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<front>
<journal-meta>
<journal-id journal-id-type="publisher">ACP</journal-id>
<journal-title-group>
<journal-title>Atmospheric Chemistry and Physics</journal-title>
<abbrev-journal-title abbrev-type="publisher">ACP</abbrev-journal-title>
</journal-title-group>
<issn pub-type="epub">1680-7324</issn>
<publisher><publisher-name>Copernicus GmbH</publisher-name>
<publisher-loc>Göttingen, Germany</publisher-loc>
</publisher>
</journal-meta>
<article-meta>
<article-id pub-id-type="doi">10.5194/acp-11-11335-2011</article-id>
<title-group>
<article-title>Cloud condensation nuclei closure study on summer arctic aerosol</article-title>
</title-group>
<contrib-group><contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Martin</surname>
<given-names>M.</given-names>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Chang</surname>
<given-names>R. Y.-W.</given-names>
</name>
<xref ref-type="aff" rid="aff2">
<sup>2</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Sierau</surname>
<given-names>B.</given-names>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Sjogren</surname>
<given-names>S.</given-names>
</name>
<xref ref-type="aff" rid="aff3">
<sup>3</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Swietlicki</surname>
<given-names>E.</given-names>
</name>
<xref ref-type="aff" rid="aff3">
<sup>3</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Abbatt</surname>
<given-names>J. P. D.</given-names>
</name>
<xref ref-type="aff" rid="aff2">
<sup>2</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Leck</surname>
<given-names>C.</given-names>
</name>
<xref ref-type="aff" rid="aff4">
<sup>4</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Lohmann</surname>
<given-names>U.</given-names>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
</contrib>
</contrib-group><aff id="aff1">
<label>1</label>
<addr-line>Institute for Atmospheric and Climate Science, ETH Zurich, Zurich, Switzerland</addr-line>
</aff>
<aff id="aff2">
<label>2</label>
<addr-line>Department of Chemistry, University of Toronto, Toronto, Canada</addr-line>
</aff>
<aff id="aff3">
<label>3</label>
<addr-line>Division of Nuclear Physics, Lund University, Lund, Sweden</addr-line>
</aff>
<aff id="aff4">
<label>4</label>
<addr-line>Department of Meteorology, Stockholm University, Stockholm, Sweden</addr-line>
</aff>
<pub-date pub-type="epub">
<day>16</day>
<month>11</month>
<year>2011</year>
</pub-date>
<volume>11</volume>
<issue>22</issue>
<fpage>11335</fpage>
<lpage>11350</lpage>
<permissions>
<license xlink:type="simple">
<license-p>This is an open-access article ditributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.</license-p>
</license>
</permissions>
<self-uri xlink:href="http://www.atmos-chem-phys.net/11/11335/2011/acp-11-11335-2011.html">This article is available from http://www.atmos-chem-phys.net/11/11335/2011/acp-11-11335-2011.html</self-uri>
<self-uri xlink:href="http://www.atmos-chem-phys.net/11/11335/2011/acp-11-11335-2011.pdf">The full text article is available as a PDF file from http://www.atmos-chem-phys.net/11/11335/2011/acp-11-11335-2011.pdf</self-uri>
<abstract>
<p>We present an aerosol – cloud condensation nuclei (CCN) closure study
on summer high Arctic aerosol based on measurements that were carried out in
2008 during the Arctic Summer Cloud Ocean Study (ASCOS) on board the Swedish
ice breaker &lt;i&gt;Oden&lt;/i&gt;. The data presented here were collected during a
three-week time period in the pack ice (&gt;85&amp;deg; N) when the
icebreaker &lt;i&gt;Oden&lt;/i&gt; was moored to an ice floe and drifted passively
during the most biological active period into autumn freeze up conditions.
