<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE article PUBLIC "-//NLM//DTD Journal Publishing DTD v3.0 20080202//EN" "http://dtd.nlm.nih.gov/publishing/3.0/journalpublishing3.dtd">
<article xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink" article-type="research-article" dtd-version="3.0" xml:lang="en">
<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-12-10535-2012</article-id>
<title-group>
<article-title>Influence of the Arctic Oscillation on the vertical distribution of clouds as observed by the A-Train constellation of satellites</article-title>
</title-group>
<contrib-group><contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Devasthale</surname>
<given-names>A.</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>Tjernström</surname>
<given-names>M.</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>Caian</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>Thomas</surname>
<given-names>M. A.</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>Kahn</surname>
<given-names>B. H.</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>Fetzer</surname>
<given-names>E. J.</given-names>
</name>
<xref ref-type="aff" rid="aff3">
<sup>3</sup>
</xref>
</contrib>
</contrib-group><aff id="aff1">
<label>1</label>
<addr-line>Swedish Meteorological and Hydrological Institute (SMHI), Norrköping, Sweden</addr-line>
</aff>
<aff id="aff2">
<label>2</label>
<addr-line>Department of Meteorology (MISU) and Bert Bolin Center for Climate Research, Stockholm University, Stockholm, Sweden</addr-line>
</aff>
<aff id="aff3">
<label>3</label>
<addr-line>Jet Propulsion Laboratory/CALTECH, NASA, Pasadena, USA</addr-line>
</aff>
<pub-date pub-type="epub">
<day>12</day>
<month>11</month>
<year>2012</year>
</pub-date>
<volume>12</volume>
<issue>21</issue>
<fpage>10535</fpage>
<lpage>10544</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/12/10535/2012/acp-12-10535-2012.html">This article is available from http://www.atmos-chem-phys.net/12/10535/2012/acp-12-10535-2012.html</self-uri>
<self-uri xlink:href="http://www.atmos-chem-phys.net/12/10535/2012/acp-12-10535-2012.pdf">The full text article is available as a PDF file from http://www.atmos-chem-phys.net/12/10535/2012/acp-12-10535-2012.pdf</self-uri>
<abstract>
<p>The main purpose of this study is to investigate the influence of the Arctic
Oscillation (AO), the dominant mode of natural variability over the
northerly high latitudes, on the spatial (horizontal and vertical)
distribution of clouds in the Arctic. To that end, we use a suite of sensors
onboard NASA&apos;s A-Train satellites that provide accurate observations of the
distribution of clouds along with information on atmospheric thermodynamics.
Data from three independent sensors are used (AQUA-AIRS, CALIOP-CALIPSO and
CPR-CloudSat) covering two time periods (winter half years, November through
March, of 2002–2011 and 2006–2011, respectively) along with data from the
ERA-Interim reanalysis.
&lt;br&gt;&lt;br&gt;
We show that the zonal vertical distribution of cloud fraction anomalies
averaged over 67–82° N
to a first approximation follows a dipole structure
(referred to as &quot;Greenland cloud dipole anomaly&quot;, GCDA), such that during
the positive phase of the AO, positive and negative cloud anomalies are
observed eastwards and westward of Greenland respectively, while the
opposite is true for the negative phase of AO. By investigating the
concurrent meteorological conditions (temperature, humidity and winds), we
show that differences in the meridional energy and moisture transport during
