@article{EliassonPalssonWeber2011, author = {El{\´i}asson, J{\´o}nas and Palsson, Asgeir and Weber, Konradin}, title = {Monitoring ash clouds for aviation}, series = {Nature}, volume = {475}, journal = {Nature}, number = {7357}, publisher = {Springer Nature}, doi = {10.1038/475455b}, pages = {455}, year = {2011}, language = {en} } @article{EliassonWeberVogeletal.2016, author = {El{\´i}asson, Jonas and Weber, Konradin and Vogel, Andreas and P{\´a}lsson, Thorgeir and Yoshitani, Junichi and Miki, Daisuke}, title = {Investigation and Separation of Turbulent Fluctuations in Airborne Measurements of Volcanic Ash with Optical Particle Counters}, series = {Journal of Disaster Research}, volume = {11}, journal = {Journal of Disaster Research}, number = {1}, publisher = {Fuji Technology Press Ltd.}, issn = {1883-8030}, doi = {10.20965/jdr.2016.p0072}, url = {http://nbn-resolving.de/urn:nbn:de:hbz:due62-opus-50023}, pages = {72 -- 84}, year = {2016}, abstract = {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.}, language = {en} } @article{EliassonYoshitaniMikietal.2016, author = {El{\´i}asson, Jonas and Yoshitani, Junichi and Miki, Daisuke and Weber, Konradin and B{\"o}lke, Christoph and Scharifi, Emad}, title = {Measurements of Particle Distribution and Ash Fluxes in the Plume of Sakurajima Volcano with Optical Particle Counter}, series = {Journal of Disaster Research}, volume = {11}, journal = {Journal of Disaster Research}, number = {1}, publisher = {Fuji Technology Press Ltd.}, issn = {1883-8030}, doi = {10.20965/jdr.2016.p0085}, url = {http://nbn-resolving.de/urn:nbn:de:hbz:due62-opus-50030}, pages = {85 -- 95}, year = {2016}, abstract = {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 (Eyjafjallaj{\"o}kull) and 2011 (Gr{\´i}msv{\"o}tn). 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.}, language = {en} } @inproceedings{WeberEliassonArnasonetal.2015, author = {Weber, Konradin and Eliasson, Jonas and Arnason, Gylfi and R{\"o}gnvaldsson, {\´O}lafur and Thorsteinsson, Throstur and Palsson, Thorgeir and B{\"o}hlke, Christoph and Fischer, Christian and Smith, Paul and Jones, Roderic L. and Tirpitz, Lukas and Platt, Ulrich}, title = {Airborne Investigations and WRF - Model Calculations of the Bardarbunga-Holuhraun Eruption Plume}, series = {Geophysical Research Abstracts: EGU General Assembly 2015}, volume = {17}, booktitle = {Geophysical Research Abstracts: EGU General Assembly 2015}, publisher = {Copernicus}, address = {G{\"o}ttingen}, year = {2015}, abstract = {The eruption in Holuhraun is the largest producer of lava and gas in Iceland since 1783. The Volcanic Ash Research (VAR) group organized an airborne measurement campaign including 10 flights, where emissions of SO2 and ash concentrations were measured at the source and at the far plume. The highest SO2 concentration at the source was nearly up to 100 mg/m3. This is an extremely high value, compared to other airborne campaigns and a contamination considered to cause serious illness by the Icelandic Directorate of Health. Volcanic ash consisted of very fine particles, but the concentration was low when compared to other recent eruptions. Measurements of the far plume showed that scavenging is very active. The dispersion was successfully modeled with the Weather Research and Foreast (WRF-chem) model and analysis using the model showed that a large amount of the sulphur was precipitated in the Icelandic highlands.}, subject = {Vulkanismus}, language = {en} } @article{EliassonYoshitaniWeberetal.2014, author = {Eliasson, Jonas and Yoshitani, Junichi and Weber, Konradin and Yasuda, Nario and Iguchi, Masato and Vogel, Andreas}, title = {Airborne Measurement in the Ash Plume from Mount Sakurajima: Analysis of Gravitational Effects on Dispersion and Fallout}, series = {International Journal of Atmospheric Sciences}, volume = {2014}, journal = {International Journal of Atmospheric Sciences}, publisher = {Wiley}, issn = {2314-4122}, doi = {10.1155/2014/372135}, url = {http://nbn-resolving.de/urn:nbn:de:hbz:due62-opus-50955}, pages = {16}, year = {2014}, abstract = {Volcanic ash concentrations in the