Auflistung nach Autor:in "Meinhardt, Frank"

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Adaptive selection of diurnal minimum variation: a statistical strategy to obtain representative atmospheric CO2 data and its application to European elevated mountain stations
(2018) Yuan, Ye; Couret, Cédric; Petermeier, Hannes; Ries, Ludwig; Meinhardt, Frank
Critical data selection is essential for determining representative baseline levels of atmospheric trace gases even at remote measurement sites. Different data selection techniques have been used around the world, which could potentially lead to reduced compatibility when comparing data from different stations. This paper presents a novel statistical data selection method named adaptive diurnal minimum variation selection (ADVS) based on CO2 diurnal patterns typically occurring at elevated mountain stations. Its capability and applicability were studied on records of atmospheric CO2 observations at six Global Atmosphere Watch stations in Europe, namely, Zugspitze-Schneefernerhaus (Germany), Sonnblick (Austria), Jungfraujoch (Switzerland), Izanã (Spain), Schauinsland (Germany), and Hohenpeissenberg (Germany). Three other frequently applied statistical data selection methods were included for comparison. Among the studied methods, our ADVS method resulted in a lower fraction of data selected as a baseline with lower maxima during winter and higher minima during summer in the selected data. The measured time series were analyzed for long-term trends and seasonality by a seasonal-trend decomposition technique. In contrast to unselected data, mean annual growth rates of all selected datasets were not significantly different among the sites, except for the data recorded at Schauinsland. However, clear differences were found in the annual amplitudes as well as the seasonal time structure. Based on a pairwise analysis of correlations between stations on the seasonal-trend decomposed components by statistical data selection, we conclude that the baseline identified by the ADVS method is a better representation of lower free tropospheric (LFT) conditions than baselines identified by the other methods. © Author(s) 2018.
Aerosol signature size distributions: comparison of different clustering methods applied to data from the German Ultrafine Aerosol Network (GUAN)
(2021) Lazemi, Leila; Bath, Olaf; Birmili, Wolfram; Gerwig, Holger; Meinhardt, Frank; Ries, Ludwig; Schwerin, Andreas; Wirtz, Klaus
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, Klaus
Anthropogenic 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/
Intercomparison of 15 aerodynamic particle size spectrometers (APS 3321): uncertainties in particle sizing and number size distribution
(2016) Pfeifer, Sascha; Müller, Thomas; Weinhold, Kay; Ries, Ludwig; Meinhardt, Frank
Aerodynamic particle size spectrometers are a well-established method to measure number size distributions of coarse mode particles in the atmosphere. Quality assurance is essential for atmospheric observational aerosol networks to obtain comparable results with known uncertainties. In a laboratory study within the framework of ACTRIS (Aerosols, Clouds, and Trace gases Research Infrastructure Network), 15 aerodynamic particle size spectrometers (APS model 3321, TSI Inc., St. Paul, MN, USA) were compared with a focus on flow rates, particle sizing, and the unit-to-unit variability of the particle number size distribution. Flow rate deviations were relatively small (within a few percent), while the sizing accuracy was found to be within 10?% compared to polystyrene latex (PSL) reference particles. The unit-to-unit variability in terms of the particle number size distribution during this study was within 10?% to 20?% for particles in the range of 0.9 up to 3 Nano-m, which is acceptable for atmospheric measurements. For particles smaller than that, the variability increased up to 60?%, probably caused by differences in the counting efficiencies of individual units. Number size distribution data for particles smaller than 0.9?Ţm in aerodynamic diameter should only be used with caution. For particles larger than 3?Ţm, the unit-to-unit variability increased as well. A possible reason is an insufficient sizing accuracy in combination with a steeply sloping particle number size distribution and the increasing uncertainty due to decreasing counting. Particularly this uncertainty of the particle number size distribution must be considered if higher moments of the size distribution such as the particle volume or mass are calculated, which require the conversion of the aerodynamic diameter measured to a volume equivalent diameter. In order to perform a quantitative quality assurance, a traceable reference method for the particle number concentration in the size range 0.5-3 Nano-m is needed. Quelle: http://www.atmos-meas-tech.net
