References

AMT

Atmospheric Measurement Techniques

AMT

Atmos. Meas. Tech.

1867-8548

Copernicus Publications

Göttingen, Germany

10.5194/amt-8-921-2015

The white-light humidified optical particle spectrometer (WHOPS) – a novel airborne system to characterize aerosol hygroscopicity

Rosati

https://orcid.org/0000-0003-4930-3638

¹ Wehrle

¹ Gysel

https://orcid.org/0000-0002-7453-1264

¹ Zieger

https://orcid.org/0000-0001-7000-6879

¹ ² Baltensperger

¹ Weingartner

https://orcid.org/0000-0002-2427-4634

¹ ³

Laboratory of Atmospheric Chemistry, Paul Scherrer Institute (PSI), 5232 Villigen, Switzerland

now at: Department of Applied Environmental Science, Stockholm University, 10691 Stockholm, Sweden

now at: Institute for Aerosol and Sensor Technology, University of Applied Science Northwestern Switzerland, 5210 Windisch, Switzerland

25 02 2015

8 2 921 939

2015

This work is licensed under the Creative Commons Attribution 3.0 Unported License. To view a copy of this licence, visit https://creativecommons.org/licenses/by/3.0/

This article is available from https://amt.copernicus.org/articles/8/921/2015/amt-8-921-2015.html

The full text article is available as a PDF file from https://amt.copernicus.org/articles/8/921/2015/amt-8-921-2015.pdf

Aerosol particles experience hygroscopic growth at enhanced relative humidity (RH), which leads to changes in their optical properties. We developed the white-light humidified optical particle spectrometer (WHOPS), a new instrument to investigate the particles' hygroscopic growth. Here we present a detailed technical description and characterization of the WHOPS in laboratory and field experiments. The WHOPS consists of a differential mobility analyzer, a humidifier/bypass and a white-light aerosol spectrometer (WELAS) connected in series to provide fast measurements of particle hygroscopicity at subsaturated RH and optical properties on airborne platforms. The WELAS employs a white-light source to minimize ambiguities in the optical particle sizing. In contrast to other hygroscopicity instruments, the WHOPS retrieves information of relatively large particles (i.e., diameter D > 280 nm), therefore investigating the more optically relevant size ranges. The effective index of refraction of the dry particles is retrieved from the optical diameter measured for size-selected aerosol samples with a well-defined dry mobility diameter. The data analysis approach for the optical sizing and retrieval of the index of refraction was extensively tested in laboratory experiments with polystyrene latex size standards and ammonium sulfate particles of different diameters. The hygroscopic growth factor (GF) distribution and aerosol mixing state is inferred from the optical size distribution measured for the size-selected and humidified aerosol sample. Laboratory experiments with pure ammonium sulfate particles revealed good agreement with Köhler theory (mean bias of ~3% and maximal deviation of 8% for GFs at RH = 95%). During first airborne measurements in the Netherlands, GFs (mean value of the GF distribution) at RH = 95% between 1.79 and 2.43 with a median of 2.02 were observed for particles with a dry diameter of 500 nm. This corresponds to hygroscopicity parameters (κ) between 0.25 and 0.75 with a median of 0.38. The GF distributions indicate externally mixed particles covering the whole range of GFs between ~1.0 and 3.0. On average, ~74% of the 500 nm particles had GFs > 1.5, ~15% had GF < 1.1 and the remaining ~1% showed values of 1.1 < GF < 1.5. The more hygroscopic mode sometimes peaked at GF > 2, indicating influence of sea-salt particles, consistent with previous ground-based particle hygroscopicity measurements in this area. The mean dry effective index of refraction for 500 nm particles was found to be rather constant with a value of 1.42 ± 0.04 (mean ± 1SD).

References 1

Andreae, M. O. and Rosenfeld, D.: Aerosol–cloud–precipitation interactions, Part 1. The nature and sources of cloud-active aerosols, Earth-Sci. Rev., 89, 13–41, <a href="http://dx.doi.org/10.1016/j.earscirev.2008.03.001">https://doi.org/10.1016/j.earscirev.2008.03.001</a>, 2008.

