<?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-9-8189-2009</article-id>
<title-group>
<article-title>Airborne measurements of the nitric acid partitioning in persistent contrails</article-title>
</title-group>
<contrib-group><contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Schäuble</surname>
<given-names>D.</given-names>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
<xref ref-type="aff" rid="aff2">
<sup>2</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Voigt</surname>
<given-names>C.</given-names>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
<xref ref-type="aff" rid="aff2">
<sup>2</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Kärcher</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>Stock</surname>
<given-names>P.</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>Schlager</surname>
<given-names>H.</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>Krämer</surname>
<given-names>M.</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>Schiller</surname>
<given-names>C.</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>Bauer</surname>
<given-names>R.</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>Spelten</surname>
<given-names>N.</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>de Reus</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>Szakáll</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>Borrmann</surname>
<given-names>S.</given-names>
</name>
<xref ref-type="aff" rid="aff2">
<sup>2</sup>
</xref>
<xref ref-type="aff" rid="aff4">
<sup>4</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Weers</surname>
<given-names>U.</given-names>
</name>
<xref ref-type="aff" rid="aff5">
<sup>5</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Peter</surname>
<given-names>Th.</given-names>
</name>
<xref ref-type="aff" rid="aff5">
<sup>5</sup>
</xref>
</contrib>
</contrib-group><aff id="aff1">
<label>1</label>
<addr-line>Deutsches Zentrum für Luft- und Raumfahrt, Institut für Physik der Atmosphäre, Oberpfaffenhofen, Germany</addr-line>
</aff>
<aff id="aff2">
<label>2</label>
<addr-line>Institut für Physik der Atmosphäre, Johannes-Gutenberg Universität Mainz, Mainz, Germany</addr-line>
</aff>
<aff id="aff3">
<label>3</label>
<addr-line>Institut für Stratosphärenforschung, FZ Jülich, Jülich, Germany</addr-line>
</aff>
<aff id="aff4">
<label>4</label>
<addr-line>Max-Planck-Institut für Chemie, Mainz, Germany</addr-line>
</aff>
<aff id="aff5">
<label>5</label>
<addr-line>Institut für Atmosphäre und Klima, ETH Zürich, Zürich, Switzerland</addr-line>
</aff>
<pub-date pub-type="epub">
<day>02</day>
<month>11</month>
<year>2009</year>
</pub-date>
<volume>9</volume>
<issue>21</issue>
<fpage>8189</fpage>
<lpage>8197</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/9/8189/2009/acp-9-8189-2009.html">This article is available from http://www.atmos-chem-phys.net/9/8189/2009/acp-9-8189-2009.html</self-uri>
<self-uri xlink:href="http://www.atmos-chem-phys.net/9/8189/2009/acp-9-8189-2009.pdf">The full text article is available as a PDF file from http://www.atmos-chem-phys.net/9/8189/2009/acp-9-8189-2009.pdf</self-uri>
<abstract>
<p>This study reports the first systematic measurements of nitric acid (HNO&lt;sub&gt;3&lt;/sub&gt;)
uptake in contrail ice particles at typical aircraft cruise altitudes. During
the CIRRUS-III campaign cirrus clouds and almost 40 persistent contrails were
probed with in situ instruments over Germany and Northern Europe in November
2006. Besides reactive nitrogen, water vapor, cloud ice water content, ice
particle size distributions, and condensation nuclei were measured during 6
flights. Contrails with ages up to 12 h were detected at altitudes
10–11.5 km and temperatures 211–220 K. These contrails