plume from Sakurajima volcano in Japan are observed from airplanes equipped with optical particle counters and GPS tracking devices. The volcano emits several puffs a day. The puffs are also recorded by the Sakurajima Volcanological Observatory. High concentrations are observed in the puffs and fallout driven by vertical air current, called streak fallout. Puffs dispersion is analyzed by the classical diffusion-advection method and a new gravitational dispersion method. The fluid mechanic of the gravitational dispersion, streak fallout, and classical diffusion-advection theory is described in three separate appendices together with methods to find the time gravitational dispersion constant and the diffusion coefficient from satellite photos. The diffusion-advection equation may be used to scale volcanic eruptions so the same eruption plumes can be scaled to constant flux and wind conditions or two eruptions can be scaled to each other. The dispersion analyses show that dispersion of volcanic plumes does not follow either theories completely. It is most likely diffusion in the interface of the plume and the ambient air, together with gravitational flattening of the plumes core. This means larger boundary concentration gradients and smaller diffusion coefficients than state of the art methods can predict.}, subject = {Vulkanismus}, language = {en} } @inproceedings{WeberFischerVogeletal.2013, author = {Weber, Konradin and Fischer, Christian and Vogel, Andreas and Pohl, Tobias and B{\"o}hlke, Christoph and Lau, Hendrik and Eliasson, Jonas and Palsson, Thorgeir}, title = {First results of an airborne release of volcanic ash for testing of volcanic ash plume measurement instruments}, series = {Recent Advances in Energy and Environmental Management}, volume = {Energy, Environmental and Structural Engineering Series 13}, booktitle = {Recent Advances in Energy and Environmental Management}, editor = {Mladenov, Valeri and Tasho, Tashev and Hui, Wang and Ivan, Kralov and Sergey, Stankevich and Pelin, Yildiz and Jon, Burley}, publisher = {WSEAS}, pages = {169 -- 172}, year = {2013}, subject = {Vulkanasche}, language = {en} } @article{EliassonYasudaWeberetal.2014, author = {Eliasson, Jonas and Yasuda, Nario and Weber, Konradin and Vogel, Andreas and Palsson, Thorgeir}, title = {The role of in-situ measurements of volcanic ash concentrations in preventing economic disasters due to volcanic ash clouds}, series = {Journal of Integrated Disaster Risk Management}, volume = {4}, journal = {Journal of Integrated Disaster Risk Management}, number = {1}, publisher = {Journal of Integrated Disaster Risk Management}, issn = {2185-8322}, doi = {10.5595/idrim.2014.0092}, pages = {48 -- 60}, year = {2014}, language = {en} } @inproceedings{EliassonPalssonWeber2017, author = {Eliasson, Jonas and Palsson, Thorgeir and Weber, Konradin}, title = {State of volcanic ash dispersion prediction}, series = {Geophysical Research Abstracts: EGU General Assembly 2017}, booktitle = {Geophysical Research Abstracts: EGU General Assembly 2017}, publisher = {Copernicus}, address = {G{\"o}ttingen}, year = {2017}, abstract = {The Eyjafjallajokull 2010 and Grimsvotn 2011 eruptions created great problems for commercial aviation in Western Europe and in the North Atlantic region. Comparison of satellite images of the visible and predicted ash clouds showed the VAAC prediction to be much larger than the actual ash clouds. No official explanation of this discrepancy exists apart from the definition of the ash cloud boundary. Papers on simulation of the Eyjafjallaj{\"o}kull ash cloud in peer reviewed journals, typically attempted to simulate the VAAC predictions rather than focusing on the satellite pictures. Sporadic measurements made in-situ showed much lower ash concentrations over Europe than the predicted values. Two of the weak points in ash cloud prediction have been studied in airborne measurements of volcanic ash by the Universities in Kyoto Japan, Iceland and D{\"u}sseldorf Germany of eruptions in Sakurajima, Japan. It turns out that gravitational deformation of the plume and a streak fallout