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.

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.

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.

The aging process of ambient black carbon and brown carbon from biomass burning emission during MOYA-2017 aircraft campaign

2020 ◽  
Author(s):  
HuiHui Wu ◽  
Jonathan Taylor ◽  
Justin Langridge ◽  
Chenjie Yu ◽  
Paul Williams ◽  
...  
Keyword(s):  
Black Carbon ◽  
Biomass Burning ◽  
Aging Process ◽  
Atmospheric Dispersion ◽  
Chemical Properties ◽  
Carbonaceous Aerosol ◽  
Brown Carbon ◽  
Research Aircraft ◽  
Flaming Combustion ◽  
The Uk

<p>The biomass burning over West Africa during the dry season (December – February) is a globally significant source of trace gases and carbonaceous aerosol particles in the atmosphere. The MOYA-2017 (Methane Observations Yearly Assessments 2017) campaign were conducted using the UK FAAM Bae-146 airborne research aircraft, to investigate biomass burning emissions in this region. Research sorties were flown out of Senegal, with some flights directly over terrestrial fires and others sampling transported smokes over the Atlantic ocean.</p><p>The aircraft was equipped with a variety of aerosol-related instruments to measure submicron aerosol chemical properties (aerosol mass spectrometer, AMS and single-particle soot photometer, SP2) and absorption at different wavelengths (Photoacoustic spectrometer, PAS, measure at 405, 514 and 658 nm). In this study, we focus on the aging process of ambient black carbon (BC) and brown carbon (BrC) from biomass burning, in time scale from (<0.5) h to (9 – 15) h. The transport age of smokes was estimated using Met Office's Numerical Atmospheric-dispersion Modelling Environment (NAME).</p><p>The sampled smokes during MOYA-2017 were controlled by flaming-phase combustion. The enhancement ratios of BC with respect to CO ranged from 14 to 26 (ng m<sup>–3</sup> / ppbv) at sources. Our measurements show that count and mass median diameters of BC core size were relatively stable, which were around 106 and 190 nm respectively. Average BC coating thickness increased from (1.16 ± 0.03) to (1.71 ± 0.06) after approximately half-day transport. Average absorption angstrom exponents (AAE<sub>405-658</sub>) increased from (1.1 ± 0.1) to (1.8 ± 0.3), suggesting that BrC contributed little in the very freshly emitted aerosols (<0.5 h) and were formed during aging process. In order to investigate the importance of BrC in this area, we also attributed the measured aerosol absorption into BC and BrC separately. By linking AAE<sub>405-658</sub> with organic (OA) composition measured by the AMS, we found that the increasing AAE<sub>405-658</sub> is positively correlated with O/C ratio (oxygenation) of the OA. These data indicate that BrC in smokes controlled by flaming combustion is likely to be from the condensation of semi-volatile OA during cooling stage of smokes, and from the aged primary OA or secondary OA formation.</p>

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 Perturbation of the European free troposphere aerosol by North American forest fire plumes during the ICARTT-ITOP Experiment in summer 2004

2007 ◽  
Vol 7 (2) ◽  
pp. 4925-4979 ◽  
Author(s):  
A. Petzold ◽  
B. Weinzierl ◽  
H. Huntrieser ◽  
A. Stohl ◽  
E. Real ◽  
...  
Keyword(s):  
Central Europe ◽  
Forest Fire ◽  
Forest Fires ◽  
General Circulation ◽  
Atmospheric Transport ◽  
Dispersion Model ◽  
Circulation Model ◽  
Distribution Width ◽  
Fire Plumes ◽  
Research Aircraft

Abstract. During the ICARTT-ITOP Experiment in summer 2004 plumes from large wildfires in North America were transported to Central Europe at 3–8 km altitude above sea level (a.s.l.). These plumes were studied with the DLR (Deutsches Zentrum fuer Luft- und Raumfahrt) research aircraft Falcon which was equipped with an extensive set of in situ aerosol and trace gas instruments. Analyses by the Lagrangian dispersion model FLEXPART provided source regions, transport times and horizontal extent of the fire plumes. Results from the general circulation model ECHAM/MADE and data from previous aerosol studies over Central Europe provided reference vertical profiles of black carbon (BC) mass concentrations for year 2000 conditions with forest fire activities below the long-term average. Smoke plume observations yielded a BC mass fraction of total aerosol mass with respect to PM2.5 of 3–10%. The ratio of BC mass to excess CO was 3–7.5 mg BC (g CO)−1. Even after up to 10 days of atmospheric transport, both characteristic properties were of the same order as for fresh emissions. This suggests an efficient lifting of BC from forest fires to higher altitudes with only minor scavenging removal of particulate matter. Maximum aerosol absorption coefficient values were 7–8×10–6m−1 which is about two orders of magnitude above the average European free tropospheric background value. Forest fire aerosol size distributions were characterised by a strong internally mixed accumulation mode centred at modal diameters of 0.25–0.30 μm with an average distribution width of 1.30. Nucleation and small Aitken mode particles were almost completely depleted. Even after more than one week of atmospheric transport, no steady state of the size distribution was observed.

scholarly journals Perturbation of the European free troposphere aerosol by North American forest fire plumes during the ICARTT-ITOP experiment in summer 2004

2007 ◽  
Vol 7 (19) ◽  
pp. 5105-5127 ◽  
Author(s):  
A. Petzold ◽  
B. Weinzierl ◽  
H. Huntrieser ◽  
A. Stohl ◽  
E. Real ◽  
...  
Keyword(s):  
Central Europe ◽  
Forest Fire ◽  
Forest Fires ◽  
General Circulation ◽  
Atmospheric Transport ◽  
Dispersion Model ◽  
Circulation Model ◽  
Distribution Width ◽  
Fire Plumes ◽  
Research Aircraft

Abstract. During the ICARTT-ITOP Experiment in summer 2004 plumes from large wildfires in North America were transported to Central Europe at 3–8 km altitude above sea level (a.s.l.). These plumes were studied with the DLR (Deutsches Zentrum fuer Luft- und Raumfahrt) research aircraft Falcon which was equipped with an extensive set of in situ aerosol and trace gas instruments. Analyses by the Lagrangian dispersion model FLEXPART provided source regions, transport times and horizontal extent of the fire plumes. Results from the general circulation model ECHAM/MADE and data from previous aerosol studies over Central Europe provided reference vertical profiles of black carbon (BC) mass concentrations for year 2000 conditions with forest fire activities below the long-term average. Smoke plume observations yielded a BC mass fraction of total aerosol mass with respect to PM 2.5 of 2–8%. The ratio of BC mass to excess CO was 3–7.5 mg BC (g CO)−1. Even after up to 10 days of atmospheric transport, both characteristic properties were of the same order as for fresh emissions. This suggests an efficient lifting of BC from forest fires to higher altitudes with only minor scavenging removal of particulate matter. Maximum aerosol absorption coefficient values were 7–8 Mm−1 which is about two orders of magnitude above the average European free tropospheric background value. Forest fire aerosol size distributions were characterised by a strong internally mixed accumulation mode centred at modal diameters of 0.25–0.30 µm with an average distribution width of 1.30. Nucleation and small Aitken mode particles were almost completely depleted.

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.

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