TY - CHAP A1 - Fischer, C. A1 - Pohl, T. A1 - Weber, Konradin A1 - Vogel, A. A1 - van Haren, G. A1 - Schweikert, W. ED - Lewis, Colin ED - Burgess, Douglas T1 - TATP stand-off detection with open path: FTIR techniques T2 - Optics and photonics for counterterrorism, crime fighting and defence VIII : 24 - 26 September 2012, Edinburgh, United Kingdom KW - Luftreinhaltung Y1 - 2012 SN - 978-0-8194-9287-6 U6 - https://doi.org/10.1117/12.974592 SN - 0277-786X VL - 8546 PB - SPIE CY - Bellingham, Wash ER - TY - JOUR A1 - Leadbetter, S. J. A1 - Hort, M. C. A1 - von Löwis, S. A1 - Weber, Konradin A1 - Witham, C. S. T1 - Modeling the resuspension of ash deposited during the eruption of Eyjafjallajökull in spring 2010 JF - Journal of Geophysical Research: Atmospheres N2 - Eyjafjallajökull, a volcano in southern Iceland, erupted explosively in April and May 2010 depositing ash over a region of more than 3000 km2 to the east and southeast of the volcano. This deposited ash has been frequently remobilized by the wind causing concern for the health of Icelanders living in the region. An investigation was carried out to determine whether it would be possible to produce forecasts of days when high airborne ash concentrations were likely to occur. Information about the spatially varying surface characteristics of the region of deposited ash is not available so in the modeling approach adopted here ash is released from the surface at a rate proportional to the cube of the excess friction velocity (local friction velocity minus a threshold) only when the friction velocity exceeds a threshold. Movement of the resuspended ash is then modeled in a Lagrangian dispersion model. Modeled ash concentrations are compared to observed concentrations from two periods; PM10 observations between 23 May and 2 July 2010 and airborne particle counts between 21 September 2010 and 16 February 2011. More than 66% of the resuspension episodes between May and July are captured by the model and the relative magnitudes of the modeled episodes in this period are in good agreement with the observations. 66% of episodes between October and February are also captured by the model although there is an increase in the false alarm rate which appears to be due to the influence of precipitation. KW - Luftreinhaltung Y1 - 2012 U6 - https://doi.org/10.1029/2011JD016802 SN - 0148-0227 VL - 117 IS - D20 PB - American Geophysical Union (AGU) ER - TY - JOUR A1 - General, S. A1 - Pöhler, D. A1 - Sihler, H. A1 - Bobrowski, N. A1 - Frieß, U. A1 - Zielcke, J. A1 - Horbanski, M. A1 - Shepson, P. B. A1 - Stirm, B. H. A1 - Simpson, W. R. A1 - Weber, Konradin A1 - Fischer, C. A1 - Platt, U. T1 - The Heidelberg Airborne Imaging DOAS Instrument (HAIDI) – a novel imaging DOAS device for 2-D and 3-D imaging of trace gases and aerosols JF - Atmospheric Measurement Techniques N2 - Abstract. Many relevant processes in tropospheric chemistry take place on rather small scales (e.g., tens to hundreds of meters) but often influence areas of several square kilometer. Thus, measurements of the involved trace gases with high spatial resolution are of great scientific interest. In order to identify individual sources and sinks and ultimately to improve chemical transport models, we developed a new airborne instrument, which is based on the well established Differential Optical Absorption Spectroscopy (DOAS) method. The Heidelberg Airborne Imaging DOAS Instrument (HAIDI) is a passive imaging DOAS spectrometer, which is capable of recording horizontal and vertical trace gas distributions with a resolution of better than 100 m. Observable species include NO2, HCHO, C2H2O2, H2O, O3, O4, SO2, IO, OClO and BrO. Here we give a technical description of the instrument including its custom-built spectrographs and CCD detectors. Also first results from measurements with the new instrument are presented. These comprise spatial resolved SO2 and BrO in volcanic plumes, mapped at Mt. Etna (Sicily, Italy), NO2 emissions in the metropolitan area of Indianapolis (Indiana, USA) as well as BrO and NO2 distributions measured during arctic springtime in context of the BRomine, Ozone, and Mercury EXperiment (BROMEX) campaign, which was performed 2012 in Barrow (Alaska, USA). KW - Luftreinhaltung Y1 - 2014 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:hbz:due62-opus-50179 SN - 1867-8548 VL - 7 IS - 10 SP - 3459 EP - 3485 PB - Copernicus ER - TY - JOUR A1 - Moxnes, E. D. A1 - Kristiansen, N. I. A1 - Stohl, A. A1 - Clarisse, L. A1 - Durant, A. A1 - Weber, Konradin A1 - Vogel, A. T1 - Separation of ash and sulfur dioxide during the 2011 Grímsvötn eruption JF - Journal of Geophysical Research: Atmospheres KW - Luftreinhaltung Y1 - 2014 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:hbz:due62-opus-50162 SN - 2169-8996 VL - 119 IS - 12 SP - 7477 EP - 7501 PB - American Geophysical Union (AGU) ER - TY - CHAP A1 - Comeron, Adolfo A1 - Kassianov, Evgueni I. A1 - Schäfer, Klaus A1 - Picard, Richard H. A1 - Weber, Konradin T1 - Remote Sensing of Clouds and the Atmosphere XX. Remote Sensing of Clouds and the Atmosphere, Toulouse), 23.-24.09.2015 KW - Luftreinhaltung Y1 - 2015 SN - 978-1-62841-850-7 SN - 0277-786X VL - Proceedings of SPIE ; volume 9640 PB - SPIE CY - Bellingham, Washington, USA ER - TY - CHAP A1 - Eliasson, J. A1 - Watson, I.M. A1 - Weber, Konradin T1 - In Situ Observations of Airborne Ash From Manned Aircraft T2 - Volcanic Ash KW - Luftreinhaltung Y1 - 2016 SN - 9780081004050 U6 - https://doi.org/10.1016/B978-0-08-100405-0.00009-4 SP - 89 EP - 98 PB - Elsevier ER - TY - JOUR A1 - Bonn, Boris A1 - von Schneidemesser, Erika A1 - Andrich, Dorota A1 - Quedenau, Jörn A1 - Gerwig, Holger A1 - Lüdecke, Anja A1 - Kura, Jürgen A1 - Pietsch, Axel A1 - Ehlers, Christian A1 - Klemp, Dieter A1 - Kofahl, Claudia A1 - Nothard, Rainer A1 - Kerschbaumer, Andreas A1 - Junkermann, Wolfgang A1 - Grote, Rüdiger A1 - Pohl, Tobias A1 - Weber, Konradin A1 - Lode, Birgit A1 - Schönberger, Philipp A1 - Churkina, Galina A1 - Butler, Tim M. A1 - Lawrence, Mark G. T1 - BAERLIN2014 – the influence of land surface types on and the horizontal heterogeneity of air pollutant levels in Berlin JF - Atmospheric Chemistry and Physics N2 - Abstract. Urban air quality and human health are among the key aspects of future urban planning. In order to address pollutants such as ozone and particulate matter, efforts need to be made to quantify and reduce their concentrations. One important aspect in understanding urban air quality is the influence of urban vegetation which may act as both emitter and sink for trace gases and aerosol particles. In this context, the "Berlin Air quality and Ecosystem Research: Local and long-range Impact of anthropogenic and Natural hydrocarbons 2014" (BAERLIN2014) campaign was conducted between 2 June and 29 August in the metropolitan area of Berlin and Brandenburg, Germany. The predominant goals of the campaign were (1) the characterization of urban gaseous and particulate pollution and its attribution to anthropogenic and natural sources in the region of interest, especially considering the connection between biogenic volatile organic compounds and particulates and ozone; (2) the quantification of the impact of urban vegetation on organic trace gas levels and the presence of oxidants such as ozone; and (3) to explain the local heterogeneity of pollutants by defining the distribution of sources and sinks relevant for the interpretation of model simulations. In order to do so, the campaign included stationary measurements at urban background station and mobile observations carried out from bicycle, van and airborne platforms. This paper provides an overview of the mobile measurements (Mobile BAERLIN2014) and general conclusions drawn from the analysis. Bicycle measurements showed micro-scale variations of temperature and particulate matter, displaying a substantial reduction of mean temperatures and particulate levels in the proximity of vegetated areas compared to typical urban residential area (background) measurements. Van measurements extended the area covered by bicycle observations and included continuous measurements of O3, NOx, CO, CO2 and point-wise measurement of volatile organic compounds (VOCs) at representative sites for traffic- and vegetation-affected sites. The quantification displayed notable horizontal heterogeneity of the short-lived gases and particle number concentrations. For example, baseline concentrations of the