydrostatic, non-linear, time-dependent numerical model designed for idealized studies of atmospheric phenomena.

Or, in other words: CM1 is a computer code used for atmospheric research. It is ideally suited to study relatively small-scale processes in the Earth's atmosphere, such as thunderstorms.

For more information, please read these answers to frequently asked questions about CM1.

Code

Download the code here. (Most recent version: cm1r16, available since 6 February 2012)

Documentation

About CM1:

• Acknowledgments.
• Answers to frequently asked questions about CM1.
• The governing equations for CM1 (Last updated: 16 October 2009)
• presentation on CM1 parallelization (pdf) (From presentation at NCSA, December 2009)
• Parallel Performance (Last updated: 18 April 2012)

Helpful Information for New Users of CM1:

• A brief summary of how to run cm1.
• README.namelist -- explains the various settings in the namelist.input file.
• Pre-configured namelist.input files
• Soundings for idealized simulations
• Sample submission scripts for NCAR's supercomputers

Other Information about CM1:

• CHANGES in release 16 -- new features, modifications, and code fixes for the newest version (6 February 2012)
  • History of all CHANGES (from r2 to present)
• Known problems and fixes (last updated: 5 January 2012)
• Instructions for adding a new microphysics scheme to CM1 (pdf)
• Some useful GrADS scripts
• Some useful programs for MPI users

Testing and evaluation of CM1

Here are reports on some basic tests of the accuracy and capability of CM1. (Note: all of these tests have been completed, but I haven't had time to write up the results. I plan to have all of these posted online in the near future.)

• Gravity current
• Inertia-gravity waves
• Two-dimensional mountain waves
• Potential flow over a mountain in dry and moist environments
• Bryan-Fritsch moist benchmark
• Large eddy simulation of the convective boundary layer
• A comparison of axisymmetric and three-dimensional simulations of a tropical cyclone

Research Results

Peer-reviewed articles that use CM1: (Please contact George Bryan if you have something to add to this list.)

