| 1. |
- Fernandez-Rodriguez, Santiago, et al.
(författare)
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Identification of potential sources of airborne Olea pollen in the Southwest Iberian Peninsula
- 2014
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Ingår i: International Journal of Biometeorology. - : Springer Science and Business Media LLC. - 1432-1254 .- 0020-7128. ; 58:3, s. 337-348
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Tidskriftsartikel (refereegranskat)abstract
- This study aims to determine the potential origin of Olea pollen recorded in Badajoz in the Southwest of the Iberian Peninsula during 2009-2011. This was achieved using a combination of daily average and diurnal (hourly) airborne Olea pollen counts recorded at Badajoz (south-western Spain) and A parts per thousand vora (south-eastern Portugal), an inventory of olive groves in the studied area and air mass trajectory calculations computed using the HYSPLIT model. Examining olive pollen episodes at Badajoz that had distinctly different diurnal cycles in olive pollen in relation to the mean, allowed us to identify three different scenarios where olive pollen can be transported to the city from either distant or nearby sources during conditions with slow air mass movements. Back trajectory analysis showed that olive pollen can be transported to Badajoz from the West on prevailing winds, either directly or on slow moving air masses, and from high densities of olive groves situated to the Southeast (e.g. Andalucia). Regional scale transport of olive pollen can result in increased nighttime concentrations of this important aeroallergen. This could be particularly important in Mediterranean countries where people can be outdoors during this time due to climate and lifestyle. Such studies that examine sources and the atmospheric transport of pollen are valuable for allergy sufferers and health care professionals because the information can be incorporated into forecasts, the outputs of which are used for avoiding exposure to aeroallergens and planning medication. The results of studies of this nature can also be used for examining gene flow in this important agricultural crop.
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| 2. |
- Geels, C., et al.
(författare)
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Improved modelling of atmospheric ammonia over Denmark using the coupled modelling system DAMOS
- 2012
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Ingår i: Biogeosciences. - : Copernicus GmbH. - 1726-4189. ; 9:7, s. 2625-2647
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Tidskriftsartikel (refereegranskat)abstract
- A local-scale Gaussian dispersion-deposition model (OML-DEP) has been coupled to a regional chemistry-transport model (DEHM with a resolution of approximately 6 km x 6 km over Denmark) in the Danish Ammonia Modelling System, DAMOS. Thereby, it has been possible to model the distribution of ammonia concentrations and depositions on a spatial resolution down to 400 m x 400 m for selected areas in Denmark. DAMOS has been validated against measured concentrations from the dense measuring network covering Denmark. Here measured data from 21 sites are included and the validation period covers 2-5 years within the period 2005-2009. A standard time series analysis (using statistic parameters like correlation and bias) shows that the coupled model system captures the measured time series better than the regional- scale model alone. However, our study also shows that about 50% of the modelled concentration level at a given location originates from non-local emission sources. The local-scale model covers a domain of 16 km x 16 km, and of the locally released ammonia (NH3) within this domain, our simulations at five sites show that 14-27% of the locally (within 16 km x 16 km) emitted NH3 also deposits locally. These results underline the importance of including both high-resolution local-scale modelling of NH3 as well as the regional-scale component described by the regional model. The DAMOS system can be used as a tool in environmental management in relation to assessments of total nitrogen load of sensitive nature areas in intense agricultural regions. However, high spatio-temporal resolution in input parameters like NH3 emissions and land-use data is required.
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| 3. |
- Grewling, L., et al.
