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List of Abstracts 80The recent upward extension of the data assimilation system at the Meteorological Service of Canada from10 hPa to 0.1 hPa has contributed significantly to the improvment of meteorological analyses and forecasts.This development effort has provided the opportunity of generating global analyses of chemical constituentswhich are used for improving the representation of radiative processes particularly in the upper tropospherelower stratosphere region. Radiative heating in the region depends on ozone absorption in both UV-visibleand Infrared spectral regions and has a significant impact on temperature forecasts at the medium rangetimescale. This study shows the overall benefits of chemical assimilation in the context of NWP studies.P-Chemistry Climate.42 ID:4285 15:35Climate Response to 1950-2050 US Aerosol TrendsEric Leibensperger 1 , Loretta Mickley 1 , Daniel Jacob 1 , Wei-Ting Chen 2 , Athanasios Nenes 3 , PeterAdams 4 , John Seinfeld 5 , Naresh Kumar 61 Harvard University2 Jet Propulsion Laboratory, California Institute of Technology3 Georgia Institute of Technology4 Carnegie Mellon University5 California Institute of Technology6 Electric Power Research InstituteContact: eleibens@fas.harvard.eduUnited States aerosol concentrations peaked in the 1980s and have been decreasing since. Continueddecreases are expected in the future in order to meet air quality standards. The associated change in aerosolradiative forcing could have significant climatic implications. Here we use a general circulation model(GISS GCM 3) with aerosol fields from a global chemical transport model (GEOS-Chem CTM) to study theclimatic effects of US aerosol emissions over the 1950-2050 period. GEOS-Chem simulates coupled aerosoland gas-phase chemistry for 1950-2050 with decadal resolution, using historical and projected (IPCC A1B)anthropogenic emissions and either including or excluding US emissions. We conduct ensemble GCMsimulations including both direct and indirect aerosol effects to determine the climate sensitivity to these USaerosol trends. Preliminary simulations accounting for only the aerosol direct effect indicate that US aerosolsources cooled the eastern US by 0.5°C in summer 1950-2000, and that the regional pattern of coolinglargely follows that of radiative forcing. After 2000 the aerosol decline causes the US to warm 0.4°C.Additional simulations incorporating the aerosol indirect effects on cloud albedo and lifetime will bepresented.P-Chemistry Climate.43 ID:4137 15:35Potential climate change impacts on air quality; new methodology and simulationAmir Mohammad YadgharConcordia UniversityContact: a_yadgha@encs.concordia.caClimate change affects the air quality in several ways. Air quality is dependent to meteorological parametersincluding humidity, temperature, wind speed and direction, radiation rate and mixing height which havedirect effect on emissions, transport, dilution, chemical transformation, and final deposition of air pollutantsin a region. Although the Kyoto Protocol is a great step toward reducing climate change impacts, moreserious works is necessary to cut green house gas (GHG) emissions to effectively control global warmingimpacts. GHG emissions are projected to significantly grow in next decades. It is shown that many methodsintended principally to reduce air pollution, decrease GHG emissions as well. On the other hand, many ofGHG reduction plans result in reductions of air pollution, too. It is necessary to assess potential futureiCACGP-IGAC 2010 12 July, 2010