Characterization of a volcanic ash episode in southern Finland caused by the Grimsvötn eruption in Iceland in May 2011

Abstract. The volcanic eruption of Grimsvötn in Iceland in May 2011 affected surface-layer air quality at several locations in Northern Europe. In Helsinki, Finland, the main pollution episode lasted for more than 8 h around the noon of 25 May. We characterized this episode by relying on detailed physical, chemical and optical aerosol measurements. The analysis was aided by air mass trajectory calculations, satellite measurements, and dispersion model simulations. During the episode, volcanic ash particles were present at sizes from less than 0.5 μm up to sizes >10 μm. The mass mean diameter of ash particles was a few μm in the Helsinki area, and the ash enhanced PM10 mass concentrations up to several tens of μg m−3. Individual particle analysis showed that some ash particles appeared almost non-reacted during the atmospheric transportation, while most of them were mixed with sea salt or other type of particulate matter. Also sulfate of volcanic origin appeared to have been transported to our measurement site, but its contribution to the aerosol mass was minor due the separation of ash-particle and sulfur dioxide plumes shortly after the eruption. The volcanic material had very little effect on PM1 mass concentrations or sub-micron particle number size distributions in the Helsinki area. The aerosol scattering coefficient was increased and visibility was slightly decreased during the episode, but in general changes in aerosol optical properties due to volcanic aerosols seem to be difficult to be distinguished from those induced by other pollutants present in a continental boundary layer. The case investigated here demonstrates clearly the power of combining surface aerosol measurements, dispersion model simulations and satellite measurements in analyzing surface air pollution episodes caused by volcanic eruptions. None of these three approaches alone would be sufficient to forecast, or even to unambiguously identify, such episodes.

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Characterization of a volcanic ash episode in southern Finland caused by the Grimsvötn eruption in Iceland in May 2011

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-11-24933-2011 ◽

2011 ◽

Vol 11 (9) ◽

pp. 24933-24968 ◽

Cited By ~ 2

Author(s):

V.-M. Kerminen ◽

J. V. Niemi ◽

H. Timonen ◽

M. Aurela ◽

A. Frey ◽

...

Keyword(s):

Volcanic Ash ◽

Dispersion Model ◽

Volcanic Eruptions ◽

Particle Analysis ◽

Satellite Measurements ◽

Volcanic Origin ◽

Model Simulations ◽

Volcanic Material ◽

Micron Particle ◽

Mass Concentrations

Abstract. The volcanic eruption of Grimsvötn in Iceland in May 2011, affected surface-layer air quality at several locations in Northern Europe. In Helsinki, Finland, the main pollution episode lasted for more than 8 h around the noon of 25 May. We characterized this episode by relying on detailed physical, chemical and optical aerosol measurements. The analysis was aided by air mass trajectory calculations, satellite measurements, and dispersion model simulations. During the episode, volcanic ash particles were present at sizes from less than 0.5 μm up to sizes >10 μm. The mass mean diameter of ash particles was a few μm in the Helsinki area, and the ash enhanced PM10 mass concentrations up to several tens of μg m−3. Individual particle analysis showed that some ash particles appeared almost non-reacted during the atmospheric transportation, while most of them were mixed with sea salt or other type of particulate matter. Also sulfate of volcanic origin appeared to have been transported to our measurement site, but its contribution to the aerosol mass was minor due the separation of ash-particle and sulfur dioxide plumes shortly after the eruption. The volcanic material had very little effect on PM1 mass concentrations or sub-micron particle number size distributions in the Helsinki area. The aerosol scattering coefficient was increased and visibility was slightly decreased during the episode, but in general changes in aerosol optical properties due to volcanic aerosols seem to be difficult to be distinguished from those induced by other pollutants present in a continental boundary layer. The case investigated here demonstrates clearly the power of combining surface aerosol measurements, dispersion model simulations and satellite measurements in analyzing surface air pollution episodes caused by volcanic eruptions. None of these three approaches alone would be sufficient to forecast, or even to unambiguously identify, such episodes.

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Determination of time- and height-resolved volcanic ash emissions and their use for quantitative ash dispersion modeling: the 2010 Eyjafjallajökull eruption

Atmospheric Chemistry and Physics ◽

10.5194/acp-11-4333-2011 ◽

2011 ◽

Vol 11 (9) ◽

pp. 4333-4351 ◽

Cited By ~ 242

Author(s):

A. Stohl ◽

A. J. Prata ◽

S. Eckhardt ◽

L. Clarisse ◽

A. Durant ◽

...

