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  1. Book ; Online ; Thesis: Airborne in situ measurements of ice particles in the tropical tropopause layer

    Frey, Wiebke

    2011  

    Author's details Wiebke Frey
    Language English
    Size Online-Ressource (Online-Ressource)
    Publisher Universitätsbibliothek Mainz
    Publishing place Mainz
    Document type Book ; Online ; Thesis
    Thesis / German Habilitation thesis Univ., Diss.--Mainz, 2011
    Database Former special subject collection: coastal and deep sea fishing

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  2. Book ; Online ; Thesis: Airborne in situ measurements of ice particles in the tropical tropopause layer

    Frey, Wiebke

    2011  

    Author's details Wiebke Frey
    Language English
    Size Online-Ressource (Online-Ressource)
    Publisher Universitätsbibliothek Mainz
    Publishing place Mainz
    Document type Book ; Online ; Thesis
    Thesis / German Habilitation thesis Univ., Diss.--Mainz, 2011
    Database Library catalogue of the German National Library of Science and Technology (TIB), Hannover

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  3. Book ; Online ; Thesis: Airborne in situ measurements of ice particles in the tropical tropopause layer

    Frey, Wiebke [Verfasser]

    2011  

    Author's details Wiebke Frey
    Keywords Geowissenschaften ; Earth Sciences
    Subject code sg550
    Language English
    Publisher Universitätsbibliothek Mainz
    Publishing place Mainz
    Document type Book ; Online ; Thesis
    Database Digital theses on the web

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  4. Book ; Online: Contactless optical hygrometry in LACIS-T

    Nowak, Jakub L. / Grosz, Robert / Frey, Wiebke / Niedermeier, Dennis / Mijas, Jędrzej / Malinowski, Szymon P. / Ort, Linda / Schmalfuß, Silvio / Stratmann, Frank / Voigtländer, Jens / Stacewicz, Tadeusz

    eISSN: 1867-8548

    2022  

    Abstract: The Fast Infrared Hygrometer (FIRH), employing open-path tunable diode laser absorption spectroscopy at the wavelengths near the 1364.6896 nm line, was adapted to perform contactless humidity measurements at the Turbulent Leipzig Aerosol Cloud ... ...

    Abstract The Fast Infrared Hygrometer (FIRH), employing open-path tunable diode laser absorption spectroscopy at the wavelengths near the 1364.6896 nm line, was adapted to perform contactless humidity measurements at the Turbulent Leipzig Aerosol Cloud Interaction Simulator (LACIS-T), a unique turbulent moist-air wind tunnel. The configuration of the setup allows for scanning from outside the walls of the wind tunnel and at various positions without the need for repeated optics adjustments. We identified three factors which significantly influence the measurement – self-broadening of the absorption line, interference in the glass windows and parasitic absorption in the ambient air outside the wind tunnel – and developed correction methods which satisfactorily account for these effects. The comparison between FIRH and a reference hygrometer (dew-point mirror MBW 973) indicated a good agreement within the expected errors across the wide range of water vapour concentration 1.0–6.1 ×10 17 cm −3 (equivalent to dew-point temperature of −5.4 to +21 ∘ C at the temperature of 23 ∘ C ). High temporal resolution ( ∼2 kHz ) allowed for studying turbulent fluctuations in the course of intensive mixing of two air streams which had the same mean velocity but differed in temperature and humidity, also including the settings for which the mixture can be supersaturated. The obtained results contribute to improved understanding and interpretation of cloud formation studies conducted in LACIS-T by complementing the previous characterizations of turbulent velocity and temperature fields inside the wind tunnel.
    Subject code 333
    Language English
    Publishing date 2022-07-12
    Publishing country de
    Document type Book ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  5. Article ; Online: Contactless optical hygrometry in LACIS-T

    Nowak, Jakub L. / Grosz, Robert / Frey, Wiebke / Niedermeier, Dennis / Mijas, Jędrzej / Malinowski, Szymon P. / Ort, Linda / Schmalfuß, Silvio / Stratmann, Frank / Voigtländer, Jens / Stacewicz, Tadeusz

    Atmospheric Measurement Techniques

    2022  Volume 15, Issue 13

    Abstract: The Fast Infrared Hygrometer (FIRH), employing open-path tunable diode laser absorption spectroscopy at the wavelengths near the 1364.6896 nm line, was adapted to perform contactless humidity measurements at the Turbulent Leipzig Aerosol Cloud ... ...

