Exploring forecast variability during volcanic ash cloud events 

2021 ◽  
Author(s):  
Frances Beckett ◽  
Ralph Burton ◽  
Fabio Dioguardi ◽  
Claire Witham ◽  
John Stevenson ◽  
...  
Keyword(s):  
Real Time ◽  
Volcanic Ash ◽  
Atmospheric Transport ◽  
Dispersion Model ◽  
Meteorological Data ◽  
Atmospheric Dispersion ◽  
Dispersion Models ◽  
British Geological Survey ◽  
Volcanic Ash Cloud ◽  
Ash Cloud

<p>Atmospheric transport and dispersion models are used by Volcanic Ash Advisory Centers (VAACs) to provide timely information on volcanic ash clouds to mitigate the risk of aircraft encounters. Inaccuracies in dispersion model forecasts can occur due to the uncertainties associated with source terms, meteorological data and model parametrizations. Real-time validation of model forecasts against observations is therefore essential to ensure their reliability. Forecasts can also benefit from comparison to model output from other groups; through understanding how different modelling approaches, variations in model setups, model physics, and driving meteorological data, impact the predicted extent and concentration of ash. The Met Office, the National Centre for Atmospheric Science (NCAS) and the British Geological Survey (BGS) are working together to consider how we might compare data (both qualitatively and quantitatively) from the atmospheric dispersion models NAME, FALL3D and HYSPLIT, using meteorological data from the Met Office Unified Model and the NOAA Global Forecast System (providing an effective multi-model ensemble). Results from the model inter-comparison will be used to provide advice to the London VAAC to aid forecasting decisions in near real time during a volcanic ash cloud event. In order to facilitate this comparison, we developed a Python package (ash-model-plotting) to read outputs from the different models into a consistent structure. Here we present our framework for generating comparable plots across the different partners, with a focus on total column mass loading products. These are directly comparable to satellite data retrievals and therefore important for model validation. We also present outcomes from a recent modelling exercise and discuss next steps for further improving our forecast validation.</p>

Dispersion Modelling at the London VAAC 10 Years after the Eyjafjallajökull Ash Cloud

2020 ◽  
Author(s):  
Frances Beckett ◽  
Claire Witham ◽  
Susan Leadbetter ◽  
Ric Crocker ◽  
Helen Webster ◽  
...  
Keyword(s):  
Volcanic Ash ◽  
Dispersion Model ◽  
Meteorological Data ◽  
Weather Prediction ◽  
Source Parameters ◽  
Atmospheric Dispersion ◽  
Lessons Learned ◽  
Volcanic Ash Cloud ◽  
Atmospheric Dispersion Models ◽  
Ash Cloud

<p>It has been 10 years since the ash cloud from the eruption of Eyjafjallajökull caused chaos to air traffic across Europe. Although disruptive, the longevity of the event afforded the scientific community the opportunity to observe and extensively study the transport and dispersion of a volcanic ash cloud. Here we present the development of the NAME atmospheric dispersion model and modifications to its application in the London VAAC forecasting system since 2010, based on the lessons learned.</p><p>Our ability to represent both the vertical and horizontal transport of ash in the atmosphere and its removal have been improved through the introduction of new schemes to represent the sedimentation and wet deposition of volcanic ash, and updated schemes to represent deep atmospheric convection and parameterizations for plume spread due to unresolved mesoscale motions. A good simulation of the transport and dispersion of a volcanic ash cloud requires an accurate representation of the source and we have introduced more sophisticated approaches to representing the eruption source parameters, and their uncertainties, used to initialize NAME. Further, atmospheric dispersion models are driven by 3-dimensional meteorological data from Numerical Weather Prediction (NWP) models and the Met Office’s upper air wind field data is now more accurate than it was in 2010. These developments have resulted in a more robust modelling system at the London VAAC, ready to provide forecasts and guidance during the next volcanic ash event affecting their region.</p>

scholarly journals Atmospheric Dispersion Modelling at the London VAAC: A Review of Developments since the 2010 Eyjafjallajökull Volcano Ash Cloud

Atmosphere ◽  
2020 ◽  
Vol 11 (4) ◽  
pp. 352 ◽  
Author(s):  
Frances M. Beckett ◽  
Claire S. Witham ◽  
Susan J. Leadbetter ◽  
Ric Crocker ◽  
Helen N. Webster ◽  
...  
Keyword(s):  
Volcanic Ash ◽  
Dispersion Model ◽  
Source Parameters ◽  
Atmospheric Dispersion ◽  
Lessons Learned ◽  
Dispersion Modelling ◽  
Atmospheric Dispersion Modelling ◽  
Volcanic Ash Cloud ◽  
Atmospheric Dispersion Model ◽  
Ash Cloud

