Person: Ries, Ludwig
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Veröffentlichung Supplement of Decreasing trends of particle number and black carbon mass concentrations at 16 observational sites in Germany from 2009 to 2018(2020) Sun, Jia; Bath, Olaf; Birmili, Wolfram; Hermann, Markus; Gerwig, Holger; Ries, Ludwig; Schwerin, Andreas; Meinhardt, Frank; Sohmer, Ralf; Wirtz, KlausAnthropogenic emissions are a dominant contributor to air pollution. Consequently, mitigation policies have attempted to reduce anthropogenic pollution emissions in Europe since the 1990s. To evaluate the effectiveness of these mitigation policies, the German Ultrafine Aerosol Network (GUAN) was established in 2008, focusing on black carbon and sub-micrometer aerosol particles, especially ultrafine particles. In this investigation, trends of the size-resolved particle number concentrations (PNC) and the equivalent black carbon (eBC) mass concentration over a 10-year period (2009-2018) were evaluated for 16 observational sites for different environments among GUAN. The trend analysis was done for both, the full-length time series and on subsets of the time series in order to test the reliability of the results. The results show generally decreasing trends of both, the PNCs for all size ranges as well as eBC mass concentrations in all environments, except PNC in 10-30 nm at regional background and mountain sites. The annual slope of the eBC mass concentration varies between -7.7% and -1.8% per year. The slopes of the PNCs varies from -6.3% to 2.7%, -7.0% to -2.0%, and -9.5% to -1.5% per year (only significant trends) for 10-30 nm, 30-200 nm, and 200-800 nm particle diameter, respectively. The regional Mann-Kendall test yielded regional-scale trends of eBC mass concentration, N[30-200] and N[200-800] of -3.8%, -2.0% and -2.4%, respectively, indicating an overall decreasing trend for eBC mass concentration and sub-micrometer PNC (except N[10-30]) all over Germany. The most significant decrease was observed on working days and during daytime in urban areas, which implies a strong evidence of reduced anthropogenic emissions. For the seasonal trends, stronger reductions were observed in winter. Possible reasons for this reduction can be the increased average ambient temperatures and wind speed in winter, which resulted in less domestic heating and stronger dilution. In addition, decreased precipitation in summer also diminishes the decrease of the PNCs and eBC mass concentration. For the period of interest, there were no significant changes in long-range transport patterns. The most likely factors for the observed decreasing trends are declining anthropogenic emissions due to emission mitigation policies of the European Union. © Author(s) 2020Veröffentlichung Zugspitze ozone 1970-2020: the role of stratosphere-troposphere transport(2023) Trickl, Thomas; Couret, Cédric; Ries, Ludwig; Vogelmann, HannesThe pronounced increase in ozone observed at the Alpine station Zugspitze (2962 ma.s.l.) since the 1970s has been ascribed to an increase in stratospheric air descending to the Alps. In this paper, we present a reanalysis of the data from for both ozone (1978 to 2011) and carbon monoxide (1990-2011), which has been extended until 2020 by the data from the Global Atmosphere Watch site at the Umweltforschungsstation Schneefernerhaus (UFS; 2671 ma.s.l. - above sea level), which is located just below the Zugspitze summit. For ozone between 1970 and 1977, a constant annual average of 36.25 ppb (parts per billion) was assumed to have been obtained by extrapolation. The analysis is based on data filtering, utilizing the isotope 7Be (measured between 1970 and 2006) and relative humidity (1970 to 2011; UFS from 2002 to 2020). We estimate both the influence of stratospheric intrusions directly descending to the northern rim of the Alps from the full data filtering and the aged ("indirect") intrusions from applying a relationship between ozone and the 7Be data. The evaluated total stratospheric contribution to the annual average ozone rises roughly from 12 ppb in 1970 to 24 ppb in 2003. It turns out that the increase in the stratospheric influence is particularly strong in winter. A lowering in positive trend is seen afterwards, with a delay of roughly 1 decade after the beginning of the decrease in the solar irradiation. The air masses hitting the Zugspitze summit became drier until 2003, and we see the growing stratospheric contribution as being an important factor for this drying. Both an increase in the lower-stratospheric ozone and the growing thickness of the intruding layers departing downward from just above the tropopause must be taken into consideration. Carbon monoxide in the intrusions did not change much during the full measurement period from 1990 