traffic-related chemical species CO and NO varied on average by up to ±22.2 and ±63.5 %, respectively, on the scale of 100 m around any measurement location. Airborne observations revealed the dominant source of elevated urban particulate number and mass concentrations being local, i.e., not being caused by long-range transport. Surface-based observations related these two parameters predominantly to traffic sources. Vegetated areas lowered the pollutant concentrations substantially with ozone being reduced most by coniferous forests, which is most likely caused by their reactive biogenic VOC emissions. With respect to the overall potential to reduce air pollutant levels, forests were found to result in the largest decrease, followed by parks and facilities for sports and leisure. Surface temperature was generally 0.6–2.1 °C lower in vegetated regions, which in turn will have an impact on tropospheric chemical processes. Based on our findings, effective future mitigation activities to provide a more sustainable and healthier urban environment should focus predominantly on reducing fossil-fuel emissions from traffic as well as on increasing vegetated areas. KW - Luftreinhaltung Y1 - 2016 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:hbz:due62-opus-50065 SN - 1680-7324 VL - 16 IS - 12 SP - 7785 EP - 7811 PB - Copernicus ER - TY - JOUR A1 - Fu, Guangliang A1 - Heemink, Arnold A1 - Lu, Sha A1 - Segers, Arjo A1 - Weber, Konradin A1 - Lin, Hai-Xiang T1 - Model-based aviation advice on distal volcanic ash clouds byassimilating aircraft in situ measurements JF - Atmospheric Chemistry and Physics N2 - Abstract. The forecast accuracy of distal volcanic ash clouds is important for providing valid aviation advice during volcanic ash eruption. However, because the distal part of volcanic ash plume is far from the volcano, the influence of eruption information on this part becomes rather indirect and uncertain, resulting in inaccurate volcanic ash forecasts in these distal areas. In our approach, we use real-life aircraft in situ observations, measured in the northwestern part of Germany during the 2010 Eyjafjallajökull eruption, in an ensemble-based data assimilation system combined with a volcanic ash transport model to investigate the potential improvement on the forecast accuracy with regard to the distal volcanic ash plume. We show that the error of the analyzed volcanic ash state can be significantly reduced through assimilating real-life in situ measurements. After a continuous assimilation, it is shown that the aviation advice for Germany, the Netherlands and Luxembourg can be significantly improved. We suggest that with suitable aircrafts measuring once per day across the distal volcanic ash plume, the description and prediction of volcanic ash clouds in these areas can be greatly improved. KW - Luftreinhaltung Y1 - 2016 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:hbz:due62-opus-50058 SN - 1680-7324 VL - 16 IS - 14 SP - 9189 EP - 9200 PB - Copernicus ER - TY - CHAP A1 - Comeron, Adolfo A1 - Jack, James A1 - Kassianov, Evgueni I. A1 - Schäfer, Kiaus A1 - Picard, Richard H A1 - Weber, Konradin T1 - Remote Sensing of Clouds and the Atmosphere XXI Introduction T2 - Remote Sensing of Clouds and the Atmosphere XXI : 28-29 September 2016, Edinburgh, United Kingdom KW - Luftreinhaltung Y1 - 2016 SN - 978-1-5106-0406-3 PB - SPIE CY - Bellingham, Washington, USA ER - TY - JOUR A1 - Elíasson, Jonas A1 - Yoshitani, Junichi A1 - Miki, Daisuke A1 - Weber, Konradin A1 - Bölke, Christoph A1 - Scharifi, Emad T1 - Measurements of Particle Distribution and Ash Fluxes in the Plume of Sakurajima Volcano with Optical Particle Counter JF - Journal of Disaster Research N2 - Volcanic eruptions have caused very costly disturbances of international air traffic. This problem has been dealt with by simulating the formation and migration of dangerous ash plumes. However, the results of the simulations have sometimes been too safe, producing ash clouds that are too large. This was especially the case for the North Atlantic in 2010 (Eyjafjallajökull) and 2011 (Grímsvötn). Since 2012, an international cooperation team led by the Disaster Prevention Research Institute (DPRI) of Kyoto University