process make estimated ash content of clouds larger than the actual, both features are not included in the simulation model. Tropospheric plumes tend to ride in stable inversions this causes gravitational flattening (pancaking) of the volcanic plume, while diffusion in the mixing layer is insignificant. New rules from ICAO, effective from November 2014, reiterate that jetliners should avoid visible ash, this makes information on visible ash important. A procedure developed by JMA′s Tokyo VAAC uses satellite images of visible ash to correct the prediction. This and the fact that meteorological data necessary to model gravitational dispersion and streak fallout do not exist in the international database available to the VAAC′s. This shows that close monitoring by airborne measurements and satellite and other photographic surveillance is necessary.}, subject = {Vulkanismus}, language = {en} } @inproceedings{ArnasonEliassonWeberetal.2015, author = {Arnason, Gylfi and Eliasson, Jonas and Weber, Konradin and B{\"o}hlke, Christoph and Palsson, Thorgeir and R{\"o}gnvaldsson, {\´O}lafur and Thorsteinsson, Throstur and Platt, Ulrich and Tirpitz, Lukas and Jones, Roderic L. and Smith, Paul D.}, title = {Results of airborne measurements in the plume near and far from the 2014 Bardarbunga-Holuhraun eruption}, series = {Geophysical Research Abstracts: EGU General Assembly 2015}, volume = {17}, booktitle = {Geophysical Research Abstracts: EGU General Assembly 2015}, publisher = {Copernicus}, address = {G{\"o}ttingen}, year = {2015}, abstract = {The Volcanic Ash Research (VAR) group is focused on airborne measurement of ash contamination to support safe air travel. In relations to the recent eruption, the group measured ash and several gaseous species in the plume 10-300 km from the volcano. The eruption emitted ash turned out to be mostly in the fine aerosol range (much less than 10 micrometers in diameter). Our highest measured concentrations were lower than 1 mg/m3 indicating that commercial air traffic was not threatened (greater than 2 mg/m3) by the ash contamination. But we measured sulfur dioxide (SO2 ) up to 90 mg/m3, which presented a potentially dangerous pollution problem. However, airborne measurements indicate that the sulfur concentration decays (probably due to scavenging) as the plume is carried by the wind from the volcano, which limits the area of immediate danger to the public. Here we present size distribution for particulate matter collected during flights, near and far from the crater at various times. The particle data is then compared with simultaneously collected sulfur dioxide data and the rate of decay of is estimated. Sulfur and particle concentration variations with height in the far plume are presented. Some airborne measurements for H2S, NO, NO2 and CO2 will also be presented. This includes correlation matrices for simultaneous measurements of these gases and comparison to National Air Quality Standards and background values.}, subject = {Vulkanasche}, language = {en} } @inproceedings{RoegnvaldssonArnasonPalssonetal.2015, author = {R{\"o}gnvaldsson, {\´O}lafur and Arnason, Gylfi and Palsson, Thorgeir and Eliasson, Jonas and Weber, Konradin and B{\"o}hlke, Christoph and Thorsteinsson, Throstur and Tirpitz, Lukas and Platt, Ulrich and Smith, Paul D. and Jones, Roderic L.}, title = {Modeling of SO2 dispersion from the 2014 Holuhraun eruption in Iceland using WRF-Chem}, series = {Geophysical Research Abstracts: EGU General Assembly 2015}, volume = {17}, booktitle = {Geophysical Research Abstracts: EGU General Assembly 2015}, publisher = {Copernicus}, address = {G{\"o}ttingen}, year = {2015}, abstract = {The fissure eruption in Holuhraun in central Iceland is the country's largest lava and gas eruption since 1783 but has produced very little volcanic ash. The eruption started in late August 2014 and is still ongoing as of January 2015. The main threat from this event has been atmospheric pollution of SO2 that is carried by wind to all parts of the country and produces elevated concentrations of SO2 that have frequently violated National Air