had a larger ice phase fraction of total nitric acid
(HNO&lt;sub&gt;3&lt;/sub&gt;&lt;sup&gt;ice&lt;/sup&gt;/HNO&lt;sub&gt;3&lt;/sub&gt;&lt;sup&gt;tot&lt;/sup&gt; = 6%) than the ambient
cirrus layers (3%). On average, the contrails contained twice as much
HNO&lt;sub&gt;3&lt;/sub&gt;&lt;sup&gt;ice&lt;/sup&gt; as the cirrus clouds, 14 pmol/mol and
6 pmol/mol, respectively. Young contrails with ages below 1 h
had a mean HNO&lt;sub&gt;3&lt;/sub&gt;&lt;sup&gt;ice&lt;/sup&gt; of 21 pmol/mol. The contrails had
higher nitric acid to water molar ratios in ice and slightly higher ice water
contents than the cirrus clouds under similar meteorological conditions. The
differences in ice phase fractions and molar ratios between developing
contrails and cirrus are likely caused by high plume concentrations of
HNO&lt;sub&gt;3&lt;/sub&gt; prior to contrail formation. The location of the measurements
in the upper region of frontal cirrus layers might account for slight
differences in the ice water content between contrails and adjacent cirrus
clouds. The observed dependence of molar ratios as a function of the mean ice
particle diameter suggests that ice-bound HNO&lt;sub&gt;3&lt;/sub&gt; concentrations are
controlled by uptake of exhaust HNO&lt;sub&gt;3&lt;/sub&gt; in the freezing plume aerosols
in young contrails and subsequent trapping of ambient HNO&lt;sub&gt;3&lt;/sub&gt; in
growing ice particles in older (age &gt; 1 h) contrails.</p>
</abstract>
<counts><page-count count="9"/></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"> Anderson, B E., Cofer, W R., Crawford, J., Gregory, G L., Vay, S A., Brunke, K E., Kondo, Y., Koike, M., Schlager, H., Baughcum, S L., Jensen, E., Zhao, Y., and Kita, K.: An assessment of aircraft as a source of particles to the upper troposphere, Geophys. Res. Lett., 26, 3069–3072, 1999. </mixed-citation>
</ref>
<ref id="ref2">
<label>2</label><mixed-citation publication-type="other" xlink:type="simple"> Arnold, F., Scheid, J., Stilp, T., Schlager, H., and Reinhardt, M E.: Measurements of jet aircraft emissions at cruise altitude I: the odd- nitrogen gases NO, $\mathrmNO_2$, $\mathrmHNO_2$ and $\mathrmHNO_3$, Geophys. Res. Lett., 19, 2421–2424, 1992. </mixed-citation>
</ref>
<ref id="ref3">
<label>3</label><mixed-citation publication-type="other" xlink:type="simple"> Bartels, T., Eichler, B., Zimmermann, P., Gäggeler, H. W., and Ammann, M.: The adsorption of nitrogen oxides on crystalline ice, Atmos. Chem. Phys., 2, 235–247, 2002. </mixed-citation>
</ref>
<ref id="ref4">
<label>4</label><mixed-citation publication-type="other" xlink:type="simple"> Belyaev, S P. and Levin, L M.: Techniques for collection of representative aerosol samples, J. Aerosol Sci., 5, 325–338, 1974. </mixed-citation>
</ref>
<ref id="ref5">
<label>5</label><mixed-citation publication-type="other" xlink:type="simple"> Borrmann, S., Luo, B., and Mishchenko, M.: Application of the T-matrix method to the measurement of aspherical (ellipsoidal) particles with forward scattering optical particle counters, J. Aerosol Sci., 31, 789–799, 2000. </mixed-citation>
</ref>
<ref id="ref6">
<label>6</label><mixed-citation publication-type="other" xlink:type="simple"> de Reus, M., Borrmann, S., Bansemer, A., Heymsfield, A. J., Weigel, R., Schiller, C., Mitev, V., Frey, W., Kunkel, D., Kürten, A., Curtius, J., Sitnikov, N. M., Ulanovsky, A., and Ravegnani, F.: Evidence for ice particles in the tropical stratosphere from in-situ measurements, Atmos. Chem. Phys., 9, 6775–6792, 2009. </mixed-citation>
</ref>
<ref id="ref7">
<label>7</label><mixed-citation publication-type="other" xlink:type="simple"> Fahey, D W., Eubank, C S., Hubler, G., and Fehsenfeld, F C.: Evaluation of a catalytic reduction technique for the measurement of total reactive odd-nitrogen NO&lt;sub&gt;y&lt;/sub&gt; in the atmosphere, J. Atmos. Chem., 3, 435–468, 1985. </mixed-citation>
