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45 results on '"KRISTENSEN, T. B."'

1. THE GLOBAL AEROSOL SYNTHESIS AND SCIENCE PROJECT (GASSP) : Measurements and Modeling to Reduce Uncertainty

Author

Reddington, C. L., Carslaw, K. S., Stier, P., Schutgens, N., Coe, H., Liu, D., Allan, J., Browse, J., Pringle, K. J., Lee, L. A., Yoshioka, M., Johnson, J. S., Regayre, L. A., Spracklen, D. V., Mann, G. W., Clarke, A., Hermann, M., Henning, S., Wex, H., Kristensen, T. B., Leaitch, W. R., Pöschl, U., Rose, D., Andreae, M. O., Schmale, J., Kondo, Y., Oshima, N., Schwarz, J. P., Nenes, A., Anderson, B., Roberts, G. C., Snider, J. R., Leck, C., Quinn, P. K., Chi, X., Ding, A., Jimenez, J. L., and Zhang, Q.

Published
2017

2. THE SAHARAN AEROSOL LONG-RANGE TRANSPORT AND AEROSOL–CLOUD-INTERACTION EXPERIMENT : Overview and Selected Highlights

Author

Weinzierl, Bernadett, Ansmann, A., Prospero, J. M., Althausen, D., Benker, N., Chouza, F., Dollner, M., Farrell, D., Fomba, W. K., Freudenthaler, V., Gasteiger, J., Groß, S., Haarig, M., Heinold, B., Kandler, K., Kristensen, T. B., Mayol-Bracero, O. L., Müller, T., Reitebuch, O., Sauer, D., Schäfler, A., Schepanski, K., Spanu, A., Tegen, I., Toledano, C., and Walser, A.

Published
2017

3. SUPPLEMENT : THE SAHARAN AEROSOL LONG-RANGE TRANSPORT AND AEROSOL–CLOUD-INTERACTION EXPERIMENT Overview and Selected Highlights

Author

Weinzierl, Bernadett, Ansmann, A., Prospero, J. M., Althausen, D., Benker, N., Chouza, F., Dollner, M., Farrell, D., Fomba, W. K., Freudenthaler, V., Gasteiger, J., Groß, S., Haarig, M., Heinold, B., Kandler, K., Kristensen, T. B., Mayol-Bracero, O. L., Müller, T., Reitebuch, O., Sauer, D., Schäfler, A., Schepanski, K., Spanu, A., Tegen, I., Toledano, C., and Walser, A.

Published
2017

5. Effects of surface tension time-evolution for CCN activation of a complex organic surfactant

Author

Lin, J. J. (Jack J.), Kristensen, T. B. (Thomas B.), Calderón, S. M. (Silvia M.), Malila, J. (Jussi), and Prisle, N. L. (Nønne L.)

