Hugues Brenot (1), Nicolas Theys (1), Lieven Clarisse (2), Daniel Hurtmans (3), Pascal Hedelt (3)... more Hugues Brenot (1), Nicolas Theys (1), Lieven Clarisse (2), Daniel Hurtmans (3), Pascal Hedelt (3), Margarita Vasquez (3), Lucia Mona (4), Gelsomina Pappalardo (4), Simona Scollo (5), Mauro Coltelli (5), Tuomas Peltonen (6), Juhani Lahtinen (6), Marcus Hirtl (7), Delia Arnold (7), Timo Virtanen (8), Gerrit de Leeuw (8), Guðrún NÃna Petersen (9), Sara Barsotti (9), Matthieu Plu (10), Gerhard Wotawa (7), and the EUNADICS-AV WP5 team
The regional weather forecast model ALADIN of the Central Institute for Meteorology and Geodynami... more The regional weather forecast model ALADIN of the Central Institute for Meteorology and Geodynamics (ZAMG) is used in combination with the chemical transport model CAMx (www.camx.com) to conduct forecasts of gaseous and particulate air pollution over Europe. The forecasts which are done in cooperation with the University of Natural Resources and Applied Life Sciences in Vienna (BOKU) are supported by the regional governments since 2005 with the main interest on the prediction of tropospheric ozone.
. The purpose of the EUNADICS prototype Early Warning System (EWS) is to proceed the combined use... more . The purpose of the EUNADICS prototype Early Warning System (EWS) is to proceed the combined use of harmonise data products from satellite, ground-based and in situ instruments to produce alerts of airborne hazard (volcanic, dust, smoke and radionuclide clouds), satisfying the requirement of ATM stakeholders (www.eunadics.eu). The alert products developed by EUNADICS EWS (i.e. NRT observations, email notifications and NetCDF Alert data Products, called NCAP) have shown shows the significant interest in using selective detection of natural airborne hazards from polar orbiting satellite. The combination of several sensors inside a single global system demonstrates the advantage of using a triggered approach to obtain selective detection from observations, which cannot initially discriminate the different aerosol types. Satellite products from hyperspectral UV and IR sensors (e.g. TROPOMI, IASI) and broadband geostationary imager (SEVIRI), and retrievals from ground-based networks (e.g. EARLINET, E-PROFILE and the regional network from volcanic observatories), are combined by our system to create tailored alert products (e.g. selective ash detection, SO2 column and plume height, dust cloud and smoke from wildfires). A total of 23 different alert products are implemented, using 1 geostationary and 12 polar orbiting satellite platforms, 3 external existing service, 2 EU and 2 regional ground-based networks. This allows the identification and the traceability of extreme events. EUNADICS EWS has also shown the interest to proceed a future relay of radiological data (gamma dose rate and radionuclides concentrations in ground-level air) in case of nuclear accident, highlighting the capability of operating early warnings with the use of homogenised dataset. For the four types of airborne hazard, EUNADICS EWS has demonstrated its capability to provide NRT alert data products to trigger data assimilation and dispersion modelling providing forecasts, and inverse modelling for source term estimate. All our alert data products (NCAP files) are not publicly disseminated. Access to our alert products is currently restricted to key users (i.e. Volcanic Ash Advisory Centres, National Meteorological Services, World Meteorological Organization, governments, volcanic observatories and research collaborators), as these are considered pre-decisional products. On the other hand, thanks to the SACS/EUNADICS web interface (https://sacs.aeronomie.be), the main part of the satellite observations used by EUNADICS EWS, are shown in NRT, with public email notification of volcanic emission and delivery of tailored images and NCAP files. All the ATM stakeholders (e.g. VAACs, NMSs, WMOs, Airlines and Pilots) can access and benefit of these alert products through this free channel.