&lt;br&gt;&lt;br&gt;
CCN number concentrations were obtained using two CCN counters
measuring at different supersaturations. The directly measured CCN
number concentration was then compared with a CCN number concentration
calculated using both bulk aerosol mass composition data from an aerosol mass
spectrometer (AMS) and aerosol number size distributions obtained from a
differential mobility particle sizer, assuming κ-Köhler theory,
surface tension of water and an internally mixed aerosol. The last assumption
was supported by measurements made with a hygroscopic tandem differential
mobility analyzer (HTDMA) for particles &gt;70 nm.
&lt;br&gt;&lt;br&gt;
For the two highest measured supersaturations, 0.73 and 0.41%, closure
could not be achieved with the investigated settings concerning
hygroscopicity and density. The calculated CCN number concentration was
always higher than the measured one for those two supersaturations. This
might be caused by a relative larger insoluble organic mass fraction of the
smaller particles that activate at these supersaturations, which are thus
less good CCN than the larger particles. On average, 36% of the mass
measured with the AMS was organic mass. At 0.20, 0.15 and 0.10%
supersaturation, closure could be achieved with different combinations of
hygroscopic parameters and densities within the uncertainty range of the fit.
The best agreement of the calculated CCN number concentration with the
observed one was achieved when the organic fraction of the aerosol was
treated as nearly water insoluble (&amp;kappa;&lt;sub&gt;org&lt;/sub&gt;=0.02), leading to a
mean total κ, &amp;kappa;&lt;sub&gt;tot&lt;/sub&gt;, of 0.33 &amp;plusmn; 0.13. However, several
settings led to closure and &amp;kappa;&lt;sub&gt;org&lt;/sub&gt;=0.2 is found to be an upper
limit at 0.1% supersaturation. &amp;kappa;&lt;sub&gt;org&lt;/sub&gt;≤0.2 leads to a
&amp;kappa;&lt;sub&gt;tot&lt;/sub&gt; range of 0.33  &amp;plusmn; 013 to 0.50  &amp;plusmn; 0.11. Thus, the organic
material ranges from being sparingly soluble to effectively insoluble. These
results suggest that an increase in organic mass fraction in particles of a
certain size would lead to a suppression of the Arctic CCN activity.</p>
</abstract>
<counts><page-count count="16"/></counts>
</article-meta>
</front>
<body/>
<back>
<ref-list>
<title>References</title>
<ref id="ref1">
<label>1</label><mixed-citation publication-type="other" xlink:type="simple"> 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,  http://dx.doi.org/10.1016/j.earscirev.2008.03.001doi:10.1016/j.earscirev.2008.03.001, 2008. </mixed-citation>
</ref>
<ref id="ref2">
<label>2</label><mixed-citation publication-type="other" xlink:type="simple"> Bigg, E K. and Leck, C.: Cloud-active particles over the central Arctic Ocean, J. Geophys. Res., 106, 32155–32166, 2001.  </mixed-citation>
</ref>
<ref id="ref3">
<label>3</label><mixed-citation publication-type="other" xlink:type="simple"> Bigg, E K., Leck, C., and Nilsson, E D.: Sudden changes in arctic atmospheric aerosol concentrations during summer and autumn, Tellus 48B, 254–271, 1996.  </mixed-citation>
</ref>
<ref id="ref4">
