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List of Abstracts 176P-Observations 2.23 ID:4259 10:30Effects of regional pollution and long range transport on the lower tropospheric ozone over an urbansite in western IndiaShuchita Srivastava 1 , Shyam Lal 1 , Manish Naja 2 , S. Venkataramani 1 , T.A. Rajesh 11 Physical Research Laboratory, Ahmedabad, India2 Aryabhatta Research Institute of Observational Sciences, Nainital, IndiaContact: shuchita@prl.res.inThe balloon borne measurements of vertical distribution of ozone and meteorological parameters were madefortnightly from April 2003 to July 2007 at Physical Research Laboratory, Ahmedabad (23.03º N, 72.54º E,49m amsl). The seasonal distributions of ozone are investigated for the boundary layer (1-2 km) and lowertroposphere (2.5 to 4 km) using back-trajectory analysis. Three geographical sectors are defined for theregional pollution, marine region and long range transport, and residence time of trajectories for balloonflight days are estimated. These residence times are tagged with the corresponding ozone mixing ratios. Theozone levels increase with increasing residence time till 4-6 days for all seasons except winter in the regionalsector. The significant ozone build up is absent during winter probably due to high levels of local pollutants.The slope of ozone vs residence time is extrapolated to zeroth day to get the “background ozone mixingratio”. The average background ozone mixing ratios are found to be about 28 ppbv for boundary layer and42 ppbv for the free troposphere. The background ozone mixing ratio is comparable to average ozone mixingratio during summer-monsoon season in the boundary layer. The seasonal variation of ozone shows higherozone levels during late autumn, winter and early spring (> 50 ppbv) and minimum during summer-monsoon(~30 ppbv) in the boundary layer. The higher ozone levels during late autumn, winter and spring seasons aredominated by regionally polluted airmass whereas poor ozone levels during summer-monsoon are influencedby marine airmass. In the lower troposphere, seasonal variation of ozone is found to be affected by regionalpollution and long range transport. Detailed results will be presented.P-Observations 2.24 ID:4578 10:30High-resolution tropospheric ozone fields for INTEX and ARCTAS from IONS ozonesondesDavid Tarasick 1 , Jinjian Jin 2 , Vitali Fioletov 3 , Guiping Liu 3 , Anne Thompson 4 , Samuel Oltmans 5 ,Christopher Sioris 3 , Xiong Liu 6 , Owen Cooper 7 , Tom Dann 3 , Jingxian Liu 31 Department of Meteorology, 510 Walker Building, Pennsylvania State University2 Jet Propulsion Laboratory, California Institute of Technology3 Environment Canada4 Department of Meteorology, Pennsylvania State University5 NOAA Climate Monitoring and Diagnostics Laboratory6 Goddard Earth Sciences and Technology Center, University of Maryland7 Cooperative Institute for Research in Environmental Sciences, University of ColoradoContact: david.tarasick@ec.gc.caThe IONS-04, IONS-06 and ARC-IONS ozone sounding campaigns over North America in 2004, 2006 and2008 obtained approximately 1400 profiles, in five series of coordinated and closely-spaced (typically daily)launches. Although this coverage is unprecedented, it is still somewhat sparse in its geographical spacing.Here we use forward and back- trajectory calculations for each sounding to map ozone measurements to anumber of other locations, and so to fill in the spatial domain. This is possible because the lifetime of ozonein the troposphere is of the order of weeks. The trajectory-mapped ozone values show reasonable correlationwith estimates from OMI and, where they overlap, to each other. Further validation with MOZAIC profilesand surface station data will be presented. A variable-length smoothing algorithm is used to fill data gaps.The total tropospheric ozone column maps calculated by integrating the smoothed fields agree well withsimilar maps derived from TOMS and OMI/MLS measurements. The resulting three-dimensional picture ofiCACGP-IGAC 2010 14 July, 2010