This paper demonstrates the environmental impacts of the wildfires occurring at the beginning of ... more This paper demonstrates the environmental impacts of the wildfires occurring at the beginning of April 2020 in and around the highly contaminated Chernobyl Exclusion Zone (CEZ). Due to the critical fire location, concerns arose about secondary radioactive contamination potentially spreading over Europe. The impact of the fire was assessed through the evaluation of fire plume dispersion and re-suspension of the radionuclide Cs-137, whereas, to assess the smoke plume effect, a WRF-Chem simulation was performed and compared to Tropospheric Monitoring Instrument (TROPOMI) satellite columns. The results show agreement of the simulated black carbon and carbon monoxide plumes with the plumes as observed by TROPOMI, where pollutants were also transported to Belarus. From an air quality and health perspective, the wildfires caused extremely bad air quality over Kiev, where the WRF-Chem model simulated mean values of PM2.5 up to 300 µg/m3 (during the first fire outbreak) over CEZ. The re-susp...
. High quality volcanic ash forecasts are crucial to minimize the economic impact of volcanic haz... more . High quality volcanic ash forecasts are crucial to minimize the economic impact of volcanic hazards on air traffic. Decision-making is usually based on numerical dispersion modeling with only one model realization. Given the inherent uncertainty of such approach, a multi-model multi-source term ensemble has been designed and evaluated for the Eyjafjallajökull eruption in May 2010. Its use for air traffic management is discussed. Two multi-model ensembles were built: the first is based on the output of four dispersion models and their own implementation of ash ejection. All a priori model source terms were constrained by observational evidence of the volcanic ash cloud top as a function of time. The second ensemble is based on the same four dispersion models, which were run with three additional source terms: (i) a source term obtained with background modeling constrained with satellite data (a posteriori source term), (ii) its lower bound estimate, and (iii) its upper bound estimate. The a priori ensemble gives valuable information about the probability of ash dispersion during the early phase of the eruption, when observational evidence is limited. However, its evaluation with observational data reveals lower quality compared to the second ensemble. While the second ensemble ash column load and ash horizontal location compare well to satellite observations, 3D ash concentrations are negatively biased. This might be caused by the vertical distribution of ash, which is too much diluted in all model runs, probably due to defaults in the a posteriori source term and vertical transport and/or diffusion processes in all models. Relevant products for the air traffic management are horizontal maps of ash concentration quantiles (median, 75 %, 99 %) at a fine-resolved flight level grid. These maps can be used for route optimization in the areas where ash does not pose a direct and urgent threat to aviation. Cost-optimized consideration of such hazards will result in much less impact on flight cancellations, reroutings, and traffic flow congestions.
Volcanic eruptions may generate volcanic ash and sulfur dioxide (SO 2) plumes with strong tempora... more Volcanic eruptions may generate volcanic ash and sulfur dioxide (SO 2) plumes with strong temporal and vertical variations. When simulating these changing volcanic plumes and the afar dispersion of emissions, it is important to provide the best available information on the temporal and vertical emission distribution during the eruption. The volcanic emission preprocessor of the chemical transport model WRF-Chem has been extended to allow the integration of detailed temporally and vertically resolved input data from volcanic eruptions. The new emission preprocessor is tested and evaluated for the eruption of the Grimsvötn volcano in Iceland 2011. The initial ash plumes of the Grimsvötn eruption differed significantly from the SO 2 plumes, posing challenges to simulate plume dynamics within existing modelling environments: observations of the Grimsvötn plumes revealed strong vertical wind shear that led to different transport directions of the respective ash and SO 2 clouds. Three source terms, each of them based on different assumptions and observational data, are applied in the model simulations. The emission scenarios range from (i) a simple approach, which assumes constant emission fluxes and a predefined vertical emission profile, to (ii) a more complex approach, which integrates temporarily varying observed plume-top heights and estimated emissions based on them, to (iii) the most complex method that calculates temporal and vertical variability of the emission fluxes based on satellite observations and inversion techniques. Comparisons between model results and independent observations from satellites, lidar, and surface air quality measurements reveal the best performance of the most complex source term.