(författare)
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Variation in Artemisia pollen seasons in Central and Eastern Europe
- 2012
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Ingår i: Agricultural and Forest Meteorology. - : Elsevier BV. - 1873-2240 .- 0168-1923. ; 160, s. 48-59
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Tidskriftsartikel (refereegranskat)abstract
- This paper aims to address some gaps in current knowledge by studying temporal and spatial variations in Artemisia pollen counts (2000-2009) at 13 sites located in different biogeographical areas of Central and Eastern Europe. Analysis showed that start dates of Artemisia pollen seasons are greatly dependent on temperature during June and July, with hot summer temperatures having a tendency to delay summer flowering. However, this relationship is not linear and the rate at which seasons become later increases when mean minimum June-July temperatures reach a threshold of about 13 degrees C. No explanation for variations in pollen season intensity could be found. The geographical location or amount of urbanisation did not influence, either positively or negatively, the seasonal pollen index. Second peaks in Artemisia pollen seasons can be described as the pollen seasons of late flowering Artemisia species, and mainly occurred in the geographical area south of the Carpathian Mountains. These second peaks can significantly influence the seasonal pollen index, contributing over 50% to the season's total Artemisia pollen recorded at one site. (C) 2012 Elsevier B.V. All rights reserved.
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| 4. |
- Hansen, K., et al.
(författare)
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Ammonia emissions from deciduous forest after leaf fall
- 2013
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Ingår i: Biogeosciences. - : Copernicus GmbH. - 1726-4189. ; 10:7, s. 4577-4589
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Tidskriftsartikel (refereegranskat)abstract
- The understanding of biochemical feedback mechanisms in the climate system is lacking knowledge in relation to bi-directional ammonia (NH3) exchange between natural ecosystems and the atmosphere. We therefore study the atmospheric NH3 fluxes during a 25-day period during autumn 2010 (21 October to 15 November) for the Danish beech forest Lille Bogeskov to address the hypothesis that NH3 emissions occur from deciduous forests in relation to leaf fall. This is accomplished by using observations of vegetation status, NH3 fluxes and model calculations. Vegetation status was observed using plant area index (PAI) and leaf area index (LAI). NH3 fluxes were measured using the relaxed eddy accumulation (REA) method. The REA-based NH3 concentrations were compared to NH3 de-nuder measurements. Model calculations of the atmospheric NH3 concentration were obtained with the Danish Ammonia MOdelling System (DAMOS). The relative contribution from the forest components to the atmospheric NH3 flux was assessed using a simple two-layer bi-directional canopy compensation point model. A total of 57.7% of the fluxes measured showed emission and 19.5% showed deposition. A clear tendency of the flux going from deposition of -0.25 +/- 0.30 mu gNH(3)-Nm(-2) s(-1) to emission of up to 0.67 +/- 0.28 mu gNH(3)-Nm(-2) s(-1) throughout the measurement period was found. In the leaf fall period (23 October to 8 November), an increase in the atmospheric NH3 concentrations was related to the increasing forest NH3 flux. Following leaf fall, the magnitude and temporal structure of the measured NH3 emission fluxes could be adequately reproduced with the bi-directional resistance model; it suggested the forest ground layer (soil and litter) to be the main contributing component to the NH3 emissions. The modelled concentration from DAMOS fits well the measured concentrations before leaf fall, but during and after leaf fall, the modelled concentrations are too low. The results indicate that the missing contribution to atmospheric NH3 concentration from vegetative surfaces related to leaf fall are of a relatively large magnitude. We therefore conclude that emissions from deciduous forests are important to include in model calculations of atmospheric NH3 for forest ecosystems. Finally, diurnal variations in the measured NH3 concentrations were related to meteorological conditions, forest phenology and the spatial distribution of local anthropogenic NH3 sources. This suggests that an accurate description of ammonia fluxes over forest ecosystems requires a dynamic description of atmospheric and vegetation processes.
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| 5. |
- Hertel, Ole, et al.
