Version 3 GEOSCCM

Version 3 of the GEOSCCM model includes the GEOS-5 atmospheric general circulation model and the "Combo CTM" tropospheric/stratospheric chemical package developed within the Global Modeling Initiative (GMI) program (Duncan et al., 2007). The Combo CTM chemistry combines tropospheric and stratospheric mechanisms and includes 117 species, 322 chemical reactions, and 81 photolysis reactions. A detailed description of tropospheric O3-NOx-hydrocarbon chemistry in included in the tropospheric chemistry package. The stratospheric package is described in Kinnison et al. (2001) and Douglass et al. (2004). The Combo CTM simulates the radiative and heterogeneous chemical effects of sulfate, dust, sea salt, organic carbon and black carbon on tropospheric chemistry.

Douglass, A.R., R.S. Stolarski, S.E. Strahan, and P.S. Connell (2004), Radicals and reservoirs in the GMI chemistry and transport model: Comparison to measurements, J. Geophys. Res., 109, D16302,doi:10.1029/2004JD004632.

Duncan, B.N., S.E. Strahan, Y. Yoshida, S.D. Steenrod and N. Livesey, (2007), Model study of the cross-tropopause transport of biomass burning pollution, Atmos. Chem. Phys., 7, 3713-3736.

Kinnison, D.E., et al.(2001), The Global Model Initiative Assessment Model: Applications to high-speed civil transport perturbation, J. Geophys. Res., 106, 1693-1712.

Molod, A., L. Takacs, M. Suarez, J. Bacmeister, I.-S. Song, and A. Eichmann, (2012), The GEOS-5 Atmospheric General Circulation Model: Mean Climate and Development from MERRA to Fortuna, Technical Report Series on Global Modeling and Data Assimilation, 28. <>

Version 2 GEOSCCM

Version 2 of the GEOSCCM model includes an update of the atmospheric general circulation model from GEOS-4 to GEOS-5. The Lin and Rood (1996) dynamical core was retained, but new versions of several physical processes, most importantly the moist physics, have been implemented [Bachmeister, 2006, Reineker et al 2008]. In addition, a catchment approach [Koster, 2000] is now used to model the land-surface.

Koster, R. D., M. J. Suarez, A. Ducharne, M. Stieglitz, and P. Kumar (2000), A catchment-based approach to modeling land surface processes in a general circulation model: 1. Model structure, J. Geopshys. Res., 105, 24,809-24,822.

Bacmeister, J. T., M. J. Suarez, and F. R. Robertson (2006), Rain Re-evaporation, Boundary Layer Convection Interactions, and Pacific Rainfall Patterns in an AGCM. J. Atmos. Sci., 8. SRef-ID: 1607-7962/gra/EGU06-A-08925.

Rienecker M. M., Coauthors, 2008: The GEOS-5 Data Assimilation System-Documentation of versions 5.0.1, 5.1.0, and 5.2.0. NASA/TM-2008-104606, Vol. 27, Tech. Rep. Series on Global Modeling and Data Assimilation, 118 pp.
(available at

Version 1 GEOSCCM

Version 1 of the GEOSCCM model couples the GEOS-4 GMAO atmospheric general circulation model [Bloom et al., 2005] with an updated version of the stratospheric chemistry package used in the chemistry transport model developed within NASA Goddard Space Flight Center Code 613.3 [Stolarski et al., 2006]. The CTM's stratospheric photochemistry includes all gas-phase chemical reactions known to be of importance in the stratosphere [Sander et al., 2003]. Through the coupling, changes in stratospheric chemical constituents feedback to the radiation code in the general circulation model, thus affecting the dynamics and subsequent transport of chemical species. In the GEOSCCM model, The simulated concentrations of CO2 H2O, N2O, O3, CH4, CFC-11, and CFC-12 are used to determine heating and cooling rates. Version 1 does not include solar cycle or volcanic aerosol perturbations. A background volcanic aerosol is prescribed using the 1979 values from the Considine aerosols record. Photolysis rates are computed using a mean solar flux averaged over 76 years.

Bloom, S., et al. (2005), The Goddard Earth Observation System Data Assimilation System, GEOS DAS version 4.0.3: Documentation and validation, NASA Tech. Memo., TM-2005-104606, vol. 26, 166 pp.

Sander, S. P., et al. (Eds.) (2003), Chemical kinetics and photochemical data for use in atmospheric studies, JPL Publ., 02-25.

Stolarski, R. S., A. R. Douglass, S. Steenrod, and S. Pawson (2006), Trends in stratospheric ozone: Lessons learned from a 3D chemistry transport model, J. Atmos. Sci., 63, 1028\u20131041.