<p>ZAMG runs two models for air-quality forecasts operationally: ALARO-CAMx and WRF... more <p>ZAMG runs two models for air-quality forecasts operationally: ALARO-CAMx and WRF-Chem.</p> <p>ALARO-CAMx is a combination of the meteorological model ALARO and the photochemical dispersion model CAMx and is operated at ZAMG since 2005. The emphasis of this modeling system is to predict ozone peaks in the north-eastern Austrian flatlands. The outer model grid covers Central Europe with a resolution of 13.8 km, the inner domain is centered over Austria with a resolution of 4.6 km. The model runs twice per day for a period of 48 hours.</p> <p>The second operational air quality model at ZAMG is the on-line coupled model WRF-Chem. Meteorology is simulated simultaneously with the emission, turbulent mixing, transport, transformation as well as the fate of trace gases and aerosols. Two modeling domains are used for these simulations. The mother domain covers Europe with a resolution of 12 km. The inner, nested domain covers the Alpine region with a horizontal resolution of 4 km. The model runs two times per day for a period of 72 hours and is initialized with ECMWF forecasts.</p> <p>The evaluation of both models is conducted for the period from January to September 2019 with the focus on ozone. The summer 2019 was the 2<sup>nd</sup> warmest summer since the beginning of the meteorological measurements in Austria more than 200 years ago. Although this summer had favorable conditions for Ozone production (sunny and hot weather, less rain), only a few air quality stations in Eastern Austria have measured exceedances of the ozone information threshold (180 µg/m³) on overall 5 days. The measurements of the air-quality stations are compared with the area forecasts for every province of Austria. Besides the evaluation, air quality forecasts of ALARO-CAMx and WRF-Chem are compared.</p>
Volcanic eruptions eject ash and gases into the atmosphere that can contribute to significant haz... more 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.
Natural Hazards and Earth System Sciences Discussions
Volcanic eruptions comprise one of the most important airborne hazards for aviation. Although sig... more Volcanic eruptions comprise one of the most important airborne hazards for aviation. Although significant events are rare, they have a very high impact. The current state of tools and abilities to mitigate aviation hazards associated with an assumed volcanic cloud was tested within an international demonstration exercise. Experts in the field assembled at the Schwarzenberg barracks in Salzburg, Austria, in order to simulate the sequence of procedures for the volcanic case scenario of an artificial eruption of Etna volcano in Italy. The scope of the exercise ranged from the detection of the assumed event to the issuance of early warnings. Volcanic emission concentration charts were generated applying modern ensemble techniques. The exercise products provided an important basis for decision making for aviation traffic management during a volcanic eruption crisis. By integrating the available wealth of data, observations and modelling results directly into a widely used flight planning software, it was demonstrated that route optimization measures could be implemented effectively. With timely and rather precise warnings available, the new tools and processes tested during the exercise demonstrated vividly
Atmospheric aerosols modify the radiative budget of the Earth due to their optical, microphysical... more Atmospheric aerosols modify the radiative budget of the Earth due to their optical, microphysical and chemical properties, and are considered one of the most uncertain forcing agents. In order to characterise the uncertainties associated with satellite and modelling approaches to represent aerosol optical properties, their representation by different remote sensing sensors and regional online coupled chemistry-climate models over Europe is evaluated. This work also characterises whether the inclusion of aerosol-radiation (ARI) or aerosol-cloud interactions (ACI) helps improve the skills of modelling outputs. <br><br> Two case studies were selected within the EuMetChem COST Action ES1004 framework, when important aerosol episodes in 2010 all over Europe took place: a Russian wildfire episode and a Saharan desert dust outbreak that covered most of Mediterranean Sea. The model data came from different regional air quality-climate simulations performed by working group 2 of ...