has conducted airborne measurements of volcanic ash concentrations in the plume from Mount Sakurajima in Kagoshima Prefecture, Japan. This volcano was chosen because of its frequent but limited eruptions, which allow close observation. These measurement campaigns have provided data showing gravitational flattening of the plume, a new and previously unknown dispersion process of volcanic plumes. A new and previously unknown fallout process, called streak fallout, also has been measured. Results concerning plume flux, concentration distributions, aerosol (PM10) content of the plume, and content of very fine particles (PM2.5 and PM1) are presented, and the ways by which the observational methods can be used to produce reliable initial data and boundary values for simulations of plume dispersion are discussed. KW - Luftreinhaltung Y1 - 2016 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:hbz:due62-opus-50030 SN - 1883-8030 VL - 11 IS - 1 SP - 85 EP - 95 PB - Fuji Technology Press Ltd. ER - TY - JOUR A1 - Elíasson, Jonas A1 - Weber, Konradin A1 - Vogel, Andreas A1 - Pálsson, Thorgeir A1 - Yoshitani, Junichi A1 - Miki, Daisuke T1 - Investigation and Separation of Turbulent Fluctuations in Airborne Measurements of Volcanic Ash with Optical Particle Counters JF - Journal of Disaster Research N2 - The science of measuring airborne volcanic ash concentrations supports research in such fields as atmospheric environmental science and the modeling of atmospheric pollution from volcanoes, and is thus very valuable to the aviation industry. These measurements show large scatter directly traceable to turbulent fluctuations responsible for diffusing volcanic dust. Before semistationary components in observations can be compared to each other or to simulation results, they must be separated from fluctuations. In the design of the separation process, however, neither seasonal or diurnal periodicity nor random disturbance with known properties exists to serve as a guideline. It has been suggested that fluctuations could be eliminated through repeated convolutions of a simple 3-point filter enough times. The number of convolutions is chosen from the change in the rate of increase of a special variability parameter. When semistationary concentrations are separated from fluctuations, their statistics are compared to turbulence parameters and the autocorrelation of the series. The method is demonstrated using three measurement series from Sakurajima, Japan measured in 2013. It is concluded that this new method is simple and trustworthy where knowledge and experience of the environmental parameters can be utilized to support the results. They indicate a variability of 40% in the relative fluctuations of the PM10 and around 20% of the PM2.5. The relative fluctuations may be considered completely random, but normally distributed rather than a white noise with an evenly distributed variance spectrum. KW - Luftreinhaltung Y1 - 2016 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:hbz:due62-opus-50023 SN - 1883-8030 VL - 11 IS - 1 SP - 72 EP - 84 PB - Fuji Technology Press Ltd. ER - TY - CHAP A1 - Maas, Peter A1 - Höfert, Norbert A1 - Schäfer, Klaus A1 - Weber, Konradin A1 - Richter, Andreas ED - Comerón, Adolfo ED - Kassianov, Evgueni I. ED - Schäfer, Klaus ED - Picard, Richard H. ED - Weber, Konradin T1 - Standards VDI 4211 and VDI 4212 on passive FTIR and DOAS remote sensing techniques T2 - Proceedings Volume 10786, Remote Sensing of Clouds and the Atmosphere XXIII; 107860W (2018) KW - Luftreinhaltung Y1 - 2018 U6 - https://doi.org/10.1117/12.2325145 PB - SPIE ER - TY - JOUR A1 - Naraparaju, R. A1 - Lau, H. A1 - Lange, Martin A1 - Fischer, Christian A1 - Kramer, D. A1 - Schulz, U. A1 - Weber, Konradin T1 - Integrated testing approach using a customized micro turbine for a volcanic ash and CMAS related degradation study of thermal barrier coatings JF - Surface and Coatings Technology KW - Luftreinhaltung Y1 - 2018 U6 - https://doi.org/10.1016/j.surfcoat.2018.01.030 SN - 0257-8972 VL - 337 SP - 198 EP - 208 PB - Elsevier ER - TY - JOUR A1 - Wannek, C. A1 - Nehr, Sascha A1 - Vahlenkamp, M. A1 - Mergel, J. A1 - Stolten, D. T1 - Pseudo-half-cell measurements on symmetrical catalyst-coated