A physically-based model, once properly verified, can provide more robust estimates of all meteorological parameters needed for climate change impact assessment. Each model can be driven by observations alone, or by data simulated by its parent. The figure below summarizes some of the characteristics of the model system. Global Aerosol Modeling Motivation Aerosols are produced by natural processes particulate emission from forest fires and dust storms condensation of gases emitted by volcanoes, plants, and phytoplankton human activities particulate emission from combustion of biomass and fossil fuels condensation of gases emitted by combustion of biomass and fossil fuels. Anthropogenic aerosols scatter sunlight to space, which cools the planet.
Anthropogenic aerosols absorb sunlight, which warms the planet.
Present estimates of the radiative cooling due to anthropogenic aerosols are comparable to the radiative warming by increasing greenhouse gases. The uncertainty in the estimates of the radiative cooling due to anthropogenic aerosols is very high. Empirical methods of estimating the aerosol radiative forcing cannot isolate anthropogenic from natural aerosols. A physically-based model, once properly verified, can provide more robust estimates of the radiative forcing. To meet the need for physically-based predictions of aerosol radiative forcing, we have developed a coupled model system that features a global climate model coupled with a global tropospheric chemistry model .