(författare)
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Assessing atmospheric nitrogen deposition to natural and semi-natural ecosystems - Experience from Danish studies using the DAMOS
- 2013
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Ingår i: Atmospheric Environment. - : Elsevier BV. - 1352-2310. ; 66, s. 151-160
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Tidskriftsartikel (refereegranskat)abstract
- Local agricultural emissions contribute significantly to the atmospheric reactive nitrogen loads of Danish terrestrial ecosystems. In the vicinity of the sources this may be up to 6-8 kg N ha(-1) yr(-1) depending on location and ecosystem type. This contribution arises from dry deposition of gas phase ammonia derived from local livestock production. Long-range transport, however, often constitutes the largest contribution to the overall atmospheric terrestrial reactive nitrogen loadings in Denmark. This is often in the range 10-15 kg N ha(-1) yr(-1) and consists mainly of aerosol phase nitrate and ammonium (reaction products of nitrogen oxides and ammonia), but also dry deposition of other reactive nitrogen compounds (mainly nitrogen oxides in the form of gas phase nitric acid and nitrogen dioxide). In Denmark's environmental management of the sensitive terrestrial ecosystems modelling tools are required that account for both the local and the long-range transported contributions. This motivated development of the Danish Ammonia MOdelling System (DAMOS) that has been successfully applied to the assessment of atmospheric nitrogen loadings to sensitive Danish ecosystems. We present here three different examples of such assessments. Our results show that ecosystems located in Western Denmark (Case 1) receive the highest loads of atmospheric nitrogen depositions which generally exceed the critical load. This part of the country has the highest livestock density. In the Eastern part of the country, the atmospheric loadings are often below or close to the lower end of the interval for critical load values. These lower loads in Eastern Denmark (Case 2) are due to lower density of agricultural activities, as well as, lower precipitation rates, which leads to less wet deposition of reactive nitrogen. In general there is a gradient in atmospheric deposition over the country, with the highest depositions in the South-Western part of Denmark (Case 3) due to long-range transport contributions from North-Western Europe, but also due to local ammonia deposition associated with the high local emission from the high density livestock farming in this area. (c) 2012 Elsevier Ltd. All rights reserved.
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| 6. |
- Hertel, O., et al.
(författare)
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Governing processes for reactive nitrogen compounds in the European atmosphere
- 2012
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Ingår i: Biogeosciences. - : Copernicus GmbH. - 1726-4170 .- 1726-4189. ; 9:12, s. 4921-4954
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Forskningsöversikt (refereegranskat)abstract
- Reactive nitrogen (Nr) compounds have different fates in the atmosphere due to differences in the governing processes of physical transport, deposition and chemical transformation. N r compounds addressed here include reduced nitrogen (NH x : ammonia (NH 3 ) and its reaction product ammonium (NH 4 + )), oxidized nitrogen (NO y : nitrogen monoxide (NO) + nitrogen dioxide (NO 2 ) and their reaction products) as well as organic nitrogen compounds (organic N). Pollution abatement strategies need to take into account the differences in the governing processes of these compounds when assessing their impact on ecosystem services, biodiversity, human health and climate. NO x (NO + NO 2 ) emitted from traffic affects human health in urban areas where the presence of buildings increases the residence time in streets. In urban areas this leads to enhanced exposure of the population to NO x concentrations. NO x emissions generally have little impact on nearby ecosystems because of the small dry deposition rates of NO x . These compounds need to be converted into nitric acid (HNO 3 ) before removal through deposition is efficient. HNO 3 sticks quickly to any surface and is thereby either dry deposited or incorporated into aerosols as nitrate (NO 3 + ). In contrast to NOx compounds, NH 3 has potentially high impacts on ecosystems near the main agricultural sources of NH 3 because of its large ground-level concentrations along with large dry deposition rates. Aerosol phase NH 4 + and NO 3 + contribute significantly to background PM 2.5 and PM 10 (mass of aerosols with an aerodynamic diameter of less than 2.5 and 10 μm, respectively) with an impact on radiation balance as well as potentially on human health. Little is known quantitatively and qualitatively about organic N in the atmosphere, other than that it contributes a significant fraction of wet-deposited N, and is present in both gaseous and particulate forms. Further studies are needed to characterise the sources, air chemistry and removal rates of organic N emissions.
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| 7. |
- McLachlan, Michael S., et al.