Subjects
complex mixtures
Abstract

The physical processes and time scales underlying the evolution of surface tension in atmospheric solution droplets are largely unaccounted for in present models describing cloud droplet formation. Adsorption of surface-active molecules at the surface of a solution droplet depresses the droplet surface tension but also depletes solute from the droplet bulk, which have opposing and sometimes canceling effects in cloud droplet formation. In this work, we study the effect of time-evolving surface tension for cloud droplet activation of particles composed of Nordic Aquatic Fulvic Acid (NAFA) mixed with sodium chloride (NaCl). We model the formation of cloud droplets using Köhler theory with surface tension depression and bulk/surface partitioning evaluated from two different thermodynamic surface models. Continuous ternary parameterizations were constructed from surface tension measurements of macroscopic droplets at different time steps after the formation of a droplet surface. The predicted results are compared to previous measurements of mixed NAFA–NaCl cloud condensation nuclei (CCN) activity and a bulk solution model that does not take the NAFA bulk/surface partitioning equilibrium into account. Whereas the bulk model shows a trend in cloud droplet formation following that of macroscopic surface tension depression with time, the variation with time essentially disappears when bulk/surface partitioning is taken explicitly into account during droplet activation. For all equilibrium time steps considered, the effect of surface tension depression in the NAFA–NaCl system is counteracted by the depletion of solute from the finite-sized droplet bulk phase. Our study highlights that a comprehensive data set is necessary to obtain continuous parameterizations of surface tension and other solution properties required to fully account for the bulk/surface partitioning in growing droplets. To our knowledge, no similar data set currently exists for other aqueous organic systems of atmospheric interest. Additional work is necessary to deconvolve the effects of bulk/surface partitioning in the context of time-evolution on cloud droplet activation and to determine whether the results presented here can be further generalized. Environmental significance The time-evolution of aqueous surface tension is a well-known result of partitioning of surface-active compounds from the bulk to the surface. Surfactants are ubiquitous components of atmospheric organic aerosol. Equilibration time scales potentially impact interpretation of all measurements of cloud condensation nuclei (CCN) activity and modeled effects taking surface tension into account, including closure studies between instruments with different residence times and analysis using κ-Köhler theory. Using continuous surface tension parameterizations at different times, we provide a thermodynamically consistent analysis of the impact of time-dependency for predictions of CCN activity. We show that although time-evolution is clearly seen in surface partitioning, its signature decreases in droplet surface tension and we find no trends in CCN activity with time.

Published
2020

6. Observation of viscosity transition in a-pinene secondary organic aerosol

Author

Järvinen E., Ignatius K., Nichman L., Kristensen T. B., Fuchs C., Hoyle C. R., Höppel N., Corbin J. C., Craven J., Duplissy J., Ehrhart S., El Haddad I., Frege C., Gordon H., Jokinen T., Kallinger P., Kirkby J., Kiselev A., Naumann K. H., Petäjä T., Pinterich T., Prevot A. S. H., Saathoff H., Schiebel T., and Sengupta K.

Published
2016

10. Discrimination of water, ice and aerosols by light polarisation in the CLOUD experiment

Author

Nichman, L., Fuchs, C., Jaervinen, E., Ignatius, K., Hoppel, N. F., Dias, A., Heinritzi, M., Simon, M., Trostl, J., Wagner, A. C., Wagner, R., Williamson, C., Yan, C., Bianchi, F., Connolly, P. J., Dorsey, J. R., Duplissy, J., Ehrhart, S., Frege, C., Gordon, H., Hoyle, C. R., Kristensen, T. B., Steiner, G., Donahue, N. M., Flagan, R., Gallagher, M. W., Kirkby, J., Mohler, O., Saathoff, H., Schnaiter, M., Stratmann, F., and Tome, A.

Published
2015

11. The SPectrometer for Ice Nuclei (SPIN): a new instrument to investigate ice nucleation

Author

Garimella, Sarvesh, Ardon-Dryer, K., Dorsey, J., Ignatius, K., Kirchgaessner, A., Kok, G., Kristensen, T. B., Ladkin, R., Nichman, L., Roesch, M., Sagan, F., Stratmann, F., Wex, H., Wilson, T. W., and Cziczo, D. J.

Subjects
Astrophysics::Earth and Planetary Astrophysics, Physics::Atmospheric and Oceanic Physics
Abstract

The SPectrometer for Ice Nuclei (SPIN) is a new commercially available ice nuclei counter manufactured by Droplet Measurement Technologies in Boulder, CO. SPIN is a continuous flow diffusion chamber with parallel plate geometry similar to the Zurich Ice Nucleation Chamber (ZINC) (Stetzer et al., 2007) and Portable Ice Nuclei Chamber (PINC) (Chou et al., 2011). It creates supersaturation conditions by coating two parallel plates with ice, holding them at different temperatures (both below 0ºC), and flowing an aerosol stream in the center of a sheath flow between the walls. After flowing through the main chamber, the air stream enters an isothermal evaporation section to evaporate liquid droplets. It then passes through a linear depolarization optical particle counter for particle, droplet, and ice counting. The instrument can be operated at aerosol temperatures as low as -55ºC and ice supersaturations exceeding 60%. This study characterizes the behavior of the SPIN chamber and reports data that validate its performance. In particular, ammonium sulfate experiments are used to compare the deliquescence and homogeneous freezing points reported by SPIN to literature values. Also, silver iodide and NX illite particles are used to investigate the heterogeneous ice nucleation onset conditions (with an ice fraction of 1%) for comparison to literature., American Meteorological Society Annual Meeting, 6-11 January, 2014, Boston, MA, USA