membranes and their relevance for optimizing DMFC anodes JF - Journal of Applied Electrochemistry KW - Luftreinhaltung Y1 - 2009 U6 - https://doi.org/10.1007/s10800-009-9960-9 SN - 0021-891X VL - 40 IS - 1 SP - 29 EP - 38 PB - Springer Nature ER - TY - JOUR A1 - Nehr, Sascha A1 - Bohn, Birger A1 - Fuchs, Hendrik A1 - Hofzumahaus, Andreas A1 - Wahner, Andreas T1 - HO2 formation from the OH + benzene reaction in the presence of O2 JF - Physical Chemistry Chemical Physics KW - Luftreinhaltung Y1 - 2011 U6 - https://doi.org/10.1039/c1cp20334g SN - 1463-9076 VL - 13 IS - 22 PB - Royal Society of Chemistry (RSC) ER - TY - JOUR A1 - Fuchs, H. A1 - Bohn, Birger A1 - Hofzumahaus, A. A1 - Holland, F. A1 - Lu, K. D. A1 - Nehr, Sascha A1 - Rohrer, F. A1 - Wahner, A. T1 - Detection of HO2 by laser-induced fluorescence: calibration and interferences from RO2 radicals JF - Atmospheric Measurement Techniques N2 - Abstract. HO2 concentration measurements are widely accomplished by chemical conversion of HO2 to OH including reaction with NO and subsequent detection of OH by laser-induced fluorescence. RO2 radicals can be converted to OH via a similar radical reaction sequence including reaction with NO, so that they are potential interferences for HO2 measurements. Here, the conversion efficiency of various RO2 species to HO2 is investigated. Experiments were conducted with a radical source that produces OH and HO2 by water photolysis at 185 nm, which is frequently used for calibration of LIF instruments. The ratio of HO2 and the sum of OH and HO2 concentrations provided by the radical source was investigated and was found to be 0.50 ± 0.02. RO2 radicals are produced by the reaction of various organic compounds with OH in the radical source. Interferences via chemical conversion from RO2 radicals produced by the reaction of OH with methane and ethane (H-atom abstraction) are negligible consistent with measurements in the past. However, RO2 radicals from OH plus alkene- and aromatic-precursors including isoprene (mainly OH-addition) are detected with a relative sensitivity larger than 80 % with respect to that for HO2 for the configuration of the instrument with which it was operated during field campaigns. Also RO2 from OH plus methyl vinyl ketone and methacrolein exhibit a relative detection sensitivity of 60 %. Thus, previous measurements of HO2 radical concentrations with this instrument were biased in the presence of high RO2 radical concentrations from isoprene, alkenes or aromatics, but were not affected by interferences in remote clean environment with no significant emissions of biogenic VOCs, when the OH reactivity was dominated by small alkanes. By reducing the NO concentration and/or the transport time between NO addition and OH detection, interference from these RO2 species are suppressed to values below 20 % relative to the HO2 detection sensitivity. The HO2 conversion efficiency is also smaller by a factor of four, but this is still sufficient for atmospheric HO2 concentration measurements for a wide range of conditions. KW - Luftreinhaltung Y1 - 2011 U6 - https://doi.org/10.5194/amt-4-1209-2011 SN - 1867-8548 VL - 4 IS - 6 SP - 1209 EP - 1225 PB - Copernicus ER - TY - JOUR A1 - Nehr, Sascha A1 - Bohn, Birger A1 - Wahner, Andreas T1 - Prompt HO2Formation Following the Reaction of OH with Aromatic Compounds under Atmospheric Conditions JF - The Journal of Physical Chemistry A KW - Luftreinhaltung Y1 - 2012 U6 - https://doi.org/10.1021/jp210946y SN - 1089-5639 VL - 116 IS - 24 SP - 6015 EP - 6026 PB - American Chemical Society (ACS) ER - TY - JOUR A1 - Lu, K. D. A1 - Rohrer, F. A1 - Holland, F. A1 - Fuchs, H. A1 - Bohn, Birger A1 - Brauers, Theo A1 - Chang, C. C. A1 - Häseler, R. A1 - Hu, M. A1 - Kita, K. A1 - Kondo, Y. A1 - Li, X. A1 - Lou, S. R. A1 - Nehr, Sascha A1 - Shao, M. A1 - Zeng, L. M. A1 - Wahner, A. A1 - Zhang, Y. H. A1 - Hofzumahaus, A. T1 - Observation and modelling of OH and HO2 concentrations in the Pearl River Delta 2006: a missing OH source in a VOC rich atmosphere JF - Atmospheric Chemistry and Physics N2 - Abstract. Ambient OH and HO2 concentrations were measured by laser induced fluorescence (LIF) during the PRIDE-PRD2006 (Program of Regional Integrated Experiments