<label>4</label><mixed-citation publication-type="other" xlink:type="simple"> Bigg, E K., Leck, C., and Nilsson, E D.: Sudden Changes in Aerosol and Gas concentrations in the central Arctic Marine Boundary Layer – Causes and Consequences, J. Geophys. Res., 106, 32,167–32,185, 2001.  </mixed-citation>
</ref>
<ref id="ref5">
<label>5</label><mixed-citation publication-type="other" xlink:type="simple"> Birmili, W., Stratmann, F., and Wiedensohler, A.: Design of a DMA-based size s pectrometer for a large particle size range and stable operation, J. Aerosol Sci., 30, 549–553, 1999. </mixed-citation>
</ref>
<ref id="ref6">
<label>6</label><mixed-citation publication-type="other" xlink:type="simple"> Canagaratna, M R., Jayne, J T.,Jimenez, J L., Allan, J D., Alfarra, M R., Zhang, Q., Onasch, T B., Drewnick,  F., Coe, H., Middlebrook, A M., Delia, A E., Williams, L R., Trimborn, A M.,  Northway, M J., DeCarlo, P F., Kolb, C E., Davidovits, P., and Worsnop, D R.:  Chemical and microphysical characterization of ambient aerosols with the Aerodyne   aerosol mass spectrometer, Mass Spec. Rev., 26, 185–222, 2007. </mixed-citation>
</ref>
<ref id="ref7">
<label>7</label><mixed-citation publication-type="other" xlink:type="simple"> Ceburnis, D., O&apos;Dowd, C D., Jennings, G S., Facchini, M C., Emblico, L., Decesari, S., Fuzzi, S., and Sakalys, J.: Marine aerosol chemistry gradients: Elucidating primary and secondary processes and fluxes, Geophys. Res. Lett., 35, L07804, http://dx.doi.org/10.1029/2008GL033462doi:10.1029/2008GL033462, 2008. </mixed-citation>
</ref>
<ref id="ref8">
<label>8</label><mixed-citation publication-type="other" xlink:type="simple"> %Chang, R Y.-W., Leck, C., Graus, %M., Müller, M., Paatero, J., Burkhart, J F., Stohl, A., Orr, L H., Hayden, K., Li, S.-M., Hansel, A., Tjermström, M., Leaitch, W R., and %Abbatt, J P D.: Aerosol composition and sources in the Central Arctic Ocean during ASCOS, Atmos. Chem. Phys. Discuss., 11, 14837–14881, 2011. Chang, R. Y.-W., Leck, C., Graus, M., Müller, M., Paatero, J., Burkhart, J. F., Stohl, A., Orr, L. H., Hayden, K., Li, S.-M., Hansel, A., Tjernström, M., Leaitch, W. R., and Abbatt, J. P. D.: Aerosol composition and sources in the central Arctic Ocean during ASCOS, Atmos. Chem. Phys., 11, 10619–10636, http://dx.doi.org/10.5194/acp-11-10619-2011doi:10.5194/acp-11-10619-2011, 2011.  </mixed-citation>
</ref>
<ref id="ref9">
<label>9</label><mixed-citation publication-type="other" xlink:type="simple"> Charlson, R J., Lovelock, J E., Andreae, M O., and Warren, S G.: Oceanic Phytoplankton, Atmospheric Sulfur, Cloud Albedo and Climate, Nature, 326, 655–661, 1987. \bibitem[Covert et~al.(1996)Covert, Wiedensohler, Aalto, Heintzenberg, McMurry, and Leck] Covert1996 Covert, D S., Wiedensohler, A., Aalto, P P., Heintzenberg, J., McMurry, P H., and Leck, C.: Aerosol number size distributions from 3 to 500 nm diameter in the arctic marine boundary layer during summer and autumn, Tellus 48B, 197–212, 1996. \bibitem[Denman et~al.(2007) Denman, Brasseur, Chidthaisong, Ciais, Cox, Dickinson, Hauglustaine, Heinze, Holland, Jacob, Lohmann, Ramachandran, Silva~Dias, Wofsy, and Zhang] Denman07 Denman, K., Brasseur, G., Chidthaisong, A., Ciais, P., Cox, P., Dickinson, R., Hauglustaine, D., Heinze, C., Holland, E., Jacob, D., Lohmann, U., Ramachandran, S., Silva~Dias, P., Wofsy, S., and Zhang, X.: Couplings between changes in the climate system and biogeochemistry, Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, 499–588, edited by: Solomon, S., Qin, D., Manning, M., Chen, Z., Marquis, M., Averyt, K B., Tignor, M., and Miller, H L., Cambridge Univ. Press, Cambridge, United Kingdom and New York, NY, USA, 2007. </mixed-citation>