Keyword(s):

Volcanic Ash ◽

Dispersion Model ◽

A Priori ◽

Volcanic Eruptions ◽

General Nature ◽

Aviation Industry ◽

Dispersion Modeling ◽

Source Information ◽

European Area ◽

Ash Dispersion

Abstract. The April–May, 2010 volcanic eruptions of Eyjafjallajökull, Iceland caused significant economic and social disruption in Europe whilst state of the art measurements and ash dispersion forecasts were heavily criticized by the aviation industry. Here we demonstrate for the first time that large improvements can be made in quantitative predictions of the fate of volcanic ash emissions, by using an inversion scheme that couples a priori source information and the output of a Lagrangian dispersion model with satellite data to estimate the volcanic ash source strength as a function of altitude and time. From the inversion, we obtain a total fine ash emission of the eruption of 8.3 ± 4.2 Tg for particles in the size range of 2.8–28 μm diameter. We evaluate the results of our model results with a posteriori ash emissions using independent ground-based, airborne and space-borne measurements both in case studies and statistically. Subsequently, we estimate the area over Europe affected by volcanic ash above certain concentration thresholds relevant for the aviation industry. We find that during three episodes in April and May, volcanic ash concentrations at some altitude in the atmosphere exceeded the limits for the "Normal" flying zone in up to 14 % (6–16 %), 2 % (1–3 %) and 7 % (4–11 %), respectively, of the European area. For a limit of 2 mg m−3 only two episodes with fractions of 1.5 % (0.2–2.8 %) and 0.9 % (0.1–1.6 %) occurred, while the current "No-Fly" zone criterion of 4 mg m−3 was rarely exceeded. Our results have important ramifications for determining air space closures and for real-time quantitative estimations of ash concentrations. Furthermore, the general nature of our method yields better constraints on the distribution and fate of volcanic ash in the Earth system.

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The fate of volcanic ash aggregates: premature or delayed sedimentation?

10.5194/egusphere-egu2020-5278 ◽

2020 ◽

Author(s):

Eduardo Rossi ◽

Frances Beckett ◽

Costanza Bonadonna ◽

Gholamhossein Bagheri

Keyword(s):

Volcanic Ash ◽

Dispersion Model ◽

Volcanic Eruptions ◽

Fall Velocity ◽

Field Evidence ◽

Aggregation Processes ◽

Lagrangian Dispersion ◽

Theoretical Evidence

Most volcanic ash produced during explosive volcanic eruptions sediments as aggregates of various types that typically have a greater fall velocity than the particles of which they are composed. As a result, aggregation processes are commonly known to affect the sedimentation of fine ash by considerably reducing its residence time in the atmosphere. Nonetheless, speculations also exist in the literature that aggregation does not always result in a premature sedimentation of their constitute particles but that it can also result in a delayed sedimentation (i.e. the so-called rafting effect). However, previous studies have considered rafting as a highly improbable phenomenon due to a biased representation of aggregate shapes.Here we provide the first theoretical evidence that rafting may not only occur, but it is probably more common than previously thought, helping to elucidate often unexplained field observations. Starting from field evidence of rafted aggregates at Sakurajima Volcano (Japan), we clarify the conditions for which aggregation of volcanic ash results either in a premature or a delayed sedimentation.Moreover, using the Lagrangian dispersion model NAME, we show the practical consequences of rafting on the final sedimentation distance of aggregates with different morphological features. As an application we chose the case study of the 2010 eruption of Eyjafjallaj&#246;kull volcano (Iceland), for which rafting can increase the travel distances of ash <500 &#61549;m up 3.7 times with respect to sedimentation of individual particles.These findings have fundamental implications both for real-time forecasting and long-term hazard assessment of volcanic ash dispersal and sedimentation and for weather modelling. The constraints on rafting presented and discussed in this work will help the scientific community to clarify the often unexpected role of aggregation in creating a delayed sedimentation of coarse ash.

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Dispersion Model Evaluation for the Sulfur Dioxide Plume from the 2019 Raikoke Eruption using Satellite Measurements.

10.5194/egusphere-egu2020-16028 ◽

2020 ◽

Author(s):

Johannes de Leeuw ◽

Anja Schmidt ◽

Claire Witham ◽

Nicolas Theys ◽

Richard Pope ◽

...