the positive and negative phases of the AO and the associated thermodynamics
are responsible for the conditions that are conducive for the formation of
this dipole structure. All three satellite sensors broadly observe this
large-scale GCDA despite differences in their sensitivities, spatio-temporal
and vertical resolutions, and the available lengths of data records,
indicating the robustness of the results. The present study also provides a
compelling case to carry out process-based evaluation of global and regional
climate models.</p>
</abstract>
<counts><page-count count="10"/></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"> Baldwin, M. P. and Dunkerton, T. J.: Downward propagation of the Arctic Oscillation from the stratosphere to the troposphere, J. Geophys. Res., 104, 30937–30946, 1999. </mixed-citation>
</ref>
<ref id="ref2">
<label>2</label><mixed-citation publication-type="other" xlink:type="simple"> Benedict, J. J., Lee, S., and Feldstein, S. B.: Synoptic view of the North Atlantic Interactive Oscillation, J. Atmos. Sci., 61, 121–144, 2004. </mixed-citation>
</ref>
<ref id="ref3">
<label>3</label><mixed-citation publication-type="other" xlink:type="simple"> Chahine, M. T., Pagano, T. S., Aumann, H. H., Atlas, R., Barnet, C., Blaisdell, J., Chen, L., Divakarla, M., Fetzer, E. J., Goldberg, M., Gautier, C., Granger, S., Hannon, S., Irion, F. W., Kakar, R., Kalnay, E., Lambrigtsen, B. H., Lee, S.-Y., Le Marshall, J., McMillan, W. W., McMillin, L., Olsen, E. T., Revercomb, H., Rosenkranz, P., Smith, W. L., Staelin, D., Strow, L. L., Susskind, J., Tobin, D., Wolf, W., and Zhou, L.: AIRS: Improving Weather Forecasting and Providing New Data on Greenhouse Gases, B. Am. Meteorol. Soc., 87, 911–926, 2006. </mixed-citation>
</ref>
<ref id="ref4">
<label>4</label><mixed-citation publication-type="other" xlink:type="simple"> Christiansen, B.: On the physical nature of the Arctic Oscillation, Geophys. Res. Lett., 29, 1805, http://dx.doi.org/10.1029/2002GL015208doi:10.1029/2002GL015208, 2002. </mixed-citation>
</ref>
<ref id="ref5">
<label>5</label><mixed-citation publication-type="other" xlink:type="simple"> Cohen, J., and Barlow, M.: The NAO, the AO, and Global Warming: How Closely Related?, J. Climate, 18, 4498–4513, http://dx.doi.org/10.1175/JCLI3530.1doi:10.1175/JCLI3530.1, 2005. </mixed-citation>
</ref>
<ref id="ref6">
<label>6</label><mixed-citation publication-type="other" xlink:type="simple"> Dee, D. P., Uppala, S. M., Simmons, A. J., Berrisford, P., Poli, P., Kobayashi, S., Andrae, U., Balmaseda, M. A., Balsamo, G., Bauer, P., Bechtold, P., Beljaars, A. C. M., van de Berg, L., Bidlot, J., Bormann, N., Delsol, C., Dragani, R., Fuentes, M., Geer, A. J., Haimberger, L., Healy, S. B., Hersbach, H., Hólm, E. V., Isaksen, L., Kållberg, P., Köhler, M., Matricardi, M., McNally, A. P., Monge-Sanz, B. M., Morcrette, J.-J., Park, B.-K., Peubey, C., de Rosnay, P., Tavolato, C., Thépaut, J.-N., and Vitart, F.: The ERA-Interim reanalysis: Configuration and performance of the data assimilation system, Q. J. Roy. Meteor. Soc., 137, 553–597, http://dx.doi.org/10.1002/qj.828doi:10.1002/qj.828, 2011. </mixed-citation>
</ref>
<ref id="ref7">
<label>7</label><mixed-citation publication-type="other" xlink:type="simple"> DelSole, T. and Yang, X.: Field Significance of Regression Patterns, J. Climate, 24, 5094–5107, 2011. </mixed-citation>
</ref>
<ref id="ref8">
<label>8</label><mixed-citation publication-type="other" xlink:type="simple"> Deser, C., Walsh, J. E., and Timlin, M. S.: Arctic sea ice variability in the context of recent atmospheric circulation trends, J. Climate, 13, 617–633, 2000. </mixed-citation>