• 2012:
• Bryan, G. H., 2012: Comments on "Sensitivity of tropical-cyclone models to the surface drag coefficient". Quart. J. Roy. Meteor. Soc., in press.
• Naylor, J., and M. S. Gilmore, 2012: Environmental factors influential to the duration and intensity of tornadoes in simulated supercells. Geophys. Res. Let., 39, L17802, doi:10.1029/2012GL053041
• Naylor, J., and M. S. Gilmore, 2012: Convective initiation in an idealized cloud model using an updraft nudging technique. Mon. Wea. Rev., in press, doi:10.1175/MWR- D-12-00163.1.
• Orf, L., and E. Kantor, and E. Savory, 2012: Simulation of a downburst-producing thunderstorm using a very high-resolution three-dimensional cloud model. J. of Wind Engineering and Industrial Aerodynamics, 104, 547-557.
• Kirshbaum, D. J., and A. L. M. Grant, 2012: Invigoration of cumulus cloud fields by mesoscale ascent. Quart. J. Roy. Meteor. Soc., in press, doi:10.1002/qj.1954
• Dahl, J. M. L., M. D. Parker, and L. J. Wicker, 2012: Uncertainties in trajectory calculations within near-surface mesocyclones of simulated supercells. Mon. Wea. Rev., in press, doi:10.1175/MWR-D-12-00131.1
• Naylor, J., M. S. Gilmore, R. L. Thompson, R. Edwards, and R. B. Wilhelmson, 2012: Comparison of objective supercell identification techniques using an idealized cloud model. Mon. Wea. Rev., 140, 2090-2102, doi:10.1175/MWR-D-11-00209.1
• Rotunno, R., and G. H. Bryan, 2012: Effects of parameterized diffusion on simulated hurricanes. J. Atmos. Sci., 69, 2284-2299, doi:10.1175/JAS-D-11-0204.1
• Miglietta, M. M., and R. Rotunno, 2012: Application of theory to simulations of observed cases of orographically forced convective rainfall. Mon. Wea. Rev., in press, doi:10.1175/MWR-D-11-00253.1
• Kang, S.-L., D. Lenschow, and P. Sullivan, 2012: Effects of mesoscale surface thermal heterogeneity on low-level horizontal wind speeds . Bound. Layer Meteor., 143, 409-432, doi:10.1007/s10546-011-9691-4.
• Bryan, G. H., 2012: Effects of surface exchange coefficients and turbulence length scales on the intensity and structure of numerically simulated hurricanes. Mon. Wea. Rev., in 140, 1135-1143, doi:10.1175/MWR-D-11-00231.1.
• Billings, J. M., and M. D. Parker, 2012: Evolution and maintenance of the 22-23 June 2003 nocturnal convection during BAMEX. Wea. Forecasting, 27, 279-300, doi:10.1175/WAF-D-11-00056.1
• Parker, M. D., 2012: Impacts of lapse rates upon low-level rotation in idealized storms. J. Atmos. Sci., 69, 538-559, doi:10.1175/JAS-D-11-058.1
• Reasor, P. D., and M. D. Eastin, 2012: Rapidly Intensifying Hurricane Guillermo (1997). Part II: Resilience in Shear. Mon. Wea. Rev., 140, 425-444, doi:10.1175/MWR-D-11-00080.1
• Bryan, G. H., and H. Morrison, 2012: Sensitivity of a simulated squall line to horizontal resolution and parameterization of microphysics. Mon. Wea. Rev., 140, 202-225, doi:10.1175/MWR-D-11-00046.1
• 2011:
• Vermeire, B. C., L. G. Orf, and E. Savory, 2011: Improved modelling of downburst outflows for wind engineering applications using a cooling source approach. J. Wind Engineering and Industrial Aerodynamics, 99, 801-814, doi:10.1016/j.jweia.2011.03.003
• Wissmeier, U., and R. K. Smith, 2011: Tropical cyclone convection: the effects of ambient vertical vorticity. Quart. J. Roy. Meteor. Soc., 137, 845-857.
• Vermeire, B. C., L. G. Orf, and E. Savory, 2011: A parametric study of downburst line near-surface outflows. J. Wind Engineering and Industrial Aerodynamics, 99, 226-238, doi:10.1016/j.jweia.2011.01.019
• Letkewicz, C. E., and M. D. Parker, 2011: Impact of environmental variations on simulated squall lines interacting with terrain. Mon. Wea. Rev., 139, 3163-3183, doi:10.1175/2011MWR3635.1
• Nowotarski, C. J., P. M. Markowski, and Y. P. Richardson, 2011: The characteristics of numerically simulated supercell storms situated over statically stable noundary layers. Mon. Wea. Rev., 139, 3139-3162, doi:10.1175/MWR-D-10-05087.1
• Doyle, J. D., S. Gabersek, Q. Jiang, L. Bernardet, J. M. Brown, A. Dornbrack, E. Filaus, V. Grubisic, D. J. Kirshbaum, O. Knoth, S. Koch, J. Schmidli, I. Stiperski, S. Vosper, and S. Zhong, 2011: An intercomparison of T-REX mountain wave simulations and implications for mesoscale predictability. Mon. Wea. Rev., 139, 2811-2831, doi:10.1175/MWR-D-10-05042.1
• Markowski, P. M., and N. Dotzek, 2011: A numerical study of the effects of orography on supercells. Atmos. Res., 100, 457-478, doi:10.1016/j.atmosres.2010.12.027
• Kang, S.-L., and G. H. Bryan, 2011: A large eddy simulation study of moist convection initiation over heterogeneous surface fluxes. Mon. Wea. Rev., 139, 2901-2917.
• Hakim, G. J., 2011: The mean state of axisymmetric hurricanes in statistical equilibrium. J. Atmos. Sci., 68, 1364-1376.
• Kirshbaum, D. J., 2011: Cloud-resolving simulations of deep convection over a heated mountain. J. Atmos. Sci., 68, 361-378.
• 2010:
• Wissmeier, U., R. K. Smith, and R. Goler, 2010: The formation of a multicell thunderstorm behind a sea-breeze front. Quart. J. Roy. Meteor. Soc., 136, 2176-2188.
