The Dynamical Core, Physical Parameterizations, and Basic Simulation Characteristics of the Atmospheric Component AM3 of the GFDL Global Coupled Model CM3
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- 1 July 2011
- journal article
- Published by American Meteorological Society in Journal of Climate
- Vol. 24 (13), 3484-3519
- https://doi.org/10.1175/2011jcli3955.1
Abstract
The Geophysical Fluid Dynamics Laboratory (GFDL) has developed a coupled general circulation model (CM3) for the atmosphere, oceans, land, and sea ice. The goal of CM3 is to address emerging issues in climate change, including aerosol–cloud interactions, chemistry–climate interactions, and coupling between the troposphere and stratosphere. The model is also designed to serve as the physical system component of earth system models and models for decadal prediction in the near-term future—for example, through improved simulations in tropical land precipitation relative to earlier-generation GFDL models. This paper describes the dynamical core, physical parameterizations, and basic simulation characteristics of the atmospheric component (AM3) of this model. Relative to GFDL AM2, AM3 includes new treatments of deep and shallow cumulus convection, cloud droplet activation by aerosols, subgrid variability of stratiform vertical velocities for droplet activation, and atmospheric chemistry driven by emissions with advective, convective, and turbulent transport. AM3 employs a cubed-sphere implementation of a finite-volume dynamical core and is coupled to LM3, a new land model with ecosystem dynamics and hydrology. Its horizontal resolution is approximately 200 km, and its vertical resolution ranges approximately from 70 m near the earth’s surface to 1 to 1.5 km near the tropopause and 3 to 4 km in much of the stratosphere. Most basic circulation features in AM3 are simulated as realistically, or more so, as in AM2. In particular, dry biases have been reduced over South America. In coupled mode, the simulation of Arctic sea ice concentration has improved. AM3 aerosol optical depths, scattering properties, and surface clear-sky downward shortwave radiation are more realistic than in AM2. The simulation of marine stratocumulus decks remains problematic, as in AM2. The most intense 0.2% of precipitation rates occur less frequently in AM3 than observed. The last two decades of the twentieth century warm in CM3 by 0.32°C relative to 1881–1920. The Climate Research Unit (CRU) and Goddard Institute for Space Studies analyses of observations show warming of 0.56° and 0.52°C, respectively, over this period. CM3 includes anthropogenic cooling by aerosol–cloud interactions, and its warming by the late twentieth century is somewhat less realistic than in CM2.1, which warmed 0.66°C but did not include aerosol–cloud interactions. The improved simulation of the direct aerosol effect (apparent in surface clear-sky downward radiation) in CM3 evidently acts in concert with its simulation of cloud–aerosol interactions to limit greenhouse gas warming.Keywords
This publication has 102 references indexed in Scilit:
- Carbon cycling under 300 years of land use change: Importance of the secondary vegetation sinkGlobal Biogeochemical Cycles, 2009
- A global simulation of tropospheric ozone and related tracers: Description and evaluation of MOZART, version 2Journal of Geophysical Research: Atmospheres, 2003
- Seasonal evolution of the albedo of multiyear Arctic sea iceJournal of Geophysical Research: Oceans, 2002
- Convective quasi‐equilibrium in midlatitude continental environment and its effect on convective parameterizationJournal of Geophysical Research: Atmospheres, 2002
- A new multiple‐band solar radiative parameterization for general circulation modelsJournal of Geophysical Research: Atmospheres, 1999
- A stratospheric ozone trends data set for global modeling studiesGeophysical Research Letters, 1999
- Radiative effects of CH4, N2O, halocarbons and the foreign‐broadened H2O continuum: A GCM experimentJournal of Geophysical Research: Atmospheres, 1999
- Global sensitivity studies of the direct radiative forcing due to anthropogenic sulfate and black carbon aerosolsJournal of Geophysical Research: Atmospheres, 1998
- Thermodynamic and optical properties of sea salt aerosolsJournal of Geophysical Research: Atmospheres, 1997
- An analytic expression for the composition of aqueous HNO3‐H2SO4 stratospheric aerosols including gas phase removal of HNO3Geophysical Research Letters, 1995