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 (21) ◽  
pp. 10145-10159 ◽  
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 ◽  
Atmospheric Measurements ◽  
Position Errors ◽  
The Uk ◽  
Ash Cloud

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. The location and impact of the eruption led to a wealth of observations of the ash cloud were being obtained which can be used to assess modelling of the long range transport of ash in the troposphere. The UK FAAM (Facility for Airborne Atmospheric Measurements) BAe-146-301 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. In this study ash concentrations derived from the lidar 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 simulated ash clouds are compared to the lidar data to determine how well NAME simulates the horizontal and vertical structure of the ash clouds. Comparison between the ash concentrations derived from the lidar and those from NAME is used to define the fraction of ash emitted in the eruption that is transported over long distances compared to the total emission of tephra. In making these comparisons possible position errors in the simulated ash clouds are identified and accounted for. The ash layers seen by the lidar considered in this study 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, although the layers in the simulated ash clouds that are 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 obtained by assuming that the emission occurred at the top of the eruption plume, consistent with the observed structure of eruption plumes. However, early in the period when the intensity of the eruption was low, assuming that the emission of ash was uniform with height gives better guidance on the horizontal and vertical structure of the ash cloud. Comparison of the lidar concentrations with those from NAME show that 2–5% of the total mass erupted by the volcano remained in the ash cloud over the United Kingdom.

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.

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>

Using emissions derived from atmospheric observations to inform the reported UK inventory

2021 ◽  
Author(s):  
Alistair Manning ◽  
Alison Redington ◽  
Simon O'Doherty ◽  
Dickon Young ◽  
Dan Say ◽  
...  
Keyword(s):  
Best Practice ◽  
Dispersion Model ◽  
Regional Scale ◽  
Atmospheric Dispersion ◽  
Three Dimensional ◽  
Ghg Emissions ◽  
Atmospheric Observations ◽  
Emission Modelling ◽  
National Inventory Report ◽  
The Uk

<p align="justify">Verification of the nationally reported greenhouse gas (GHG) inventories using inverse modelling and atmospheric observations is considered to be best practice by the United Nations Framework Convention on Climate Change (UNFCCC). It allows for an independent assessment of the nationally reported GHG emissions using a comprehensively different approach to the inventory methods. Significant differences in the emissions estimated using the two approaches are a means of identifying areas worthy of further investigation.</p><p align="justify"> </p><p align="justify"><span>An inversion methodology called Inversion Technique for Emission Modelling (InTEM) has been developed that uses a non-negative least squares minimisation technique to determine the emission magnitude and distribution that most accurately reproduces the observations. By estimating the underlying </span><span><em>baseline</em></span><span> time series, atmospheric concentrations where the short-term impact of regional pollution has been removed, and by modelling where the air has passed over on route to the observation stations on a regional scale, estimates of UK emissions are made. </span>In this study we use an extensive network of observations with six stations across the UK and six more in neighbouring countries<span>. InTEM uses information from a</span> Lagrangian dispersion model NAME (Numerical Atmospheric dispersion Modelling Environment), driven by three-dimensional, modelled meteorology, to understand how the air mixes during transport from the emission sources to observation points. <span>The InTEM inversion results are submitted annually by the UK as part of their National Inventory Report to the UNFCCC. They are used within the UK inventory team to highlight areas for investigation and have led to significant improvements to the submitted UK inventory. The latest UK comparisons will be shown along with examples of how the inversion results have informed the inventory.</span></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.

scholarly journals Dimethylsulphide (DMS) emissions from the West Pacific Ocean: a potential marine source for the stratospheric sulphur layer

2012 ◽  
Vol 12 (11) ◽  
pp. 30543-30570
Author(s):  
C. A. Marandino ◽  
S. Tegtmeier ◽  
K. Krüger ◽  
C. Zindler ◽  
E. L. Atlas ◽  
...  
Keyword(s):  
Pacific Ocean ◽  
Transport Model ◽  
Atmospheric Transport ◽  
Dispersion Model ◽  
Transport Processes ◽  
Atmospheric Measurements ◽  
The West ◽  
West Pacific ◽  
West Pacific Ocean ◽  
The West Pacific Ocean

Abstract. Sea surface and atmospheric measurements of dimethylsulphide (DMS) were performed during the TransBrom cruise in the West Pacific Ocean between Japan and Australia in October 2009. Air-sea DMS fluxes were computed between 0 and 30 μmol m−2 d−1, which are in agreement with those computed by the current climatology, and peak emissions of marine DMS into the atmosphere were found during the occurrence of tropical storm systems. Atmospheric variability in DMS, however, did not follow that of the computed fluxes and was more related to atmospheric transport processes. The computed emissions were used as input fields for the Langrangian dispersion model FLEXPART, which was set up with actual meteorological fields from ERA-interim data and different chemical lifetimes of DMS. A comparison with aircraft in-situ data from the adjacent HIPPO2 campaign revealed an overall good agreement between modeled versus observed DMS profiles over the tropical West Pacific ocean. Based on observed DMS emissions and the meteorological fields over the cruise track region, the model projected that up to 30 g S per month in the form of DMS can be transported above 17 km in this region. This surprisingly large DMS entrainment into the stratosphere is disproportionate to the regional extent of the cruise track area and mainly due to the high convective activity in this region as simulated by the transport model. Thus, we conclude that the considerably larger area of the tropical West Pacific Ocean can be an important source of sulphur to the stratospheric persistent sulphur layer, which has not been considered as yet.

