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

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.

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

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

<p>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.</p><p>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.</p><p>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 Eyjafjallajökull volcano (Iceland), for which rafting can increase the travel distances of ash <500 m up 3.7 times with respect to sedimentation of individual particles.</p><p>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.</p>

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

2011 ◽  
Vol 11 (9) ◽  
pp. 4333-4351 ◽  
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.

scholarly journals Operational Modelling of Umbrella Cloud Growth in a Lagrangian Volcanic Ash Transport and Dispersion Model

Atmosphere ◽  
2020 ◽  
Vol 11 (2) ◽  
pp. 200 ◽  
Author(s):  
Helen N. Webster ◽  
Benjamin J. Devenish ◽  
Larry G. Mastin ◽  
David J. Thomson ◽  
Alexa R. Van Eaton
Keyword(s):  
Flow Rate ◽  
Volcanic Ash ◽  
Dispersion Model ◽  
Volume Flow Rate ◽  
Gravity Current ◽  
Volume Flow ◽  
Lateral Spread ◽  
Lagrangian Model ◽  
Model Predictions ◽  
Ash Transport

Large explosive eruptions can result in the formation of an umbrella cloud which rapidly expands, spreading ash out radially from the volcano. The lateral spread by the intrusive gravity current dominates the transport of the ash cloud. Hence, to accurately forecast the transport of ash from large eruptions, lateral spread of umbrella clouds needs to be represented within volcanic ash transport and dispersion models. Here, we describe an umbrella cloud parameterisation which has been implemented into an operational Lagrangian model and consider how it may be used during an eruption when information concerning the eruption is limited and model runtime is key. We examine different relations for the volume flow rate into the umbrella, and the rate of spreading within the cloud. The scheme is validated against historic eruptions of differing scales (Pinatubo 1991, Kelud 2014, Calbuco 2015 and Eyjafjallajökull 2010) by comparing model predictions with satellite observations. Reasonable predictions of umbrella cloud spread are achieved using an estimated volume flow rate from the empirical equation by Bursik et al. and the observed eruption height. We show how model predictions can be refined during an ongoing eruption as further information and observations become available.

scholarly journals Improvements on Near Real Time Detection of Volcanic Ash Emissions for Emergency Monitoring with Limited Satellite Bands

2015 ◽  
Vol 57 ◽  
Author(s):  
Torge Steensen ◽  
Peter Webley ◽  
Jon Dehn
Keyword(s):  
Real Time ◽  
Satellite Data ◽  
Volcanic Ash ◽  
Dispersion Model ◽  
Volcano Monitoring ◽  
Quantitative Comparison ◽  
Title Page ◽  
Model Data ◽  
Dispersion Models ◽  
Ash Transport

<div class="page" title="Page 1"><div class="layoutArea"><div class="column"><p><span>Quantifying volcanic ash emissions syneruptively is an important task for the global aviation community. However, due to the near real time nature of volcano monitoring, many parameters important for accurate ash mass estimates cannot be obtained easily. Even when using the best possible estimates of those parameters, uncertainties associated with the ash masses remain high, especially if the satellite data is only available in the traditional 10.8 and 12.0 μm bands. To counteract this limitation, we developed a quantitative comparison between the ash extents in satellite and model data. The focus is the manual cloud edge definition based on the available satellite reverse absorption (RA) data as well as other knowledge like pilot reports or ground-based observations followed by an application of the Volcanic Ash Retrieval on the defined subset with an RA threshold of 0 K. This manual aspect, although subjective to the experience of the observer, can show a significant improvement as it provides the ability to highlight ash that otherwise would be obscured by meteorological clouds or, by passing over different surfaces with unaccounted temperatures, might be lost entirely and thus remains undetectable for an automated satellite approach. We show comparisons to Volcanic Ash Transport and Dispersion models and outline a quantitative match as well as percentages of overestimates based on satellite or dispersion model data which can be converted into a level of reliability for near real time volcano monitoring. </span></p></div></div></div>

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

2011 ◽  
Vol 11 (9) ◽  
pp. 24933-24968 ◽  
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.

scholarly journals Analysis of Japanese Volcanic Ash Dispersion on the Korean Peninsula using Satellite Imagery

