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Global Atmospheric Models


AM4/LM4 is a new generation global atmosphere and land model that serves as a base for a new set of climate and Earth system models (CM4 and ESM4) and prediction model (SPEAR) developed at NOAA’s Geophysical Fluid Dynamics Laboratory (GFDL). AM4/LM4 has roughly 100 km horizontal resolution and contains an aerosol model that generates aerosol fields from emissions. AM4/LM4 has two versions, which differ primarily in the treatment of atmospheric chemistry and stratospheric vertical resolution. AM4.0/LM4.0 contains 33 vertical levels with a light chemistry mechanism designed to support the aerosol model but with prescribed ozone and it is used in CM4 and SPEAR. AM4.1/LM4.1 contains 49 vertical levels and more comprehensive treatment of atmospheric chemistry with prognostic ozone and it is used in ESM4. Read more…

The code for AM4.0/LM4.0 (Zhao et al., 2018a,b) is publicly available at


AM3 (Donner et al., 2011), the atmospheric component of the GFDL coupled model CM3, was designed with an awareness of key emerging issues in climate science, including aerosol-cloud interactions in climate and climate change, chemistry-climate feedbacks, land and ocean carbon cycles and their interactions with climate change, and decadal prediction. It is GFDL’s first global atmospheric model to include cloud-aerosol interactions, with 20 interactive aerosol species. AM3 includes interactive tropospheric and stratospheric chemistry (85 species). AM3 uses emissions to drive its chemistry and aerosols. Its inclusion of stratospheric chemistry and dynamics will enable possible interactions between the stratosphere and troposphere on interannual scales to be included in future studies of decadal predictability. Its stratosphere has increased vertical resolution over AM2, with the uppermost level at about 1 Pascal. AM3’s improved simulation of Amazon precipitation will enhance future coupling into an earth-system model. Read more…

AM3 Code Released March 2012

The code for this model is publicly available.


HiRAM, the GFDL global HIgh Resolution Atmospheric Model, was developed with a goal of providing an improved representation of significant weather events in a global climate model. Our intention was to produce a model capable of simulating the statistics of tropical storms, with sufficient fidelity that it can be used with confidence to study the causes of year-to-year variability in storm activity, recent trends in activity, as well as the predictability of the Atlantic hurricane season. As the credibility of the model improves, based on comparisons with observations, we will apply it to study the effects of global warming on tropical storms. Read more…

HiRAM Code Released April 2012

The code for this model is publicly available.

CMIP Experiments with HiRAM

Simulations with two HiRAM models have been provided to the CMIP5 archive. For HiRAM-C180, the grid has 180 x 180 points on each face, and for HiRAM-C360, it has 360 x 360 points.

These simulations consist, first of all, of controls using the 1979-2008 period with observed sea surface temperatures and sea ice cover. We currently have deposited data from three C180 controls and two C360 controls.

These controls are themselves useful for diagnostic and attribution studies. We then took estimates, from the CM3 and ESM2M coupled models, of the anomalies in ocean temperature and sea ice cover between this control period and a 10 year period centered on 2030 and on a 10-year period centered on 2095, for the 4.5 and 8.5 RCP scenarios, and added these anomalies to the observed boundary conditions in the control simulations. Several realizations were generated for each case. These anomalies do not contain interannual variability, so, for example, the ENSO variability in the future simulations is assumed to be the same as in the control runs. For all future simulations we used the ENSO variability of the last 10 years of the control simulation (1999-2008).

To obtain CMIP5 HiRAM data, click here.

Idealized Spectral Models

Several idealized models are available: barotropic, shallow water, and both moist and dry multilevel models with full dynamics. The forcing for the dry model is that of Held and Suarez: Held, Isaac M., and M J Suarez, 1994: A proposal for the intercomparison of the dynamical cores of atmospheric general circulation models. Bulletin of the American Meteorological Society, 75(10), 1825-1830.

Idealized Spectral Code Released Jan 25 2013

The code for the dry models is publicly available.

The code for the moist model is publicly available.

Idealized Cubed Sphere

A “vertically Lagrangian” finite-volume dynamical model. The forcing is that of Held and Suarez: Held, Isaac M., and M J Suarez, 1994: A proposal for the intercomparison of the dynamical cores of atmospheric general circulation models. Bulletin of the American Meteorological Society, 75(10), 1825-1830.

The code for this model is publicly available.

Model History

Click here for a brief history of atmospheric modeling at GFDL