Atmospheric Chemistry and Physics Discussions, 2017
The climate effect of atmospheric aerosols is associated to their influence on the radiative budg... more The climate effect of atmospheric aerosols is associated to their influence on the radiative budget of the Earth due to direct aerosol-radiation interactions (ARI) and indirect effects, resulting from aerosol-cloud interactions (ACI). On-line coupled meteorology-chemistry models permit the description of these effects on the basis of simulated atmospheric aerosol concentrations, although there is still some uncertainty associated to the use of these models. In this sense, the objective of this work is to assess whether the inclusion of atmospheric aerosol radiative feedbacks of an ensemble of on-line coupled models improves the simulation results for maximum, mean and minimum temperature over Europe. The evaluated model outputs originate from EuMetChem COST Action ES1004 simulations for Europe, differing in the inclusion (or omission) of ARI and ACI in the various models. The case studies cover two important atmospheric aerosol episodes over Europe in the year 2010, a heat wave and ...
Atmospheric Chemistry and Physics Discussions, 2016
Interactive comment on "Improving the deterministic skill of air quality ensembles" by Ioannis Ki... more Interactive comment on "Improving the deterministic skill of air quality ensembles" by Ioannis Kioutsioukis et al.
Air quality is a key element for the well-being and quality of life of European citizens. Air pol... more Air quality is a key element for the well-being and quality of life of European citizens. Air pollution measurements and modeling tools are essential for assessment of air quality according to EU legislation. The responsibilities of ZAMG as the national weather service of Austria include the support of the federal states and the public in questions connected to the protection of the environment in the frame of advisory and counseling services as well as expert opinions. The Air Quality model for Austria (AQA) is operated at ZAMG in cooperation with the University of Natural Resources and Applied Life Sciences in Vienna (BOKU) by order of the regional governments since 2005. AQA conducts daily forecasts of gaseous and particulate (PM10) air pollutants over Austria. In the frame of the project AQA-PM (funded by FFG), satellite measurements of the Aerosol Optical Thickness (AOT) and ground-based PM10-measurements are combined to highly-resolved initial fields using assimilation techniq...
Hugues Brenot (1), Nicolas Theys (1), Lieven Clarisse (2), Daniel Hurtmans (3), Pascal Hedelt (3)... more Hugues Brenot (1), Nicolas Theys (1), Lieven Clarisse (2), Daniel Hurtmans (3), Pascal Hedelt (3), Margarita Vasquez (3), Lucia Mona (4), Gelsomina Pappalardo (4), Simona Scollo (5), Mauro Coltelli (5), Tuomas Peltonen (6), Juhani Lahtinen (6), Marcus Hirtl (7), Delia Arnold (7), Timo Virtanen (8), Gerrit de Leeuw (8), Guðrún NÃna Petersen (9), Sara Barsotti (9), Matthieu Plu (10), Gerhard Wotawa (7), and the EUNADICS-AV WP5 team
The regional weather forecast model ALADIN of the Central Institute for Meteorology and Geodynami... more The regional weather forecast model ALADIN of the Central Institute for Meteorology and Geodynamics (ZAMG) is used in combination with the chemical transport model CAMx (www.camx.com) to conduct forecasts of gaseous and particulate air pollution over Europe. The forecasts which are done in cooperation with the University of Natural Resources and Applied Life Sciences in Vienna (BOKU) are supported by the regional governments since 2005 with the main interest on the prediction of tropospheric ozone.
