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List of Abstracts 105frequency of the ozone hole that reaches Ushuaia GAW Station and the effect that it produces in the totalozone concentration and trends.P-Observations 1.37 ID:4542 15:35Sources and seasonal variations of atmospheric hydrogen and carbon monoxide: Tall towermeasurements and Lagrangian modelingMichael Mohr 1 , Lu Hu 1 , John Lin 2 , Dylan Millet 11 University of Minnesota - TC2 University of WaterlooContact: mohrx061@umn.eduCarbon monoxide (CO) and hydrogen (H2) play important roles in atmospheric chemistry: CO is thedominant global sink for the OH radical and H2 is the most abundant non-methane reactive gas in theatmosphere. Here we present measurement and modeling results from an ongoing field campaign aimed atimproving our understanding of these two trace gases. Continuous H2 and CO measurements have beenongoing at the University of Minnesota Trace Gas Observatory (TGO, 200m AGL) since January 2009.TGO is located 24km south of the Twin Cities metropolitan area and at the intersection of the major U.S.ecosystems, providing the opportunity to constrain regional anthropogenic and biogenic sources of CO andH2. We apply here two atmospheric models (STILT and GEOS-Chem) to interpret the measuredconcentrations, daily-to-seasonal fluctuations, and covariance in terms of present understanding of CO andH2 sources and sinks.P-Observations 1.38 ID:4378 15:35Monitoring vegetation using DOAS satellite observationsEllen Eigemeier 1 , Steffen Beirle 1 , Thierry Marbach 1 , Ulrich Platt 2 , Thomas Wagner 11 Max-Planck-Institute for Chemistry, Mainz, Germany2 Institut für Umweltphysik, University of Heidelberg, GermanyContact: ellen.eigemeier@mpic.deVegetation-cycles are of general interest for many applications. Be it for harvest-predictions, globalmonitoring of climate-change or as input to atmospheric models. From novel spectrally resolving UV/vissatellite instruments (like GOME or SCIAMACHY) the spectral signatures of different types of vegetationcan be identified and analysed. Although the spatial resolution of GOME and SCIAMACHY observations ismuch coarser than those of conventional satellite instruments for vegetation monitoring, our data sets ondifferent vegetation types add new and useful information, not obtainable from other sources.Common vegetation indices are based on the fact that the difference between Red and Near Infraredreflection is higher than in any other material on Earth’s surface. This gives a very high degree of confidencefor vegetation-detection. The spectrally resolving data from GOME and SCIAMACHY provide the chanceto concentrate on finer spectral features throughout the red and near infrared spectrum. We look at thesefeatures using a technique known as Differential Optical Absorption Spectroscopy (DOAS). Althoughoriginally developed to retrieve information on trace gases, it can also be used to gain information onvegetation. Another advantage is that this method automatically corrects for atmospheric effects. Thisrenders the vegetation-information easily comparable over long time-spans.In addition, high-frequency-structures from vegetation also effect the retrieval of tropospheric trace-gasesand aerosols.iCACGP-IGAC 2010 12 July, 2010