TY - JOUR A1 - Prata, A. J. A1 - Dezitter, F. A1 - Davies, I. A1 - Weber, Konradin A1 - Birnfeld, M. A1 - Moriano, D. A1 - Bernardo, C. A1 - Vogel, A. A1 - Prata, G. S. A1 - Mather, T. A. A1 - Thomas, H. E. A1 - Cammas, J. A1 - Weber, M. T1 - Artificial cloud test confirms volcanic ash detection using infrared spectral imaging JF - Scientific reports N2 - Airborne volcanic ash particles are a known hazard to aviation. Currently, there are no means available to detect ash in flight as the particles are too fine (radii < 30 μm) for on-board radar detection and, even in good visibility, ash clouds are difficult or impossible to detect by eye. The economic cost and societal impact of the April/May 2010 Icelandic eruption of Eyjafjallajökull generated renewed interest in finding ways to identify airborne volcanic ash in order to keep airspace open and avoid aircraft groundings. We have designed and built a bi-spectral, fast-sampling, uncooled infrared camera device (AVOID) to examine its ability to detect volcanic ash from commercial jet aircraft at distances of more than 50 km ahead. Here we report results of an experiment conducted over the Atlantic Ocean, off the coast of France, confirming the ability of the device to detect and quantify volcanic ash in an artificial ash cloud created by dispersal of volcanic ash from a second aircraft. A third aircraft was used to measure the ash in situ using optical particle counters. The cloud was composed of very fine ash (mean radii ~10 μm) collected from Iceland immediately after the Eyjafjallajökull eruption and had a vertical thickness of ~200 m, a width of ~2 km and length of between 2 and 12 km. Concentrations of ~200 μg m(-3) were identified by AVOID at distances from ~20 km to ~70 km. For the first time, airborne remote detection of volcanic ash has been successfully demonstrated from a long-range flight test aircraft. KW - Luftreinhaltung Y1 - 2016 U6 - https://doi.org/10.1038/srep25620 VL - 6 PB - Springer Nature 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 - 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 - 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 - 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 - Pohl, T. A1 - Heweling, G. A1 - Fischer, C. A1 - Weber, Konradin T1 - Traffic Influenced Nitrogen Dioxide, Ultrafine Particle and Black Carbon Concentrations at a Busy Urban Street in Duesseldorf, Germany JF - International Journal of Environmental Science N2 - In this study the road traffic related air pollution within a busy urban street canyon in the City of Duesseldorf, Germany was investigated. For the investigations the measurement truck of the laboratory for environmental measurement techniques of the HSD was equipped with different measurement devices for gaseous and aerosol species as well as meteorological sensors. The measurement truck was placed next to a stationary air quality measurement container of the Environmental State Agency of North-Rhine-Westphalia (LANUV). The measurement site is located at the Cornelius street, a direct north south connecting street through the city of Duesseldorf, which is highly frequented by road traffic with an daily amount of about 45,000 vehicles. The street is located within the low emission zone (LEZ). Additionally the pass through of vehicles with a higher weight than 7.5 tons is prohibited. Within this study over a period of several weeks the particle mass concentrations PM10, PM2.5 and PM1, and the particle number size distribution (PNSD) were measured over a broad range from 5 nm to 32 µm with a high temporal resolution. Additionally, an aethalometer was used to determine the proportion of black carbon in the particle ensembles. Gaseous pollutants like nitrogen dioxide, ozone and sulphur dioxide were measured as well. Nitrogen dioxide is a typical species originating from combustion processes. In this study the data from NO2 strongly correlate with ultrafine particle and black carbon concentrations and for this reason all three species are clearly influenced by road traffic. However, this effect is not so pronounced for the particle mass concentrations, which are additionally influenced by the varying local background concentrations. During the measurements, the averaged concentration for PM10 was on a moderate level at 20.6 µg/m³ (PM2.5 13.4 µg/m³, PM1 10.7 µg/m³). The averaged NO2 concentration was 54.2 µg/m³ during the measurement period, which is above the yearly limit value of 40 µg/m³. However, the hourly limit value of 200 µg/m³ was not exceeded during the measurement period of this study. The averaged particle number concentration (PNC5-250 nm) and black carbon concentration were on a low level compared with values from other studies at roadsides. The PNC5-250 nm was at 6,400 #/cm³ and for black carbon at 1.8 µg/m³. The lower values for PNC and BC are possibly explained as a result due to the measures from the clean air plan. The measurements of this study took place in summertime. The air pollution concentrations might be higher during colder times of the year due to domestic fuel burning. After all it can be stated, that the additional monitoring of ultrafine particles and black carbon is relevant and important to characterize the composition of the air quality at roadsides and offer a better understanding for the temporal resolution of air pollutants in cities. Moreover, estimations on the risk of air pollution for the human health can more precisely be specified. KW - Luftreinhaltung KW - urban air pollution KW - road traffic emissions KW - ultrafine particles KW - black carbon KW - nitrogen dioxide Y1 - 2017 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:hbz:due62-opus-50355 SN - 2367-8941 VL - 2 SP - 410 EP - 417 ER - TY - JOUR A1 - Henin, Stefano A1 - Petit, Yannick A1 - Rohwetter, Philipp A1 - Stelmaszczyk, Kamil A1 - Hao, Zuoqiang A1 - Nakaema, Walter Morinobu A1 - Vogel, Andreas A1 - Pohl, Tobias A1 - Schneider, Friedhelm A1 - Kasparian, Jérôme A1 - Weber, Konradin A1 - Wöste, Ludger A1 - Wolf, Jean-Pierre T1 - Field measurements suggest the mechanism of laser-assisted water condensation JF - Nature Communications N2 - Because of the potential impact on agriculture and other key human activities, efforts have been dedicated to the local control of precipitation. The most common approach consists of dispersing small particles of dry ice, silver iodide, or other salts in the atmosphere. Here we show, using field experiments conducted under various atmospheric conditions, that laser filaments can induce water condensation and fast droplet growth up to several μm in diameter in the atmosphere as soon as the relative humidity exceeds 70%. We propose that this effect relies mainly on photochemical formation of p.p.m.-range concentrations of hygroscopic Hno3, allowing efficient binary Hno3–H2o condensation in the laser filaments. Thermodynamic, as well as kinetic, numerical modelling based on this scenario semiquantitatively reproduces the experimental results, suggesting that particle stabilization by Hno3 has a substantial role in the laser-induced condensation. KW - Luftreinhaltung KW - Kondensation KW - Laser KW - Niederschlag Y1 - 2011 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:hbz:due62-opus-52439 SN - 2041-1723 VL - 2 IS - 1 PB - Springer Nature ER -