Bohren, C. F. and Huffman, D. R.: Absorption and Scattering of Light by Small Particles, Wiley-VCH Verlag GmbH, 530, 2007.

Després, V. R., Huffman, J. A., Burrows, S. M., Hoose, C., Safatov, A. S., Buryak, G., Fröhlich-Nowoisky, J., Elbert, W., Andreae, M. O., Pöschl, U., and Jaenicke, R.: Primary biological aerosol particles in the atmosphere: a review, Tellus B, 64, 15598, <a href="http://dx.doi.org/10.3402/tellusb.v64i0.15598">https://doi.org/10.3402/tellusb.v64i0.15598</a>, 2012.

Ebert, M., Weinbruch, S., Rausch, A., Gorzawski, G., Helas, G., Hoffmann, P., and Wex, H.: Complex refractive index of aerosols during LACE 2010; as derived from the analysis of individual particles, J. Geophys. Res.-Atmos., 107, 8121, <a href="http://dx.doi.org/10.1029/2000JD000195">https://doi.org/10.1029/2000JD000195</a>, 2002.

Fierz-Schmidhauser, R., Zieger, P., Wehrle, G., Jefferson, A., Ogren, J. A., Baltensperger, U., and Weingartner, E.: Measurement of relative humidity dependent light scattering of aerosols, Atmos. Meas. Tech., 3, 39–50, <a href="http://dx.doi.org/10.5194/amt-3-39-2010">https://doi.org/10.5194/amt-3-39-2010</a>, 2010.

Flores, J. M., Trainic, M., Borrmann, S., and Rudich, Y.: Effective broadband refractive index retrieval by a white light optical particle counter, Phys. Chem. Chem. Phys., 11, 7943–7950, 2009.

Gaigalas, A. K., Wang, L., and Choquette, S.: Measurement of scattering and absorption cross sections of microspheres for wavelengths between 240 <abbr>nm</abbr> and 800 <abbr>nm</abbr>, J. Res. Natl. Inst. Stan., 118, 1–14, 2013.

Gysel, M., Weingartner, E., Nyeki, S., Paulsen, D., Baltensperger, U., Galambos, I., and Kiss, G.: Hygroscopic properties of water-soluble matter and humic-like organics in atmospheric fine aerosol, Atmos. Chem. Phys., 4, 35–50, <a href="http://dx.doi.org/10.5194/acp-4-35-2004">https://doi.org/10.5194/acp-4-35-2004</a>, 2004.

Gysel, M., McFiggans, G.B., and Coe, H.: Inversion of tandem differential mobility analyser (TDMA) measurements, J. Aerosol Sci., 2, 134–151, 2009.

Hand, J. L. and Kreidenweis, S. M.: A new method for retrieving particle refractive index and effective density from aerosol size distribution data, Aerosol Sci. Tech., 10, 1012–1026, <a href="http://dx.doi.org/10.1080/02786820290092276">https://doi.org/10.1080/02786820290092276</a>, 2002.

Heim, M., Mullins, B. J., Umhauer, H., and Kasper, G.: Performance evaluation of three optical particle counters with an efficient "multimodal" calibration method, J. Aerosol Sci., 12, 1019–1031, 2008.

Herich, H., Tritscher, T., Wiacek, A., Gysel, M., Weingartner, E., Lohmann, U., Baltensperger, U., and Cziczo, D. J.: Water uptake of clay and desert dust aerosol particles at sub- and supersaturated water vapor conditions, Phys. Chem. Chem. Phys., 11, 7804–7809, <a href="http://dx.doi.org/10.1039/b901585j">https://doi.org/10.1039/b901585j</a>, 2009.