Published
2014

12. Characterization of humic-like substances in Arctic aerosols

Author

Nguyen, Q. T., Kristensen, T. B., Hansen, A. M. K., Skov, H., Bossi, R., Massling, A., Sorensen, L. L., Bilde, M., Glasius, M., and Nojgaard, J. K.

Subjects
HULIS Arctic brown carbon light absorption aerosol mass SOLUBLE ORGANIC-COMPOUNDS TANDEM MASS-SPECTROMETRY SIZE-EXCLUSION CHROMATOGRAPHY MOLECULAR-WEIGHT DISTRIBUTION FINE ATMOSPHERIC AEROSOL BIOMASS-BURNING AEROSOLS ELECTROSPRAY-IONIZATION CHEMICAL-COMPOSITION OPTICAL-PROPERTIES FULVIC-ACIDS
Abstract

Humic-like substances (HULIS) are a complex group of relatively high molecular weight organic compounds which contribute considerably to the mass of organic carbon (OC) and influence the light-absorbing properties of aerosols. In this work, HULIS were investigated for the first time in the high-Arctic atmosphere, focusing on the chemical characterization and mass contribution of HULIS to the total suspended particle (TSP) mass using weekly aerosol samples collected at Station Nord, northeast Greenland every fourth week during 2010. Average HULIS-C concentration was 11ng C m(-3) during the darker months (November-April) and 4ng C m(-3) during the other months (May-October) with an annual mass concentration of 0.020.01 mu gm(-3). HULIS-C contributed to 3-16% of water-soluble organic carbon (WSOC), whereas HULIS accounted for 0.7-4.1% of TSP mass, with TSP typically below 1.0 mu gm(-3). Concentrations of OC, WSOC, HULIS, selected HULIS functional groups (carboxylic acids, aromatic carboxylic acids, and organosulfates) and levoglucosan overlapped with the typical Arctic haze pattern with elevated concentrations during winter to early spring. The aromatic carboxylic acid portion accounted for a larger share of total carboxylic acid of HULIS during the darker months (7%) compared to the brighter months (3%). The more abundant aromatic carboxylic acid functional groups and the moderate correlation between HULIS and levoglucosan concentrations during the darker months both indicate that biomass burning aerosols and thereby emissions of aromatic compounds could contribute to HULIS in the Arctic, especially during late winter. During the brighter months, relatively higher average molecular weight of HULIS was observed.

Published
2014

13. Aqueous phase oxidation of sulphur dioxide by ozone in cloud droplets

Author

Hoyle, C. R., primary, Fuchs, C., additional, Järvinen, E., additional, Saathoff, H., additional, Dias, A., additional, El Haddad, I., additional, Gysel, M., additional, Coburn, S. C., additional, Tröstl, J., additional, Bernhammer, A.-K., additional, Bianchi, F., additional, Breitenlechner, M., additional, Corbin, J. C., additional, Craven, J., additional, Donahue, N. M., additional, Duplissy, J., additional, Ehrhart, S., additional, Frege, C., additional, Gordon, H., additional, Höppel, N., additional, Heinritzi, M., additional, Kristensen, T. B., additional, Molteni, U., additional, Nichman, L., additional, Pinterich, T., additional, Prévôt, A. S. H., additional, Simon, M., additional, Slowik, J. G., additional, Steiner, G., additional, Tomé, A., additional, Vogel, A. L., additional, Volkamer, R., additional, Wagner, A. C., additional, Wagner, R., additional, Wexler, A. S., additional, Williamson, C., additional, Winkler, P. M., additional, Yan, C., additional, Amorim, A., additional, Dommen, J., additional, Curtius, J., additional, Gallagher, M. W., additional, Flagan, R. C., additional, Hansel, A., additional, Kirkby, J., additional, Kulmala, M., additional, Möhler, O., additional, Stratmann, F., additional, Worsnop, D. R., additional, and Baltensperger, U., additional