</ref>
<ref id="ref10">
<label>10</label><mixed-citation publication-type="other" xlink:type="simple"> Drewnick, F., Hings, S S., DeCarlo, P., Jayne, J T., Gonin, M., Fuhrer, K., Weimer, S., Jimenez, J L., Demerjian, K L., Borrmann, S., and Worsnop, D R.: A new time-of-flight aerosol mass spectrometer  (TOF-AMS) – Instrument description and first field deployment, Aerosol Sci. Technol.,  39, 637–658, 2005. </mixed-citation>
</ref>
<ref id="ref11">
<label>11</label><mixed-citation publication-type="other" xlink:type="simple"> Facchini, M C., Rinaldi, M., Decesari, S., Carbone, C., Finessi, E., Mircea, M., Fuzzi, S., Ceburnis, D., Flanagan, R., Nilsson, E D., de Leeuw, G., Martino, M., Woeltjen, J., and O&apos;Dowd, C D.: Primary submicron marine aerosol dominated by insoluble organic colloids and aggregates, Geophys. Res. Lett., 35, L17814, http://dx.doi.org/10.1029/2008GL034210doi:10.1029/2008GL034210, 2008. </mixed-citation>
</ref>
<ref id="ref12">
<label>12</label><mixed-citation publication-type="other" xlink:type="simple"> Fors, E O., Swietlicki, E., Svenningsson, B., Kristensson, A., Frank, G P., and Sporre, M.: Hygroscopic properties of the ambient aerosol in southern Sweden – a two year study, Atmos. Chem. Phys., 11, 8343–8361, 2011. </mixed-citation>
</ref>
<ref id="ref13">
<label>13</label><mixed-citation publication-type="other" xlink:type="simple"> Fuentes, E., Coe, H., Green, D., and McFiggans, G.: On the impacts of phytoplankton-derived organic matter on the properties of the primary marine aerosol - Part 2: Composition, hygroscopicity and cloud condensation activity, Atmos. Chem. Phys., 11, 2585–2602, http://dx.doi.org/10.5194/acp-11-2585-2011doi:10.5194/acp-11-2585-2011, 2011. </mixed-citation>
</ref>
<ref id="ref14">
<label>14</label><mixed-citation publication-type="other" xlink:type="simple"> Gysel, M., McFiggans, G B., and Coe, H.: Inversion of tandem differential mobility analyser (TDMA) measurements, J. Aerosol Sci., 40, 134–151, http://dx.doi.org/10.1016/j.jaerosci.2008.07.013doi:10.1016/j.jaerosci.2008.07.013, 2009. </mixed-citation>
</ref>
<ref id="ref15">
<label>15</label><mixed-citation publication-type="other" xlink:type="simple">Heintzenberg, J., and Leck, C.: Seasonal variations of the atmospheric aerosol near the top of the marine boundary layer over Spitsbergen related to the Arctic sulfur cycle, Tellus 46B, 52–67, 1994. </mixed-citation>
</ref>
<ref id="ref16">
<label>16</label><mixed-citation publication-type="other" xlink:type="simple"> Heintzenberg, J., Leck, C., Birmili, W., Wehner, B., Tjernström, M., and Wiedensohler A.: Aerosol number-size distributions during clear and fog periods in the summer high Arctic: 1991, 1996 and 2001, Tellus B, 58, 41–50, http://dx.doi.org/10.1111/j.1600-0889.2005.00171.xdoi:10.1111/j.1600-0889.2005.00171.x, 2006.  </mixed-citation>