Quality Standards (NAQS) in many population centers. The Volcanic Ash Research (VAR) group in Iceland is focused on airborne measurement of ash contamination to support safe air travel, as well as various gas concentrations. In relation to the Holuhraun eruption the VAR group has organized an investigation campaign including 10 measurement flights and performed measurements of both the source emissions and the plume distribution. SO2 concentrations measured at the source showed clear potential for creating pollution events in the toxic range and contamination of surface waters. The data obtained in the measurement campaign was used for calibration of the WRF-chem model of the dispersion of SO2 and volcanic ash concentration. The model has both been run in operational forecast mode (since mid October) as well as in a dynamical downscaling mode, to estimate the dispersion and fallout of SO2 from the plume. The model results indicate that a large part of the sulphur was precipitated in the Icelandic highlands. The first melt waters during the spring thaw are likely to contain acid sulphur compounds that can be harmful for vegetation, with the highland vegetation being the most vulnerable. These results will be helpful to estimate the pollution load on farmlands and pastures of farmers.}, subject = {Vulkanismus}, language = {en} } @inproceedings{WeberReichardtFischeretal.2012, author = {Weber, Konradin and Reichardt, R. and Fischer, Christian and Moser, H. M. and Eliasson, Jonas}, title = {Computational Visualization of Volcanic Ash Plume Concentrations Measured by light Aircrafts over Germany and Iceland during the Recent Eruptions of the Volcanoes Eyjafjallaj{\"o}kull and Grimsv{\"o}tn}, series = {Recent advances in Fluid Mechanics, Heat \& Mass Transfer, Biology and Ecology}, booktitle = {Recent advances in Fluid Mechanics, Heat \& Mass Transfer, Biology and Ecology}, editor = {Jha, Manoj K. and Lazard, Myriam and Zaharim, Azami and Sopian, Kamaruzzaman}, publisher = {WSEAS}, isbn = {978-1-61804-065-7}, pages = {236 -- 240}, year = {2012}, subject = {Vulkanasche}, language = {en} } @inproceedings{VogelWeberEliassonetal.2012, author = {Vogel, Andreas and Weber, Konradin and Eliasson, Jonas and Palsson, Asgeir and Moser, H. M. and Palsson, Thorgeir and von L{\"o}wis, S. and Fischer, Christian}, title = {Airborne and groundbased measurements of ash particles on Iceland and over Germany during the Gr{\´i}msv{\"o}tn eruption May 2011 [Abstract]}, series = {Geophysical Research Abstracts:EGU General Assembly 2012, held 22-27 April, 2012 in Vienna, Austria}, booktitle = {Geophysical Research Abstracts:EGU General Assembly 2012, held 22-27 April, 2012 in Vienna, Austria}, publisher = {Copernicus}, address = {G{\"o}ttingen}, pages = {12854}, year = {2012}, abstract = {The eruption of the Grimsv{\"o}tn volcano in May 2010 posed with its ash plume a thread to the aviation in northern Europe. Because of ash plume forecasts of the VAAC London the airport of Keflavik in Iceland as well as airports in England, Scotland and Scandinavia were closed for some time, which caused the cancellation or change of about 500 flights in Europe. Even in Germany the airports of Bremen, Hamburg and Berlin were closed for several hours on 25 May 2011. During this eruption period in May 2011, a team of the Duesseldorf University of Applied Sciences, the University of Iceland, the University of Reykjavik and the IMO has performed airborne in-situ measurements over Iceland and Germany as well as ground based measurements in the south of Iceland. The ground based measurements were performed continuously during the whole eruption period at two significant positions (Skogar and Hvollsv{\"o}llur) with optical particle counters (OPCs). The measurement method was based on measuring the airborne concentrations of the classic aerosol components (PM10, PM2.5 and PM1) and TSP (total suspended particles) every 6 seconds. Additional measurement flights on Iceland were started already one day after the beginning of the eruption (twelve in-situ measurement flights) and marked the spatial and temporal