</ref>
<ref id="ref8">
<label>8</label><mixed-citation publication-type="other" xlink:type="simple"> Gao, R S., Popp, P J., Fahey, D W., Marcy, T P., Herman, R L., Weinstock, E M., Baumgardner, D., Garrett, T J., Rosenlof, K H., Thompson, T L., Bui, T P., Ridley, B A., Wofsy, S C., Toon, O B., Tolbert, M A., Kärcher, B., Peter, T., Hudson, P K., Weinheimer, A J., and Heymsfield, A J.: Evidence that nitric acid increases relative humidity in low-temperature cirrus clouds, Science, 303, 516–520, 2004. </mixed-citation>
</ref>
<ref id="ref9">
<label>9</label><mixed-citation publication-type="other" xlink:type="simple"> Gerz, T., Dürbeck, T., and Konopka, P.: Transport and effective diffusion of aircraft emissions, J. Geophys. Res., 103, 25905–25913, 1998. </mixed-citation>
</ref>
<ref id="ref10">
<label>10</label><mixed-citation publication-type="other" xlink:type="simple"> Hegglin, M. I., Brunner, D., Peter, T., Hoor, P., Fischer, H., Staehelin, J., Krebsbach, M., Schiller, C., Parchatka, U., and Weers, U.: Measurements of NO, NO&lt;sub&gt;y&lt;/sub&gt;, N&lt;sub&gt;2&lt;/sub&gt;O, and O&lt;sub&gt;3&lt;/sub&gt; during SPURT: implications for transport and chemistry in the lowermost stratosphere, Atmos. Chem. Phys., 6, 1331–1350, 2006. </mixed-citation>
</ref>
<ref id="ref11">
<label>11</label><mixed-citation publication-type="other" xlink:type="simple"> Heymsfield, A J.: On measurements of small ice particles in clouds, Geophys. Res. Lett., 34, L23812, doi:10.1029/2007GL030951, 2007. </mixed-citation>
</ref>
<ref id="ref12">
<label>12</label><mixed-citation publication-type="other" xlink:type="simple"> Kärcher, B.: Aircraft-generated aerosols and visible contrails, Geophys. Res. Lett., 23, 1933–1936, 1996. </mixed-citation>
</ref>
<ref id="ref13">
<label>13</label><mixed-citation publication-type="other" xlink:type="simple"> Kärcher, B.: Supersaturation, dehydration, and denitrification in Arctic cirrus, Atmos. Chem. Phys., 5, 1757–1772, 2005. </mixed-citation>
</ref>
<ref id="ref14">
<label>14</label><mixed-citation publication-type="other" xlink:type="simple"> Kärcher, B., Abbatt, J. P D., Cox, R A., Popp, P J., and Voigt, C.: Trapping of trace gases by growing ice surfaces including surface-saturated adsorption, J. Geophys. Res., 114, D13306, doi:10.1029/2009JD011857, 2009.  </mixed-citation>
</ref>
<ref id="ref15">
<label>15</label><mixed-citation publication-type="other" xlink:type="simple"> Kärcher, B., Hirschberg, M M., and Fabian, P.: Small-scale chemical evolution of aircraft exhaust species at cruising altitudes, J. Geophys. Res., 101, 15169–15190, 1996. </mixed-citation>
</ref>
<ref id="ref16">
<label>16</label><mixed-citation publication-type="other" xlink:type="simple"> Kärcher, B. and Voigt, C.: Formation of nitric acid/water ice particles in cirrus clouds, Geophys. Res. Lett., 33, L08806, doi:10.1029/2006GL025927, 2006. </mixed-citation>
</ref>
<ref id="ref17">
<label>17</label><mixed-citation publication-type="other" xlink:type="simple"> Kondo, Y., Toon, O B., Irie, H., Gamblin, B., Koike, M., Takegawa, N., Tolbert, M A., Hudson, P K., Viggiano, A A., Avallone, L M., Hallar, A G., Anderson, B E., Sachse, G W., Vay, S A., Hunton, D E., Ballenthin, J O., and Miller, T M.: Uptake of reactive nitrogen on cirrus cloud particles in the upper troposphere and lowermost stratosphere, Geophys. Res. Lett., 30, 1154, doi:10.1029/2002GL016539, 2003. </mixed-citation>
</ref>
<ref id="ref18">
<label>18</label><mixed-citation publication-type="other" xlink:type="simple"> Kraab$\o$l, A G., Berntsen, T K., Sundet, J K., and Stordal, F.: Impacts of NO&lt;sub&gt;x&lt;/sub&gt; emissions from subsonic aircraft in a global three-dimensional chemistry transport model including plume processes, J. Geophys. Res., 107, 4655, doi:10.1029/2001JD001019, 2002. </mixed-citation>