</ref>
<ref id="ref17">
<label>17</label><mixed-citation publication-type="other" xlink:type="simple"> Held, A., Held, A., Brooks, I. M., Leck, C., and Tjernström, M.: On the potential contribution of open lead particle emissions to the central Arctic aerosol concentration, Atmos. Chem. Phys., 11, 3093–3105, http://dx.doi.org/10.5194/acp-11-3093-2011doi:10.5194/acp-11-3093-2011, 2011. </mixed-citation>
</ref>
<ref id="ref18">
<label>18</label><mixed-citation publication-type="other" xlink:type="simple"> Intrieri, J M., Shupe, M D., Uttal, T., and McCarty, B J.: An annual cycle of Arctic cloud characteristics observed by radar and lidar at SHEBA, J. Geophys. Res., 107, 8030, http://dx.doi.org/10.1029/2000JC000423doi:10.1029/2000JC000423, 2002. </mixed-citation>
</ref>
<ref id="ref19">
<label>19</label><mixed-citation publication-type="other" xlink:type="simple"> Jimenez, J L., Jayne, J T., Shi, Q., Kolb, C E., Worsnop, D R., Yourshaw, I., Seinfeld, J H., Flagan, R C., Zhang, X., Smith, K A., Morris, J W., and Davidovits, P.: Ambient aerosol sampling using the Aerodyne Aerosol Mass Spectrometer, J. Geophys. Res., 108,  8425, http://dx.doi.org/10.1029/2001JD001213doi:10.1029/2001JD001213, 2003. </mixed-citation>
</ref>
<ref id="ref20">
<label>20</label><mixed-citation publication-type="other" xlink:type="simple"> Kammermann, L., Gysel, M., Weingartner, E., Herich, H., Cziczo, D J., Holst, T., Svenningsson, B., Arneth, A., and Baltensperger, U.: Subarctic atmospheric aerosol composition: 3. Measured and modeled properties of cloud condensation nuclei, J. Geophys. Res., 115, D04202, http://dx.doi.org/10.1029/2009JD012447doi:10.1029/2009JD012447, 2010. </mixed-citation>
</ref>
<ref id="ref21">
<label>21</label><mixed-citation publication-type="other" xlink:type="simple">Kay, J E. and Gettelman, A.: Cloud influence on and response to seasonal Arctic sea ice loss, J. Geophys. Res., 114, D18204, http://dx.doi.org/10.1029/2009JD011773doi:10.1029/2009JD011773, 2009. \bibitem[Korhonen et~al.(2008)Korhonen, Carslaw, Spracklen, Ridley, and Strom] Korhonen2008 Korhonen, H., Carslaw, K S., Spracklen, D V., Ridley, D A., and Strom, J.: A global model study of processes controlling aerosol size distributions in the Arctic spring and summer, J. Geophys. Res., 113, D08211, http://dx.doi.org/10.1029/2007JD009114doi:10.1029/2007JD009114, 2008. </mixed-citation>
</ref>
<ref id="ref22">
<label>22</label><mixed-citation publication-type="other" xlink:type="simple"> Lannefors, H., Heintzenberg, J., and Hansson, H C.: A comprehensive study of physical and chemical parameters of the Arctic summer aerosol; results from the Swedish expedition Ymer-80, Tellus, 35B, 40–54, 1983. </mixed-citation>
</ref>
<ref id="ref23">
<label>23</label><mixed-citation publication-type="other" xlink:type="simple"> Leck, C. and Bigg, E K.: Biogenic particles in the surface microlayer and overlaying atmosphere in the central Artic ocean during summer, Tellus, 57B, 305, 305–316, 2005a. </mixed-citation>
</ref>
<ref id="ref24">
<label>24</label><mixed-citation publication-type="other" xlink:type="simple"> Leck, C. and Bigg, E K.: Source and evolution of the marine aerosol – a new perspective, Geophys. Res. Lett., 32, L19803, http://dx.doi.org/10.1029/2005GL023651doi:10.1029/2005GL023651, 2005b. </mixed-citation>