(författare)
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Concentrations and Fate of Decamethylcyclopentasiloxane (D-5) in the Atmosphere
- 2010
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Ingår i: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 44:14, s. 5365-5370
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Tidskriftsartikel (refereegranskat)abstract
- Decamethylcyclopentasiloxane (D-5) is a volatile compound used in personal care products that is released to the atmosphere in large quantities. Although D-5 is currently under consideration for regulation, there have been no field investigations of its atmospheric fate. We employed a recently developed, quality assured method to measure D-5 concentration in ambient air at a rural site in Sweden. The samples were collected with daily resolution between January and June 2009. The 05 concentration ranged from 0.3 to 9 ng m(-3), which is 1-3 orders of magnitude lower than previous reports. The measured data were compared with D-5 concentrations predicted using an atmospheric circulation model that included both OH radical and D-5 chemistry. The model was parametrized using emissions estimates and physical chemical properties determined in laboratory experiments. There was good agreement between the measured and modeled D-5 concentrations. The results show that D-5 is clearly subject to long-range atmospheric transport, but that it is also effectively removed from the atmosphere via phototransformation. Atmospheric deposition has little influence on the atmospheric fate. The good agreement between the model predictions and the field observations indicates that there is a good understanding of the major factors governing D-5 concentrations in the atmosphere.
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| 8. |
- Newnham, R. M., et al.
(författare)
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Pollen season and climate: Is the timing of birch pollen release in the UK approaching its limit?
- 2013
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Ingår i: International Journal of Biometeorology. - : Springer Science and Business Media LLC. - 1432-1254 .- 0020-7128. ; 57:3, s. 391-400
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Tidskriftsartikel (refereegranskat)abstract
- In light of heightened interest in the response of pollen phenology to temperature, we investigated recent changes to the onset of Betula (birch) pollen seasons in central and southern England, including a test of predicted advancement of the Betula pollen season for London. We calculated onset of birch pollen seasons using daily airborne pollen data obtained at London, Plymouth and Worcester, determined trends in the start of the pollen season and compared timing of the birch pollen season with observed temperature patterns for the period 1995-2010. We found no overall change in the onset of birch pollen in the study period although there was evidence that the response to temperature was nonlinear and that a lower asymptotic start of the pollen season may exist. The start of the birch pollen season was strongly correlated with March mean temperature. These results reinforce previous findings showing that the timing of the birch pollen season in the UK is particularly sensitive to spring temperatures. The climate relationship shown here persists over both longer decadal-scale trends and shorter, seasonal trends as well as during periods of 'sign-switching' when cooler spring temperatures result in later start dates. These attributes, combined with the wide geographical coverage of airborne pollen monitoring sites, some with records extending back several decades, provide a powerful tool for the detection of climate change impacts, although local site factors and the requirement for winter chilling may be confounding factors.
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| 9. |
- Oderbolz, D. C., et al.
(författare)
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A comprehensive emission inventory of biogenic volatile organic compounds in Europe: improved seasonality and land-cover
- 2013
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Ingår i: Atmospheric Chemistry and Physics. - : Copernicus GmbH. - 1680-7324. ; 13:4, s. 1689-1712
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Tidskriftsartikel (refereegranskat)abstract
- Biogenic volatile organic compounds (BVOC) emitted from vegetation are important for the formation of secondary pollutants such as ozone and secondary organic aerosols (SOA) in the atmosphere. Therefore, BVOC emission are an important input for air quality models. To model these emissions with high spatial resolution, the accuracy of the underlying vegetation inventory is crucial. We present a BVOC emission model that accommodates different vegetation inventories and uses satellite-based measurements of greenness instead of pre-defined vegetation periods. This approach to seasonality implicitly treats effects caused by water or nutrient availability, altitude and latitude on a plant stand. Additionally, we test the influence of proposed seasonal variability in enzyme activity on BVOC emissions. In its present setup, the emission model calculates hourly emissions of isoprene, monoterpenes, sesquiterpenes and the oxygenated volatile organic compounds (OVOC) methanol, formaldehyde, formic