</ref>
<ref id="ref19">
<label>19</label><mixed-citation publication-type="other" xlink:type="simple"> Krämer, M., Schiller, C., Voigt, C., Schlager, H., and Popp, P J.: A climatological view of $\mathrmHNO_3$ partitioning in cirrus clouds, Q. J. Roy. Meteorol. Soc., 134, 905–912, 2008. </mixed-citation>
</ref>
<ref id="ref20">
<label>20</label><mixed-citation publication-type="other" xlink:type="simple"> Meier, A. and Hendricks, J.: Model studies on the sensitivity of upper tropospheric chemistry to heterogeneous uptake of $\mathrmHNO_3$ on cirrus ice particles, J. Geophys. Res., 107, 4696, doi:10.1029/2001JD000735, 2002. </mixed-citation>
</ref>
<ref id="ref21">
<label>21</label><mixed-citation publication-type="other" xlink:type="simple"> Meilinger, S. K., Kärcher, B., and Peter, Th.: Microphysics and heterogeneous chemistry in aircraft plumes – high sensitivity on local meteorology and atmospheric composition, Atmos. Chem. Phys., 5, 533–545, 2005. </mixed-citation>
</ref>
<ref id="ref22">
<label>22</label><mixed-citation publication-type="other" xlink:type="simple"> Neuman, J A., Gao, R S., Fahey, D W., Holecek, J C., Ridley, B A., Walega, J G., Grahek, F E., Richard, E C., McElroy, C T., Thompson, T L., Elkins, J W., Moore, F L., and Ray, E A.: In situ measurements of $\mathrmHNO_3$, $\mathrmNO_y$, NO, and $\mathrmO_3$ in the lower stratosphere and upper troposphere, Atmos. Environ., 35, 5789–5797, 2001. </mixed-citation>
</ref>
<ref id="ref23">
<label>23</label><mixed-citation publication-type="other" xlink:type="simple"> Popp, P J., Gao, R S., Marcy, T P., Fahey, D W., Hudson, P K., Thompson, T L., Kärcher, B., Ridley, B A., Weinheimer, A J., Knapp, D J., Montzka, D D., Baumgardner, D., Garrett, T J., Weinstock, E M., Smith, J B., Sayres, D S., Pittman, J V., Dhaniyala, S., Bui, T P., and Mahoney, M J.: Nitric acid uptake on subtropical cirrus cloud particles, J. Geophys. Res., 109, D06302, doi:10.1029/2003JD004255, 2004. </mixed-citation>
</ref>
<ref id="ref24">
<label>24</label><mixed-citation publication-type="other" xlink:type="simple"> Schiller, C., Krämer, M., Afchine, A., Spelten, N., and Sitnikov, N.: Ice water content of Arctic, midlatitude, and tropical cirrus, J. Geophys. Res., 113, D24208, doi:10.1029/2008JD010342, 2008. </mixed-citation>
</ref>
<ref id="ref25">
<label>25</label><mixed-citation publication-type="other" xlink:type="simple"> Schlager, H., Petzold, A., Ziereis, H., Dörnbrack, A., Grimm, F., Arnold, F., and Schiller, C.: In-situ observations of particulate NO&lt;sub&gt;y&lt;/sub&gt; in cirrus clouds for different atmospheric conditions, in: Proceedings of the European Workshop on Aviation, Aerosols, Contrails, and Cirrus Clouds, edited by: Schumann, U. and Amanatidis, G T., European Commission, Brussels, Seeheim, Germany, 68–73, 1999. </mixed-citation>
</ref>
<ref id="ref26">
<label>26</label><mixed-citation publication-type="other" xlink:type="simple"> Schröder, F., Kärcher, B., Duroure, C., Ström, J., Petzold, A., Gayet, J F., Strauss, B., Wendling, P., and Borrmann, S.: On the transition of contrails into cirrus clouds, J. Atmos. Sci., 57, 464–480, 2000. </mixed-citation>
</ref>
<ref id="ref27">
<label>27</label><mixed-citation publication-type="other" xlink:type="simple"> Schumann, U., Schlager, H., Arnold, F., Baumann, R., Haschberger, P., and Klemm, O.: Dilution of aircraft exhaust plumes at cruise altitudes, Atmos. Environ., 32, 3097–3103, 1998. </mixed-citation>
</ref>
<ref id="ref28">