</ref>
<ref id="ref9">
<label>9</label><mixed-citation publication-type="other" xlink:type="simple"> Devasthale, A., Willén, U., Karlsson, K.-G., and Jones, C. G.: Quantifying the clear-sky temperature inversion frequency and strength over the Arctic Ocean during summer and winter seasons from AIRS profiles, Atmos. Chem. Phys., 10, 5565–5572, http://dx.doi.org/10.5194/acp-10-5565-2010doi:10.5194/acp-10-5565-2010, 2010. </mixed-citation>
</ref>
<ref id="ref10">
<label>10</label><mixed-citation publication-type="other" xlink:type="simple"> Devasthale, A., Sedlar, J., and Tjernström, M.: Characteristics of water-vapour inversions observed over the Arctic by Atmospheric Infrared Sounder (AIRS) and radiosondes, Atmos. Chem. Phys., 11, 9813–9823, http://dx.doi.org/10.5194/acp-11-9813-2011doi:10.5194/acp-11-9813-2011, 2011a. </mixed-citation>
</ref>
<ref id="ref11">
<label>11</label><mixed-citation publication-type="other" xlink:type="simple"> Devasthale, A., Tjernström, M., Karlsson, K-G., Thomas, M. A., Jones, C., Sedlar, J., and Omar, A. H.: The vertical distribution of thin features over the Arctic analysed from CALIPSO observations. Part I: Optically thin clouds, Tellus B, 63, 77–85, 2011b. </mixed-citation>
</ref>
<ref id="ref12">
<label>12</label><mixed-citation publication-type="other" xlink:type="simple"> Dickson, R. R., Osborn, T. J., Hurrell, J. W., Meincke, J., Blindheim, J., Adlandsvik, B., Vinje, T., Alekseev, G., and Maslowski, W.: The Arctic Ocean response to the North Atlantic Oscillation, J. Climate, 13, 2671–2696, 2000. </mixed-citation>
</ref>
<ref id="ref13">
<label>13</label><mixed-citation publication-type="other" xlink:type="simple"> Divakarla, M. G., Barnet, C. D., Goldberg, M. D., McMillin, L. M., Maddy, E., Wolf, W., Zhou, L., and Liu, X.: Validation of Atmospheric Infrared Sounder temperature and water vapor retrievals with matched radiosonde measurements and forecasts, J. Geophys. Res., 111, D09S15, http://dx.doi.org/10.1029/2005JD006116doi:10.1029/2005JD006116, 2006. </mixed-citation>
</ref>
<ref id="ref14">
<label>14</label><mixed-citation publication-type="other" xlink:type="simple"> Fetzer, E. J.: Preface to special section: Validation of Atmospheric Infrared Sounder Observations, J. Geophys. Res., 111, D09S01, http://dx.doi.org/10.1029/2005JD007020doi:10.1029/2005JD007020, 2006. </mixed-citation>
</ref>
<ref id="ref15">
<label>15</label><mixed-citation publication-type="other" xlink:type="simple"> Groves, D. G. and Francis, J. A.: Variability of the Arctic atmospheric moisture budget from TOVS satellite data, J. Geophys. Res., 107, 4785, http://dx.doi.org/10.1029/2002JD002285doi:10.1029/2002JD002285, 2002. </mixed-citation>
</ref>
<ref id="ref16">
<label>16</label><mixed-citation publication-type="other" xlink:type="simple"> Holz, R. E., Ackerman, S., Antonelli, P., Nagle, F., Knuteson, R. O., McGill, M., Hlavka, D. L., and Hart, W. D.: An improvement to the high spectral resolution CO&lt;sub&gt;2&lt;/sub&gt; slicing cloud top altitude retrieval, J. Atmos. Ocean. Tech., 23, 653–670, 2006. </mixed-citation>
</ref>
<ref id="ref17">
<label>17</label><mixed-citation publication-type="other" xlink:type="simple"> Hoskins, B. J. and Hodges, K. I.: New Perspectives on the Northern Hemisphere Winter Storm Tracks, J. Atmos. Sci., 59, 1041–1061, 2002. </mixed-citation>
</ref>
<ref id="ref18">
<label>18</label><mixed-citation publication-type="other" xlink:type="simple"> Hu, Y., Winker, D., Vaughan, M., Lin, B., Omar, A., Trepte, C., Flittner, D., Yang, P., Nasiri, S. L., Baum, B., Sun, W., Liu, Z., Wang, Z., Young, S., Stamnes, K., Huang, J., Kuehn, R., and Holz, R.: CALIPSO/CALIOP cloud phase discrimination algorithm, J. Atmos. Ocean. Tech., 26, 2293–2309 2009. </mixed-citation>