It has been 10 years since the ash cloud from the eruption of Eyjafjallajökull caused unprecedented disruption to air traffic across Europe. During this event, the London Volcanic Ash Advisory Centre (VAAC) provided advice and guidance on the expected location of volcanic ash in the atmosphere using observations and the atmospheric dispersion model NAME (Numerical Atmospheric-Dispersion Modelling Environment). Rapid changes in regulatory response and procedures during the eruption introduced the requirement to also provide forecasts of ash concentrations, representing a step-change in the level of interrogation of the dispersion model output. Although disruptive, the longevity of the event afforded the scientific community the opportunity to observe and extensively study the transport and dispersion of a volcanic ash cloud. We present the development of the NAME atmospheric dispersion model and modifications to its application in the London VAAC forecasting system since 2010, based on the lessons learned. Our ability to represent both the vertical and horizontal transport of ash in the atmosphere and its removal have been improved through the introduction of new schemes to represent the sedimentation and wet deposition of volcanic ash, and updated schemes to represent deep moist atmospheric convection and parametrizations for plume spread due to unresolved mesoscale motions. A good simulation of the transport and dispersion of a volcanic ash cloud requires an accurate representation of the source and we have introduced more sophisticated approaches to representing the eruption source parameters, and their uncertainties, used to initialize NAME. Finally, upper air wind field data used by the dispersion model is now more accurate than it was in 2010. These developments have resulted in a more robust modelling system at the London VAAC, ready to provide forecasts and guidance during the next volcanic ash event.

Near-real-time volcanic ash cloud detection: Experiences from the Alaska Volcano Observatory

2009 ◽  
Vol 186 (1-2) ◽  
pp. 79-90 ◽  
Author(s):  
P.W. Webley ◽  
J. Dehn ◽  
J. Lovick ◽  
K.G. Dean ◽  
J.E. Bailey ◽  
...  
Keyword(s):  
Real Time ◽  
Volcanic Ash ◽  
Cloud Detection ◽  
Volcano Observatory ◽  
Volcanic Ash Cloud ◽  
Ash Cloud

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>

Radionuclide atmospheric transport after the forest fires in the Chernobyl Exclusion zone in 2015-2018: An impact of the source term parameterization and input meteorological data on modeling results

2020 ◽  
Author(s):  
Mykola Talerko ◽  
Ivan Kovalets ◽  
Shigekazu Hirao ◽  
Mark Zheleznyak ◽  
Yuriy Kyrylenko ◽  
...  
Keyword(s):  
Real Time ◽  
Forest Fires ◽  
Source Term ◽  
Atmospheric Transport ◽  
Meteorological Data ◽  
Atmospheric Dispersion ◽  
Lagrangian Model ◽  
Wildland Fires ◽  
Exclusion Zone ◽  
The Impact

&lt;p&gt;The highly contaminated Chernobyl exclusion zone (ChEZ) still remains a potential source of the additional atmosphere radioactive contamination due to forest fires there. The possible radionuclide transport outside the ChEZ in the direction of populated regions (including Kyiv, 115 km from the ChEZ borders) and its consequences for people health is a topic of a constant public concern in Ukraine and neighboring countries. The problem of additional radiation exposure of fire-fighters and other personnel within the ChEZ during forest fires is actual too. The reliable models of radionuclide rising and following atmospheric transport, which should be integrated with data of stationary and mobile radiological monitoring, are necessary for real-time forecast and assessment of consequences of wildland fires.&lt;/p&gt;&lt;p&gt;Results of intercomparison of models developed within the set of the national and international projects are presented, including: i) the point source term model of Atmospheric Dispersion Module (ADM) of the real -time online decision support system for offsite nuclear emergency &amp;#8211; RODOS, which development was funded by EU; ii) the specialized new tool for modeling radionuclide dispersion from the polygons of the fired areas using the Lagrangian model LASAT incorporated into RODOS system; iii) the Lagrangian-Eulerian atmospheric dispersion model LEDI using a volume source term and including a module for calculation of&amp;#160; parameters of a convective plume&amp;#160; formed over a fire area; iv) the Lagrangian model of Fukushima University. All atmospheric transport models use the results of the numerical weather forecast model WRF as the input meteorological information.&lt;/p&gt;&lt;p&gt;The models evaluation was carried out using the measurement data during large wildland fires occurred in ChEZ in 2015 and June 2018, including the &lt;sup&gt;137&lt;/sup&gt;Cs and &lt;sup&gt;90&lt;/sup&gt;Sr volume activity measured with the monitoring network within the Zone and results due to special measurements with a mobile radiological laboratory outside it.&lt;/p&gt;&lt;p&gt;The sensitivity of atmospheric transport modeling results was estimated to: 1) internal parameterization of different models, first of all, parameterization of the value of the deposited radionuclide fraction re-entering into the atmosphere during forest fires, 2) different parameterization of the source term formed due to the forest fire; 3) quality of input meteorological information, including the space and time step of the used WRF model grid, and the impact of chosen parameterization of some WRF modules (e.g. the atmospheric boundary layer module) on the atmospheric transport model results. Additionally, results of forest fires consequences modeling was compared which were obtained with different sets of input meteorological data: the WRF forecast of metrological fields (on-line calculations) and the similar WRF calculations on the base of objective analysis results.&lt;/p&gt;