    Abstract The Fast Infrared Hygrometer (FIRH), employing open-path tunable diode laser absorption spectroscopy at the wavelengths near the 1364.6896 nm line, was adapted to perform contactless humidity measurements at the Turbulent Leipzig Aerosol Cloud Interaction Simulator (LACIS-T), a unique turbulent moist-air wind tunnel. The configuration of the setup allows for scanning from outside the walls of the wind tunnel and at various positions without the need for repeated optics adjustments.We identified three factors which significantly influence the measurement – self-broadening of the absorption line, interference in the glass windows and parasitic absorption in the ambient air outside the wind tunnel – and developed correction methods which satisfactorily account for these effects. The comparison between FIRH and a reference hygrometer (dew-point mirror MBW 973) indicated a good agreement within the expected errors across the wide range of water vapour concentration 1.0–6.1×1017 cm−3 (equivalent to dew-point temperature of −5.4 to +21 ∘C at the temperature of 23 ∘C).High temporal resolution (∼2 kHz) allowed for studying turbulent fluctuations in the course of intensive mixing of two air streams which had the same mean velocity but differed in temperature and humidity, also including the settings for which the mixture can be supersaturated. The obtained results contribute to improved understanding and interpretation of cloud formation studies conducted in LACIS-T by complementing the previous characterizations of turbulent velocity and temperature fields inside the wind tunnel.
    Keywords Life Science
    Subject code 600
    Language English
    Publishing country nl
    Document type Article ; Online
    ZDB-ID 2505596-3
    ISSN 1867-8548 ; 1867-1381
    ISSN (online) 1867-8548
    ISSN 1867-1381
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  6. Article ; Online: The efficiency of secondary organic aerosol particles acting as ice-nucleating particles under mixed-phase cloud conditions

    Frey, Wiebke / Hu, Dawei / Dorsey, James / Rami Alfarra, M. / Pajunoja, Aki / Virtanen, Annele / Connolly, Paul / McFiggans, Gordon

    Atmospheric Chemistry and Physics

    2018  Volume 18, Issue 13

    Abstract: Secondary organic aerosol (SOA) particles have been found to be efficient ice-nucleating particles under the cold conditions of (tropical) upper-tropospheric cirrus clouds. Whether they also are efficient at initiating freezing under slightly warmer ... ...

    Abstract Secondary organic aerosol (SOA) particles have been found to be efficient ice-nucleating particles under the cold conditions of (tropical) upper-tropospheric cirrus clouds. Whether they also are efficient at initiating freezing under slightly warmer conditions as found in mixed-phase clouds remains undetermined. Here, we study the ice-nucleating ability of photochemically produced SOA particles with the combination of the Manchester Aerosol Chamber and Manchester Ice Cloud Chamber. Three SOA systems were tested resembling biogenic and anthropogenic particles as well as particles of different phase state. These are namely α-pinene, heptadecane, and 1,3,5-trimethylbenzene. After the aerosol particles were formed, they were transferred into the cloud chamber, where subsequent quasi-adiabatic cloud activation experiments were performed. Additionally, the ice-forming abilities of ammonium sulfate and kaolinite were investigated as a reference to test the experimental setup. Clouds were formed in the temperature range of −20 to −28.6 °C. Only the reference experiment using dust particles showed evidence of ice nucleation. No ice particles were observed in any other experiment. Thus, we conclude that SOA particles produced under the conditions of the reported experiments are not efficient ice-nucleating particles starting at liquid saturation under mixed-phase cloud conditions.
    Keywords Life Science
    Subject code 540
    Language English
    Publishing country nl
    Document type Article ; Online
    ISSN 1680-7316
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  7. Article ; Online: Porous aerosol in degassing plumes of Mt. Etna and Mt. Stromboli