scholarly journals Validation of dispersion model designated for the coke production industry

2021 ◽  
Vol 193 (4) ◽  
Author(s):  
Jacek Żeliński ◽  
Dorota Kaleta ◽  
Jolanta Telenga-Kopyczyńska
Keyword(s):  
Dispersion Model ◽  
Mechanical Energy ◽  
Atmospheric Dispersion ◽  
Coke Production ◽  
General Purpose ◽  
Assessment Model ◽  
Factors Affecting ◽  
Air Quality Assessment ◽  
Almost All ◽  
Special Factors

AbstractIn the practical application of air protection, diverse dispersion models are used to calculate the concentration of contaminants in the air. They usually involve a universal character, which typically makes them sufficient for use in almost all conditions, with the exception of those clearly deviating from the average. This is especially relevant to industrial objects of large areas, introducing a great amount of heat and mechanical energy into the air. For such cases, the standard models can be extended in order to adapt them to the unusual local diffusion conditions. Next, to be applied in practice, they must have undergone validation to document the correctness of its operation. The article describes the process of validation of the air quality assessment model containing extended procedures to incorporate special factors affecting atmospheric dispersion in a coke industry. The set of statistical indicators, obtained on the basis of SF6 field experiment, evaluate its performance. The short comparison with some popular models of general-purpose character and an assessment of the suitability of individual indicators for validation purposes are also presented.

scholarly journals Estimates of sub-national methane emissions from inversion modelling

2018 ◽  
Author(s):  
Sarah Connors ◽  
Alistair J. Manning ◽  
Andrew D. Robinson ◽  
Stuart N. Riddick ◽  
Grant L. Forster ◽  
...  
Keyword(s):  
Spatial Resolution ◽  
High Spatial Resolution ◽  
Dispersion Model ◽  
Methane Emissions ◽  
Particle Dispersion ◽  
Eastern Region ◽  
Atmospheric Methane ◽  
Atmospheric Measurements ◽  
East Anglia ◽  
The Uk

Abstract. Methane is a strong contributor to global climate change, yet our current understanding and quantification of its sources and their variability is incomplete. There is a growing need for comparisons between emission estimates produced using bottom-up inventory approaches and top-down inversion techniques based on atmospheric measurements, especially at higher spatial resolutions. To meet this need, this study presents using an inversion approach based on the Inversion Technique for Emissions Modelling (InTEM) framework and measurements from four sites in East Anglia, United Kingdom. Atmospheric methane concentrations were recorded at 1–2 minute time-steps at each location within the region of interest. These observations, coupled with the UK Met Office's Lagrangian particle dispersion model, NAME (Numerical Atmospheric dispersion Modelling Environment), were used within InTEM2014 to produce methane emission estimates for a 1-year period (June 2013–May 2014) in this eastern region of the UK (~ 100 × 150 km) at high spatial resolution (up to 4 × 4 km). InTEM2014 was able to produce realistic emissions estimates for East Anglia, and highlighted potential areas of difference from the UK National Atmospheric Emissions Inventory (NAEI). As this study was part of the UK Greenhouse gAs Uk and Global Emissions (GAUGE) project, observations were included within a national inversion using all eleven measurement sites across the UK to directly compare emission estimates for the East Anglia Region. Results show similar methane estimates for the East Anglia region. Methane emissions from Norfolk and Suffolk show good agreement with the estimates in NAEI, with differences of ~ 5 %. Larger differences are found for Cambridgeshire where our estimate is 22.5 % lower than that of NAEI. The addition of the EA sites within the national inversion system enabled finer spatial resolution and a decrease in the associated uncertainty for that area. Further development of our approach to include a more robust analysis of the methane concentration in the air entering this region and the uncertainty associated with the resulting emissions would strengthen this inverse method. Nonetheless, our results show there is value in high spatial resolution measurement networks and the resulting inversion emission estimates.

scholarly journals Do atmospheric events explain the arrival of an invasive ladybird (Harmonia axyridis) in the UK?

2019 ◽  
Author(s):  
Pilvi Siljamo ◽  
Kate Ashbrook ◽  
Richard F. Comont ◽  
Carsten Ambelas Skjøth
Keyword(s):  
Invasive Species ◽  
Harmonia Axyridis ◽  
Dispersion Model ◽  
Atmospheric Dispersion ◽  
Early Years ◽  
Control Measures ◽  
Substantial Evidence ◽  
Natural Range ◽  
Atmospheric Dispersion Model ◽  
The Uk

AbstractSpecies introduced outside their natural range threaten global biodiversity and despite greater awareness of invasive species risks at ports and airports, control measures in place only concern anthropogenic routes of dispersal. Here, we use the Harlequin ladybird, Harmonia axyridis, an invasive species which first arrived in the UK from continental Europe in 2003, to test whether records from 2004 and 2005 were associated with atmospheric events. We used the atmospheric dispersion model SILAM to model the movement of this species from known distributions in continental Europe and tested whether the predicted atmospheric events were associated with the frequency of ladybird records in the UK. We show that the distribution of this species in the early years of its arrival does not provide substantial evidence for a purely anthropogenic introduction and show instead that atmospheric events can better explain this invasion event. Our results suggest that air flows which may assist dispersal over the English Channel are relatively frequent; ranging from once a week from Belgium and the Netherlands to 1-2 times a week from France over our study period. Given the frequency of these events, we demonstrate that atmospheric-assisted dispersal is a viable route for flying species to cross natural barriers.

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>

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