spread of volcanic ash in the atmosphere. For the flights light slow flying piston engine powered airplanes where used. The flights over Iceland focused on the western part of Iceland in the region of Reykjavik and Keflavik and over the international airport in Keflavik and were mostly coordinated by ISAVIA. The measurement flights helped to keep Keflavik International Airport open for many additional hours despite of adverse predictions by the London VAAC model, because it was possible to observe the particle concentration on-line during the flights. In Germany a measurement flight was performed on 25 May 2012 over the northern part of Germany where the volcanic ash cloud was forecasted from the dispersion model of the London VAAC. This flight was performed on the behalf of the German Weather Service (DWD). The measurement flights revealed most time relative low airborne ash concentrations over western Iceland, although the groundbased measured ash concentrations in the south of Iceland nearer to the Grimsv{\"o}tn were very high. In Germany the measured concentrations during the flight were low enough to be consistent with the re-opening of the airports Bremen, Hamburg and Berlin, which were closed by the authorities for several hours on 25 May 2011 because of high concentration predictions by the VAAC-model. The measurement flights clearly proved that OPCs, based on slow flying piston-motor driven aircrafts, are very suitable for the determination of airborne ash particles during volcanic eruptions. This is an important issue for air traffic safety.}, language = {en} } @article{WeberFischerPohletal.2015, author = {Weber, Konradin and Fischer, Christian and Pohl, Tobias and B{\"o}hlke, Christoph and Lange, Martin and Scharifi, Emad and Eliasson, Jonas and Yoshitani, Junichi}, title = {The Application of Light Research Aircraft for the Investigation of Volcano Eruption Plumes, Industrial Emissions and Urban Plumes}, series = {WSEAS Transactions on Environment and Development}, volume = {11}, journal = {WSEAS Transactions on Environment and Development}, publisher = {WSEAS}, issn = {2224-3496}, url = {http://nbn-resolving.de/urn:nbn:de:hbz:due62-opus-50892}, pages = {89 -- 94}, year = {2015}, abstract = {Airborne measurements have proved to be an important tool for the investigation of volcanic emission plumes, industrial pollution plumes, fugitive emissions and urban pollution plumes. In this paper several examples are demonstrated, how these investigations can be performed by light and microlight propeller aircraft. Throughout the last years innovative aircraft were developed in the light and microlight class showing an excellent flight performance. This enables airborne measurements, which were performed in former years normally by big jet engine driven research aircraft. Moreover, these light and microlight aircraft are equipped with piston motors, which are sturdy enough to operate even in adverse and harsh flight conditions, e.g. in volcanic plumes with high ash concentration. Additionally, turbo charged versions of these airborne piston motors are available, which allow flight altitudes of 7000m - 9000m enabling a large variety of research missions. Another advantage of light and microlight research aircraft is that they are quite cost effective and have a comparatively short certification process for the installation of new measurement equipment. This made it possible to respond fast to the eruption of the Icelandic volcano Eyjafjallaj{\"o}kull 2010 and Grimsv{\"o}tn 2011 with research flights in volcanic ash plumes over Germany and Iceland. In this way it was possible to deliver real airborne measurements additional to the ash plume model calculations of the London Volcanic Ash Advisory Center (VAAC). In this paper examples of airborne measurements in the volcanic plumes of the recent eruptions of Icelandic volcanoes are given. Moreover examples are presented, which highlight the outstanding capabilities of these aircraft for pinpointing industrial emissions and for characterizing urban pollution plumes.}, subject = {Vulkanismus}, language = {en} }