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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
Separate determination of PM10 emission factors of road traffic for tailpipe emissions and emissions from abrasion and resuspension processes
(Inderscience, 28.10.2004) Gehrig, Robert; Hill, Matz; Buchmann, Brigitte; Imhof, David; Weingartner, Ernest; Baltensperger, Urs
Little is known about the relevance of mechanically produced particles of road traffic from abra-sion and resuspension processes in relation to the exhaust pipe particles. In this paper, emis-sion factors of PM10 and PM1 for light and heavy-duty vehicles were derived for different repre-sentative traffic regimes from concentration differences of particles and nitrogen oxides (NOₓ) in ambient air upwind and downwind of busy roads, or alternatively of kerbsides and nearby back-ground sites. Hereby, PM1 was interpreted as direct exhaust emissions and PM10-PM1 as me-chanically produced emissions from abrasion and resuspension processes. The results show that abrasion and resuspension processes represent a significant part of the total primary PM10 emissions of road traffic. At sites with relatively undisturbed traffic flow they are in the same range as the exhaust pipe emissions. At sites with disturbed traffic flow due to traffic lights, emissions from abrasion/resuspension are even higher than those from the exhaust pipes.
01A - Beitrag in wissenschaftlicher Zeitschrift
Ground-based and airborne in-situ measurements of the Eyjafjallajökull volcanic aerosol plume in Switzerland in spring 2010
(Copernicus, 04.10.2011) Bukowiecki, Nicolas; Zieger, Paul; Weingartner, Ernest; Jurányi, Zsófia; Gysel, Martin; Neininger, Bruno; Schneider, Boris; Hueglin, Christoph; Ulrich, Andrea; Wichser, Adrian; Henne, Stephan; Brunner, Dominik; Kaegi, Ralf; Schwikowski, Margit; Tobler, Leonhard; Wienhold, Frank G.; Engel, Ilana; Buchmann, Brigitte; Peter, Thomas; Baltensperger, Urs
The volcanic aerosol plume resulting from the Eyjafjallajökull eruption in Iceland in April and May 2010 was detected in clear layers above Switzerland during two periods (17–19 April 2010 and 16–19 May 2010). In-situ measurements of the airborne volcanic plume were performed both within ground-based monitoring networks and with a research aircraft up to an altitude of 6000 m a.s.l. The wide range of aerosol and gas phase parameters studied at the high altitude research station Jungfraujoch (3580 m a.s.l.) allowed for an in-depth characterization of the detected volcanic aerosol. Both the data from the Jungfraujoch and the aircraft vertical profiles showed a consistent volcanic ash mode in the aerosol volume size distribution with a mean optical diameter around 3 ± 0.3 μm. These particles were found to have an average chemical composition very similar to the trachyandesite-like composition of rock samples collected near the volcano. Furthermore, chemical processing of volcanic sulfur dioxide into sulfate clearly contributed to the accumulation mode of the aerosol at the Jungfraujoch. The combination of these in-situ data and plume dispersion modeling results showed that a significant portion of the first volcanic aerosol plume reaching Switzerland on 17 April 2010 did not reach the Jungfraujoch directly, but was first dispersed and diluted in the planetary boundary layer. The maximum PM10 mass concentrations at the Jungfraujoch reached 30 μgm−3 and 70 μgm−3 (for 10-min mean values) duri ng the April and May episode, respectively. Even low-altitude monitoring stations registered up to 45 μgm−3 of volcanic ash related PM10 (Basel, Northwestern Switzerland, 18/19 April 2010). The flights with the research aircraft on 17 April 2010 showed one order of magnitude higher number concentrations over the northern Swiss plateau compared to the Jungfraujoch, and a mass concentration of 320 (200–520) μgm−3 on 18 May 2010 over the northwestern Swiss plateau. The presented data significantly contributed to the time-critical assessment of the local ash layer properties during the initial eruption phase. Furthermore, dispersion models benefited from the detailed information on the volcanic aerosol size distribution and its chemical composition.
01A - Beitrag in wissenschaftlicher Zeitschrift

Hochschule für Technik und Umwelt FHNW

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