</ref>
<ref id="ref25">
<label>25</label><mixed-citation publication-type="other" xlink:type="simple"> Leck, C. and Persson, C.: The central Arctic Ocean as a source of dimethyl sulfide-Seasonal variability in relation to biological activity, Tellus B, 48, 156–177, 1996. </mixed-citation>
</ref>
<ref id="ref26">
<label>26</label><mixed-citation publication-type="other" xlink:type="simple"> Leck, C., Bigg, E K., Covert, D S., Heintzenberg, J., Maenhaut, W., Nilsson, E D., and Wiedensohler, A.: Overview of the Atmospheric research program during the International Arctic Ocean Expedition 1991 (IAOE-91) and its scientific results, Tellus, 48B, 136–155, 1996. </mixed-citation>
</ref>
<ref id="ref27">
<label>27</label><mixed-citation publication-type="other" xlink:type="simple"> Leck, C., Nilsson, E D., Bigg, E K., and Bäcklin, L.: Atmospheric program on the Arctic Ocean Expedition 1996 (AOE-96): An overview of scientific goals, experimental approach, and instruments, J. Geophys. Res., 106, 32051–32067, 2001. </mixed-citation>
</ref>
<ref id="ref28">
<label>28</label><mixed-citation publication-type="other" xlink:type="simple"> Leck, C., Norman, M., Bigg, E K., and Hillamo, R.: Chemical composition and sources of the high Arctic aerosol relevant for fog and cloud formation, J. Geophys. Res., 107, http://dx.doi.org/10.1029/2001JD001463doi:10.1029/2001JD001463, 4135, 2002. </mixed-citation>
</ref>
<ref id="ref29">
<label>29</label><mixed-citation publication-type="other" xlink:type="simple"> Leck, C., Tjernström, M., Matrai, P., Swietlicki, E., and Bigg, E K.: Can Marine Micro-organisms Influence Melting of the Arctic Pack Ice?, Eos, 85, 3, 25–36, 2004.  </mixed-citation>
</ref>
<ref id="ref30">
<label>30</label><mixed-citation publication-type="other" xlink:type="simple"> Li, S M. and Barrie, L A.: Biogenic sulphur aerosol in the Arctic troposphere: 1. Contributions to total sulfate, J. Geophys. Res., 98, 20613–20622, 1993. </mixed-citation>
</ref>
<ref id="ref31">
<label>31</label><mixed-citation publication-type="other" xlink:type="simple"> Lohmann, U. and Feichter, J.: Global indirect aerosol effects: a review, Atmos. Chem. Phys., 5, 715–737, http://dx.doi.org/10.5194/acp-5-715-2005doi:10.5194/acp-5-715-2005, 2005. </mixed-citation>
</ref>
<ref id="ref32">
<label>32</label><mixed-citation publication-type="other" xlink:type="simple"> Lohmann, U. and Leck, C.: Importance of submicron surface-active organic aerosols for pristine Arctic clouds, Tellus B, 57, 261–268, 2005. </mixed-citation>
</ref>
<ref id="ref33">
<label>33</label><mixed-citation publication-type="other" xlink:type="simple"> Mauritsen, T., Sedlar, J., Tjernström, M., Leck, C., Martin, M., Shupe, M., Sjogren, S., Sierau, B., Persson, P. O. G., Brooks, I. M., and Swietlicki, E.: An Arctic CCN-limited cloud-aerosol regime, Atmos. Chem. Phys., 11, 165–173, http://dx.doi.org/10.5194/acp-11-165-2011doi:10.5194/acp-11-165-2011, 2011. </mixed-citation>
</ref>
<ref id="ref34">