• Wang, W., and M. W. Rotach, 2010: Flux footprints over an undulating surface . Bound.-Layer Meteor., 136, 325-340.
• French, A. J.,, and M. D. Parker, 2010: The response of simulated nocturnal convective systems to a developing low-level jet. J. Atmos. Sci., 67, 3384-3408.
• Miglietta, M. M., and R. Rotunno, 2010: Numerical simulations of low-CAPE flows over a mountain ridge. J. Atmos. Sci., 67, 2391-2401.
• Parker, M. D., 2010: Comments on "A comparison of tropical and midlatitude thunderstorm evolution in response to wind shear." J. Atmos. Sci., 67, 1700-1707.
• James, R. P., and P. M. Markowski, 2010: A numerical investigation of the effects of dry air aloft on deep convection. Mon. Wea. Rev., 138, 140-161.
• Wang, W., 2010: The influence of topography on single-tower-based carbon flux measurements under unstable conditions: a modeling perspective. Theor. Appl. Climatol., 99, 125-138.
• 2009:
• Bryan, G. H., and R. Rotunno, 2009: Evaluation of an analytical model for the maximum intensity of tropical cyclones. J. Atmos. Sci., 66, 3042-3060.
• Kirshbaum, D. J., and R. B. Smith, 2009: Orographic precipitation in the tropics: large-eddy simulations and theory. J. Atmos. Sci., 66, 2559-2578.
• Wissmeier, U., and R. Goler, 2009: A comparison of tropical and mid-latitude thunderstorm evolution in response to wind shear. J. Atmos. Sci., 66, 2385-2401.
• Miglietta, M. M., and R. Rotunno, 2009: Numerical simulations of conditionally unstable flows over a mountain ridge. J. Atmos. Sci., 66, 1865-1885.
• Bryan, G. H., and R. Rotunno, 2009: The maximum intensity of tropical cyclones in axisymmetric numerical model simulations. Mon. Wea. Rev., 137, 1770-1789.
• Schumacher, R. S., 2009: Mechanisms for quasi-stationary behavior in simulated heavy-rain-producing convective systems. J. Atmos. Sci., 66, 1543-1568.
• Kang, S.-L., 2009: Temporal oscillations in the convective boundary layer forced by mesoscale surface heat-flux variations. Bound.-Layer Meteor., 132, 59-81.
• Wang, W., 2009: The influence of thermally-induced mesoscale circulations on turbulence statistics over an idealized urban area under a zero background wind. Bound.-Layer Meteor., 131, 403-423.
• 2008:
• Smith, J. W., and P. R. Bannon, 2008:A comparison of compressible and anelastic models of deep dry convection. Mon. Wea. Rev., 136, 4555-4571.
• Kang, S.-L., and K. J. Davis, 2008: The effects of mesoscale surface heterogeneity on the fair-weather convective atmospheric boundary layer. J. Atmos. Sci., 65, 3197-3213.
• Schumacher, R. S., and R. H. Johnson, 2008: Mesoscale processes contributing to extreme rainfall in a midlatitude warm-season flash flood. Mon. Wea. Rev., 136, 3964-3986.
• Wang, W., and K. J. Davis, 2008: A numerical study of the influence of a clearcut on eddy-covariance fluxes of CO2 measured above a forest. Agricultural and Forest Meteor., 148, 1488-1500.
• Parker, M. D., 2008: Response of simulated squall lines to low-level cooling. J. Atmos. Sci., 65, 1323-1341.
• Edson, A. R., and P. R. Bannon, 2008: Nonlinear atmospheric adjustment to momentum forcing. J. Atmos. Sci., 65, 953-969.
• Bryan, G. H., and R. Rotunno, 2008: Gravity currents in a deep anelastic atmosphere. J. Atmos. Sci., 65, 536-556.
• 2007:
• Kirshbaum, D. J., R. Rotunno, and G. H. Bryan, 2007: The spacing of orographic rainbands triggered by small-scale topography. J. Atmos. Sci., 64, 4222-4245.
• Lin, W. E., L. G. Orf, E. Savory, and C. Novacco, 2007: Proposed large-scale modelling of the transient features of a downburst outflow. Wind & Structures, 10, 315-346.
• Kirshbaum, D. J., G. H. Bryan, R. Rotunno, and D. R. Durran, 2007: The triggering of orographic rainbands by small-scale topography. J. Atmos. Sci., 64, 1530-1549.
• Bryan, G. H., R. Rotunno, and J. M. Fritsch, 2007: Roll circulations in the convective region of a simulated squall line. J. Atmos. Sci., 64, 1249-1266.
• 2006:
• Bannon, P. R., J. M. Chagnon, and R. P. James, 2006: Mass conservation and the anelastic approximation. Mon. Wea. Rev., 134, 2989-3005.
• Bryan, G. H., J. C. Knievel, and M. D. Parker, 2006: A multimodel assessment of RKW Theory's relevance to squall-line characteristics. Mon. Wea. Rev., 134, 2772-2792.
• James, R. P., P. M. Markowski, and J. M. Fritsch, 2006: Bow echo sensitivity to ambient moisture and cold pool strength. Mon. Wea. Rev., 134, 950-964.
• 2005:
• Fanelli, P. F., and P. R. Bannon, 2005: Nonlinear atmospheric adjustment to thermal forcing. J. Atmos. Sci., 62, 4253-4272.
• James, R. P., J. M. Fritsch, and P. M. Markowski, 2005: Environmental distinctions between cellular and slabular convective lines. Mon. Wea. Rev., 133, 2669-2691.
• Bryan, G. H., 2005: Spurious convective organization in simulated squall lines owing to moist absolutely unstable layers. Mon. Wea. Rev., 133, 1978-1997.
• 2003:
• Bryan, G. H., J. C. Wyngaard, and J. M. Fritsch, 2003: Resolution requirements for the simulation of deep moist convection. Mon. Wea. Rev., 131, 2394-2416.
• 2002:
• Bryan, G. H., and J. M. Fritsch, 2002: A benchmark simulation for moist nonhydrostatic numerical models. Mon. Wea. Rev., 130, 2917-2928.