acid, ethanol, acetaldehyde, acetone and acetic acid. In this study, emissions based on three different vegetation inventories are compared with each other and diurnal and seasonal variations in Europe are investigated for the year 2006. Two of these vegetation inventories require information on tree-cover as an input. We compare three different land-cover inventories (USGS GLCC, GLC2000 and Globcover 2.2) with respect to tree-cover. The often-used USGS GLCC land-cover inventory leads to a severe reduction of BVOC emissions due to a potential miss-attribution of broad-leaved trees and reduced tree-cover compared to the two other land-cover inventories. To account for uncertainties in the land-cover classification, we introduce land-cover correction factors for each relevant land-use category to adjust the tree-cover. The results are very sensitive to these factors within the plausible range. For June 2006, total monthly BVOC emissions decreased up to -27% with minimal and increased up to +71% with maximal factors, while in January 2006, the changes in monthly BVOC emissions were -54 and +56% with minimal and maximal factors, respectively. The new seasonality approach leads to a reduction in the annual emissions compared with non-adjusted data. The strongest reduction occurs in OVOC (up to -32%), the weakest in isoprene (as little as -19%). If also enzyme seasonality is taken into account, however, isoprene reacts with the steepest decrease of annual emissions, which are reduced by -44% to -49%, annual emissions of monoterpenes reduce between -30 and -35%. The sensitivity of the model to changes in temperature depends on the climatic zone but not on the vegetation inventory. The sensitivity is higher for temperature increases of 3K (+31% to +64%) than decreases by the same amount (-20 to -35%). The climatic zones "Cold except summer" and "arid" are most sensitive to temperature changes in January for isoprene and monoterpenes, respectively, while in June, "polar" is most sensitive to temperature for both isoprene and monoterpenes. Our model predicts the oxygenated volatile organic compounds to be the most abundant fraction of the annual European emissions (3571-5328 Gg yr(-1)), followed by monoterpenes (2964-4124 Gg yr(-1)), isoprene (1450-2650 Gg yr(-1)) and sesquiterpenes (150-257 Gg yr(-1)). We find regions with high isoprene emissions (most notably the Iberian Peninsula), but overall, oxygenated VOC dominate with 43-45% (depending on the vegetation inventory) contribution to the total annual BVOC emissions in Europe. Isoprene contributes between 18-21 %, monoterpenes 33-36% and sesquiterpenes contribute 1-2%. We compare the concentrations of biogenic species simulated by an air quality model with measurements of isoprene and monoterpenes in Hohenpeissenberg (Germany) for both summer and winter. The agreement between observed and modelled concentrations is better in summer than in winter. This can partly be explained with the difficulty to model weather conditions in winter accurately, but also with the increased anthropogenic influence on the concentrations of BVOC compounds in winter. Our results suggest that land-cover inventories used to derive tree-cover must be chosen with care. Also, uncertainties in the classification of land-cover pixels must be taken into account and remain high. This problem must be addressed together with the remote sensing community. Our new approach using a greenness index for addressing seasonality of vegetation can be implemented easily in existing models. The importance of OVOC for air quality should be more deeply addressed by future studies, especially in smog chambers. Also, the fate of BVOC from the dominant region of the Iberian Peninsula should be studied more in detail.
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| 10. |
- Sikoparija, B., et al.
(författare)
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A mechanism for long distance transport of Ambrosia pollen from the Pannonian Plain
- 2013
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Ingår i: Agricultural and Forest Meteorology. - : Elsevier BV. - 0168-1923 .- 1873-2240. ; 180, s. 112-117
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Tidskriftsartikel (refereegranskat)abstract
- The pollen grains of ragweed are important aeroallergens that have the potential to be transported long distances through the air. The arrival of ragweed pollen in Nordic countries from the Pannonian Plain can occur when certain conditions are met, which this study aims to describe for the first time. Atmospheric ragweed pollen concentrations were collected at 16 pollen-monitoring sites. Other factors included in the analysis were the overall synoptic weather situation, surface wind speeds, wind direction and temperatures as well as examining regional scale orography and satellite observations. Hot and dry weather in source areas on the Pannonian Plain aid the release of ragweed pollen during the flowering season and result in the deep Planetary Boundary Layers needed to lift the pollen over the Carpathian Mountains to the north. Suitable synoptic conditions are also required for the pollen bearing air masses to move northward. These same conditions produce the jet-effect Kosava and orographic foehn winds that aid the release and dispersal of ragweed pollen and contribute towards its movement into Poland and beyond.
