Background The implementation of emission mitigation policies in Europe over the last two decades has generally improved the air quality, which resulted in lower aerosol particle mass, particle number, and black carbon mass concentration. However, little is known whether the decreasing particle concentrations at a lower-altitude level can be observed in the free troposphere (FT), an important layer of the atmosphere, where aerosol particles have a longer lifetime and may affect climate dynamics. In this study, we used data from two high-Alpine observatories, Zugspitze-Schneefernerhaus (ZSF) and Jungfraujoch (JFJ), to assess the long-term trends on size-resolved particle number concentrations (PNCs) and equivalent black carbon (eBC) mass concentration separated for undisturbed lower FT conditions and under the influence of air from the planetary boundary layer (PBL) from 2009 to 2018. Results The FT and PBL-influenced conditions were segregated for both sites. We found that the FT conditions in cold months were more prevalent than in warm months, while the measured aerosol parameters showed different seasonal patterns for the FT and PBL-influenced conditions. The pollutants in the PBL-influenced condition have a higher chance to be transported to high-altitudes due to the mountainous topography, leading to a higher concentration and more distinct seasonal variation, and vice versa. The long-term trends of the measured aerosol parameters were evaluated and the decreased aerosol concentrations were observed for both FT and PBL-influenced conditions. The observed decreasing trends in eBC concentration in the PBL-influenced condition are well consistent with the reported trends in total BC emission in Germany and Switzerland. The decreased concentrations in the FT condition suggest that the background aerosol concentration in the lower FT over Central Europe has correspondingly decreased. The change of back trajectories in the FT condition at ZSF and JFJ was further evaluated to investigate the other possible drivers for the decreasing trends. Conclusions The background aerosol concentration in the lower FT over Central Europe has significantly decreased during 2009-2018. The implementation of emission mitigation policies is the most decisive factor and the decrease of the regional airmass occurrence over Central Europe also has contributed to the decreasing trends. © 2021, The Author(s)
Sea salt aerosol (SSA) is one of the major components of primary aerosols and has significant impact on the formation of secondary inorganic particles mass on a global scale. In this study, the fully online coupled WRF-Chem model was utilized to evaluate the SSA emission scheme and its influence on the nitrate simulation in a case study in Europe during 10-20 September 2013. Meteorological conditions near the surface, wind pattern and thermal stratification structure were well reproduced by the model. Nonetheless, the coarse-mode (PM1?-?10) particle mass concentration was substantially overestimated due to the overestimation of SSA and nitrate. Compared to filter measurements at four EMEP stations (coastal stations: Bilthoven, Kollumerwaard and Vredepeel; inland station: Melpitz), the model overestimated SSA concentrations by a factor of 8-20. We found that this overestimation was mainly caused by overestimated SSA emissions over the North Sea during 16-20 September. Over the coastal regions, SSA was injected into the continental free troposphere through an "aloft bridgeŁ (about 500 to 1000?m above the ground), a result of the different thermodynamic properties and planetary boundary layer (PBL) structure between continental and marine regions. The injected SSA was further transported inland and mixed downward to the surface through downdraft and PBL turbulence. This process extended the influence of SSA to a larger downwind region, leading, for example, to an overestimation of SSA at Melpitz, Germany, by a factor of ?~??20. As a result, the nitrate partitioning fraction (ratio between particulate nitrate and the summation of particulate nitrate and gas-phase nitric acid) increased by about 20?% for the coarse-mode nitrate due to the overestimation of SSA at Melpitz. However, no significant difference in the partitioning fraction for the fine-mode nitrate was found. About 140?% overestimation of the coarse-mode nitrate resulted from the influence of SSA at Melpitz. In contrast, the overestimation of SSA inhibited the nitrate particle formation in the fine mode by about 20?% because of the increased consumption of precursor by coarse-mode nitrate formation.Quelle: http://www.atmos-chem-phys.net