Some recent conference papers that use CM1:

• Chavas, D. R., and K. Emanuel, 2012: Equilibrium Tropical Cyclone Size in an Idealized State of Axisymmetric Radiative-Convective Equilibrium. 30th Conference on Hurricanes and Tropical Meteorology, Ponte Vedra Beach, FL, Amer. Meteor. Soc., 10C.4.
• Hastings, R. M., Y. P. Richardson, P. M. Markowski, J. M. Wurman, and C. C. Weiss, 2012: Mergers in Supercell Environments. Part I: Conceptual models of mechanisms governing merger outcomes. 26th Conference on Severe Local Storms, Nashville, TN, Amer. Meteor. Soc., 11B.6.
• Hastings, R. M., Y. P. Richardson, and P. M. Markowski, 2012: Mergers in supercell environments. Part II: Tornadogenesis potential during merger as evaluated by changes in the near-surface low-level mesocyclone. 26th Conference on Severe Local Storms, Nashville, TN, Amer. Meteor. Soc., P143.
• Nowotarski, C. J., P. M. Markowski, Y. P. Richardson, and G. H. Bryan, 2012: The influence of horizontal convective rolls on the morphology of low-level rotation in idealized simulations of supercell thunderstorms. 26th Conference on Severe Local Storms, Nashville, TN, Amer. Meteor. Soc., 11.B4.
• French, A. J., and M. D. Parker, 2012: Idealized simulations of mergers between squall lines and isolated supercell thunderstorms. 26th Conference on Severe Local Storms, Nashville, TN, Amer. Meteor. Soc., P148.
• Bryan, G. H., R. Rotunno, and M. L. Weisman, 2012: What is RKW Theory?. 26th Conference on Severe Local Storms, Nashville, TN, Amer. Meteor. Soc., 4B.6.

Honors and awards

• 2012: Daniel Chavas of MIT won the 2012 Max Eaton Prize from the AMS for his paper, Equilibrium tropical cyclone size in an idealized state of axisymmetric radiative-convective equilibrium.
• 2010: George Bryan and Richard Rotunno were awarded the Banner I. Miller Award by the AMS for their article "The maximum intensity of tropical cyclones in axisymmetric numerical model simulations".
• 2009: An analysis of a supercell thunderstorm by Leigh Orf of Central Michigan University was selected for the cover of the Coalition for Academic Scientific Computation's 2010 brochure.
• 2008: Casey Letkewicz of the Department of Marine, Earth, and Atmospheric Sciences at North Carolina State University won the Best Student Poster award at the 24th Conference on Severe Local Storms for her studies of simulated mesoscale convective systems crossing the Appalachian Mountains.
• 2008: Chris Nowotarski of the Department of Meteorology at The Pennsylvania State University won the Best Student Oral Presentation award at the 24th Conference on Severe Local Storms for his study of numerically simulated supercells in varying low-level environmental stability.

Links

• Grid Analysis and Display System (GrADS) (supported by Institute of Global Environment and Society)
• NetCDF (supported by Unidata)
• HDFtools (supported by Leigh Orf, Central Michigan University)
• Visualization and Analysis Platform for Ocean, Atmosphere, and Solar Researchers (VAPOR) (supported by the National Center for Atmospheric Research)

Send comments and/or questions about this page to:

George H. Bryan
National Center for Atmospheric Research
3090 Center Green Drive
Boulder, CO 80301, USA
email: gbryan at ucar dot edu

Last updated: 11 October 2012