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List of Abstracts 173quality problems. The high alpine surface ozone series show an increase in ozone during the 1990s, as doesthe MOZAIC data for 1994-2000. However, after about 2000, all data series (sonde, aircraft, and mountainsites) indicate stabilization of ozone. This is in contrast to recent results for western North America.P-Observations 2.18 ID:4263 10:30Temporal trends in near-surface ozone and N,°tropospheric column ozone at a tropical coastal siteTrivandrum (8.5 E): effects of precursors and meteorology°77Prabha R. Nair, Mary David Liji, Imran Asatar GirachSpace Physics Laboratory, Vikram Sarabhai Space Centre, Thiruvananthapuram, IndiaContact: prabha_nair@vssc.gov.inOzone plays a vital role in tropospheric chemistry through its reactions with water vapour producing thehighly reactive OH radicals. Tropospheric ozone has two major sources namely (1) transport fromstratosphere and (2) photochemical production from gases like CH4, non-methane hydrocarbons (NMHC),other volatile organic compounds (VOCs), CO, and NOx (NO and NO2. The mixing ratio of ozone at anylocation is controlled by availability of precursors, photochemistry, meteorological conditions and verticaltransport. Continuous measurements of ozone and NOx (NO+NO2) are carried out at Trivandrum (8.55ºN,77ºE) by using an on-line UV Photometric Ozone analyzer (Model 49C of Thermo Electron Corporation)and a Chemiluminescence NOx 9841B of ME). This paper presents the seasonal®analyzer (Model MLtrends in near-surface ozone and nitrogen oxides at the tropical coastal site Trivandrum. In addition, theseasonal changes in the satellite-retrieved (TOMS/OMI) tropospheric column ozone data during 2005-2009also have been investigated in detail and compared with the surface data. The monthly variation is found tobe the same in both tropospheric and surface ozone over a year. Meteorological data available from anAutomatic weather station, airflow patterns obtained from NCEP/NCAR reanalysis and airmassbacktrajectories obtained from HySplit model are used to understand the meteorological effects in thetemporal behaviour of ozone at this location. High mixing ratios are observed in the winter months in bothtropospheric and surface ozone. The prevailing northerly/north-easterly airflow which favours advection ofprecursors from inland locations causes the high mixing ratios during winter. During monsoon when airflowis from ocean, these gases exhibit low mixing ratios. It is also observed that, the mesoscale circulations -seabreeze and land breeze- modifies the diurnal patterns. The contribution of surface ozone to totaltropospheric column ozone varies with season. The long-term trends in tropospheric ozone are alsoinvestigated in this paper.P-Observations 2.19 ID:4368 10:30Links between tropospheric O3 and weather conditions over India: evidence from spaceborneobservationsBrice Barret, Eric Le Flochmoën, Jean-Pierre Cammas, Bastien SauvageLaboratoire d'Aérologie / CNRSContact: barp@aero.obs-mip.frBetween November and May, South Asia is affected by an 'Atmospheric Brown Cloud' (ABC),characterized by high levels of pollutants (aerosols, O3 precursors) in the lower troposphere. In the tropicalUpper Troposphere (UT), O3 is dynamically influenced by interactions between midlatitude and tropicalsystems. Our study aims at characterizing the impact of severe weather conditions upon both lower andupper tropospheric O3 over the Indian sub-continent based upon O3 data from the Infrared AtmosphericSounding Interferometer (IASI). The high spatio-temporal coverage and high sensitivity of the IASI datawill enable such a study on a continental scale for the first time. We will present our results as follows: 1/-iCACGP-IGAC 2010 14 July, 2010