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Incorporating urban systems into global climate models: part 1, model description Johannes J. Feddema1, Keith Oleson2, and Gordon Bonan2 Human impacts on the land surface are important to climate models in a number of significant ways. Changes to land cover change the energy and water balance of the surface leading to regional climate impacts. Although small in aerial extent, urban systems are known to have significant impacts on local climate, an effect manifested as urban heat islands. It is currently unknown how much of an impact this effect has on a global scale. Incorporating an urban canyon type model into the National Center for Atmospheric Research (NCAR) Community Climate System Model (CCSM) will allow us to evaluate the potential impacts of urban areas on global and regional climates. We will describe the function of this model and show its ability to simulate typical urban climates. Parameterization for this model will be discussed in a companion paper. Urban systems also play other significant roles in regulating climates. Most of the anthropogenic emissions originate in urban areas. These chemicals in turn have a significant impact on atmospheric composition and have direct and indirect impacts on climate. Currently most models assume that anthropogenic constituents are evenly distributed on a global scale, but this is not true especially for more volatile compounds. Here we propose some mechanisms that can be incorporated into the model to simulate the release of energy and various atmospheric emissions though an urban model and some of the datasets required to simulate anthropogenic emissions through this model. |