Fraunhofer-Institut für Atmosphärische Umweltforschung IFU

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  • Publication
    Airborne measurements of nucleation mode particles I: Coastal nucleation and growth rates
    ( 2007)
    O'Dowd, C.D.
    ;
    Yoon, Y.J.
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    Junkerman, W.
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    Aalto, P.
    ;
    Kulmala, M.
    ;
    Lihavainen, H.
    ;
    Viisanen, Y.
    A light aircraft was equipped with a bank of Condensation Particle Counters (CPCs) (50% cut from 3-5.4-9.6 nm) and a nano-Scanning Mobility Particle Sizer (nSMPS) and deployed along the west coast of Ireland, in the vicinity of Mace Head. The objective of the exercise was to provide high resolution micro-physical measurements of the coastal nucleation mode in order to map the spatial extent of new particle production regions and to evaluate the evolution, and associated growth rates of the coastal nucleationmode aerosol plume. Results indicate that coastal new particle production is occurring over most areas along the landsea interface with peak concentrations at the coastal plume-head in excess of 106 cm-3. Pseudo-Lagrangian studies of the coastal plume evolution illustrated significant growth of new particles to sizes in excess of 8 nm approximately 10 km downwind of the source region. Close to the plume head (<1km) growth rates can be as high as 123-171 nm h-1, de creasing gradually to 53-72 nm h-1 at 3km. Further along the plume, at distances up to 10km, the growth rates are calculated to be 17-32 nm h-1. Growth rates of this magnitude suggest that after a couple of hours, coastal nucleation mode particles can reach significant sizes where they can contribution to the regional aerosol loading.
  • Publication
    Factors and processes controlling the concentration of the cosmogenic radionuclide 7Be at high-altitude Alpine stations
    ( 2005)
    Gerasopoulos, E.
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    Zanis, P.
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    Zerefos, C.S.
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    Papastefanou, C.
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    Ringer, W.
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    Gäggeler, H.W.
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    Tobler, L.
    ;
    Kanter, H.J.
  • Publication
    Multipass open-path Fourier-transform infrared measurements for nonintrusive monitoring of gas turbine exhaust composition
    ( 2005)
    Schafer, K.
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    Brockmann, K.
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    Heland, J.
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    Wiesen, P.
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    Jahn, C.
    ;
    Legras, O.
    The detection limits for NO and NO2 in turbine exhausts by nonintrusive monitoring have to be improved. Multipass mode Fourier-transform infrared (FTIR) absorption spectrometry and use of a White mirror system were found from a sensitivity study with spectra simulations in the mid-infrared to be essential for the retrieval of NO2 abundances. A new White mirror system with a parallel infrared beam was developed and tested successfully with a commercial FTIR spectrometer in different turbine test beds. The minimum detection limits for a typical turbine plume of 50 cm in diameter are approximately 6 parts per million (ppm) for NO and 9 ppm for NO2 (as well 100 ppm for CO2 and 4 ppm for CO).
  • Patent
    Vorrichtung zur Messung eines Spektrums
    ( 2003)
    Misslbeck, M.
    ;
    Seckmayer, G.
    ;
    Thiel, S.
    Es wird eine Vorrichtung zur Messung eines Spektrums einer Strahlung, insbesondere im UV-Bereich, vorgeschlagen, das einen Eingangsspalt, eine Anordnung zum Aufspalten der einfallenden Strahlung in ein Spektrum und Abbilden des Eingangsspaltes auf eine erste Fokalebene nach Wellenlaengen getrennt aufweist. Eine erste Empfaengeranordnung ist zeilenfoermig in der ersten Fokalebene vorgesehen und erfasst einen ersten Wellenlaengenbereich. Weiterhin ist der ersten Fokalebene eine Oeffnung und hinter der eine zweite Anordnung zum Aufspalten der durch die Oeffnung gelangenden Strahlung in ein zweites Spektrum und Abbilden der Oeffnung der ersten Fokalebene in eine zweite Fokalebene vorgesehen. Eine zweite Empfaengeranordnung in der zweiten Fokalebene erfasst somit einen zweiten Wellenlaengenbereich selektiv.
  • Patent
    Verfahren zur Ermittlung der Nitrifikations- und/oder Denitrifikationsrate von Boeden und Vorrichtung hierzu
    ( 2003)
    Butterbach-Bahl, K.
    DE 19906872 A UPAB: 20001023 NOVELTY - Determining soil nitrification and denitrification rates comprising introducing a soil sample into a gas- and pressure-tight vessel to leave a gas space above the soil, hermetically sealing the vessel, and measuring the pressure, and oxygen (O2) and carbon dioxide (CO2) concentrations at least at the start and end of an incubation period of 0.5-24 hours, is new. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is also included for apparatus for carrying out the novel method, comprising a sealable gas-tight vessel having at least one pressure sensor access port and at least one sealable inlet. USE - For determining soil nitrification and denitrification rates using a complex set of equations given in the specification. ADVANTAGE - The method is simple and inexpensive.
  • Publication
    Emissions of the city of Augsburg determined using the mass balance method
    ( 2002)
    Kalthoff, N.
    ;
    Corsmeier, U.
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    Schmidt, K.
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    Kottmeier, C.
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    Fiedler, F.
    ;
    Habram, M.
    ;
    Slemr, F.
    Air quality models require emission data of air pollutants with high temporal and spatial resolution. The highly resolved emissions are calculated by complex emission models and may thus be subject to considerable uncertainties. To assess the uncertainty of the emission model calculations, emissions of the city of Augsburg in southern Germany were determined experimentally on several days in October 1998 using the technique of mass balance. Two algorithms were used to estimate the CO and NOx emissions from the data measured by two research aircraft, two tethered balloons, and an airship on the lateral surface enclosing the area of investigation. The two algorithms provided results which agree within the calculated uncertainties. The differences can be attributed mainly to the different interpolation methods applied to the layer between the lowest flight level and the ground. The measurements show that on the different weekdays both CO and NOx emissions varied by about a factor of two which is much larger than the variability predicted by the emission model. Higher than predicted CO emissions were observed on Saturday, 10 October 1998, whereas NOx emissions on 10 October were substantially smaller than predicted by the emission model.