. The purpose of the EUNADICS prototype Early Warning System (EWS) is to proceed the combined use... more . The purpose of the EUNADICS prototype Early Warning System (EWS) is to proceed the combined use of harmonise data products from satellite, ground-based and in situ instruments to produce alerts of airborne hazard (volcanic, dust, smoke and radionuclide clouds), satisfying the requirement of ATM stakeholders (www.eunadics.eu). The alert products developed by EUNADICS EWS (i.e. NRT observations, email notifications and NetCDF Alert data Products, called NCAP) have shown shows the significant interest in using selective detection of natural airborne hazards from polar orbiting satellite. The combination of several sensors inside a single global system demonstrates the advantage of using a triggered approach to obtain selective detection from observations, which cannot initially discriminate the different aerosol types. Satellite products from hyperspectral UV and IR sensors (e.g. TROPOMI, IASI) and broadband geostationary imager (SEVIRI), and retrievals from ground-based networks (e.g. EARLINET, E-PROFILE and the regional network from volcanic observatories), are combined by our system to create tailored alert products (e.g. selective ash detection, SO2 column and plume height, dust cloud and smoke from wildfires). A total of 23 different alert products are implemented, using 1 geostationary and 12 polar orbiting satellite platforms, 3 external existing service, 2 EU and 2 regional ground-based networks. This allows the identification and the traceability of extreme events. EUNADICS EWS has also shown the interest to proceed a future relay of radiological data (gamma dose rate and radionuclides concentrations in ground-level air) in case of nuclear accident, highlighting the capability of operating early warnings with the use of homogenised dataset. For the four types of airborne hazard, EUNADICS EWS has demonstrated its capability to provide NRT alert data products to trigger data assimilation and dispersion modelling providing forecasts, and inverse modelling for source term estimate. All our alert data products (NCAP files) are not publicly disseminated. Access to our alert products is currently restricted to key users (i.e. Volcanic Ash Advisory Centres, National Meteorological Services, World Meteorological Organization, governments, volcanic observatories and research collaborators), as these are considered pre-decisional products. On the other hand, thanks to the SACS/EUNADICS web interface (https://sacs.aeronomie.be), the main part of the satellite observations used by EUNADICS EWS, are shown in NRT, with public email notification of volcanic emission and delivery of tailored images and NCAP files. All the ATM stakeholders (e.g. VAACs, NMSs, WMOs, Airlines and Pilots) can access and benefit of these alert products through this free channel.
This paper demonstrates the environmental impacts of the wildfires occurring at the beginning of ... more This paper demonstrates the environmental impacts of the wildfires occurring at the beginning of April 2020 in and around the highly contaminated Chernobyl Exclusion Zone (CEZ). Due to the critical fire location, concerns arose about secondary radioactive contamination potentially spreading over Europe. The impact of the fire was assessed through the evaluation of fire plume dispersion and re-suspension of the radionuclide Cs-137, whereas, to assess the smoke plume effect, a WRF-Chem simulation was performed and compared to Tropospheric Monitoring Instrument (TROPOMI) satellite columns. The results show agreement of the simulated black carbon and carbon monoxide plumes with the plumes as observed by TROPOMI, where pollutants were also transported to Belarus. From an air quality and health perspective, the wildfires caused extremely bad air quality over Kiev, where the WRF-Chem model simulated mean values of PM2.5 up to 300 µg/m3 (during the first fire outbreak) over CEZ. The re-susp...
. High quality volcanic ash forecasts are crucial to minimize the economic impact of volcanic haz... more . High quality volcanic ash forecasts are crucial to minimize the economic impact of volcanic hazards on air traffic. Decision-making is usually based on numerical dispersion modeling with only one model realization. Given the inherent uncertainty of such approach, a multi-model multi-source term ensemble has been designed and evaluated for the Eyjafjallajökull eruption in May 2010. Its use for air traffic management is discussed. Two multi-model ensembles were built: the first is based on the output of four dispersion models and their own implementation of ash ejection. All a priori model source terms were constrained by observational evidence of the volcanic ash cloud top as a function of time. The second ensemble is based on the same four dispersion models, which were run with three additional source terms: (i) a source term obtained with background modeling constrained with satellite data (a posteriori source term), (ii) its lower bound estimate, and (iii) its upper bound estimate. The a priori ensemble gives valuable information about the probability of ash dispersion during the early phase of the eruption, when observational evidence is limited. However, its evaluation with observational data reveals lower quality compared to the second ensemble. While the second ensemble ash column load and ash horizontal location compare well to satellite observations, 3D ash concentrations are negatively biased. This might be caused by the vertical distribution of ash, which is too much diluted in all model runs, probably due to defaults in the a posteriori source term and vertical transport and/or diffusion processes in all models. Relevant products for the air traffic management are horizontal maps of ash concentration quantiles (median, 75 %, 99 %) at a fine-resolved flight level grid. These maps can be used for route optimization in the areas where ash does not pose a direct and urgent threat to aviation. Cost-optimized consideration of such hazards will result in much less impact on flight cancellations, reroutings, and traffic flow congestions.