Keyword(s):

Sulfur Dioxide ◽

Dispersion Model ◽

European Space Agency ◽

Volcanic Eruptions ◽

Numerical Dispersion ◽

Aviation Industry ◽

Volcanic Plume ◽

Satellite Measurements ◽

Volcanic Gas ◽

Vertical Column

Volcanic eruptions pose a serious threat to the aviation industry causing widespread disruption. To identify any potential impacts, nine Volcanic Ash Advisory Centres (VAACs) provide global monitoring of all eruptions, informing stakeholders how each volcanic eruption might interfere with aviation. Numerical dispersion models represent a vital infrastructure when assessing and forecasting the atmospheric conditions from a volcanic plume.In this study we investigate the 2019 Raikoke eruption, which emitted approximately 1.5 Tg of sulfur dioxide (SO2) representing the largest volcanic emission of SO2 into the stratosphere since the Nabro eruption in 2011. Using the UK Met Office&#8217;s Numerical Atmospheric-dispersion Modelling Environment (NAME), we simulate the evolution of the volcanic gas and aerosol particle plumes (SO2 and sulfate, SO4) across the Northern Hemisphere between 21st June and 17th July. We evaluate the skills and limitations of NAME in terms of modelling volcanic SO2 plumes, by comparing our simulations to high-resolution measurements from the Tropospheric Monitoring Instrument (TROPOMI) on-board the European Space Agency (ESA)&#8217;s Sentinel 5 &#8211; Precursor (S5P) satellite.Our comparisons show that NAME accurately simulates the observed location and shape of the SO2 plume in the first few weeks after the eruption. NAME also reproduces the magnitude of the observed SO2 vertical column densities, when emitting 1.5 Tg of SO2, during the first 48 hours after the eruption. On longer timescales, we find that the model-simulated SO2 plume in NAME is more diffuse than in the TROPOMI measurements, resulting in an underestimation of the peak SO2 vertical column densities in the model. This suggests that the diffusion parameters used in NAME are too large in the upper troposphere and lower stratosphere.Finally, NAME underestimates the total mass of SO2 when compared to estimates from TROPOMI, however emitting 2 Tg of SO2 in the model improves the comparison, resulting in very good agreement with the satellite measurements.

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Radiative forcing by volcanic eruptions since 1990, calculated with a chemistry-climate model and a new emission inventory based on vertically resolved satellite measurements

10.5194/acp-2021-654 ◽

2021 ◽

Author(s):

Jennifer Schallock ◽

Christoph Brühl ◽

Christine Bingen ◽

Michael Höpfner ◽

Landon Rieger ◽

...

Keyword(s):

Radiative Forcing ◽

Emission Inventory ◽

Climate Model ◽

Aerosol Particles ◽

Volcanic Eruptions ◽

Stratospheric Aerosol ◽

Radiation Budget ◽

Vertical Profiles ◽

Satellite Measurements ◽

Model Simulations

Abstract. This paper presents model simulations of stratospheric aerosols with a focus on explosive volcanic eruptions. Using various (occulation and limb based) satellite instruments, with vertical profiles of sulfur dioxide (SO2) from the MIPAS (Michelson Interferometer for Passive Atmospheric Sounding) instrument and vertical profiles of aerosol extinction from GOMOS (Global Ozone Monitoring by Occultation of Stars), OSIRIS (Optical Spectrograph and InfraRed Imaging System), and SAGE II (Stratospheric Aerosol and Gas Experiment), we characterised the inﬂuence of volcanic aerosols for the period between 1990 and 2019. We established a volcanic sulfur emission inventory that includes more than 500 eruptions. The identified SO2 perturbations were incorporated as three-dimensional pollution plumes into a chemistry-climate model, which converts the gases into aerosol particles and computes their optical properties. The Aerosol Optical Depth (AOD) and the climate radiative forcing are calculated online. Combined with model improvements, the simulations reproduce the observations of the various satellites. Slight deviations between the observations and model simulations were found only for the large volcanic eruption of Pinatubo in 1991. This is likely due to either an overestimation of the removal of aerosol particles in the model, or limitations of the satellite measurements, which are related to saturation effects associated with anomalously high aerosol concentrations. Since Pinatubo, only smaller-sized volcanic eruptions have taken place. Weak- and medium-strength volcanic eruptions captured in satellite data and the Smithsonian database typically inject about 10 kt to 50 kt SO2 directly into the upper troposphere/lower stratosphere (UTLS) region or transport it indirectly via convection and advection. Our results show that these relatively smaller eruptions, which occur quite frequently, can nevertheless contribute significantly to the stratospheric aerosol layer and are relevant for the Earth's radiation budget. These eruptions are found to cause a global radiative forcing in the order of −0.1 Wm−2 at the tropopause.