Published
2016
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14. The SPectrometer for Ice Nuclei (SPIN): An instrument to investigate ice nucleation

Author

Garimella, S., primary, Kristensen, T. B., additional, Ignatius, K., additional, Welti, A., additional, Voigtländer, J., additional, Kulkarni, G. R., additional, Sagan, F., additional, Kok, G. L., additional, Dorsey, J., additional, Nichman, L., additional, Rothenberg, D., additional, Rösch, M., additional, Kirchgäßner, A., additional, Ladkin, R., additional, Wex, H., additional, Wilson, T. W., additional, Ladino, L. A., additional, Abbatt, J. P. D., additional, Stetzer, O., additional, Lohmann, U., additional, Stratmann, F., additional, and Cziczo, D. J., additional

Published
2016
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16. Heterogeneous ice nucleation of viscous secondary organic aerosol produced from ozonolysis of α-pinene

Author

Ignatius, K., primary, Kristensen, T. B., additional, Järvinen, E., additional, Nichman, L., additional, Fuchs, C., additional, Gordon, H., additional, Herenz, P., additional, Hoyle, C. R., additional, Duplissy, J., additional, Garimella, S., additional, Dias, A., additional, Frege, C., additional, Höppel, N., additional, Tröstl, J., additional, Wagner, R., additional, Yan, C., additional, Amorim, A., additional, Baltensperger, U., additional, Curtius, J., additional, Donahue, N. M., additional, Gallagher, M. W., additional, Kirkby, J., additional, Kulmala, M., additional, Möhler, O., additional, Saathoff, H., additional, Schnaiter, M., additional, Tomé, A., additional, Virtanen, A., additional, Worsnop, D., additional, and Stratmann, F., additional

Published
2015
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17. Aqueous phase oxidation of sulphur dioxide by ozone in cloud droplets

Author

Hoyle, C. R., primary, Fuchs, C., additional, Järvinen, E., additional, Saathoff, H., additional, Dias, A., additional, El Haddad, I., additional, Gysel, M., additional, Coburn, S. C., additional, Tröstl, J., additional, Bernhammer, A.-K., additional, Bianchi, F., additional, Breitenlechner, M., additional, Corbin, J. C., additional, Craven, J., additional, Donahue, N. M., additional, Duplissy, J., additional, Ehrhart, S., additional, Frege, C., additional, Gordon, H., additional, Höppel, N., additional, Heinritzi, M., additional, Kristensen, T. B., additional, Molteni, U., additional, Nichman, L., additional, Pinterich, T., additional, Prévôt, A. S. H., additional, Simon, M., additional, Slowik, J. G., additional, Steiner, G., additional, Tomé, A., additional, Vogel, A. L., additional, Volkamer, R., additional, Wagner, A. C., additional, Wagner, R., additional, Wexler, A. S., additional, Williamson, C., additional, Winkler, P. M., additional, Yan, C., additional, Amorim, A., additional, Dommen, J., additional, Curtius, J., additional, Gallagher, M. W., additional, Flagan, R. C., additional, Hansel, A., additional, Kirkby, J., additional, Kulmala, M., additional, Möhler, O., additional, Stratmann, F., additional, Worsnop, D., additional, and Baltensperger, U., additional

Published
2015
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18. Discrimination of water, ice and aerosols by light polarisation in the CLOUD experiment