<label>34</label><mixed-citation publication-type="other" xlink:type="simple"> Moore, R., Ingall, E., Sorooshian, A. and Nenes, A.: Molar mass, surface tension, and droplet growth kinetics of marine organics from measurements of CCN activity, Geophys. Res. Lett., 35, L07801, http://dx.doi.org/10.1029/2008GL033350doi:10.1029/2008GL033350, 2008. </mixed-citation>
</ref>
<ref id="ref35">
<label>35</label><mixed-citation publication-type="other" xlink:type="simple"> Muhlbauer, A., Spichtinger, P., and Lohmann, U.: Application and Comparison of Robust Linear Regression Methods for Trend Estimation, J. Appl. Meteor. Climatol., 48, 1961–1970, 2009. </mixed-citation>
</ref>
<ref id="ref36">
<label>36</label><mixed-citation publication-type="other" xlink:type="simple"> Nilsson, E D. and Leck, C.: A pseudo-Lagrangian study of the arctic remote marine sulfur cycle, Tellus, 54B, 213–230, 2002. </mixed-citation>
</ref>
<ref id="ref37">
<label>37</label><mixed-citation publication-type="other" xlink:type="simple"> Paatero, J., Vaattovaara, P., Vestenius, M., Meinander, O., Makkonen, U., Kivi, R., Hyvärinen, A., Asmi, E., Tjernström, M., and Leck, C.: Finnish contribution to the Arctic Summer Cloud Ocean Study (ASCOS) expedition, Arctic Ocean 2008, Geophysica, 45, 119–146, 2009. </mixed-citation>
</ref>
<ref id="ref38">
<label>38</label><mixed-citation publication-type="other" xlink:type="simple"> 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, http://dx.doi.org/10.5194/acp-7-1961-2007doi:10.5194/acp-7-1961-2007, 2007. </mixed-citation>
</ref>
<ref id="ref39">
<label>39</label><mixed-citation publication-type="other" xlink:type="simple"> %Pringle, K J., Tost, H., Pozzer, A., Pöschl, U., and Lelieveld, J.: Global distribution of % the effective aerosol hygroscopicity parameter for \rm CCN activation, Atmos. Chem. Phys., 10, % 5241–5255, http://dx.doi.org/10.5194/acp-10-5241-2010doi:10.5194/acp-10-5241-2010, 2010. 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, http://dx.doi.org/10.5194/acp-10-5241-2010doi:10.5194/acp-10-5241-2010, 2010.  </mixed-citation>
</ref>
<ref id="ref40">
<label>40</label><mixed-citation publication-type="other" xlink:type="simple"> Quinn, P K., Miller, T L., Bates, T S., Ogren, J A., Andrews, E., and Shaw, G E.: A three-year record of simultaneously measured aerosol chemical and optical properties at Barrow, Alaska, J. Geophys. Res., 107, 4130, http://dx.doi.org/10.1029/2001JD001248doi:10.1029/2001JD001248, 2002. </mixed-citation>
</ref>
<ref id="ref41">
<label>41</label><mixed-citation publication-type="other" xlink:type="simple"> Roberts, G C. and Nenes, A.: A Continuous-Flow Streamwise Thermal-Gradient \rm CCN Chamber for Atmospheric Measurements, Aerosol Sci. Technol., 39, 206–221, http://dx.doi.org/10.1080/027868290913988doi:10.1080/027868290913988, 2005. </mixed-citation>
</ref>
<ref id="ref42">
<label>42</label><mixed-citation publication-type="other" xlink:type="simple"> Rose, D., Gunthe, S. S., Mikhailov, E., Frank, G. P., Dusek, U., Andreae, M. O., and Pöschl, U.: Calibration and measurement uncertainties of a continuous-flow cloud condensation nuclei counter (DMT-CCNC): CCN activation of ammonium sulfate and sodium chloride aerosol particles in theory and experiment, Atmos. Chem. Phys., 8, 1153–1179, http://dx.doi.org/10.5194/acp-8-1153-2008doi:10.5194/acp-8-1153-2008, 2008. </mixed-citation>
</ref>