Kasarova, S. N., Sultanova, N. G., Ivanov, C. D., and Nikolov, I. D.: Analysis of the dispersion of optical plastic materials, Opt. Mater., 29, 1481–1490, <a href="http://dx.doi.org/10.1016/j.optmat.2006.07.010">https://doi.org/10.1016/j.optmat.2006.07.010</a>, 2007.

Kiselev, A., Wex, H., Stratmann, F., Nadeev, A., and Karpushenko, D.: White-light optical particle spectrometer for in situ measurements of condensational growth of aerosol particles, Appl. Optics, 44, 4693–4701, <a href="http://dx.doi.org/10.1364/AO.44.004693">https://doi.org/10.1364/AO.44.004693</a>, 2005.

Liu, B. Y. H., Pui, D. Y. H., Whitby, K. T., Kittelson, D. B., Kousaka, Y., and McKenzie, R. L.: Aerosol mobility chromatograph – new detector for sulfuric – acid aerosols, Atmos. Environ., 12, 99–104, <a href="http://dx.doi.org/10.1016/0004-6981(78)90192-0">https://doi.org/10.1016/0004-6981(78)90192-0</a>, 1978.

Ma, X., Lu, J. Q., Brock, R. S., Jacobs, K. M., Yang, P., and Hu, X.-H.: Determination of complex refractive index of polystyrene microspheres from 370 to 1610 <abbr>nm</abbr>, Phys. Med. Biol., 48, 4165, <a href="http://dx.doi.org/10.1088/0031-9155/48/24/013">https://doi.org/10.1088/0031-9155/48/24/013</a>, 2003.

Mahowald, N., Albani, S., Kok, J. F., Engelstaeder, S., Scanza, R., Ward, D. S., and Flanner, M. G.: The size distribution of desert dust aerosols and its impact on the Earth system, Aeolian Research, 15, 53–71, <a href="http://dx.doi.org/10.1016/j.aeolia.2013.09.002">https://doi.org/10.1016/j.aeolia.2013.09.002</a>, 2014.

Meyer, N. K., Duplissy, J., Gysel, M., Metzger, A., Dommen, J., Weingartner, E., Alfarra, M. R., Prevot, A. S. H., Fletcher, C., Good, N., McFiggans, G., Jonsson, Å. M., Hallquist, M., Baltensperger, U., and Ristovski, Z. D.: Analysis of the hygroscopic and volatile properties of ammonium sulphate seeded and unseeded SOA particles, Atmos. Chem. Phys., 9, 721–732, <a href="http://dx.doi.org/10.5194/acp-9-721-2009">https://doi.org/10.5194/acp-9-721-2009</a>, 2009.

Mie, G.: Beiträge zur Optik trüber Medien, speziell kolloidaler Metallösungen, Annalen der Physik, 3, 377–445, <a href="http://dx.doi.org/10.1002/andp.19083300302">https://doi.org/10.1002/andp.19083300302</a>, 1908.

Morgan, W. T., Allan, J. D., Bower, K. N., Esselborn, M., Harris, B., Henzing, J. S., Highwood, E. J., Kiendler-Scharr, A., McMeeking, G. R., Mensah, A. A., Northway, M. J., Osborne, S., Williams, P. I., Krejci, R., and Coe, H.: Enhancement of the aerosol direct radiative effect by semi-volatile aerosol components: airborne measurements in North-Western Europe, Atmos. Chem. Phys., 10, 8151–8171, <a href="http://dx.doi.org/10.5194/acp-10-8151-2010">https://doi.org/10.5194/acp-10-8151-2010</a>, 2010.

Petters, M. D. and Kreidenweis, S. M.: A single parameter representation of hygroscopic growth and cloud condensation nucleus activity, Atmos. Chem. Phys., 7, 1961–1971, <a href="http://dx.doi.org/10.5194/acp-7-1961-2007">https://doi.org/10.5194/acp-7-1961-2007</a>, 2007.