</ref>
<ref id="ref19">
<label>19</label><mixed-citation publication-type="other" xlink:type="simple"> Hurrell, J. W.: Decadal trends in the North Atlantic Oscillation: Regional temperatures and precipitation, Science, 269, 676–679, 1995. </mixed-citation>
</ref>
<ref id="ref20">
<label>20</label><mixed-citation publication-type="other" xlink:type="simple"> Hurrell, J. W., Kushnir, Y., Ottersen, G., and Visbeck, M. (Eds.): The North Atlantic Oscillation: Climate Significance and Environmental Impact, Amer. Geophys. Union Geophysical Monograph Series, 134, 279 pp., ISSN: 0065-8448; ISBN: 0-87590-994-9, 2003. </mixed-citation>
</ref>
<ref id="ref21">
<label>21</label><mixed-citation publication-type="other" xlink:type="simple"> Kahn, B. H., Chahine, M. T., Stephens, G. L., Mace, G. G., Marchand, R. T., Wang, Z., Barnet, C. D., Eldering, A., Holz, R. E., Kuehn, R. E., and Vane, D. G.: Cloud type comparisons of AIRS, CloudSat, and CALIPSO cloud height and amount, Atmos. Chem. Phys., 8, 1231–1248, http://dx.doi.org/10.5194/acp-8-1231-2008doi:10.5194/acp-8-1231-2008, 2008. </mixed-citation>
</ref>
<ref id="ref22">
<label>22</label><mixed-citation publication-type="other" xlink:type="simple"> Karlsson, J. and Svensson, G.: The simulation of Arctic clouds and their influence on the winter present-day climate in the CMIP3 multi-model dataset, Clim. Dynam., 36, 623–635, 2011. </mixed-citation>
</ref>
<ref id="ref23">
<label>23</label><mixed-citation publication-type="other" xlink:type="simple"> Kay, J. E., Holland, M. M., Bitz, C. M., Blanchard-Wrigglesworth, E., Gettelman, A., Conley, A., and Bailey, D.: The Influence of Local Feedbacks and Northward Heat Transport on the Equilibrium Arctic Climate Response to Increased Greenhouse Gas Forcing, J. Climate, 25, 5433–5450, http://dx.doi.org/10.1175/JCLI-D-11-00622.1doi:10.1175/JCLI-D-11-00622.1, 2012. </mixed-citation>
</ref>
<ref id="ref24">
<label>24</label><mixed-citation publication-type="other" xlink:type="simple"> Kwok, R.: Recent changes in Arctic Ocean sea ice motion associated with the North Atlantic Oscillation, Geophys. Res. Lett., 27, 775–778, 2000. </mixed-citation>
</ref>
<ref id="ref25">
<label>25</label><mixed-citation publication-type="other" xlink:type="simple"> L&apos;Ecuyer, T. S. and Jiang, J.: Touring the Atmosphere Aboard the A-Train, Phys. Today, 63, 36–41, 2010. </mixed-citation>
</ref>
<ref id="ref26">
<label>26</label><mixed-citation publication-type="other" xlink:type="simple"> Livezey, R. E. and Chen, W. Y.: Statistical field significance and it&apos;s determination by Monte Carlo Techniques, Mon. Weather Rev., 111, 46–59, 1983. </mixed-citation>
</ref>
<ref id="ref27">
<label>27</label><mixed-citation publication-type="other" xlink:type="simple"> Mace, G. G., Vane, D., Stephens, G., and Reinke, D.: Level 2 Radar-Lidar GEOPROF Product Version 1.0 Process Description and Interface Control Document, JPL, Pasadena, USA, 1–20, 2007. </mixed-citation>
</ref>
<ref id="ref28">
<label>28</label><mixed-citation publication-type="other" xlink:type="simple"> Marchand, R. T., Mace, G., Ackerman, T., and Stephens, G.: Hydrometeor Detection using CloudSat – an Earth Orbiting 94 GHz Cloud Radar, J. Atmos. Ocean. Tech., 25, 519–533, http://dx.doi.org/10.1175/2007JTECHA1006.1doi:10.1175/2007JTECHA1006.1, 2008. </mixed-citation>
</ref>
<ref id="ref29">