Author

Nichman, L., primary, Fuchs, C., additional, Järvinen, E., additional, Ignatius, K., additional, Höppel, N. F., additional, Dias, A., additional, Heinritzi, M., additional, Simon, M., additional, Tröstl, J., additional, Wagner, A. C., additional, Wagner, R., additional, Williamson, C., additional, Yan, C., additional, Bianchi, F., additional, Connolly, P. J., additional, Dorsey, J. R., additional, Duplissy, J., additional, Ehrhart, S., additional, Frege, C., additional, Gordon, H., additional, Hoyle, C. R., additional, Kristensen, T. B., additional, Steiner, G., additional, Donahue, N. M., additional, Flagan, R., additional, Gallagher, M. W., additional, Kirkby, J., additional, Möhler, O., additional, Saathoff, H., additional, Schnaiter, M., additional, Stratmann, F., additional, and Tomé, A., additional

Published
2015
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19. Supplementary material to "Discrimination of water, ice and aerosols by light polarisation in the CLOUD experiment"

Author

Nichman, L., primary, Fuchs, C., additional, Järvinen, E., additional, Ignatius, K., additional, Höppel, N. F., additional, Dias, A., additional, Heinritzi, M., additional, Simon, M., additional, Tröstl, J., additional, Wagner, A. C., additional, Wagner, R., additional, Williamson, C., additional, Yan, C., additional, Bianchi, F., additional, Connolly, P. J., additional, Dorsey, J. R., additional, Duplissy, J., additional, Ehrhart, S., additional, Frege, C., additional, Gordon, H., additional, Hoyle, C. R., additional, Kristensen, T. B., additional, Steiner, G., additional, Donahue, N. M., additional, Flagan, R., additional, Gallagher, M. W., additional, Kirkby, J., additional, Möhler, O., additional, Saathoff, H., additional, Schnaiter, M., additional, Stratmann, F., additional, and Tomé, A., additional

Published
2015
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21. Observation of viscosity transition in α-pinene secondary organic aerosol

Author

Järvinen, E., primary, Ignatius, K., additional, Nichman, L., additional, Kristensen, T. B., additional, Fuchs, C., additional, Höppel, N., additional, Corbin, J. C., additional, Craven, J., additional, Duplissy, J., additional, Ehrhart, S., additional, El Haddad, I., additional, Frege, C., additional, Gates, S. J., additional, Gordon, H., additional, Hoyle, C. R., additional, Jokinen, T., additional, Kallinger, P., additional, Kirkby, J., additional, Kiselev, A., additional, Naumann, K.-H., additional, Petäjä, T., additional, Pinterich, T., additional, Prevot, A. S. H., additional, Saathoff, H., additional, Schiebel, T., additional, Sengupta, K., additional, Simon, M., additional, Tröstl, J., additional, Virtanen, A., additional, Vochezer, P., additional, Vogt, S., additional, Wagner, A. C., additional, Wagner, R., additional, Williamson, C., additional, Winkler, P. M., additional, Yan, C., additional, Baltensperger, U., additional, Donahue, N. M., additional, Flagan, R. C., additional, Gallagher, M., additional, Hansel, A., additional, Kulmala, M., additional, Stratmann, F., additional, Worsnop, D. R., additional, Möhler, O., additional, Leisner, T., additional, and Schnaiter, M., additional

Published
2015
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24. Klimaforandringers betydning for søer

Author

Jeppesen, E., Christoffersen, K., Kamp-Nielsen, L., Landkildehus, F., Lauridsen, T. L., Kristensen, T. B., Liboriussen, L., Meerhoff, M., Pedersen, Asger Roer, Søndergaard, M., Søndergaard, M., Kronvang., B., Pejrup, M. og Sand-Jensen, K. (red.), Kronvang. B., Pejrup, and M. og Sand-Jensen, K.