of Air Quality over the Pearl River Delta, 2006) campaign at a rural site downwind of the megacity of Guangzhou in Southern China. The observed OH concentrations reached daily peak values of (15–26) × 106 cm−3 which are among the highest values so far reported for urban and suburban areas. The observed OH shows a consistent high correlation with j(O1D) over a broad range of NOx conditions. The correlation cannot be reproduced by model simulations, indicating that OH stabilizing processes are missing in current models. The observed OH exhibited a weak dependence on NOx in contrast to model predictions. While modelled and measured OH agree well at NO mixing ratios above 1 ppb, a continuously increasing underprediction of the observed OH is found towards lower NO concentrations, reaching a factor of 8 at 0.02 ppb NO. A dependence of the modelled-to-measured OH ratio on isoprene cannot be concluded from the PRD data. However, the magnitude of the ratio fits into the isoprene dependent trend that was reported from other campaigns in forested regions. Hofzumahaus et al. (2009) proposed an unknown OH recycling process without NO, in order to explain the high OH levels at PRD in the presence of high VOC reactivity and low NO. Taking a recently discovered interference in the LIF measurement of HO2 into account, the need for an additional HO2 → OH recycling process persists, but the required source strength may be up to 20% larger than previously determined. Recently postulated isoprene mechanisms by Lelieveld et al. (2008) and Peeters and Müller (2010) lead to significant enhancements of OH expected for PRD, but an underprediction of the observed OH by a factor of two remains at low NO (0.1–0.2 ppb). If the photolysis of hydroperoxy aldehydes from isoprene is as efficient as proposed by Peeters and Müller (2010), the corresponding OH formation at PRD would be more important than the primary OH production from ozone and HONO. While the new isoprene mechanisms need to be confirmed by laboratory experiments, there is probably need for other, so far unidentified chemical processes to explain entirely the high OH levels observed in Southern China. KW - Luftreinhaltung Y1 - 2012 U6 - https://doi.org/10.5194/acp-12-1541-2012 SN - 1680-7324 VL - 12 IS - 3 SP - 1541 EP - 1569 PB - Copernicus ER - TY - JOUR A1 - Fuchs, H. A1 - Dorn, Hans-Peter A1 - Bachner, M. A1 - Bohn, Birger A1 - Brauers, Theo A1 - Gomm, S. A1 - Hofzumahaus, A. A1 - Holland, F. A1 - Nehr, Sascha A1 - Rohrer, F. A1 - Tillmann, R. A1 - Wahner, A. T1 - Comparison of OH concentration measurements by DOAS and LIF during SAPHIR chamber experiments at high OH reactivity and low NO concentration JF - Atmospheric Measurement Techniques N2 - Abstract. During recent field campaigns, hydroxyl radical (OH) concentrations that were measured by laser-induced fluorescence (LIF) were up to a factor of ten larger than predicted by current chemical models for conditions of high OH reactivity and low NO concentration. These discrepancies, which were observed in forests and urban-influenced rural environments, are so far not entirely understood. In summer 2011, a series of experiments was carried out in the atmosphere simulation chamber SAPHIR in Jülich, Germany, in order to investigate the photochemical degradation of isoprene, methyl-vinyl ketone (MVK), methacrolein (MACR) and aromatic compounds by OH. Conditions were similar to those experienced during the PRIDE-PRD2006 campaign in the Pearl River Delta (PRD), China, in 2006, where a large difference between OH measurements and model predictions was found. During experiments in SAPHIR, OH was simultaneously detected by two independent instruments: LIF and differential optical absorption spectroscopy (DOAS). Because DOAS is an inherently calibration-free technique, DOAS measurements are regarded as a reference standard. The comparison of the two techniques was used to investigate potential artifacts in the LIF measurements for PRD-like conditions of OH reactivities of 10 to 30 s−1 and NO mixing ratios of 0.1 to 0.3 ppbv. The analysis of twenty experiment days shows good agreement. The linear regression of the combined data set (averaged to the DOAS time resolution, 2495 data points) yields