Pringle, K. J., Tost, H., Pozzer, A., Pöschl, U., and Lelieveld, J.: Global distribution of the effective aerosol hygroscopicity parameter for CCN activation, Atmos. Chem. Phys., 10, 5241–5255, <a href="http://dx.doi.org/10.5194/acp-10-5241-2010">https://doi.org/10.5194/acp-10-5241-2010</a>, 2010.

Rose, D., Wehner, B., Ketzel, M., Engler, C., Voigtländer, J., Tuch, T., and Wiedensohler, A.: Atmospheric number size distributions of soot particles and estimation of emission factors, Atmos. Chem. Phys., 6, 1021–1031, <a href="http://dx.doi.org/10.5194/acp-6-1021-2006">https://doi.org/10.5194/acp-6-1021-2006</a>, 2006.

Rubach, F.: Ph.D. thesis: Aerosol Processes in the Planetary Boundary Layer: High Resolution Aerosol Mass Spectrometry on a Zeppelin NT Airship, Doktorgrad, Fachbereich Mathematik und Naturwissenschaften, Bergische Universität Wuppertal, 147 pp., 2013.

Sjogren, S., Gysel, M., Weingartner, E., Baltensperger, U., Cubison, M. J., Coe, H., Zardini, A. A., Marcolli, C., Krieger, U. K., and Peter, T.: Hygroscopic growth and water uptake kinetics of two-phase aerosol particles consisting of ammonium sulfate, adipic and humic acid mixtures, J. Aerosol Sci., 38, 157–171, <a href="http://dx.doi.org/10.1016/j.jaerosci.2006.11.005">https://doi.org/10.1016/j.jaerosci.2006.11.005</a>, 2007.

Sorooshian, A., Hersey, S. P., Brechtel, F. J., Corless, A., Flagan, R. C., and Seinfeld, J. H.: Rapid, size-resolved aerosol hygroscopic growth measurements: differential aerosol sizing and hygroscopicity spectrometer probe (DASH-SP), Aerosol Sci. Tech., 42, 445–464, 2008.

Stock, M., Cheng, Y. F., Birmili, W., Massling, A., Wehner, B., Müller, T., Leinert, S., Kalivitis, N., Mihalopoulos, N., and Wiedensohler, A.: Hygroscopic properties of atmospheric aerosol particles over the Eastern Mediterranean: implications for regional direct radiative forcing under clean and polluted conditions, Atmos. Chem. Phys., 11, 4251–4271, <a href="http://dx.doi.org/10.5194/acp-11-4251-2011">https://doi.org/10.5194/acp-11-4251-2011</a>, 2011.

Stratmann, F., Kiselev, A., Wurzler, S., Wendisch, M., Heintzenberg, J., Charlson, R. J., Diehl, K., Wex, H., and Schmidt, S.: Laboratory studies and numerical simulations of cloud droplet formation under realistic supersaturation conditions, J. Atmos. Ocean. Tech., 21, 876–887, <a href="http://dx.doi.org/10.1175/1520-0426(2004)021<0876:LSANSO>2.0.CO;2">https://doi.org/10.1175/1520-0426(2004)021<0876:LSANSO>2.0.CO;2</a>, 2004.

Stull, R. B.: An Introduction to Boundary Layer Meteorology, Kluwer Academic Publisher, Vancouver, Canada, 673 pp., 1988.

Swietlicki, E., Hansson, H. C., Hameri, K., Svenningsson, B., Massling, A., McFiggans, G., McMurry, P. H., Petaja, T., Tunved, P., Gysel, M., Topping, D., Weingartner, E., Baltensperger, U., Rissler, J., Wiedensohler, A., and Kulmala, M.: Hygroscopic properties of submicrometer atmospheric aerosol particles measured with H-TDMA instruments in various environments – a review, Tellus B, 60, 432–469, <a href="http://dx.doi.org/10.1111/j.1600-0889.2008.00350.x">https://doi.org/10.1111/j.1600-0889.2008.00350.x</a>, 2008.

