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List of Abstracts 933 Department of Chemistry, University of California, Berkeley, California, USA4 NASA Langley Research Center, Hampton, Virginia, USAContact: N.Bousserez@dal.caNitrogen Oxides (NOx) are important precursors of tropospheric ozone, which is a pollutant and agreenhouse gas. Remote sensing observations from space are needed in the context of global monitoring andemissions estimates of these sources. However these observations are subject to significant uncertaintiesrelated to a priori information and radiative transfer calculations used in the retrievals. Here we examineNO2 retrieved from OMI observation of solar backscatter. In our study we jointly use the LIDORT radiativetransfer model and a GEOS-Chem simulation with daily biomass burning emission inventory to assess theimpact of fires emissions on the a priori NO2 shape profiles and the scattering weights used in the air massfactor (AMF) calculation, which transforms the spectrally fitted slant column into a vertical column. Thismodelling approach is supported by the analysis of aircraft in situ data from two major experiments:ARCTAS, which took place in summer 2008 over Canada and California, and DABEX (AMMA), whichcollected data over western Africa during the winter 2006 dry season. It has been previously proposed thatunder clear sky conditions and the presence of aerosols in the boundary layer the OMI cloud algorithmcorrection implicitly takes into account most of the aerosol correction. However, our results show thenecessity of including an aerosol correction in the presence of clouds above the aerosol layer, which is afrequent situation over boreal forest fires. Over California and Canada, including the fire emissions in themodel results in a mean AMF decrease of 35% from the shape factor modification and a mean AMF increaseof 10% from the aerosol correction. Over African biomass burning, a persistent aerosol layer in the midtroposphereabove the high surface NO2 concentrations results in a significant impact of the aerosolcorrection on the AMF (-20% in average). For the case of African fires, our results suggest a linearrelationship between the aerosol optical depth (AOD) and the aerosol correction factor calculated with theradiative transfer model, which makes possible a real-time aerosol correction based on satellite aerosoloptical depth retrievals.P-Observations 1.16 ID:4253 15:35Ozone profile trends from ground-based and satellite data.I. Petropavlovskikh 1 , J.A. Logan 2 , V. Fioletov 3 , S. Frith 4 , R. Stolarski 4 , S. Godin-Beekmann 5 , S.Oltmans 6 , L. Flynn 7 , S.K. Yang 81 CU/CIRES2 Harvard University3 Meteorological Service of Canada4 NASA/Goddard5 CNRS/UPMC/UVSQ6 NOAA/ESRL7 NOAA/NESDIS8 NOAA/NCEPContact: irina.petro@noaa.govIn view of the upcoming WMO Ozone Assessment, and with four more years in the ozone record, evaluationof the current state of the ozone layer is of interest to the scientific community. The Ozone Assessment in2006 suggested that the long-term ozone decline over the mid-latitudes had stopped and that ozone hadstabilized since 1996. When extended to 2008, the ground-based and satellite data in the middle and upperstratosphere continue to show no significant changes to the ozone layer beyond its natural variability.Moreover, over the northern mid-latitudes, the recent increase in the observed total ozone column is notcaused by the expected recovery of upper stratospheric ozone, but rather by changes in the lowermoststratosphere. We will present analyses of upper and low stratospheric ozone changes at northern mid-iCACGP-IGAC 2010 12 July, 2010