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List of Abstracts 79Community Atmosphere Model (CAM3). The surface cooling over Siberian and downwind regions wherelarge amount of fire aerosols exist in the atmosphere is significantly shown in May 2003. Our analysis of theNCEP-DOE reanalysis data show 99% statistically significant increases in both surface air pressure overSiberia and precipitation over the NW Pacific, possibly associated with significant changes in surface airtemperature due to the Siberian fire aerosols, in 2003 relative to the 30 years climatology. We alsoconducted NCAR CAM3 simulations forced by 3-D daily mean biomass burning aerosols mainly consistingof black and organic carbons and sulfate aerosols from a global chemistry-transport model, GEOS-Chem.We found that the model simulation with the Siberian forest fire aerosols reproduced the observed coolingover Siberia and downwind East Asia and large-scale perturbations in surface pressure and precipitation. Thesimulated results clearly indicate a significant impact of Siberian fire aerosols on regional meteorology overEast Asia, having important implications not only for regional climate but also for synoptic scale weatherpatterns.P-Chemistry Climate.40 ID:4379 15:35Trends in concentrations of short lived components causing radiative forcingRagnhild Bieltvedt Skeie 1 , Terje Berntsen 2 , Gunnar Myhre 11 CICERO2 University of Oslo, CICEROContact: r.b.skeie@cicero.uio.noHistorical trends in concentrations of short lived components causing radiative forcing are calculated withthe Oslo CTM2 model. These trends will be used to calculate radiative forcing time series which will beused in a Bayesian statistical approach combining observations of temperature change and a simple climatemodel for constraining the climate sensitivity. Oslo CTM2 is an off-line atmospheric chemistry transportmodel. It is driven by meteorological data generated by Integrated Forecast System model at the EuropeanCentre for Medium-Range Weather Forecasts. The model is used with a tropospheric chemistry scheme,including the ozone-NOx-hydrocarbon cycle, as well as modules for sulphate, nitrate, black carbon, primaryorganic, and secondary organic aerosols. The resolution of the model used in this study is T42,approximately 2.8 x 2.8 degrees, and 60 vertical layers ranging from the surface and up to 0.1hPa. Time slicesimulations are done for the year 1850 and then every 10th year from 1900 until present usingmeteorological data for the years 2005-2006. The emission data used are the historical emission inventorydeveloped in support of the IPCC AR5. The total anthropogenic emissions have increased since 1850 untilthe end of the 20th century. The spatial distribution of the emissions has changed over these years.Emissions of relevant species have been reduced in North America and Europe at the end of the 20thcentury, while emissions in East Asia are increasing. Detailed modeling of the concentration changes ofshort lived components due to the changes in emissions is done. An improved trend for all short livedcomponents causing radiative forcing is calculated, including tropospheric ozone and sulfate, nitrate, blackcarbon, primary organic aerosols and secondary organic aerosols.P-Chemistry Climate.41 ID:4444 15:35On the radiative impact of chemical constituents using the Environment Canada numerical weatherprediction systemJean de Grandpre 1 , Chris McLinden 1 , Richard Menard 1 , Simon Chabrillat 2 , Yves Rochon 1 , Yan Yang 1 ,Alain Robichaud 1 , Cecilien Charette 11 Environment Canada2 Belgium Institute of AeronomyContact: jean.degrandpre@ec.gc.caiCACGP-IGAC 2010 12 July, 2010