    Shcherbakov, Valery / Jourdan, Olivier / Voigt, Christiane / Gayet, Jean Francois / Chauvigne, Aurélien / Schwarzenboeck, Alfons / Minikin, Andreas / Klingebiel, Marcus / Weigel, Ralf / Borrmann, Stephan / Jurkat, Tina / Kaufmann, Stefan / Schlage, Romy / Gourbeyre, Christophe / Febvre, Guy / Lapyonok, Tatyana / Frey, Wiebke / Molleker, Sergej / Weinzierl, Bernadett

    Atmospheric Chemistry and Physics

    2016  Volume 16, Issue 18

    Abstract: Aerosols of the volcanic degassing plumes from Mt. Etna and Mt. Stromboli were probed with in situ instruments on board the Deutsches Zentrum für Luft-und Raumfahrt research aircraft Falcon during the contrail, volcano, and cirrus experiment CONCERT in ... ...

    Abstract Aerosols of the volcanic degassing plumes from Mt. Etna and Mt. Stromboli were probed with in situ instruments on board the Deutsches Zentrum für Luft-und Raumfahrt research aircraft Falcon during the contrail, volcano, and cirrus experiment CONCERT in September 2011. Aerosol properties were analyzed using angular-scattering intensities and particle size distributions measured simultaneously with the Polar Nephelometer and the Forward Scattering Spectrometer probes (FSSP series 100 and 300), respectively. Aerosols of degassing plumes are characterized by low values of the asymmetry parameter (between 0.6 and 0.75); the effective diameter was within the range of 1.5-2.8μm and the maximal diameter was lower than 20μm. A principal component analysis applied to the Polar Nephelometer data indicates that scattering features of volcanic aerosols of different crater origins are clearly distinctive from angular-scattering intensities of cirrus and contrails. Retrievals of aerosol properties revealed that the particles were "optically spherical" and the estimated values of the real part of the refractive index are within the interval from 1.35 to 1.38. The interpretation of these results leads to the conclusion that the degassing plume aerosols were porous with air voids. Our estimates suggest that aerosol particles contained about 18 to 35% of air voids in terms of the total volume.
    Keywords Life Science
    Language English
    Publishing country nl
    Document type Article ; Online
    ISSN 1680-7316
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  8. Article ; Online: In situ and lidar observations of tropopause subvisible cirrus clouds during TC4

    Davis, Sean / Hlavka, Dennis / Jensen, Eric / Rosenlof, Karen / Yang, Qiong / Schmidt, Sebastian / Borrmann, Stephan / Frey, Wiebke / Lawson, Paul / Voemel, Holger / Bui, T.P.

    Journal of Geophysical Research: Atmospheres

    2010  Volume 115, Issue D10

    Abstract: During the Tropical Composition, Clouds, and Climate Coupling (TC4) experiment in July-August 2007, the NASA WB-57F and ER-2 aircraft made coordinated flights through a tropopause subvisible cirrus (SVC) layer off the Pacific Coast of Central America. ... ...

    Abstract During the Tropical Composition, Clouds, and Climate Coupling (TC4) experiment in July-August 2007, the NASA WB-57F and ER-2 aircraft made coordinated flights through a tropopause subvisible cirrus (SVC) layer off the Pacific Coast of Central America. The ER-2 aircraft was equipped with a remote sensing payload that included the cloud physics lidar (CPL). The WB-57F payload included cloud microphysical and trace gas measurements, and the aircraft made four vertical profiles through the SVC layer shortly after the ER-2 flew over. The in situ and remotely sensed data are used to quantify the meteorological and microphysical properties of the SVC layer, and these data are compared to the limited set of SVC measurements that have previously been made. It is found that the layer encountered was particularly tenuous, with optical depths (τ) between about 10-4 and 10-3. From the in situ and other meteorological data, radiative heating rate perturbations of ∼0.05-0.1 K day-1 are calculated. These heating rates are smaller than previous estimates for tropopause SVC, consistent with the smaller τ in the present study. Coverage statistics based on CPL data from other TC4 flights indicate that this cloud was not an outlier among the sampled population. SVC with properties similar to the one presented here are below the detection limit of space-based lidars such as CALIPSO, and a comparison with the TC4 statistics suggests that a majority (>50%) of tropopause SVC (with τ < 0.01) could be unaccounted for in studies using CALIPSO data.
    Keywords Life Science
    Subject code 551
    Language English
    Publishing country nl
    Document type Article ; Online
    ZDB-ID 710256-2
    ISSN 2169-8996 ; 2169-897X ; 0148-0227
    ISSN (online) 2169-8996
    ISSN 2169-897X ; 0148-0227
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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    In stock of ZB MED Bonn / Germany

