Weingartner, Ernest

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Weingartner
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Ernest
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Weingartner, Ernest

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2013 - 2019392020 - 202312
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  • Vorschaubild
    Publikation
    A novel measurement system for unattended, in situ characterization of carbonaceous aerosols
    (Copernicus, 22.12.2023) Keller, Alejandro; Specht, Patrick; Steigmeier, Peter; Weingartner, Ernest [in: Aerosol Research]
    Carbonaceous aerosol is a relevant constituent of the atmosphere in terms of climate and health impacts. Nevertheless, measuring this component poses many challenges. There is currently no simple and sensitive commercial technique that can reliably capture its totality in an unattended manner, with minimal user intervention, for extended periods of time. To address this issue we have developed the fast thermal carbon totalizator (FATCAT). Our system captures an aerosol sample on a rigid metallic filter and subsequently analyses it by rapidly heating the filter directly, through induction, to a temperature around 800°C. The carbon in the filter is oxidized and quantified as CO2 in order to establish the total carbon (TC) content of the sample. The metallic filter is robust, which solves filter displacement or leakage problems, and does not require a frequent replacement like other measurement techniques. The limit of detection of our system using the 3σ criterion is TC =0.19 µg-C (micrograms of carbon). This translates to an average ambient concentration of TC =0.32 µg-C m^−3 and TC =0.16 µg-C m^−3 for sampling interval of 1 or 2 h respectively using a sampling flow rate of 10 L min^−1. We present a series of measurements using a controlled, well-defined propane flame aerosol as well as wood-burning emissions using two different wood-burning stoves. Furthermore, we complement these measurements by coating the particles with secondary organic matter by means of an oxidation flow reactor. Our device shows a good correlation (correlation coefficient, R^2>0.99) with well-established techniques, like mass measurements by means of a tapered element oscillating microbalance and TC measurements by means of thermal–optical transmittance analysis. Furthermore, the homogeneous fast-heating of the filter produces fast thermograms. This is a new feature that, to our knowledge, is exclusive of our system. The fast thermograms contain information regarding the volatility and refractoriness of the sample without imposing an artificial fraction separation like other measurement methods. Different aerosol components, like wood-burning emissions, soot from the propane flame and secondary organic matter, create diverse identifiable patterns.
    01A - Beitrag in wissenschaftlicher Zeitschrift
  • Vorschaubild
    Publikation
    Waveguide based passively demodulated photothermal interferometer for light absorption measurements of trace substances
    (Optica Publishing Group, 2023) Visser, Bradley; Bilal, Jonas; Flöry, Nikolaus; Wipf, Manuela; Steigmeier, Peter; Rüggeberg, Tobias; Betschon, Felix; Weingartner, Ernest [in: Applied Optics]
    01A - Beitrag in wissenschaftlicher Zeitschrift
  • Vorschaubild nicht verfügbar
    Publikation
    Interdisziplinäre Perspektiven zur Bedeutung der Aerosolübertragung für das Infektionsgeschehen von SARS-CoV-2
    (Thieme, 2022) Held, Andreas; Dellweg, Dominic; Köhler, Dieter; Pfaender, Stephanie; Scheuch, Gerhard; Schumacher, Stefan; Steinmann, Eike; Weingartner, Ernest; Weinzierl, Bernadett; Asbach, Christof [in: Das Gesundheitswesen]
    Die Bedeutung der Aerosolübertragung für das Severe Acute Respiratory Syndrome Coronavirus Type 2 (SARS-CoV-2) wurde anfangs kontrovers diskutiert. Mit der Zeit haben sich zur Infektionsminderung jedoch neben Abstands- und Hygieneregeln auch aerosolphysikalisch begründete Maßnahmen wie das Tragen von Gesichtsmasken und Lüftung von Innenräumen als effektiv erwiesen. In einem interdisziplinären Workshop „Aerosol & SARS-CoV-2“ der Gesellschaft für Aerosolforschung (GAeF) in Kooperation mit der Deutschen Gesellschaft für Pneumologie und Beatmungsmedizin (DGP), dem Fachverband Allgemeine Lufttechnik im VDMA, der Gesellschaft für Virologie (GfV), der Gesundheitstechnischen Gesellschaft (GG) und der International Society for Aerosols in Medicine (ISAM) unter der Schirmherrschaft des Robert-Koch-Instituts (RKI) im März 2021 wurde der Forschungs- und Abstimmungsbedarf zu diesem Thema aufgegriffen. Wesentliche Grundlagen aus den verschiedenen Disziplinen sowie interdisziplinäre Perspektiven zur Aerosolübertragung von SARS-CoV-2 und zu infektionsmindernden Maßnahmen werden hier zusammengefasst. Abschließend werden offene Forschungsfragen und dringender Forschungsbedarf dargestellt.