Inverse modelling of European CH4 emissions during 2006-2012 using different inverse models and reassessed atmospheric observations
(2018) Bergamaschi, Peter; Karstens, Ute; Manning, Alistair J.; Meinhardt, Frank
Klimagasmessungen an der Station Schauinsland und im Messnetz des Umweltbundesamtes
(2014) Meinhardt, Frank
Klimagasmessungen im UBA-Luftmessnetz - internationale Einbettung und Beitrag für die Klimaforschung
(2015) Meinhardt, Frank
Long-term observations of tropospheric particle number size distributions and equivalent black carbon mass concentrations in the German Ultrafine Aerosol Network (GUAN)
(2016) Weinhold, Kay; Bath, Olaf; Rasch, Fabian; Birmili, Wolfram; Sonntag, Andre; Sun, Jia; Merkel, Maik; Wiedensohler, Alfred; Gerwig, Holger; Bastian, Susanne; Schladitz, Alexander; Löschau, Gunter; Cyrys, Josef; Pitz, Mike; Gu, Jianwei; Kusch, Thomas; Flentje, Harald; Quass, Ulrich; Kaminski, Heinz; Kuhlbusch, Thomas A.J.; Ries, Ludwig; Meinhardt, Frank; Schwerin, Andreas; Fiebig, Markus; Wirtz, Klaus
The German Ultrafine Aerosol Network (GUAN) is a cooperative atmospheric observation network, which aims at improving the scientific understanding of aerosol-related effects in the troposphere. The network addresses research questions dedicated to both climate- and health-related effects. GUAN's core activity has been the continuous collection of tropospheric particle number size distributions and black carbon mass concentrations at 17 observation sites in Germany. These sites cover various environmental settings including urban traffic, urban background, rural background, and Alpine mountains. In association with partner projects, GUAN has implemented a high degree of harmonisation of instrumentation, operating procedures, and data evaluation procedures. The quality of the measurement data is assured by laboratory intercomparisons as well as on-site comparisons with reference instruments. This paper describes the measurement sites, instrumentation, quality assurance, and data evaluation procedures in the network as well as the EBAS repository, where the data sets can be obtained. Quelle: http://www.earth-syst-sci-data.net
On the diurnal, weekly, and seasonal cycles and annual trends in atmospheric CO2 at Mount Zugspitze, Germany, during 1981-2016
(2019) Yuan, Ye; Couret, Cédric; Petermeier, Hannes; Ries, Ludwig; Sohmer, Ralf; Meinhardt, Frank
A continuous, 36-year measurement composite of atmospheric carbon dioxide (CO2) at three measurement locations on Mount Zugspitze, Germany, was studied. For a comprehensive site characterization of Mount Zugspitze, analyses of CO2 weekly periodicity and diurnal cycle were performed to provide evidence for local sources and sinks, showing clear weekday to weekend differences, with dominantly higher CO2 levels during the daytime on weekdays. A case study of atmospheric trace gases (CO and NO) and the passenger numbers to the summit indicate that CO2 sources close by did not result from tourist activities but instead obviously from anthropogenic pollution in the near vicinity. Such analysis of local effects is an indispensable requirement for selecting representative data at orographic complex measurement sites. The CO2 trend and seasonality were then analyzed by background data selection and decomposition of the long-term time series into trend and seasonal components. The mean CO2 annual growth rate over the 36-year period at Zugspitze is 1:8+/-0:4 ppm yr-1, which is in good agreement with Mauna Loa station and global means. The peak-to-trough amplitude of the mean CO2 seasonal cycle is 12:4+/-0:6 ppm at Mount Zugspitze (after data selection: 10:5+/-0:5 ppm), which is much lower than at nearby measurement sites at Mount Wank (15:9+/-1:5 ppm) and Schauinsland (15:9+/-1:0 ppm), but following a similar seasonal pattern. © Author(s) 2019.