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  9. Article: In situ measurements of tropical cloud properties in the West African Monsoon: upper tropospheric ice clouds, Mesoscale Convective System outflow, and subvisual cirrus

    Frey, Wiebke / Borrmann, Stephan / Kunkel, Daniel / Weigel, Ralf / Reus, Marian de / Schlager, Hans / Roiger, Anke / Voigt, Christiane / Hoor, Peter / Curtius, Joachim / Krämer, M. / Schiller, Cornelius / Volk, C.-Michael / Homan, Carine Dorianne / Fierli, Federico / Di Donfrancesco, Guido / Ulanovsky, Alexey / Ravegnani, Fabrizio / Sitnikov, Nicolay M. /
    Viciani, Silvia / D'Amato, F. / Shur, Genrikh N. / Belyaev, Gennady / Law, Kathy S. / Cairo, Francesco

    Abstract: In situ measurements of ice crystal size distributions in tropical upper troposphere/lower stratosphere (UT/LS) clouds were performed during the SCOUT-AMMA campaign over West Africa in August 2006. The cloud properties were measured with a Forward ... ...

    Abstract In situ measurements of ice crystal size distributions in tropical upper troposphere/lower stratosphere (UT/LS) clouds were performed during the SCOUT-AMMA campaign over West Africa in August 2006. The cloud properties were measured with a Forward Scattering Spectrometer Probe (FSSP-100) and a Cloud Imaging Probe (CIP) operated aboard the Russian high altitude research aircraft M-55 Geophysica with the mission base in Ouagadougou, Burkina Faso. A total of 117 ice particle size distributions were obtained from the measurements in the vicinity of Mesoscale Convective Systems (MCS). Two to four modal lognormal size distributions were fitted to the average size distributions for different potential temperature bins. The measurements showed proportionately more large ice particles compared to former measurements above maritime regions. With the help of trace gas measurements of NO, NOy, CO2, CO, and O3 and satellite images, clouds in young and aged MCS outflow were identified. These events were observed at altitudes of 11.0 km to 14.2 km corresponding to potential temperature levels of 346 K to 356 K. In a young outflow from a developing MCS ice crystal number concentrations of up to (8.3 ± 1.6) cm−3 and rimed ice particles with maximum dimensions exceeding 1.5 mm were found. A maximum ice water content of 0.05 g m−3 was observed and an effective radius of about 90 μm. In contrast the aged outflow events were more diluted and showed a maximum number concentration of 0.03 cm−3, an ice water content of 2.3 × 10−4 g m−3, an effective radius of about 18 μm, while the largest particles had a maximum dimension of 61 μm.Close to the tropopause subvisual cirrus were encountered four times at altitudes of 15 km to 16.4 km. The mean ice particle number concentration of these encounters was 0.01 cm−3 with maximum particle sizes of 130 μm, and the mean ice water content was about 1.4 × 10−4 g m−3. All known in situ measurements of subvisual tropopause cirrus are compared and an exponential fit on the size distributions is established for modelling purposes.A comparison of aerosol to ice crystal number concentrations, in order to obtain an estimate on how many ice particles may result from activation of the present aerosol, yielded low ratios for the subvisual cirrus cases of roughly one cloud particle per 30 000 aerosol particles, while for the MCS outflow cases this resulted in a high ratio of one cloud particle per 300 aerosol particles.
    Language English
    Document type Article
    Database AGRIS - International Information System for the Agricultural Sciences and Technology

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