Volcanic eruptions may generate volcanic ash and sulfur dioxide (SO 2) plumes with strong tempora... more Volcanic eruptions may generate volcanic ash and sulfur dioxide (SO 2) plumes with strong temporal and vertical variations. When simulating these changing volcanic plumes and the afar dispersion of emissions, it is important to provide the best available information on the temporal and vertical emission distribution during the eruption. The volcanic emission preprocessor of the chemical transport model WRF-Chem has been extended to allow the integration of detailed temporally and vertically resolved input data from volcanic eruptions. The new emission preprocessor is tested and evaluated for the eruption of the Grimsvötn volcano in Iceland 2011. The initial ash plumes of the Grimsvötn eruption differed significantly from the SO 2 plumes, posing challenges to simulate plume dynamics within existing modelling environments: observations of the Grimsvötn plumes revealed strong vertical wind shear that led to different transport directions of the respective ash and SO 2 clouds. Three source terms, each of them based on different assumptions and observational data, are applied in the model simulations. The emission scenarios range from (i) a simple approach, which assumes constant emission fluxes and a predefined vertical emission profile, to (ii) a more complex approach, which integrates temporarily varying observed plume-top heights and estimated emissions based on them, to (iii) the most complex method that calculates temporal and vertical variability of the emission fluxes based on satellite observations and inversion techniques. Comparisons between model results and independent observations from satellites, lidar, and surface air quality measurements reveal the best performance of the most complex source term.
&lt;p&gt;ZAMG runs two models for air-quality forecasts operationally: ALARO-CAMx and WRF... more &lt;p&gt;ZAMG runs two models for air-quality forecasts operationally: ALARO-CAMx and WRF-Chem.&lt;/p&gt; &lt;p&gt;ALARO-CAMx is a combination of the meteorological model ALARO and the photochemical dispersion model CAMx and is operated at ZAMG since 2005. The emphasis of this modeling system is to predict ozone peaks in the north-eastern Austrian flatlands. The outer model grid covers Central Europe with a resolution of 13.8 km, the inner domain is centered over Austria with a resolution of 4.6 km. The model runs twice per day for a period of 48 hours.&lt;/p&gt; &lt;p&gt;The second operational air quality model at ZAMG is the on-line coupled model WRF-Chem. Meteorology is simulated simultaneously with the emission, turbulent mixing, transport, transformation as well as the fate of trace gases and aerosols. Two modeling domains are used for these simulations. The mother domain covers Europe with a resolution of 12 km. The inner, nested domain covers the Alpine region with a horizontal resolution of 4&amp;#160;km. The model runs two times per day for a period of 72 hours and is initialized with ECMWF forecasts.&lt;/p&gt; &lt;p&gt;The evaluation of both models is conducted for the period from January to September 2019 with the focus on ozone. The summer 2019 was the 2&lt;sup&gt;nd&lt;/sup&gt; warmest summer since the beginning of the meteorological measurements in Austria more than 200 years ago. Although this summer had favorable conditions for Ozone production (sunny and hot weather, less rain), only a few air quality stations in Eastern Austria have measured exceedances of the ozone information threshold (180&amp;#160;&amp;#181;g/m&amp;#179;) on overall 5 days. The measurements of the air-quality stations are compared with the area forecasts for every province of Austria. Besides the evaluation, air quality forecasts of ALARO-CAMx and WRF-Chem are compared.&lt;/p&gt;
Volcanic eruptions eject ash and gases into the atmosphere that can contribute to significant haz... more 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.