2020 ◽  
Vol 20 (3) ◽  
pp. 269-275
Author(s):  
Jongsun Sun ◽  
Jae-kwang Ahn ◽  
Haseong Lee ◽  
Eui-Hong Hwang ◽  
Duk Kee Lee
Keyword(s):  
Korean Peninsula ◽  
Volcanic Eruption ◽  
Volcanic Ash ◽  
Satellite Images ◽  
Volcanic Eruptions ◽  
Active Volcano ◽  
Accurate Information ◽  
Secondary Damage ◽  
Hypothetical Scenario ◽  
Ash Dispersion

A volcanic eruption is a kind of global natural disaster that can occur suddenly and cause great damage to humankind. During the eruption, the magma causes fatal damage to life and property in areas near the volcano, and nearby countries are affected by the spread of volcanic ash, causing secondary damage due to air and soil pollution. Near the Korean peninsula, there exists an active volcano that can spread volcanic ash over long distances by erupting above Volcanic Explosivity Index (VEI) 4. Volcanoes in Japan have been known to cause considerable volcanic ash damage on the Korean Peninsula during eruption. Accordingly, the Korea Meteorological Administration is developing technology to predict and monitor volcanic ash spread using satellite images. However, despite the fact that empirical models for volcanic ash diffusion range prediction are used during volcanic eruptions, continuous improvement is needed for accurate information prediction. In this study, satellite images were analyzed not for the predicted distance of volcanic ash clouds, but for the actual distance of volcanic ash dispersion in cases where the volcanic ashes dispersed in the direction of the Korean peninsula. Of the 3,880 volcanoes that erupted in Japan over the last four years, 111 cases were identified where the height and spread distance of the volcanic ash that erupted toward the Korean Peninsula can be confirmed. In addition, the actual volcanic eruption cases and modeling results were analyzed to determine the extent of volcanic ash spread, and a hypothetical scenario was tested to quantify the direct damage of the volcanic ash. From the analysis of the volcanic ash spread through the virtual simulations, it was found that the height of the volcanic ash, the direction of the wind, and wind speed during volcanic eruption were important factors.

scholarly journals Modeling volcanic ash aggregation processes and related impacts on the April–May 2010 eruptions of Eyjafjallajökull volcano with WRF-Chem

2020 ◽  
Vol 20 (10) ◽  
pp. 2721-2737 ◽  
Author(s):  
Sean D. Egan ◽  
Martin Stuefer ◽  
Peter W. Webley ◽  
Taryn Lopez ◽  
Catherine F. Cahill ◽  
...  
Keyword(s):  
Volcanic Ash ◽  
Field Measurements ◽  
Volcanic Eruptions ◽  
Sensitivity Study ◽  
Collision Kernel ◽  
Aggregation Process ◽  
Airborne Measurements ◽  
Aggregation Processes ◽  
Ash Transport

Abstract. Volcanic eruptions eject ash and gases into the atmosphere that can contribute to significant hazards to aviation, public and environment health, and the economy. Several volcanic ash transport and dispersion (VATD) models are in use to simulate volcanic ash transport operationally, but none include a treatment of volcanic ash aggregation processes. Volcanic ash aggregation can greatly reduce the atmospheric budget, dispersion and lifetime of ash particles, and therefore its impacts. To enhance our understanding and modeling capabilities of the ash aggregation process, a volcanic ash aggregation scheme was integrated into the Weather Research Forecasting with online Chemistry (WRF-Chem) model. Aggregation rates and ash mass loss in this modified code are calculated in line with the meteorological conditions, providing a fully coupled treatment of aggregation processes. The updated-model results were compared to field measurements of tephra fallout and in situ airborne measurements of ash particles from the April–May 2010 eruptions of Eyjafjallajökull volcano, Iceland. WRF-Chem, coupled with the newly added aggregation code, modeled ash clouds that agreed spatially and temporally with these in situ and field measurements. A sensitivity study provided insights into the mechanics of the aggregation code by analyzing each aggregation process (collision kernel) independently, as well as by varying the fractal dimension of the newly formed aggregates. In addition, the airborne lifetime (e-folding) of total domain ash mass was analyzed for a range of fractal dimensions, and a maximum reduction of 79.5 % of the airborne ash lifetime was noted.