<ref id="ref43">
<label>43</label><mixed-citation publication-type="other" xlink:type="simple"> Rousseeuw, P J.: Least Median of Squares Regression, J. Amer. Stat. Assoc., 79(388), 871–880, 1984. </mixed-citation>
</ref>
<ref id="ref44">
<label>44</label><mixed-citation publication-type="other" xlink:type="simple"> Rousseeuw, P J. and Van Driessen, K.: Computing LTS Regression for Large Data Sets, Data Min. Knowl. Disc., 12, 29–45, 2006. </mixed-citation>
</ref>
<ref id="ref45">
<label>45</label><mixed-citation publication-type="other" xlink:type="simple">Sedlar, J., Tjernström, M., Mauritsen, T., Shupe, M., Brooks, I., Persson, P., Birch, C., Leck, C., Sirevaag, A., and Nicolaus, M.: A transitioning Arctic surface energy budget: the impacts of solar zenith angle, surface albedo and cloud radiative forcing, Clim. Dyn., 1–18, 2010. </mixed-citation>
</ref>
<ref id="ref46">
<label>46</label><mixed-citation publication-type="other" xlink:type="simple"> Seinfeld, J H. and Pandis, S N.: Atmospheric Chemistry and Physics: From Air Pollution to Climate Change, New York, John Wiley &amp; Sons, Inc., USA, 1998. </mixed-citation>
</ref>
<ref id="ref47">
<label>47</label><mixed-citation publication-type="other" xlink:type="simple"> Shaw, G E.: The Arctic Haze Phenomenon, Bull. Amer. Meteor. Soc., 76(12), 2403–2413, 1995. </mixed-citation>
</ref>
<ref id="ref48">
<label>48</label><mixed-citation publication-type="other" xlink:type="simple"> Stohl, A., Andrews, E., Burkhart, J F., Forster, C., Herber, A., Hoch, S W., Kowal, D., Lunder, C., Mefford, T., Ogren, J A., Sharma, S., Spichtinger, N., Stebel, K., Stone, R., Strom, J., Torseth, K., Wehrli, C., and Yttri, K E.: Pan-Arctic enhancements of light absorbing aerosol concentrations due to North American boreal forest fires during summer 2004, J. Geophys. Res., 111, D22214, http://dx.doi.org/10.1029/2006JD007216doi:10.1029/2006JD007216, 2006. </mixed-citation>
</ref>
<ref id="ref49">
<label>49</label><mixed-citation publication-type="other" xlink:type="simple">Tjernström, M., Sedlar, J., and Shupe, M.: How well do regional climate models reproduce radiation and clouds in the Arctic? An evaluation of ARCMIP simulations, J. Clim. Appl. Meteorol., 47, 2405–2422, 2008. </mixed-citation>
</ref>
<ref id="ref50">
<label>50</label><mixed-citation publication-type="other" xlink:type="simple">Twomey, S A.: The influence of pollution on the shortwave albedo of clouds, J. Atmos. Sci., 34, 1149–1152, 1977. </mixed-citation>
</ref>
<ref id="ref51">
<label>51</label><mixed-citation publication-type="other" xlink:type="simple">Walsh, J., Kattsov, V., Chapman, W., Govorkova, V., and Pavlova, T.: Comparison of Arctic climate simulations by uncoupled and coupled global models, J. Climate, 15, 1429–1446, 2002. </mixed-citation>
</ref>
<ref id="ref52">
<label>52</label><mixed-citation publication-type="other" xlink:type="simple"> Zhou, J., Swietlicki, E., Berg, O H., Aalto, P P., Hämeri, K., Nilsson, E D., and Leck, C.: Hygroscopic properties of aerosol particles over the central Arctic Ocean during summer, J. Geophys. Res., 106, 32111–32123, http://dx.doi.org/10.1029/2000JD900426doi:10.1029/2000JD900426, 2001. </mixed-citation>
</ref>
</ref-list>
</back>
</article>