Published
2006

30. Heterogeneous ice nucleation of viscous secondary organic aerosol produced from ozonolysis of α-pinene.

Author

Ignatius, K., Kristensen, T. B., Järvinen, E., Nichman, L., Fuchs, C., Gordon, H., Herenz, P., Hoyle, C. R., Duplissy, J., Garimella, S., Dias, A., Frege, C., Höppel, N., Tröstl, J., Wagner, R., Yan, C., Amorim, A., Baltensperger, U., Curtius, J., and Donahue, N. M.

Abstract

There are strong indications that particles containing secondary organic aerosol (SOA) exhibit amorphous solid or semi-solid phase states in the atmosphere. This may facilitate deposition ice nucleation and thus influence cirrus cloud properties. However, experimental ice nucleation studies of biogenic SOA are scarce. Here, we investigated the ice nucleation ability of viscous SOA particles. The SOA particles were produced from the ozone initiated oxidation of a-pinene in an aerosol chamber at temperatures in the range from -38 to -10 °C at 5-15 % relative humidity with respect to water to ensure their formation in a highly viscous phase state, i.e. semi-solid or glassy. The ice nucleation ability of SOA particles with different sizes was investigated with a new continuous flow diffusion chamber. For the first time, we observed heterogeneous ice nucleation of viscous a-pinene SOA in the deposition mode for ice saturation ratios between 1.3 and 1.4 significantly below the homogeneous freezing limit. The maximum frozen fractions found at temperatures between -36.5 and -38.3 °C ranged from 6 to 20 % and did not depend on the particle surface area. Global modelling of monoterpene SOA particles suggests that viscous biogenic SOA particles are indeed present in regions where cirrus cloud formation takes place. Hence, they could make up an important contribution to the global ice nuclei (IN) budget. [ABSTRACT FROM AUTHOR]

Published
2015
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31. Properties of cloud condensation nuclei (CCN) in the trade wind marine boundary layer of the Eastern Caribbean Sea.

Author

Kristensen, T. B., Müller, T., Kandler, K., Benker, N., Hartmann, M., Prospero, J. M., Wiedensohler, A., and Stratmann, F.

Abstract

Cloud optical properties in the trade winds over the Eastern Caribbean Sea have been shown to be sensitive to cloud condensation nuclei (CCN) concentrations. The objective of the current study was to investigate the CCN properties in the marine boundary layer (MBL) in the Eastern Caribbean, in order to assess the respective roles of organic species, long-range transported mineral dust, and sea salt particles. Measurements were carried out in June-July 2013, on the East Coast of Barbados and included CCN number concentrations, particle number size distributions, as well as off-line analysis of sampled particulate matter (PM) and sampled accumulation mode particles for an investigation of composition and mixing state with transmission electron microscopy (TEM) in combination with energy-dispersive X-ray spectroscopy (EDX). During most of the campaign, significant mass concentrations of long-range transported mineral dust was present in the PM, and influence from local island sources can be ruled out. The CCN and particle number concentrations were similar to what can be expected in pristine marine environments. The hygroscopicity paramete was inferred, and values in the range 0.2-0.5 were found during most of the campaign, with similar values for the Aitken and the accumulation mode. The accumulation mode particles studied with TEM were dominated by non-refractory material, and concentrations of mineral dust, sea salt, and soot were too small to influence the CCN properties. It is highly likely that the CCN were dominated by a mixture of sulphate species and organic compounds. [ABSTRACT FROM AUTHOR]

Published
2015
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32. Observation of viscosity transition in α-pinene secondary organic aerosol.

Author

Järvinen, E., Ignatius, K., Nichman, L., Kristensen, T. B., Fuchs, C., Höppel, N., Corbin, J. C., Craven, J., Duplissy, J., Ehrhart, S., El Haddad, I., Frege, C., Gates, S. J., Gordon, H., Hoyle, C. R., Jokinen, T., Kallinger, P., Kirkby, J., Kiselev, A., and Naumann, K.-H.

