Hochschule für Technik und Umwelt FHNW

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Autor:in: search.filters.author.Ammann, MarkusThema: search.filters.subject.570 - Biowissenschaften, Biologie

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    Summertime NOy speciation at the Jungfraujoch, 3580 m above sea level, Switzerland
    (Wiley, 16.03.2000) Zellweger, Christoph; Ammann, Markus; Buchmann, Brigitte; Hofer, Patrick; Lugauer, Matthias; Rüttimann, Ralph; Streit, Niklaus; Weingartner, Ernest; Baltensperger, Urs
    During summer 1997, speciated reactive nitrogen (NO, NO2, peroxyacetyl nitrate (PAN), HNO3, and particulate nitrate) was measured in conjunction with total reactive nitrogen (NOy) at the high-alpine research station Jungfraujoch (JFJ), 3580 m above sea level (asl). The individually measured NOy components averaged to 82% of total NOy. PAN was the most abundant reactive nitrogen compound and composed on average 36% of NOy, followed by NOx, (22%), particulate nitrate (17%), and HNO3 (7%). The NOx/NOy ratio averaged 0.25, but significantly lower values (0.15–0.20) were observed in the presence of high NOy mixing ratios. A classification of the data by synoptic weather conditions indicated that thermally driven vertical transport has a strong impact on the mixing ratios measured at the JFJ during summer. A strong diurnal cycle with maximum mixing ratios in the late afternoon was observed for convective days with north-westerly advection at 500 hPa. In contrast, during a period of convective days with a wind speed below 7.5 m/s at 500 hPa, no obvious diurnal cycle was observed. Under these meteorological conditions the convective boundary layer can be significantly higher over the Alps (i.e., around 4 km asl) than over the surrounding lowlands. Subsequent advection may finally result in the export of reactive nitrogen reservoir compounds to the free troposphere and hence influence global atmospheric chemistry.
    01A - Beitrag in wissenschaftlicher Zeitschrift