<label>29</label><mixed-citation publication-type="other" xlink:type="simple"> Overland, J. E., Wood, K. R., and Wang, M.: Warm Arctic – cold continents: climate impacts of the newly open Arctic sea, Polar Res., 30, 15787, http://dx.doi.org/10.3402/polar.v30i0.15787doi:10.3402/polar.v30i0.15787, 2011. </mixed-citation>
</ref>
<ref id="ref30">
<label>30</label><mixed-citation publication-type="other" xlink:type="simple"> Park, S. and Leovy, C. B.: Winter North Atlantic low cloud anomalies associated with the northern hemisphere annular mode, Geophys. Res. Lett., 27, 3357–3360, http://dx.doi.org/10.1029/2000GL011609doi:10.1029/2000GL011609, 2000. </mixed-citation>
</ref>
<ref id="ref31">
<label>31</label><mixed-citation publication-type="other" xlink:type="simple"> Perlwitz, J. and Graf, H.-F.: The statistical connection between tropospheric and stratospheric circulation of the Northern hemisphere in winter, J. Climate, 8, 2281–2295, 1995. </mixed-citation>
</ref>
<ref id="ref32">
<label>32</label><mixed-citation publication-type="other" xlink:type="simple"> Previdi, M. and Veron, D. E.: North Atlantic cloud cover response to the North Atlantic oscillation and relationship to surface temperature changes, J. Geophys. Res., 112, D07104, http://dx.doi.org/10.1029/2006JD007516doi:10.1029/2006JD007516, 2007. </mixed-citation>
</ref>
<ref id="ref33">
<label>33</label><mixed-citation publication-type="other" xlink:type="simple"> Rigor, I. G., Wallace, J. M., and Colony, R. L.: Response of sea ice to the Arctic Oscillation, J. Climate, 15, 2648–2663, 2002. </mixed-citation>
</ref>
<ref id="ref34">
<label>34</label><mixed-citation publication-type="other" xlink:type="simple"> Semenov, V. A., Latif, M., Jungclaus, J. H., and Park, W.: Is the observed NAO variability during the instrumental record unusual?, Geophys. Res. Lett., 35, L11701, http://dx.doi.org/10.1029/2008GL033273doi:10.1029/2008GL033273, 2008. </mixed-citation>
</ref>
<ref id="ref35">
<label>35</label><mixed-citation publication-type="other" xlink:type="simple"> Serreze, M. C. and Barry, R. G.: Synoptic Activity in the Arctic Basin, 1979–85, J. Climate, 1, 1276–1295, 1988. </mixed-citation>
</ref>
<ref id="ref36">
<label>36</label><mixed-citation publication-type="other" xlink:type="simple"> Shupe, M. D., Walden, V. P., Eloranta, E., Uttal, T., Campbell, J. R., Starkweather, S. M., and Shiobara, M.: Clouds at Arctic atmospheric observatories, Part I: Occurrence and macrophysical properties, J. Appl. Meteor. Clim., 50, 626–644, 2011. </mixed-citation>
</ref>
<ref id="ref37">
<label>37</label><mixed-citation publication-type="other" xlink:type="simple"> Stephens, G. L., Vane, D. G., Boain, R. J., Mace, G. G., Sassen, K., Wang, Z., Illingworth, A. J., O&apos;Connor, E. J., Rossow, W. B., Durden, S. L., Miller, S. D., Austin, R. T., Benedetti, A., Mitrescu, C., and the CloudSat Science Team: The CloudSat Mission and the A-TRAIN: A new dimension to space-based observations of clouds and precipitation, B. Am. Meteorol. Soc., 83, 1771–1790, 2002. </mixed-citation>
</ref>
<ref id="ref38">
<label>38</label><mixed-citation publication-type="other" xlink:type="simple"> Strong, C. and Magnusdottir, G.: Tropospheric Rossby Wave breaking and the NAO/NAM, J. Atmos. Sci, 65, 2861–2876, http://dx.doi.org/10.1175/2008JAS2632.1doi:10.1175/2008JAS2632.1, 2008. \hack </mixed-citation>
</ref>
<ref id="ref39">
<label>39</label><mixed-citation publication-type="other" xlink:type="simple"> Svensson, G. and Karlsson, J.: On the Arctic Wintertime Climate in Global Climate Models, J. Climate, 24, 5757–5771, http://dx.doi.org/10.1175/2011JCLI4012.1doi:10.1175/2011JCLI4012.1, 2011. </mixed-citation>