Abstract

Under certain conditions, secondary organic aerosol (SOA) particles can exist in the atmosphere in an amorphous solid or semi-solid state. To determine their relevance to processes such as ice nucleation or chemistry occurring within particles requires knowledge of the temperature and relative humidity (RH) range for SOA to exist in these states. In the CLOUD experiment at CERN, we deployed a new in-situ optical method to detect the viscosity of α-pinene SOA particles and measured their transition from the amorphous viscous to liquid state. The method is based on the depolarising properties of laboratory-produced non-spherical SOA particles and their transformation to non-depolarising spherical liquid particles during deliquescence. We found that particles formed and grown in the chamber developed an asymmetric shape through coagulation. A transition to spherical shape was observed as the RH was increased to between 35% at -10 °C and 80% at -38 °C, confirming previous calculations of the viscosity transition conditions. Consequently, α-pinene SOA particles exist in a viscous state over a wide range of ambient conditions, including the cirrus region of the free troposphere. This has implications for the physical, chemical and ice-nucleation properties of SOA and SOA-coated particles in the atmosphere. [ABSTRACT FROM AUTHOR]

Published
2015
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34. Observation of viscosity transition in α-pinene secondary organic aerosol

Author

Järvinen, E., Ignatius, K., Nichman, L., Kristensen, T. B., Fuchs, C., Höppel, N., Corbin, J. C., Craven, J., Duplissy, J., Ehrhart, S., El Haddad, I., Frege, C., Gates, S. J., Gordon, H., Hoyle, C. R., Jokinen, T., Kallinger, P., Kirkby, J., Kiselev, A., Naumann, K.-H., Petäjä, T., Pinterich, T., Prevot, A. S. H., Saathoff, H., Schiebel, T., Sengupta, K., Simon, M., Tröstl, J., Virtanen, A., Vochezer, P., Vogt, S., Wagner, A. C., Wagner, R., Williamson, C., Winkler, P. M., Yan, C., Baltensperger, U., Donahue, N. M., Flagan, R. C., Gallagher, M., Hansel, A., Kulmala, M., Stratmann, F., Worsnop, D. R., Möhler, O., Leisner, T., and Schnaiter, M.

Subjects
13. Climate action, Computer Science::Software Engineering, Physics::Atmospheric and Oceanic Physics
Abstract

Under certain conditions, secondary organic aerosol (SOA) particles can exist in the atmosphere in an amorphous solid or semi-solid state. To determine their relevance to processes such as ice nucleation or chemistry occurring within particles requires knowledge of the temperature and relative humidity (RH) range for SOA to exist in these states. In the CLOUD experiment at CERN, we deployed a new in-situ optical method to detect the viscosity of α-pinene SOA particles and measured their transition from the amorphous viscous to liquid state. The method is based on the depolarising properties of laboratory-produced non-spherical SOA particles and their transformation to non-depolarising spherical liquid particles during deliquescence. We found that particles formed and grown in the chamber developed an asymmetric shape through coagulation. A transition to spherical shape was observed as the RH was increased to between 35 % at −10 °C and 80 % at −38 °C, confirming previous calculations of the viscosity transition conditions. Consequently, α-pinene SOA particles exist in a viscous state over a wide range of ambient conditions, including the cirrus region of the free troposphere. This has implications for the physical, chemical and ice-nucleation properties of SOA and SOA-coated particles in the atmosphere.

36. A detailed characterisation of HULIS from different environments

Author

Kristensen, T. B., Wex, H., Du, L., Quynh Nguyen, Jacob Klenø Nøjgaard, Nekat, B., Pinxteren, D., Bender Koch, C., Dieckman, K., Lowenthal, D. H., Mazzoleni, L., Mentel, T. F., Marianne Glasius, Herrmann, H., Kjaergaard, H. G., Haller, A. G., Stratmann, F., and Merete Bilde

38. Klimaforandringers betydning for søer

Author

Jeppesen, E., Christoffersen, K., Kamp-Nielsen, L., Landkildehus, F., Torben Lauridsen, Kristensen, T. B., Liboriussen, L., Meerhoff, M., Asger Roer Pedersen, Søndergaard, M., Martin Søndergaard, Kronvang, B., Og Sand-Jensen Pejrup, M., and K. (red.)