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Modelling the size distribution of aggregated volcanic ash and implications for operational atmospheric dispersion modelling

10.5194/acp-2021-254 ◽

2021 ◽

Author(s):

Frances Beckett ◽

Eduardo Rossi ◽

Benjamin Devenish ◽

Claire Witham ◽

Costanza Bonadonna

Keyword(s):

Grain Size ◽

Size Distribution ◽

Grain Size Distribution ◽

Volcanic Ash ◽

Dispersion Model ◽

Aviation Industry ◽

Eruption Column ◽

Model Simulations ◽

Aggregation Scheme ◽

Ash Cloud

Abstract. We have developed an aggregation scheme for use with the Lagrangian atmospheric transport and dispersion model NAME, which is used by the London Volcanic Ash Advisory Centre (VAAC) to provide advice and guidance on the location of volcanic ash clouds to the aviation industry. The aggregation scheme uses the fixed pivot technique to solve the Smoluchowski coagulation equations to simulate aggregation processes in an eruption column. This represents the first attempt at modelling explicitly the change in the grain size distribution (GSD) of the ash due to aggregation in a model which is used for operational response. To understand the sensitivity of the output aggregated grain size distribution (AGSD) to the model parameters we conducted a simple parametric study and scaling analysis. We find that the modelled AGSD is sensitive to the density distribution and grain size distribution assigned to the non-aggregated ash at the source. Our ability to accurately forecast the long-range transport of volcanic ash clouds is, therefore, still limited by real-time information on the physical characteristics of the ash. We assess the impact of using the AGSD on model simulations of the Eyjafjallajökull 2010 ash cloud, and consider the implications for operational forecasting. Using the time-evolving AGSD at the top of the eruption column to initialise dispersion model simulations had little impact on the modelled extent and mass loadings in the distal ash cloud. Our aggregation scheme does not account for the density of the aggregates; however, if we assume that the aggregates have the same density of single grains of equivalent size the modelled extent of the Eyjafjallajökull ash cloud with high concentrations of ash, significant for aviation, is reduced by ~3 %. If we assume that the aggregates have a lower density (500 kg m−3) than the single grains of which they are composed and make-up 75 % of the mass in the ash cloud the extent is 1.2 times larger.

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Development of PUFF–Gaussian dispersion model for the prediction of atmospheric distribution of particle concentration

Scientific Reports ◽

10.1038/s41598-021-86039-y ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Jooyong Lee ◽

Sungsu Lee ◽

HyunA Son ◽

Waon-ho Yi

Keyword(s):

Numerical Analysis ◽

Volcanic Ash ◽

Dispersion Model ◽

Gaussian Model ◽

Field Measurements ◽

Volcanic Eruptions ◽

Lagrangian Model ◽

Analysis Model ◽

Ash Dispersion ◽

Gaussian Dispersion

AbstractMt. Baekdu’s eruption precursors are continuously observed and have become a global social issue. Volcanic activities in neighboring Japan are also active. There are no direct risks of proximity-related disasters in South Korea from the volcanic eruptions at Japan or Mt. Baekdu; however, severe impacts are expected from the spread of volcanic ash. Numerical analysis models are generally used to predict and analyze the diffusion of volcanic ash, and each numerical analysis model has its own limitations caused by the computational algorithm it employs. In this study, we analyzed the PUFF–UAF model, an ash dispersion model based on the Lagrangian approach, and observed that the number of particles used in tracking substantially affected the results. Even with the presence of millions of particles, the concentration of ash predicted by the PUFF–UAF model does not accurately represent the dispersion. To overcome this deficit and utilize the computational efficiency of the Lagrangian model, we developed a PUFF–Gaussian model to consider the dispersive nature of ash by applying the Gaussian dispersion theory to the results of the PUFF–UAF model. The results of the proposed method were compared with the field measurements from actual volcanic eruptions, and the comparison showed that the proposed method can produce reasonably accurate predictions for ash dispersion.

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Determination of time- and height-resolved volcanic ash emissions for quantitative ash dispersion modeling: the 2010 Eyjafjallajökull eruption

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-11-5541-2011 ◽

2011 ◽

Vol 11 (2) ◽

pp. 5541-5588 ◽

Cited By ~ 19

Author(s):

A. Stohl ◽

A. J. Prata ◽

S. Eckhardt ◽

L. Clarisse ◽

A. Durant ◽

...