<label>28</label><mixed-citation publication-type="other" xlink:type="simple"> Talbot, R W., Dibb, J E., Scheuer, E M., Kondo, Y., Koike, M., Singh, H B., Salas, L B., Fukui, Y., Ballenthin, J O., Meads, R F., Miller, T M., Hunton, D E., Viggiano, A A., Blake, D R., Blake, N J., Atlas, E., Flocke, F., Jacob, D J., and Jaegle, L.: Reactive nitrogen budget during the NASA SONEX mission, Geophys. Res. Lett., 26, 3057–3060, 1999. </mixed-citation>
</ref>
<ref id="ref29">
<label>29</label><mixed-citation publication-type="other" xlink:type="simple"> Tremmel, H G., Schlager, H., Konopka, P., Schulte, P., Arnold, F., Klemm, M., and Droste-Franke, B.: Observations and model calculations of jet aircraft exhaust products at cruise altitude and inferred initial OH emissions, J. Geophys. Res., 103, 10803–10816, 1998.  </mixed-citation>
</ref>
<ref id="ref30">
<label>30</label><mixed-citation publication-type="other" xlink:type="simple"> Voigt, C., Kärcher, B., Schlager, H., Schiller, C., Krämer, M., de Reus, M., Vössing, H., Borrmann, S., and Mitev, V.: In-situ observations and modeling of small nitric acid-containing ice crystals, Atmos. Chem. Phys., 7, 3373–3383, 2007. </mixed-citation>
</ref>
<ref id="ref31">
<label>31</label><mixed-citation publication-type="other" xlink:type="simple"> Voigt, C., Schlager, H., Roiger, A., Stenke, A., de Reus, M., Borrmann, S., Jensen, E., Schiller, C., Konopka, P., and Sitnikov, N.: Detection of reactive nitrogen containing particles in the tropopause region – evidence for a tropical nitric acid trihydrate (NAT) belt, Atmos. Chem. Phys., 8, 7421–7430, 2008.  </mixed-citation>
</ref>
<ref id="ref32">
<label>32</label><mixed-citation publication-type="other" xlink:type="simple"> Voigt, C., Schlager, H., Ziereis, H., Kärcher, B., Luo, B P., Schiller, C., Krämer, M., Popp, P J., Irie, H., and Kondo, Y.: Nitric acid in cirrus clouds, Geophys. Res. Lett., 33, L05803, doi:10.1029/2005GL025159, 2006. </mixed-citation>
</ref>
<ref id="ref33">
<label>33</label><mixed-citation publication-type="other" xlink:type="simple"> von Kuhlmann, R. and Lawrence, M. G.: The impact of ice uptake of nitric acid on atmospheric chemistry, Atmos. Chem. Phys., 6, 225–235, 2006. </mixed-citation>
</ref>
<ref id="ref34">
<label>34</label><mixed-citation publication-type="other" xlink:type="simple"> Weinheimer, A J., Campos, T L., Walega, J G., Grahek, F E., Ridley, B A., Baumgardner, D., Twohy, C H., Gandrud, B., and Jensen, E J.: Uptake of $\mathrmNO_y$ on wave-cloud ice particles, Geophys. Res. Lett., 25, 1725–1728, 1998. </mixed-citation>
</ref>
<ref id="ref35">
<label>35</label><mixed-citation publication-type="other" xlink:type="simple"> Ziereis, H., Minikin, A., Schlager, H., Gayet, J F., Auriol, F., Stock, P., Baehr, J., Petzold, A., Schumann, U., Weinheimer, A., Ridley, B., and Ström, J.: Uptake of reactive nitrogen on cirrus cloud particles during INCA, Geophys. Res. Lett., 31, L05115, doi:10.1029/2003GL018794, 2004. </mixed-citation>
</ref>
<ref id="ref36">
<label>36</label><mixed-citation publication-type="other" xlink:type="simple"> Ziereis, H., Schlager, H., Schulte, P., van Velthoven, P F J., and Slemr, F.: Distributions of NO, \chemNO_x, and \chemNO_y in the upper troposphere and lower stratosphere between 28&amp;deg; and 61&amp;deg; N during POLINAT 2, J. Geophys. Res., 105, 3653–3664, 2000.  </mixed-citation>
</ref>
<ref id="ref37">
<label>37</label><mixed-citation publication-type="other" xlink:type="simple"> Zöger, M., Afchine, A., Eicke, N., Gerhards, M T., Klein, E., McKenna, D S., Mörschel, U., Schmidt, U., Tan, V., Tuitjer, F., Woyke, T., and Schiller, C.: Fast in situ stratospheric hygrometers: A new family of balloon-borne and airborne Lyman-α photofragment fluorescence hygrometers, J. Geophys. Res., 104, 1807–1816, 1999. </mixed-citation>
</ref>
</ref-list>
</back>
</article>