39. Aqueous phase oxidation of sulphur dioxide by ozone in cloud droplets

Author

Hoyle, C. R., Fuchs, C., Jarvinen, E., Saathoff, H., Dias, A., El Haddad, I., Gysel, M., Coburn, S. C., Trostl, J., Hansel, A., Bianchi, F., Breitenlechner, M., Corbin, J. C., Craven, J., Donahue, N. M., Duplissy, J., Ehrhart, S., Frege, C., Gordon, H., Hoppel, N., Heinritzi, M., Kristensen, T. B., Molteni, U., Nichman, L., Pinterich, T., Prevôt, A. S. H., Simon, M., Slowik, J. G., Steiner, G., Tome, A., Vogel, A. L., Volkamer, R., Wagner, A. C., Wagner, R., Wexler, A. S., Williamson, C., Winkler, P. M., Yan, C., Amorim, A., Dommen, J., Curtius, J., Gallagher, M. W., Flagan, R. C., Kirkby, J., Kulmala, M., Mohler, O., Stratmann, F., Worsnop, D. R., and Baltensperger, U.

Subjects
13. Climate action, complex mixtures
Abstract

The growth of aerosol due to the aqueous phase oxidation of sulfur dioxide by ozone was measured in laboratory-generated clouds created in the Cosmics Leaving OUtdoor Droplets (CLOUD) chamber at the European Organization for Nuclear Research (CERN). Experiments were performed at 10 and -10° C, on acidic (sulfuric acid) and on partially to fully neutralised (ammonium sulfate) seed aerosol. Clouds were generated by performing an adiabatic expansion – pressurising the chamber to 220 hPa above atmospheric pressure, and then rapidly releasing the excess pressure, resulting in a cooling, condensation of water on the aerosol and a cloud lifetime of approximately 6 min. A model was developed to compare the observed aerosol growth with that predicted using oxidation rate constants previously measured in bulk solutions. The model captured the measured aerosol growth very well for experiments performed at 10 and -10° C, indicating that, in contrast to some previous studies, the oxidation rates of SO$_{2}$ in a dispersed aqueous system can be well represented by using accepted rate constants, based on bulk measurements. To the best of our knowledge, these are the first laboratory-based measurements of aqueous phase oxidation in a dispersed, supercooled population of droplets. The measurements are therefore important in confirming that the extrapolation of currently accepted reaction rate constants to temperatures below 0° C is correct.

41. Microalbuminuria in obesity.

Author

Løkkegaard N, Haupter I, and Kristensen TB

Subjects
Adult, Body Mass Index, Female, Glomerular Filtration Rate physiology, Humans, Kidney physiopathology, Male, Middle Aged, Organ Size physiology, Albuminuria urine, Kidney Function Tests, Obesity urine
Abstract

Albumin excretion rate, glomerular filtration rate (GFR) and kidney volume in obese patients and normal-weight controls were compared with body mass index (weight (kg)/height2 (m)) in 17 subjects. Body mass index varied from 21.5 to 48.0, the albumin excretion rate from 2.8 to 17.8 micrograms/min, and the kidney volume from 238 to 468 ml. Body mass index correlated significantly with albumin excretion rate and with kidney volume (p < 0.01), but not with the GFR. Neither the body mass index nor the albumin excretion rate showed any correlation with blood pressure. Albumin excretion rate in obese subjects could be as good an early predictor of complications as it is in patients with diabetes mellitus, and in the elderly.

Published
1992
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42. [Ankle fractures].

Author

KRISTENSEN TB

Subjects
Humans, Ankle, Ankle Fractures, Fractures, Bone
Published
1955

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