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| 11. |
- Skjoth, Carsten, et al.
(författare)
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Identifying urban sources as cause of elevated grass pollen concentrations using GIS and remote sensing
- 2013
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Ingår i: Biogeosciences. - : Copernicus GmbH. - 1726-4189. ; 10:1, s. 541-554
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Tidskriftsartikel (refereegranskat)abstract
- We examine here the hypothesis that during flowering, the grass pollen concentrations at a specific site reflect the distribution of grass pollen sources within a few kilometres of this site. We perform this analysis on data from a measurement campaign in the city of Aarhus (Denmark) using three pollen traps and by comparing these observations with a novel inventory of grass pollen sources. The source inventory is based on a new methodology developed for urban-scale grass pollen sources. The new methodology is believed to be generally applicable for the European area, as it relies on commonly available remote sensing data combined with management information for local grass areas. The inventory has identified a number of grass pollen source areas present within the city domain. The comparison of the measured pollen concentrations with the inventory shows that the atmospheric concentrations of grass pollen in the urban zone reflect the source areas identified in the inventory, and that the pollen sources that are found to affect the pollen levels are located near or within the city domain. The results also show that during days with peak levels of pollen concentrations there is no correlation between the three urban traps and an operational trap located just 60 km away. This finding suggests that during intense flowering, the grass pollen concentration mirrors the local source distribution and is thus a local-scale phenomenon. Model simulations aimed at assessing population exposure to pollen levels are therefore recommended to take into account both local sources and local atmospheric transport, and not to rely only on describing regional to long-range transport of pollen. The derived pollen source inventory can be entered into local-scale atmospheric transport models in combination with other components that simulate pollen release in order to calculate urban-scale variations in the grass pollen load. The gridded inventory with a resolution of 14m is therefore made available as supplementary material to this paper, and the verifying grass pollen observations are additionally available in tabular form.
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| 12. |
- Skjoth, Carsten, et al.
(författare)
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The effect of climate and climate change on ammonia emissions in Europe
- 2013
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Ingår i: Atmospheric Chemistry and Physics. - : Copernicus GmbH. - 1680-7324. ; 13:1, s. 117-128
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Tidskriftsartikel (refereegranskat)abstract
- We present here a dynamical method for modelling temporal and geographical variations in ammonia emissions in regional-scale chemistry transport models (CTMs) and chemistry climate models (CCMs). The method is based on the meteorology in the models and gridded inventories. We use the dynamical method to investigate the spatiotemporal variability of ammonia emissions across part of Europe and study how these emissions are related to geographical and year-to-year variations in atmospheric temperature alone. For simplicity we focus on the emission from a storage facility related to a standard Danish pig stable with 1000 animals and display how emissions from this source would vary geographically throughout central and northern Europe and from year to year. In view of future climate changes, we also evaluate the potential future changes in emission by including temperature projections from an ensemble of climate models. The results point towards four overall issues. (1) Emissions can easily vary by 20% for different geographical locations within a country due to overall variations in climate. The largest uncertainties are seen for large countries such as the UK, Germany and France. (2) Annual variations in overall climate can at specific locations cause uncertainties in the range of 20 %. (3) Climate change may increase emissions by 0-40% in central to northern Europe. (4) Gradients in existing emission inventories that are seen between neighbour countries (e. g. between the UK and France) can be reduced by using a dynamical methodology for calculating emissions. Acting together these four factors can cause substantial uncertainties in emission. Emissions are generally considered among the largest uncertainties in the model calculations made with CTM and CCM models. Efforts to reduce uncertainties are therefore highly relevant. It is therefore recommended that both CCMs and CTMs implement a dynamical methodology for simulating ammonia emissions in a similar way as for biogenic volatile organic compound (BVOCs) - a method that has been used for more than a decade in CTMs. Finally, the climate penalty on ammonia emissions should be taken into account at the policy level such as the NEC and IPPC directives.
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