    01A - Beitrag in wissenschaftlicher Zeitschrift
  • Vorschaubild
    Publikation
    A dual-wavelength photothermal aerosol absorption monitor. Design, calibration and performance
    (Copernicus, 2022) Drinovec, Luka; Jagodič, Uroš; Pirker, Luka; Škarabot, Miha; Kurtjak, Mario; Vidović, Kristijan; Ferrero, Luca; Visser, Bradley; Röhrbein, Jannis; Weingartner, Ernest; Kalbermatter, Daniel M.; Vasilatou, Konstantina; Bühlmann, Tobias; Pascale, Celine; Müller, Thomas; Wiedensohler, Alfred; Močnik, Griša [in: Atmospheric Measurement Techniques]
    There exists a lack of aerosol absorption measurement techniques with low uncertainties and without artefacts. We have developed the two-wavelength Photothermal Aerosol Absorption Monitor (PTAAM-2λ), which measures the aerosol absorption coefficient at 532 and 1064 nm. Here we describe its design, calibration and mode of operation and evaluate its applicability, limits and uncertainties. The 532 nm channel was calibrated with ∼ 1 µmol mol−1 NO2, whereas the 1064 nm channel was calibrated using measured size distribution spectra of nigrosin particles and a Mie calculation. Since the aerosolized nigrosin used for calibration was dry, we determined the imaginary part of the refractive index of nigrosin from the absorbance measurements on solid thin film samples. The obtained refractive index differed considerably from the one determined using aqueous nigrosin solution. PTAAM-2λ has no scattering artefact and features very low uncertainties: 4 % and 6 % for the absorption coefficient at 532 and 1064 nm, respectively, and 9 % for the absorption Ångström exponent. The artefact-free nature of the measurement method allowed us to investigate the artefacts of filter photometers. Both the Aethalometer AE33 and CLAP suffer from cross sensitivity to scattering – this scattering artefact is most pronounced for particles smaller than 70 nm. We observed a strong dependence of the filter multiple scattering parameter on the particle size in the 100–500 nm range. The results from the winter ambient campaign in Ljubljana showed similar multiple scattering parameter values for ambient aerosols and laboratory experiments. The spectral dependence of this parameter resulted in AE33 reporting the absorption Ångström exponent for different soot samples with values biased 0.23–0.35 higher than the PTAAM-2λ measurement. Photothermal interferometry is a promising method for reference aerosol absorption measurements.
    01A - Beitrag in wissenschaftlicher Zeitschrift
  • Vorschaubild
    Publikation
    Comparing black carbon and aerosol absorption measuring instruments – a new system using lab-generated soot coated with controlled amounts of secondary organic matter
    (Copernicus, 2022) Kalbermatter, Daniel M.; Močnik, Griša; Drinovec, Luka; Visser, Bradley; Röhrbein, Jannis; Oscity, Matthias; Weingartner, Ernest; Hyvärinen, Antti-Pekka; Vasilatou, Konstantina [in: Atmospheric Measurement Techniques]
    We report on an inter-comparison of black-carbon- and aerosol-absorption-measuring instruments with laboratory-generated soot particles coated with controlled amounts of secondary organic matter (SOM). The aerosol generation setup consisted of a miniCAST 5201 Type BC burner for the generation of soot particles and a new automated oxidation flow reactor based on the micro smog chamber (MSC) for the generation of SOM from the ozonolysis of α-pinene. A series of test aerosols was generated with elemental to total carbon (EC / TC) mass fraction ranging from about 90 % down to 10 % and single-scattering albedo (SSA at 637 nm) from almost 0 to about 0.7. A dual-spot Aethalometer AE33, a photoacoustic extinctiometer (PAX, 870 nm), a multi-angle absorption photometer (MAAP), a prototype photoacoustic instrument, and two prototype photo-thermal interferometers (PTAAM-2λ and MSPTI) were exposed to the test aerosols in parallel. Significant deviations in the response of the instruments were observed depending on the amount of secondary organic coating. We believe that the setup and methodology described in this study can easily be standardised and provide a straightforward and reproducible procedure for the inter-comparison and characterisation of both filter-based and in situ black-carbon-measuring (BC-measuring) instruments based on realistic test aerosols.