</ref>
<ref id="ref40">
<label>40</label><mixed-citation publication-type="other" xlink:type="simple"> Thompson, D. W. J. and Wallace, J. M.: The Arctic Oscillation signature in the wintertime geopotential height and temperature fields, Geophys. Res. Lett., 25, 1297–1300, 1998. </mixed-citation>
</ref>
<ref id="ref41">
<label>41</label><mixed-citation publication-type="other" xlink:type="simple"> Thompson, D. W. J. and Wallace, J. M.: Annular Modes in the extratropical circulation. Part I: Month-to-month variability, J. Climate, 13, 1000–1016, 2000. </mixed-citation>
</ref>
<ref id="ref42">
<label>42</label><mixed-citation publication-type="other" xlink:type="simple"> Thompson, D. W. J. and Wallace, J. M.: Regional climate impacts of the Northern, Hemisphere Annular Mode and associated climate trends, Science, 293, 85–89, 2001. </mixed-citation>
</ref>
<ref id="ref43">
<label>43</label><mixed-citation publication-type="other" xlink:type="simple"> Thompson, D. W. J., Wallace, J. M., and Hegerl, G. C.: Annular modes in the extratropical circulation. Part II: Trends, J. Climate, 13, 1018–1036, 2000. </mixed-citation>
</ref>
<ref id="ref44">
<label>44</label><mixed-citation publication-type="other" xlink:type="simple"> Tjernström, M., Sedlar, J., and Shupe, M. D.: How well do regional climate models reproduce radiation and clouds in the Arctic? An evaluation of ARCMIP simulations, J. Appl. Meteorol. Clim., 47, 2405–2422, 2008. </mixed-citation>
</ref>
<ref id="ref45">
<label>45</label><mixed-citation publication-type="other" xlink:type="simple"> Trigo, R. M., Osborn, T. J., and Corte-Real, J. M.: The North Atlantic Oscillation influence on Europe: Climate impacts and associated physical mechanisms, Clim. Res., 20, 9–17, 2002. </mixed-citation>
</ref>
<ref id="ref46">
<label>46</label><mixed-citation publication-type="other" xlink:type="simple"> Vavrus, S. J., Waliser, D., Schweiger, A., and Francis, J.: Simulations of 20th and 21st century Arctic cloud amount in the global climate models assessed in the IPCC AR4, Clim. Dynam., 33, 1099–1115, http://dx.doi.org/10.1007/s00382-008-0475-6doi:10.1007/s00382-008-0475-6, 2008. </mixed-citation>
</ref>
<ref id="ref47">
<label>47</label><mixed-citation publication-type="other" xlink:type="simple"> Wang, X. and Key, J. R.: Recent Trends in Arctic Surface, Cloud, and Radiation Properties from Space, Science, 299, 1725–1728, http://dx.doi.org/10.1126/science.1078065doi:10.1126/science.1078065, 2003. </mixed-citation>
</ref>
<ref id="ref48">
<label>48</label><mixed-citation publication-type="other" xlink:type="simple"> Wang, X. and Key, J. R.: Arctic Surface, Cloud, and Radiation Properties Based on the AVHRR Polar Pathfinder Dataset. Part II: Recent Trends, J. Climate, 18, 2575–2593, 2005. </mixed-citation>
</ref>
<ref id="ref49">
<label>49</label><mixed-citation publication-type="other" xlink:type="simple"> Winker, D. M., Vaughan, M. A., Omar, A. H., Hu, Y., Powell, K. A., Liu, Z., Hunt, W. H., and Young, S. A.: Overview of the CALIPSO Mission and CALIOP Data Processing Algorithms, J. Atmos. Ocean. Tech., 26, 2310–2323, http://dx.doi.org/10.1175/2009JTECHA1281.1doi:10.1175/2009JTECHA1281.1, 2009. </mixed-citation>
</ref>
<ref id="ref50">
<label>50</label><mixed-citation publication-type="other" xlink:type="simple"> Woolings, T., Hoskins, B., Blackburn, M., and Berrisford, P.: A New Rossby Wave Breaking Interpretation of the North Atlantic Oscillation, J. Atmos. Sci., 65, 609–626, http://dx.doi.org/10.1175/2007JAS2347.1doi:10.1175/2007JAS2347.1, 2008. </mixed-citation>
</ref>
</ref-list>
</back>
</article>