a slope of 1.02 ± 0.01 with an intercept of (0.10 ± 0.03) × 106 cm−3 and a linear correlation coefficient of R2 = 0.86. This indicates that the sensitivity of the LIF instrument is well-defined by its calibration procedure. No hints for artifacts are observed for isoprene, MACR, and different aromatic compounds. LIF measurements were approximately 30–40% (median) larger than those by DOAS after MVK (20 ppbv) and toluene (90 ppbv) had been added. However, this discrepancy has a large uncertainty and requires further laboratory investigation. Observed differences between LIF and DOAS measurements are far too small to explain the unexpected high OH concentrations during the PRIDE-PRD2006 campaign. KW - Luftreinhaltung Y1 - 2012 U6 - https://doi.org/10.5194/amt-5-1611-2012 SN - 1867-8548 VL - 5 IS - 7 SP - 1611 EP - 1626 PB - Copernicus ER - TY - JOUR A1 - Emanuelsson, E. U. A1 - Hallquist, M. A1 - Kristensen, K. A1 - Glasius, M. A1 - Bohn, Birger A1 - Fuchs, H. A1 - Kammer, B. A1 - Kiendler-Scharr, A. A1 - Nehr, Sascha A1 - Rubach, F. A1 - Tillmann, R. A1 - Wahner, A. A1 - Wu, H.-C. A1 - Mentel, Th. F. T1 - Formation of anthropogenic secondary organic aerosol (SOA) and its influence on biogenic SOA properties JF - Atmospheric Chemistry and Physics N2 - Abstract. Secondary organic aerosol (SOA) formation from mixed anthropogenic and biogenic precursors has been studied exposing reaction mixtures to natural sunlight in the SAPHIR chamber in Jülich, Germany. In this study aromatic compounds served as examples of anthropogenic volatile organic compound (VOC) and a mixture of α-pinene and limonene as an example for biogenic VOC. Several experiments with exclusively aromatic precursors were performed to establish a relationship between yield and organic aerosol mass loading for the atmospheric relevant range of aerosol loads of 0.01 to 10 μg m−3. The yields (0.5 to 9%) were comparable to previous data and further used for the detailed evaluation of the mixed biogenic and anthropogenic experiments. For the mixed experiments a number of different oxidation schemes were addressed. The reactivity, the sequence of addition, and the amount of the precursors influenced the SOA properties. Monoterpene oxidation products, including carboxylic acids and dimer esters were identified in the aged aerosol at levels comparable to ambient air. OH radicals were measured by Laser Induced Fluorescence, which allowed for establishing relations of aerosol properties and composition to the experimental OH dose. Furthermore, the OH measurements in combination with the derived yields for aromatic SOA enabled application of a simplified model to calculate the chemical turnover of the aromatic precursor and corresponding anthropogenic contribution to the mixed aerosol. The estimated anthropogenic contributions were ranging from small (≈8%) up to significant fraction (50%) providing a suitable range to study the effect of aerosol composition on the aerosol volatility (volume fraction remaining (VFR) at 343 K: 0.86–0.94). The aromatic aerosol had higher oxygen to carbon ratio O/C and was less volatile than the biogenic fraction. However, in order to produce significant amount of aromatic SOA the reaction mixtures needed a higher OH dose that also increased O/C and provided a less volatile aerosol. The SOA yields, O/C, and f44 (the mass fraction of CO2+ ions in the mass spectra which can be considered as a measure of carboxylic groups) in the mixed photo-chemical experiments could be described as linear combinations of the corresponding properties of the pure systems. For VFR there was in addition an enhancement effect, making the mixed aerosol significantly less volatile than what could be predicted from the pure systems. A strong positive correlation was found between changes in volatility and O/C with the exception during dark hours where the SOA volatility decreased while O/C did not change significantly. Thus, this change in volatility under dark conditions as well as the anthropogenic enhancement is due to chemical or morphological changes not affecting O/C. KW - Luftreinhaltung Y1 - 2013 U6 - https://doi.org/10.5194/acp-13-2837-2013 SN - 1680-7324 VL - 13 IS - 5 SP - 2837 EP - 2855 PB - Copernicus ER -