Black carbon (BC) particles have gathered worldwide attention due to their impacts on climate and adverse health effects on humans in heavily polluted environments. Such is the case in megacities of developing and emerging countries in Southeast Asia, in which rapid urbanization, vehicles of obsolete technology, outdated air quality legislations, and crumbling infrastructure lead to poor air quality. However, since measurements of BC are generally not mandatory, its spatial and temporal characteristics, especially in developing megacities, are poorly understood. To raise awareness on the urgency of monitoring and mitigating the air quality crises in megacities, we present the results of the first intensive characterization experiment in Metro Manila, Philippines, focusing on the spatial and diurnal variability of equivalent BC (eBC). The average mass concentration of eBC at the urban background station (UBS) was 7.0 - 4.8 ng m'3 while at roadside (RS), hourly concentrations reached maximum values of 138 ng m'3, levels that are significantly higher than in European cities. At RS, the diurnal cycles of eBC mass concentration were connected most strongly with traffic dynamics and street configuration, while a notable influence of planetary boundary layer evolution was observed in the UBS. Results of mobile measurements conducted multiple times along two fixed routes showed high spatial variability ranging from 3-80 ng m'3 within a 500-m radius. Alarmingly, the highest concentrations were found in the most crowded areas where people spend more than eight hours a day. Quelle: http://www.aaqr.org
High altitude stations are often emphasized as free tropospheric measuring sites but they remain influenced by atmospheric boundary layer (ABL) air masses due to convective transport processes. The local and meso-scale topographical features around the station are involved in the convective boundary layer development and in the formation of thermally induced winds leading to ABL air lifting. The station altitude alone is not a sufficient parameter to characterize the ABL influence. In this study, a topography analysis is performed allowing calculation of a newly defined index called ABL-TopoIndex. The ABL-TopoIndex is constructed in order to correlate with the ABL influence at the high altitude stations and long-term aerosol time series are used to assess its validity. Topography data from the global digital elevation model GTopo30 were used to calculate five parameters for 43 high and 3 middle altitude stations situated on five continents. The geometric mean of these five parameters determines a topography based index called ABL-TopoIndex, which can be used to rank the high altitude stations as a function of the ABL influence. To construct the ABL-TopoIndex, we rely on the criteria that the ABL influence will be low if the station is one of the highest points in the mountainous massif, if there is a large altitude difference between the station and the valleys or high plains, if the slopes around the station are steep, and finally if the inverse drainage basin potentially reflecting the source area for thermally lifted pollutants to reach the site is small. All stations on volcanic islands exhibit a low ABL-TopoIndex, whereas stations in the Himalayas and the Tibetan Plateau have high ABL-TopoIndex values. Spearman's rank correlation between aerosol optical properties and number concentration from 28 stations and the ABL-TopoIndex, the altitude and the latitude are used to validate this topographical approach. Statistically significant (SS) correlations are found between the 5th and 50th percentiles of all aerosol parameters and the ABL-TopoIndex, whereas no SS correlation is found with the station altitude. The diurnal cycles of aerosol parameters seem to be best explained by the station latitude although a SS correlation is found between the amplitude of the diurnal cycles of the absorption coefficient and the ABL-TopoIndex. © 2018 Author(s).