Toon, O. B., Pollack, J. B., and Khare, B. N.: Optical-constants of several atmospheric aerosol species – ammonium-sulfate, aluminum-oxide, and sodium-chloride, J. Geophys. Res.-Oceans, 81, 5733–5748, <a href="http://dx.doi.org/10.1029/JC081i033p05733">https://doi.org/10.1029/JC081i033p05733</a>, 1976.

Topping, D. O., McFiggans, G. B., and Coe, H.: A curved multi-component aerosol hygroscopicity model framework: Part 1 – Inorganic compounds, Atmos. Chem. Phys., 5, 1205–1222, <a href="http://dx.doi.org/10.5194/acp-5-1205-2005">https://doi.org/10.5194/acp-5-1205-2005</a>, 2005.

Tritscher, T., Juranyi, Z., Martin, M., Chirico, R., Gysel, M., Heringa, M. F., DeCarlo, P. F., Sierau, B., Prevot, A. S. H., Weingartner, E., and Baltensperger, U.: Changes of hygroscopicity and morphology during ageing of diesel soot, Environ. Res. Lett., 6, 034026, <a href="http://dx.doi.org/10.1088/1748-9326/6/3/034026">https://doi.org/10.1088/1748-9326/6/3/034026</a>, 2011.

Wiedensohler, A., Birmili, W., Nowak, A., Sonntag, A., Weinhold, K., Merkel, M., Wehner, B., Tuch, T., Pfeifer, S., Fiebig, M., Fjäraa, A. M., Asmi, E., Sellegri, K., Depuy, R., Venzac, H., Villani, P., Laj, P., Aalto, P., Ogren, J. A., Swietlicki, E., Williams, P., Roldin, P., Quincey, P., Hüglin, C., Fierz-Schmidhauser, R., Gysel, M., Weingartner, E., Riccobono, F., Santos, S., Grüning, C., Faloon, K., Beddows, D., Harrison, R., Monahan, C., Jennings, S. G., O'Dowd, C. D., Marinoni, A., Horn, H.-G., Keck, L., Jiang, J., Scheckman, J., McMurry, P. H., Deng, Z., Zhao, C. S., Moerman, M., Henzing, B., de Leeuw, G., Löschau, G., and Bastian, S.: Mobility particle size spectrometers: harmonization of technical standards and data structure to facilitate high quality long-term observations of atmospheric particle number size distributions, Atmos. Meas. Tech., 5, 657–685, <a href="http://dx.doi.org/10.5194/amt-5-657-2012">https://doi.org/10.5194/amt-5-657-2012</a>, 2012.

Zelenyuk, A., Cai, Y., and Imre, D.: From agglomerates of spheres to irregularly shaped particles: Determination of dynamic shape factors from measurements of mobility and vacuum aerodynamic diameters, Aerosol Sci. Tech., 40, 197–217, <a href="http://dx.doi.org/10.1080/02786820500529406">https://doi.org/10.1080/02786820500529406</a>, 2006.

Zieger, P., Weingartner, E., Henzing, J., Moerman, M., de Leeuw, G., Mikkilä, J., Ehn, M., Petäjä, T., Clémer, K., van Roozendael, M., Yilmaz, S., Frieß, U., Irie, H., Wagner, T., Shaiganfar, R., Beirle, S., Apituley, A., Wilson, K., and Baltensperger, U.: Comparison of ambient aerosol extinction coefficients obtained from in-situ, MAX-DOAS and LIDAR measurements at Cabauw, Atmos. Chem. Phys., 11, 2603–2624, <a href="http://dx.doi.org/10.5194/acp-11-2603-2011">https://doi.org/10.5194/acp-11-2603-2011</a>, 2011.

Zieger, P., Fierz-Schmidhauser, R., Weingartner, E., and Baltensperger, U.: Effects of relative humidity on aerosol light scattering: results from different European sites, Atmos. Chem. Phys., 13, 10609–10631, <a href="http://dx.doi.org/10.5194/acp-13-10609-2013">https://doi.org/10.5194/acp-13-10609-2013</a>, 2013.