    01A - Beitrag in wissenschaftlicher Zeitschrift
  • Vorschaubild
    Publikation
    Single aerosol particle detection by acoustic impaction
    (IEEE, 2022) Karlen, Nadine; Rüggeberg, Tobias; Visser, Bradley; Hoffmann, Jana; Weiss, Daniel; Weingartner, Ernest [in: IEEE Sensors Journal]
    01A - Beitrag in wissenschaftlicher Zeitschrift
  • Vorschaubild nicht verfügbar
    Publikation
    Employment of novel tools for the continuous characterization of the carbonaceous fraction in ambient aerosol
    (13.09.2021) Keller, Alejandro; Specht, Patrick; Steigmeier, Peter; Weingartner, Ernest
    06 - Präsentation
  • Vorschaubild nicht verfügbar
    Publikation
    Performance of the new continuous carbonaceous aerosol measurement system FATCAT during long term unattended measurement campaigns
    (23.06.2021) Keller, Alejandro; Specht, Patrick; Steigmeier, Peter; Weingartner, Ernest
    06 - Präsentation
  • Vorschaubild nicht verfügbar
    Publikation
    High resolution unattended particle-bound total carbon measurements and source identification at the Jungfraujoch global GAW station
    (18.05.2021) Keller, Alejandro; Specht, Patrick; Steigmeier, Peter; Weingartner, Ernest
    Total aerosol carbonaceous mass (TC) is a major constituent of atmospheric fine aerosol not yet continuously monitored with adequate time resolution. Adding a TC measurement to existing measurement programs is crucial for comprehensive interpretation of the impact of aerosols. To fill this gap, we developed the “fast thermal carbon totalizator” (FATCAT) for long-term unsupervised monitoring of TC. FATCAT has been deployed since 2019 at diverse sites including the Jungfraujoch global GAW station (JFJ). FATCAT collects particles on a metallic filter, and subsequently heats it to 800°C under an oxidizing atmosphere. The limit of detection is LoD=0.2 µg of carbon (µg-C). At the reduced atmospheric pressure of the JFJ, which limits the sampling flow, this corresponds to TC=0.3 µg-C/m3 using a time resolution of two hours. We discuss our experience during the first two year of continuous TC measurements and the possibility of using our instrument to distinguish carbonaceous aerosol from different source using fast, 50 seconds, thermograms. This unique feature allows us to identify source specific fingerprints. Several high TC episodes during September 2020 at JFJ show the typical pattern for biomass combustion. Back trajectories attribute them to long-range transported emissions from Californian wildfires. Graphitic carbon from, e.g., local fossil fuel combustion evolves at higher temperatures. The data collected at the JFJ is already the longest produced TC dataset for this site without instrument related interruptions. The dataset generated by our instrument and post-analysis data products represent an improvement to the available measurement inventory. It can serve as quality control for other measurement systems. Prominently, measurements of eBC via MAAP or Aethalometer and organic mass using ToF-ACSM. TC data can be used in parallel to these devices as a quality check, and to warrant carbon mass closure and reduce systematic biases.
    06 - Präsentation
  • Vorschaubild nicht verfügbar
    Publikation
    High resolution unattended particle-bound total carbon measurements and source identification at the Jungfraujoch global GAW station
    (2021) Keller, Alejandro; Specht, Patrick; Steigmeier, Peter; Weingartner, Ernest
    06 - Präsentation