Das Projekt "Windenergie fuer die bebaute Umgebung" wird vom Umweltbundesamt gefördert und von Universität Stuttgart, Institut für Baukonstruktion und Entwerfen Lehrstuhl 1 durchgeführt. General Information: Acceptability of wind turbines has met much opposition in recent years, partially because they are frequently seen as sharply contrasting intrusions into the natural landscape, since no other man-made structures are normally found around them. This proposal will address the acceptability issues by developing and integrating turbines into built environment in order to bring power generation closer to usage and also to contribute to the 'zero energy building' goal. It is also recognised that most built-up areas in Europe have low-to-moderate wind speed regime, partially because of the effect that increased surface roughness has on an atmospheric boundary layer profile. For these reasons wind applications in built-up areas have to fulfils several specific requirements which will be addressed in the proposal. The key objectives are: 1. to develop wind enhancement and integration techniques for low to moderate wind speed areas (2.5 to 5 m/s annual average) in order to increase the 'qualifying land mass area' for wind utilization in the AEU by improving the annual energy yield per installation. Particular attention would be given to wind concentration techniques using optimised building forms and purpose-made solid structures to create the 'accelerated wind environment'. 2. to develop turbine specification to cater for the above applications. Additionally these turbines would have to be closely controllable, with low noise emissions and be suitable for sensitive environmental integration in or around inhabited areas. All important environmental implications would be investigated. 3. to prove/demonstrate the above techniques on a scaled model in the field. 4. to assess and improve prospects for social, aesthetical and planning acceptability of such wind energy applications. There are specific requirements that wind turbines for inhabited areas must satisfy in response to specific problems related to this type of application. They are going to be specifically addressed in this project. 1. Physical Safety. Prevention of injury to humans, birds, etc. will be an important aspect of urban application. Safety could be compromised due to reasons like blade rotation, high winds and possible blade shedding due to material fatigue. 2. Noise. The noise levels at neighbouring properties would not normally be allowed to exceed the level of background noise or 45 dB(A), whichever is higher. For this reason, quiet turbines are needed. The mechanical gear would have to be placed in an acoustic enclosure. Special types of control may have to be implemented in order to control the rotational speed in accordance with the background noise level at reference points in the surroundings. 3. Vibration and Resonance. Special structural provisions at the interface between the turbines and surrounding structures may be needed to avoid these effects... Prime Contractor: BDSP Partnership, London.
Das Projekt "Regional differences in tropospheric ozone in europe - an analcsis of its controlling phenomena" wird vom Umweltbundesamt gefördert und von Universität Köln, Institut für Geophysik und Meteorologie durchgeführt. Objective: To create a complete 3-D hourly ozone data set covering the whole troposphere over Europe for a summer period of 6 months and to analyze this ozone data set to investigate the different ozone patterns and its controlling phenomena in the different areas in General Information: The ozone data set will be made using available experimental data (ground level and vertical soundings), by performing dedicated vertical soundings and by using available ozone data from satellites (GOME-instrument). A data-assimilation technique will be developed which, using available 3-D tropospheric Eulerian grid photo-oxidant models, and the experimental data set, will lead to a complete coherent and consistent 3-D hourly ozone data set over Europe. The data set will be created for the months of April until September (6 months) of the year 1997. With this data set, ozone budget studies to reveal differences between the North Sea/Atlantic and the Mediterranean Sea (local production versus long range transport, and the influence on the coastal areas) will be performed. Also vertical fluxes between the planetary boundary layer and the free troposphere, and the troposphere and the stratosphere will be analyzed; also the representative ness of the vertical soundings performed will be investigated. Prime Contractor: Nederlandse Organisatie voor Toegepast Natuurwetenschappelijk Onderzoek; Apeldoorn; Netherlands.
Das Projekt "Kleinaerologie bei PUKK" wird vom Umweltbundesamt gefördert und von Deutscher Wetterdienst durchgeführt. Im Rahmen des Forschungsexperiments PUKK (Projekt zur Untersuchung des Kuestenklimas) werden von zwei Wettermesszuegen des Deutschen Wetterdienstes in Nordwestdeutschland auf einer Linie senkrecht zur Kueste in der Naehe der Orte Bremervoerde und Sprakensehl kleinaerologische Sondierungen in der Troposphaere bis etwa 5500 m ueb. Gr. durchgefuehrt. Neben den meteorologischen Parametern Druck, Temperatur und Feuchte werden mittels Radar die vertikalen Verteilungen von Windrichtung und -geschwindigkeit bestimmt. Nach Pruefung und Aufbereitung der Messdaten werden diese dem PUKK-Datenzentrum beim Deutschen Wetterdienst - Seewetteramt zugefuehrt und stehen somit den uebrigen Projektteilnehmern zur Analyse der meteorologischen Bedingungen in der planetarischen Grenzschicht zur Verfuegung.