to 2020, with a slight increase until 2005. This is remarkable since, for air outside intrusions, a decrease by approximately 44 % was found, indicating a substantial improvement in the tropospheric air quality. © Author(s) 2023Veröffentlichung Decreasing trends of particle number and black carbon mass concentrations at 16 observational sites in Germany from 2009 to 2018(2020) Sun, Jia; Bath, Olaf; Birmili, Wolfram; Hermann, Markus; Gerwig, Holger; Ries, Ludwig; Schwerin, Andreas; Meinhardt, Frank; Sohmer, Ralf; Wirtz, KlausAnthropogenic emissions are a dominant contributor to air pollution. Consequently, mitigation policies have attempted to reduce anthropogenic pollution emissions in Europe since the 1990s. To evaluate the effectiveness of these mitigation policies, the German Ultrafine Aerosol Network (GUAN) was established in 2008, focusing on black carbon and sub-micrometer aerosol particles, especially ultrafine particles. In this investigation, trends of the size-resolved particle number concentrations (PNC) and the equivalent black carbon (eBC) mass concentration over a 10-year period (2009-2018) were evaluated for 16 observational sites for different environments among GUAN. The trend analysis was done for both, the full-length time series and on subsets of the time series in order to test the reliability of the results. The results show generally decreasing trends of both, the PNCs for all size ranges as well as eBC mass concentrations in all environments, except PNC in 10-30 nm at regional background and mountain sites. The annual slope of the eBC mass concentration varies between -7.7% and -1.8% per year. The slopes of the PNCs varies from -6.3% to 2.7%, -7.0% to -2.0%, and -9.5% to -1.5% per year (only significant trends) for 10-30 nm, 30-200 nm, and 200-800 nm particle diameter, respectively. The regional Mann-Kendall test yielded regional-scale trends of eBC mass concentration, N[30-200] and N[200-800] of -3.8%, -2.0% and -2.4%, respectively, indicating an overall decreasing trend for eBC mass concentration and sub-micrometer PNC (except N[10-30]) all over Germany. The most significant decrease was observed on working days and during daytime in urban areas, which implies a strong evidence of reduced anthropogenic emissions. For the seasonal trends, stronger reductions were observed in winter. Possible reasons for this reduction can be the increased average ambient temperatures and wind speed in winter, which resulted in less domestic heating and stronger dilution. In addition, decreased precipitation in summer also diminishes the decrease of the PNCs and eBC mass concentration. For the period of interest, there were no significant changes in long-range transport patterns. The most likely factors for the observed decreasing trends are declining anthropogenic emissions due to emission mitigation policies of the European Union. Quelle: https://www.atmos-chem-phys-discuss.net/Veröffentlichung Very high stratospheric influence observed in the free troposphere over the Northern Alps - just a local phenomenon?(2020) Trickl, Thomas; Ries, Ludwig; Vogelmann, HannesThe atmospheric composition is strongly influenced by a change in atmospheric dynamics, which is potentially related to climate change. A prominent example is the doubling of the stratospheric ozone component at the summit station Zugspitze (2962 m a.s.l., Garmisch-Partenkirchen, Germany) between the mid-seventies 15 and 2005, roughly from 11 ppb to 23 ppb (43 %). Systematic efforts for identifying and quantifying this influence have been made since the late 1990s. Meanwhile, routine lidar measurements of ozone and water vapour carried out at Garmisch-Partenkirchen (German Alps) since 2007, combined with in-situ and radiosonde data and trajectory calculations, have revealed that stratospheric intrusion layers are present on 84 % of the yearly measurement days. At Alpine summit stations the frequency of intrusions exhibits a seasonal cycle with a 20 pronounced summer minimum that is reproduced by the lidar measurements. The summer minimum disappears if one looks at the free troposphere as a whole. The mid- and upper-tropospheric intrusion layers seem to be dominated by very long descent on up to hemispheric scale in an altitude range starting at about 4.5 km a.s.l. Without interfering air flows, these layers remain very dry, typically with RH =< 5 % at the centre of the intrusion. Pronounced ozone maxima observed above Garmisch-Partenkirchen have been mostly related to a 25 stratospheric origin rather than to long-range transport from remote boundary layers. Our findings and results for other latitudes seem to support the idea of a rather high contribution of ozone import from the stratosphere to tropospheric ozone. Copyright: Author(s) 2019. CC BY 4.0 License