  • Publication
    Exchange of trace gases between soils and the atmosphere in Scots pine forest ecosystems of the northeastern German lowlands
    ( 2002)
    Butterbach-Bahl, K.
    ;
    Breuer, L.
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    Gasche, R.
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    Willibald, G.
    ;
    Papen, H.
  • Publication
    Evaluation of an emission inventory by comparisons of modelled and measured emission ratios of individual HCs, CO and NOx
    ( 2002)
    Mannschreck, K.
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    Klemp, D.
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    Kley, D.
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    Friedrich, R.
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    Kühlwein, J.
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    Wickert, B.
    ;
    Matuska, P.
    ;
    Habram, M.
    ;
    Slemr, F.
    Air quality models require emission inventories of individual compounds with high temporal and spatial resolution. These emission inventories are calculated by complex emission models. To evaluate these models, emission ratios of non-methane hydrocarbons (HCs, containing only H- and C-atoms), CO and NOx of the city of Augsburg were determined during two field campaigns in March and October 1998. The measured emission ratios have been compared with emission ratios calculated by an emission model at two accuracy levels. Only C-2-C-10 HCs were measured quantitatively by the applied techniques. C-11-C-13 HCs were measured with losses increasing with the number of C atoms, oxygenated and halogenated volatile organic compounds were not measured at all. The direct comparison could be made only for those HCs whose individual emissions can be specified by the model. They represent 21% of the total predicted volatile organic compound emissions and-according to the model-originate to a large percentage from traffic-related emission. The measured HCi/HCsum emission ratios (HCsum:=Sigma(HCi) for C-2-C-10-HCs and HCi:=mixing ratio of an individual hydrocarbon) for these compounds agreed within 30% for most compounds. The HCi/HCsum emission ratios measured in Augsburg are very similar to emission ratios from traffic-related sources suggesting that the emission model reflects the traffic emissions quite well. In order to consider all measured HCs for comparison the share of unspecified HCs, which are detectable by the GC system and should therefore be included in the experimental results, was estimated. Taking this into account yields a deviation between modelled and measured monthly mean values of HCi/CO and HCi/NOx of about 40%. The comparison of modelled and measured HCi/CO with HCi/HCsum emission ratios derived from the investigation based on single events confirms this finding: in this case an overestimation by the model of a factor of 1.5-2 was found. Since modelled and measured NOx and CO emissions agreed well within the uncertainty ranges, these deviations can be attributed to overestimation of HC emissions. Unspecified HC emissions mainly originate from solvent mixtures thus the overestimation of their emissions could explain the observed deviations. Regarding one specific HC which originates nearly exclusively from solvent emissions, i.e. n-decane, yields an overestimation of about a factor of 10 by the model.
  • Publication
    Comparison of modelled and measured total CO and NOx emission rates
    ( 2002)
    Kühlwein, J.
    ;
    Friedrich, R.
    ;
    Kalthoff, N.
    ;
    Corsmeier, U.
    ;
    Slemr, F.
    ;
    Habram, M.
    ;
    Möllmann-Coers, M.
    Hourly total CO and NOx emission rates determined experimentally from the city of Augsburg, a medium-sized city in southern Germany, were compared with data calculated with a high-resolution emission model. Mass balances based on Aircraft measurements and tracer techniques were used to ascertain real-world emission conditions. On the other hand, comparative emission data were modelled at two different precision levels. A 'default level' represents a mesoscale emission model providing emissions highly resolved in time and space as input data for air quality models. Improved activity data obtained by measurements were used for emission calculations at a 'superior level'. Modelled and measured CO emission rates on working days, in general, were found to be in good agreement. CO emissions on Saturday were slightly underestimated by the model. Modelled NOx emission rates at both levels agree well with the measurements on working days. On Saturday, the modelled NOx emission rates are substantially higher than the measured ones, which represent only some 50-60% of the emission estimates. Comparisons between modelled hourly emissions from point sources and spatially highly resolved Aircraft measurements indicate that the temporal allocation of some industrial activities, especially of specific plants with irregular operating hours are very difficult to reflect by the model.
  • Publication
    Determination of anthropogenic emissions in the Augsburg area by the source-tracer-ratio method
    ( 2002)
    Möllmann-Coers, M.
    ;
    Klemp, D.
    ;
    Mannschreck, K.
    ;
    Slemr, F.
    Air-quality models require as input emission inventories of individual compounds high temporal and spatial resolution. These emission inventories are calculated by complex emission models. To evaluate these models, emission rates of CO and NOx of the city of Augsburg were determined in March and October using two independent methods and were compared with emission rates calculated by an emission model. This paper outlines the source-tracer-ratio (STR) method, describes its implementation in Augsburg, and presents the results obtained in four successful experiments. The CO emission rate was derived directly from the STR method, whereas the NOx emission rate is calculated from the CO emission rate using the average CO/NOx correlation in the city plume from the long-term dataset obtained within the Augsburg experiment. The CO and NOx emission rates obtained on 10, 22, and 23 October 1998, were in reasonable agreement with emission rates determined by a mass balance method. The CO emission rate on 23 March 1998, was about twice as large as the autumn emission rates. This observation is consistent with the observed mean emission ratios in March and October obtained from long-term measurements. The CO emission rates were also used to calculate absolute emission rates for a number of hydrocarbons.