Natural Hazards and Earth System Sciences Discussions
Volcanic eruptions comprise one of the most important airborne hazards for aviation. Although sig... more Volcanic eruptions comprise one of the most important airborne hazards for aviation. Although significant events are rare, they have a very high impact. The current state of tools and abilities to mitigate aviation hazards associated with an assumed volcanic cloud was tested within an international demonstration exercise. Experts in the field assembled at the Schwarzenberg barracks in Salzburg, Austria, in order to simulate the sequence of procedures for the volcanic case scenario of an artificial eruption of Etna volcano in Italy. The scope of the exercise ranged from the detection of the assumed event to the issuance of early warnings. Volcanic emission concentration charts were generated applying modern ensemble techniques. The exercise products provided an important basis for decision making for aviation traffic management during a volcanic eruption crisis. By integrating the available wealth of data, observations and modelling results directly into a widely used flight planning software, it was demonstrated that route optimization measures could be implemented effectively. With timely and rather precise warnings available, the new tools and processes tested during the exercise demonstrated vividly
Atmospheric aerosols modify the radiative budget of the Earth due to their optical, microphysical... more Atmospheric aerosols modify the radiative budget of the Earth due to their optical, microphysical and chemical properties, and are considered one of the most uncertain forcing agents. In order to characterise the uncertainties associated with satellite and modelling approaches to represent aerosol optical properties, their representation by different remote sensing sensors and regional online coupled chemistry-climate models over Europe is evaluated. This work also characterises whether the inclusion of aerosol-radiation (ARI) or aerosol-cloud interactions (ACI) helps improve the skills of modelling outputs. <br><br> Two case studies were selected within the EuMetChem COST Action ES1004 framework, when important aerosol episodes in 2010 all over Europe took place: a Russian wildfire episode and a Saharan desert dust outbreak that covered most of Mediterranean Sea. The model data came from different regional air quality-climate simulations performed by working group 2 of ...
Atmospheric Chemistry and Physics Discussions, 2017
The climate effect of atmospheric aerosols is associated to their influence on the radiative budg... more The climate effect of atmospheric aerosols is associated to their influence on the radiative budget of the Earth due to direct aerosol-radiation interactions (ARI) and indirect effects, resulting from aerosol-cloud interactions (ACI). On-line coupled meteorology-chemistry models permit the description of these effects on the basis of simulated atmospheric aerosol concentrations, although there is still some uncertainty associated to the use of these models. In this sense, the objective of this work is to assess whether the inclusion of atmospheric aerosol radiative feedbacks of an ensemble of on-line coupled models improves the simulation results for maximum, mean and minimum temperature over Europe. The evaluated model outputs originate from EuMetChem COST Action ES1004 simulations for Europe, differing in the inclusion (or omission) of ARI and ACI in the various models. The case studies cover two important atmospheric aerosol episodes over Europe in the year 2010, a heat wave and ...
Atmospheric Chemistry and Physics Discussions, 2016
Interactive comment on "Improving the deterministic skill of air quality ensembles" by Ioannis Ki... more Interactive comment on "Improving the deterministic skill of air quality ensembles" by Ioannis Kioutsioukis et al.
Air quality is a key element for the well-being and quality of life of European citizens. Air pol... more Air quality is a key element for the well-being and quality of life of European citizens. Air pollution measurements and modeling tools are essential for assessment of air quality according to EU legislation. The responsibilities of ZAMG as the national weather service of Austria include the support of the federal states and the public in questions connected to the protection of the environment in the frame of advisory and counseling services as well as expert opinions. The Air Quality model for Austria (AQA) is operated at ZAMG in cooperation with the University of Natural Resources and Applied Life Sciences in Vienna (BOKU) by order of the regional governments since 2005. AQA conducts daily forecasts of gaseous and particulate (PM10) air pollutants over Austria. In the frame of the project AQA-PM (funded by FFG), satellite measurements of the Aerosol Optical Thickness (AOT) and ground-based PM10-measurements are combined to highly-resolved initial fields using assimilation techniq...
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