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, Klaus
Anthropogenic 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) 2020
The fingerprint of the summer 2018 drought in Europe on ground-based atmospheric CO2 measurements
(2020) Ramonet, Michel; Ciais, Philippe; Apadula, F.; Meinhardt, Frank
During the summer of 2018, a widespread drought developed over Northern and Central Europe. The increase in temperature and the reduction of soil moisture have influenced carbon dioxide (CO2) exchange between the atmosphere and terrestrial ecosystems in various ways, such as a reduction of photosynthesis, changes in ecosystem respiration, or allowing more frequent fires. In this study, we characterize the resulting perturbation of the atmospheric CO2 seasonal cycles. 2018 has a good coverage of European regions affected by drought, allowing the investigation of how ecosystem flux anomalies impacted spatial CO2 gradients between stations. This density of stations is unprecedented compared to previous drought events in 2003 and 2015, particularly thanks to the deployment of the Integrated Carbon Observation System (ICOS) network of atmospheric greenhouse gas monitoring stations in recent years. Seasonal CO2 cycles from 48 European stations were available for 2017 and 2018. Earlier data were retrieved for comparison from international databases or national networks. Here, we show that the usual summer minimum in CO2 due to the surface carbon uptake was reduced by 1.4 ppm in 2018 for the 10 stations located in the area most affected by the temperature anomaly, mostly in Northern Europe. Notwithstanding, the CO2 transition phases before and after July were slower in 2018 compared to 2017, suggesting an extension of the growing season, with either continued CO2 uptake by photosynthesis and/or a reduction in respiration driven by the depletion of substrate for respiration inherited from the previous months due to the drought. For stations with sufficiently long time series, the CO2 anomaly observed in 2018 was compared to previous European droughts in 2003 and 2015. Considering the areas most affected by the temperature anomalies, we found a higher CO2 anomaly in 2003 (+3 ppm averaged over 4 sites), and a smaller anomaly in 2015 (+1 ppm averaged over 11 sites) compared to 2018. © 2020 The Author(s)
Trends of climate forcing Gases at selected Sites in Europe and Worldwide
(2013) Ries, Ludwig; Meinhardt, Frank; Bath, Olaf
Trends of tropospheric black carbon and sub-(micro)m particle number concentration in the German Ultrafine Aerosol Network (GUAN), 2009-2014
(2015) Sun, Jia; Birmili, Wolfram; Weinhold, Kay; Rasch, Fabian; Sonntag, Andre; Wiedensohler, Alfred; Cyrys, Josef; Felntje, Harald; Löschau, Gunter; Bastian, Susanne; Schladitz, Alexander; Meinhardt, Frank; Bath, Olaf; Schwerin, Andreas; Ries, Ludwig; Gerwig, Holger; Wirtz, Klaus
Ultrafeine Partikel und Ruß
(2017) Birmili, Wolfram; Schwerin Andreas; Sun, Jia; Weinhold, Kay; Rasch, Fabian; Meinhardt, Frank; Bath, Olaf; Ries, Ludwig; Gerwig, Holger; Wirtz, Klaus
Ultrafeine Partikel und Ruß in Deutschland
(2016) Birmili, Wolfram; Weinhold, Kay; Rasch, Fabian; Sonntag, Andre; Sun, Jia; Merkel, Maik; Wiedensohler, Alfred; Bastian, Susanne; Schladitz, Alexander; Löschau, Gunter; Cyrys, Josef; Pitz, Mike; Gu, Jianwei; Kusch, Thomas; Flentje, Harald; Quass, Ulrich; Kaminski, Heinz; Kuhlbusch, Thomas A.J.; Meinhardt, Frank; Schwerin, Andreas; Bath, Olaf; Ries, Ludwig; Gerwig, Holger; Wirtz, Klaus; Fiebig, Markus
Variability of black carbon mass concentrations, sub-micrometer particle number concentrations and size distributions: results of the German Ultrafine Aerosol Network ranging from city street to high alpine locations
(2019) Sun, Junying; Birmili, Wolfram; Gerwig, Holger; Hermann, Markus; Ries, Ludwig; Schwerin, Andreas; Sohmer, Ralf; Meinhardt, Frank; Wirtz, Klaus
This work reports the first statistical analysis of multi-annual data on tropospheric aerosols from the German Ultrafine Aerosol Network (GUAN). Compared to other networks worldwide, GUAN with 17 measurement locations has the most sites equipped with particle number size distribution (PNSD) and equivalent black carbon (eBC) instruments and the most site categories in Germany ranging from city street/roadside to High Alpine. As we know, the variations of eBC and particle number concentration (PNC) are influenced by several factors such as source, transformation, transport and deposition. The dominant controlling factor for different pollutant parameters might be varied, leading to the different spatio-temporal variations among the measured parameters. Currently, a study of spatio-temporal variations of PNSD and eBC considering the influences of both site categories and spatial scale is still missing. Based on the multi-site dataset of GUAN, the goal of this study is to investigate how pollutant parameters may interfere with spatial characteristics and site categories. © 2019 The Authors