Das Projekt "Arktische Strahlungs- und Turbuelnzstudie" wird vom Umweltbundesamt gefördert und von Stiftung Alfred-Wegener-Institut für Polar- und Meeresforschung e.V. (AWI) durchgeführt. The warming of the lower atmosphere due to industrial activities is predicted by Global Circulation Models (GCM) to be most enhanced in the Arctic regions. The energy fluxes in the atmosphere and the radiative properties of clouds are of vital importance in an atmosphere of rising temperatures and especially in the Arctic are not yet represented by GCMs adequately, see results of the Atmospheric Model Intercomparison Project AMIP: WMO/TD 1992. The ARTIST programme aims to obtain an improved understanding of the radiative and thermodynamic interaction of Arctic clouds and sea-ice. The ARTIST programme will thoroughly study the energy fluxes in the atmosphere and at the surface of the polar ocean as well as cloud physical processes by field measurements atmospheric modelling and satellite remote sensing. An overall ARTIST objective is to derive optimized physical parameterizations for improved models of the Arctic Climate System. The programme ARTIST thus covers the Environment and Climate Workprogramme Basic processes in the climate system (Theme 1,Area 1,1,Topic 1,1,1, research tasks 2,3, and 4: and Area 1,2, Topic 1,2,1,2, research task 2,) Objective 1: ARTIST will assess the effects of clouds and of Arctic Haze on the radiative fluxes at the surface and in the atmospheric column for various states of the ocean surface. Objective 2: ARTIST studies the dynamics of the atmospheric boundary layer and especially the air-sea exchange of heat, momentum and vapour in Arctic regions by field experiments and process modelling.
Das Projekt "MOSAiC 2: Modellierung des Einflusses von Eisrinnen auf die atmosphärische Grenzschicht" wird vom Umweltbundesamt gefördert und von Universität Trier, Fachbereich VI Raum- und Umweltwissenschaften, Fach Umweltmeteorologie durchgeführt.
Das Projekt "Einfluss strukturierter Heizquellen auf die Dynamik auf grösseren Skalen (A02)" wird vom Umweltbundesamt gefördert und von Deutsche Forschungsgemeinschaft / Deutsches Wirtschaftswissenschaftliches Institut für Fremdenverkehr eingetragener Verein (dwif e.V.) an der Ludwig-Maximilians-Universität München durchgeführt. In diesem interdisziplinären Projekt werden wir untersuchen, wie strukturierte Heizquellen auf kleineren Skalen Prozesse auf größeren Skalen beeinflussen. Dazu werden wir hochauflösende numerische Simulationen mit Hilfe der Methoden von uncertainty quantification erweitern. Dies erlaubt die Einführung von Zufallsvariablen, z.B. für Modellparameter und Umgebungsbedingungen. Diese Ansätze werden zur Untersuchung der Vorhersagbarkeit für zwei relevante atmosphärische Szenarien benutzt: (i) Konvektion, in der turbulenten und teilweise strukturierte Grenzschicht, und (ii) Einfluss von strukturierten Heizquellen (Cirrocumulus) in der Tropopausenregion auf die Dynamik größerer Skalen.
| Origin | Count |
|---|---|
| Bund | 142 |
| Type | Count |
|---|---|
| Förderprogramm | 138 |
| unbekannt | 4 |
| License | Count |
|---|---|
| geschlossen | 4 |
| offen | 138 |
| Language | Count |
|---|---|
| Deutsch | 138 |
| Englisch | 51 |
| Resource type | Count |
|---|---|
| Keine | 110 |
| Webseite | 32 |
| Topic | Count |
|---|---|
| Boden | 109 |
| Lebewesen & Lebensräume | 111 |
| Luft | 142 |
| Mensch & Umwelt | 142 |
| Wasser | 96 |
| Weitere | 141 |