scholarly journals Airborne Volcanic Ash Forecast Area Reliability

2007 ◽  
Vol 22 (5) ◽  
pp. 1132-1139 ◽  
Author(s):  
Barbara J. B. Stunder ◽  
Jerome L. Heffter ◽  
Roland R. Draxler
Keyword(s):  
Volcanic Ash ◽  
Dispersion Model ◽  
Analysis Data ◽  
Flight Safety ◽  
Commercial Aircraft ◽  
Hysplit Model ◽  
Aircraft Flight ◽  
Two Parameters ◽  
Degree Of Overlap ◽  
Ash Transport

Abstract In support of aircraft flight safety operations, daily comparisons between modeled, hypothetical, volcanic ash plumes calculated with meteorological forecasts and analyses were made over a 1.5-yr period. The Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model simulated the ash transport and dispersion. Ash forecasts and analyses from seven volcanoes were studied. The volcanoes were chosen because of recent eruptions or because their airborne ash could impinge on well-traveled commercial aircraft flight paths. For each forecast–analysis pair, a statistic representing the degree of overlap, the threat score (TS), was calculated. A forecast was classified as acceptable if the TS was greater than 0.25. Each forecast was also categorized by two parameters: the forecast area quadrant with respect to the volcano and a factor related to the complexity of the meteorology. The forecast complexity factor was based on the degree of spread using NCEP ensemble output or using a HYSPLIT offset configuration. In general, the larger the spread of the ensemble or offset forecasts, the greater the complexity. The forecasts were sorted by complexity factor, and then classified by the quartile of the complexity. The volcanic ash forecast area reliability (VAFAR) was calculated for each forecast area quadrant and for each quartile of the complexity factor. VAFAR is the ratio of the number of acceptable forecasts to the total number of forecasts. Most VAFAR values were above 70%. VAFAR values for two of the seven volcanoes (Popocatepetl in Mexico and Tungurahua in Ecuador) tended to be lower than the others. In general, VAFAR decreased with increasing complexity of the meteorology. It should be noted that the VAFAR values reflect the reliability of the meteorological forecasts when compared to the same calculation using analysis data; the dispersion model itself was not evaluated.

scholarly journals Multi-level emulation of a volcanic ash transport and dispersion model to quantify sensitivity to uncertain parameters

2016 ◽  
Author(s):  
Natalie J. Harvey ◽  
Nathan Huntley ◽  
Helen Dacre ◽  
Michael Goldstein ◽  
David Thomson ◽  
...  
Keyword(s):  
Volcanic Ash ◽  
Dispersion Model ◽  
Model Development ◽  
Atmospheric Dispersion ◽  
Theoretical Research ◽  
Model Parameters ◽  
Formal Framework ◽  
Geographical Regions ◽  
Multi Level ◽  
Ash Transport

Abstract. Following the disruption to European airspace caused by the eruption of Eyjafjallajokull in 2010 there has been a move towards producing quantitative predictions of volcanic ash concentration using volcanic ash transport and dispersion simulators. However, there is no formal framework for determining the uncertainties on these predictions and performing many simulations using these complex models is computationally expensive. In this paper a Bayes linear emulation approach is applied to the Numerical Atmospheric-dispersion Modelling Environment (NAME) to better understand the influence of source and internal model parameters on the simulator output. Emulation is a statistical method for predicting the output of a computer simulator at new parameter choices without actually running the simulator. A multi-level emulation approach is applied to combine information from many evaluations of a computationally fast version of NAME with relatively few evaluations of a slower, more accurate, version. This approach is effective when it is not possible to run the accurate simulator many times and when there is also little prior knowledge about the influence of parameters. The approach is applied to the mean ash column loading in 75 geographical regions on 14 May 2010. Through this analysis it has been found that the parameters that contribute the most to the output uncertainty are initial plume rise height, mass eruption rate, free tropospheric turbulence levels and precipitation threshold for wet deposition. This information can be used to inform future model development and observational campaigns and routine monitoring. The analysis presented here suggests the need for further observational and theoretical research into parameterisation of atmospheric turbulence. Furthermore it can also be used to inform the most important parameter perturbations for a small operational ensemble of simulations. The use of an emulator also identifies the input and internal parameters that do not contribute significantly to simulator uncertainty. Finally, the analysis highlights that the fast, less accurate, version of NAME can provide useful information without needing the accurate version at all. This approach can easily be extended to other case studies, simulators or hazards.

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