scholarly journals The Development of Volcanic Ash Cloud Layers over Hours to Days Due to Atmospheric Turbulence Layering

Atmosphere ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 285
Author(s):  
Marcus Bursik ◽  
Qingyuan Yang ◽  
Adele Bear-Crozier ◽  
Michael Pavolonis ◽  
Andrew Tupper
Keyword(s):  
Atmospheric Turbulence ◽  
Layered Structure ◽  
Turbulent Diffusion ◽  
Volcanic Ash ◽  
Vertical Motion ◽  
Aviation Safety ◽  
Dispersion Models ◽  
Free Atmosphere ◽  
Volcanic Ash Cloud ◽  
Ash Cloud

Volcanic ash clouds often become multilayered and thin with distance from the vent. We explore one mechanism for the development of this layered structure. We review data on the characteristics of turbulence layering in the free atmosphere, as well as examples of observations of layered clouds both near-vent and distally. We then explore dispersion models that explicitly use the observed layered structure of atmospheric turbulence. The results suggest that the alternation of turbulent and quiescent atmospheric layers provides one mechanism for the development of multilayered ash clouds by modulating vertical particle motion. The largest particles, generally μ>100 μm, are little affected by turbulence. For particles in which both settling and turbulent diffusion are important to vertical motion, mostly in the range of 10–100 μμm, the greater turbulence intensity and more rapid turbulent diffusion in some layers causes these particles to spend greater time in the more turbulent layers, leading to a layering of concentration. The results may have important implications for ash cloud forecasting and aviation safety.

scholarly journals Horizontal and vertical structure of the Eyjafjallajökull ash cloud over the UK: a comparison of airborne lidar observations and simulations

2012 ◽  
Vol 12 (4) ◽  
pp. 9125-9159 ◽  
Author(s):  
A. L. M. Grant ◽  
H. F. Dacre ◽  
D. J. Thomson ◽  
F. Marenco
Keyword(s):  
Vertical Structure ◽  
Atmospheric Transport ◽  
Dispersion Model ◽  
Atmospheric Dispersion ◽  
General Purpose ◽  
Airborne Lidar ◽  
Research Aircraft ◽  
The Uk ◽  
Ash Cloud ◽  
Eruption Plume

Abstract. During April and May 2010 the ash cloud from the eruption of the Icelandic volcano Eyjafjallajökull caused widespread disruption to aviation over northern Europe. Because of the location and impact of the eruption a wealth of observations of the ash cloud were obtained and can be used to assess modelling of the long range transport of ash in the troposphere. The UK's BAe-146-301 Atmospheric Research Aircraft overflew the ash cloud on a number of days during May. The aircraft carries a downward looking lidar which detected the ash layer through the backscatter of the laser light. The ash concentrations are estimated from lidar extinction coefficients and in situ measurements of the ash particle size distributions. In this study these estimates of the ash concentrations are compared with simulations of the ash cloud made with NAME (Numerical Atmospheric-dispersion Modelling Environment), a general purpose atmospheric transport and dispersion model. The ash layers seen by the lidar were thin, with typical depths of 550–750 m. The vertical structure of the ash cloud simulated by NAME was generally consistent with the observed ash layers. The layers in the simulated ash clouds that could be identified with observed ash layers are about twice the depth of the observed layers. The structure of the simulated ash clouds were sensitive to the profile of ash emissions that was assumed. In terms of horizontal and vertical structure the best results were mainly obtained by assuming that the emission occurred at the top of the eruption plume, consistent with the observed structure of eruption plumes. However, when the height of the eruption plume was variable and the eruption was weak, then assuming that the emission of ash was uniform with height gave better guidance on the horizontal and vertical structure of the ash cloud. Comparison between the column masses in the simulated and observed ash layers suggests that about 3% of the total mass erupted by the volcano remained in the ash cloud over the United Kingdom. The problems with the interpretation of this estimate of the distal fine ash fraction are discussed.

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