Keyword(s):

Volcanic Ash ◽

Size Range ◽

Dispersion Model ◽

A Priori ◽

Volcanic Eruptions ◽

General Nature ◽

Aviation Industry ◽

Dispersion Modeling ◽

Source Information ◽

Ash Dispersion

Abstract. The April–May 2010 volcanic eruptions of Eyjafjallajökull, Iceland caused significant economic and social disruption in Europe whilst state of the art measurements and ash dispersion forecasts were heavily criticized by the aviation industry. Here we demonstrate for the first time that dramatic improvements can be made in quantitative predictions of the fate of volcanic ash emissions, by using an inversion scheme that couples a priori source information and the output of a Lagrangian dispersion model with satellite data to estimate the volcanic ash source strength as a function of altitude and time. From the inversion, we obtain a total fine ash emission of the eruption of 8.3 ± 4.2 Tg for particles in the size range of 2.8–28 μm diameter and extrapolate this to a total ash emission of 11.9 ± 5.9 Tg for the size range of 0.25–250 μm. We evaluate the results of our a posteriori model using independent ground-based, airborne and space-borne measurements both in case studies and statistically. Subsequently, we estimate the area over Europe affected by volcanic ash above certain concentration thresholds relevant for the aviation industry. We find that during three episodes in April and May, volcanic ash concentrations at some altitude in the atmosphere exceeded the limits for the "normal" flying zone in up to 14% (6–16%), 2% (1–3%) and 7% (4–11%), respectively, of the European area. For a limit of 2 mg m−3 only two episodes with fractions of 1.5% (0.2–2.8%) and 0.9% (0.1–1.6%) occurred, while the current "no-fly" zone criterion of 4 mg m−3 was rarely exceeded. Our results have important ramifications for determining air space closures and for real-time quantitative estimations of ash concentrations. Furthermore, the general nature of our method yields better constraints on the distribution and fate of volcanic ash in the Earth system.

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Impacts of Volcanic Eruptions around the Korean Peninsula: A Long-term Simulation Study for Hypothetical Eruption Scenarios

Korean Society of Hazard Mitigation ◽

10.9798/kosham.2020.20.5.361 ◽

2020 ◽

Vol 20 (5) ◽

pp. 361-371

Author(s):

Kihyun Park ◽

Byung-Il Min ◽

Sora Kim ◽

Jiyoon Kim ◽

Kyung-Suk Suh

Keyword(s):

Korean Peninsula ◽

Volcanic Ash ◽

Dispersion Model ◽

Three Dimensional ◽

Volcanic Eruptions ◽

Summer Season ◽

Assessment System ◽

Dose Assessment ◽

Ash Transport

To build a response against potential volcanic risks around Korea, we developed a three-dimensional Volcanic Ash Transport and Dispersion Model (VATDM), known as the Lagrangian Atmospheric Dose Assessment System-Volcanic Ash (LADAS-VA) model. Using the LADAS-VA model, we performed numerous simulations for multiple year-round hypothetical eruptions of several representative volcanoes around the Korean peninsula. We analyzed the simulation results and revealed the impacts of hypothetical volcanic eruptions on the Korean peninsula as counting the number of days influenced by the season. Overall simulations for hypothetical volcanic eruptions around the Korean peninsula revealed that the most impactful eruptions would potentially occur during the summer season. Long-term simulations examining hypothetical eruption scenarios at least over a decade must be conducted to enable the analysis of deviations on a year-on-year basis, in comparison with the climatological normals.

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The fate of volcanic ash: premature or delayed sedimentation?

Nature Communications ◽

10.1038/s41467-021-21568-8 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Eduardo Rossi ◽

Gholamhossein Bagheri ◽

Frances Beckett ◽

Costanza Bonadonna

Keyword(s):

Residence Time ◽

Volcanic Ash ◽

Volcanic Eruptions ◽

Theoretical Description ◽

Particle Sedimentation ◽

Weather Modeling ◽

Explosive Volcanic Eruptions ◽

Travel Distances ◽

Ash Dispersal

AbstractA large amount of volcanic ash produced during explosive volcanic eruptions has been found to sediment as aggregates of various types that typically reduce the associated residence time in the atmosphere (i.e., premature sedimentation). Nonetheless, speculations exist in the literature that aggregation has the potential to also delay particle sedimentation (rafting effect) even though it has been considered unlikely so far. Here, we present the first theoretical description of rafting that demonstrates how delayed sedimentation may not only occur but is probably more common than previously thought. The fate of volcanic ash is here quantified for all kind of observed aggregates. As an application to the case study of the 2010 eruption of Eyjafjallajökull volcano (Iceland), we also show how rafting can theoretically increase the travel distances of particles between 138–710 μm. These findings have fundamental implications for hazard assessment of volcanic ash dispersal as well as for weather modeling.

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