<?xml version="1.0" encoding="utf-8" standalone="no"?>
<!DOCTYPE article SYSTEM "http://www.ann-geophys.net/inc/angeo/copernicus.dtd">
<article language="en">
	<journal>
		<journal_title>Annales Geophysicae</journal_title>
		<journal_url>www.ann-geophys.net</journal_url>
		<issn>0992-7689</issn>
		<eissn>1432-0576</eissn>
		<volume_number>26</volume_number>
		<issue_number>1</issue_number>
		<publication_year>2008</publication_year>
	</journal>
	<doi>10.5194/angeo-26-13-2008</doi>
	<article_url>http://www.ann-geophys.net/26/13/2008/</article_url>
	<abstract_html>http://www.ann-geophys.net/26/13/2008/angeo-26-13-2008.html</abstract_html>
	<fulltext_pdf>http://www.ann-geophys.net/26/13/2008/angeo-26-13-2008.pdf</fulltext_pdf>
	<start_page>13</start_page>
	<end_page>27</end_page>
	<publication_date>2008-02-04</publication_date>
	<article_title content_type="html">Parameterisation of the chemical effect of sprites in the   middle atmosphere</article_title>
	<authors>
		<author numeration="1" affiliations="1">
			<name>C.-F. Enell</name>
			<email>carl-fredrik.enell@sgo.fi</email>
		</author>
		<author numeration="2" affiliations="2,7">
			<name>E. Arnone</name>
		</author>
		<author numeration="3" affiliations="3,8">
			<name>T. Adachi</name>
		</author>
		<author numeration="4" affiliations="4">
			<name>O. Chanrion</name>
		</author>
		<author numeration="5" affiliations="5">
			<name>P. T. Verronen</name>
		</author>
		<author numeration="6" affiliations="5">
			<name>A. Seppälä</name>
		</author>
		<author numeration="7" affiliations="4">
			<name>T. Neubert</name>
		</author>
		<author numeration="8" affiliations="1">
			<name>T. Ulich</name>
		</author>
		<author numeration="9" affiliations="1">
			<name>E. Turunen</name>
		</author>
		<author numeration="10" affiliations="3">
			<name>Y. Takahashi</name>
		</author>
		<author numeration="11" affiliations="6">
			<name>R.-R. Hsu</name>
		</author>
	</authors>
	<affiliations>
		<affiliation numeration="1" content_type="html">Sodankylä Geophysical Observatory, University of Oulu, Sodankylä, Finland</affiliation>
		<affiliation numeration="2" content_type="html">Dept. of Physics and Astronomy, Leicester University, UK</affiliation>
		<affiliation numeration="3" content_type="html">Dept. of Geophysics, Tohoku University, Sendai, Japan</affiliation>
		<affiliation numeration="4" content_type="html">Danish National Space Center, Technical University of Denmark, Copenhagen, Denmark</affiliation>
		<affiliation numeration="5" content_type="html">Earth Observation unit, Finnish Meteorological Institute, Helsinki, Finland</affiliation>
		<affiliation numeration="6" content_type="html">Dept. of Physics, National Cheng Kung University, Tainan, Taiwan</affiliation>
		<affiliation numeration="7" content_type="html">now at: Dept. of Physical Chemistry, University of Bologna, Italy</affiliation>
		<affiliation numeration="8" content_type="html">now at: Research Institute for Sustainable Humanosphere, Kyoto University, Uji, Japan</affiliation>
	</affiliations>
	<abstract content_type="html">Transient luminous events, such as red sprites, occur in the middle
  atmosphere in the electric field above thunderstorms.  We here
  address the question whether these processes may be a significant
  source of odd nitrogen and affect ozone or other important trace
  species. A well-established coupled ion-neutral chemical model has
  been extended for this purpose and applied together with estimated
  rates of ionisation, excitation and dissociation based on
  spectroscopic ratios from ISUAL on FORMOSAT-2. This approach is used
  to estimate the NO&lt;sub&gt;x&lt;/sub&gt; and ozone changes for two type
  cases.

&lt;br&gt;&lt;br&gt;

  The NO&lt;sub&gt;x&lt;/sub&gt; enhancements are at most one order of magnitude in
  the streamers, which means a production of at most 10 mol per
  event, or (given a global rate of occurrence of three events per
  minute) some 150&amp;ndash;1500 kg per day.  The present study
  therefore indicates that sprites are insignificant as a global
  source of NO&lt;sub&gt;x&lt;/sub&gt;. Local effects on ozone are also negligible,
  but the local enhancement of NO&lt;sub&gt;x&lt;/sub&gt; may be significant, up to 5
  times the minimum background at 70 km in extraordinary cases.</abstract>
	<references>
		<reference numeration="1" content_type="text"> Adachi, T., Fukunishi, H., Takahashi, Y., Hiraki, Y., Hsu, R.-R., Su, H.-T., Chen, A B., Mende, S B., Frey, H U., and Lee, L C.: Electric field transition between the diffuse and streamer regions of sprites estimated from ISUAL/array photometer measurements, Geophys. Res. Lett., 33, L17803, \doi10.1029/2006GL026495, 2006. </reference>
		<reference numeration="2" content_type="text"> Arnone, E., Berg, P., Boberg, F., Bór, J., Chanrion, O., Enell, C.-F., Ignaccolo, M., Mika, \&apos;A., Odzimek, A., van~der Velde, O., Farges, T., Laursen, S., Neubert, T., and Sátori, G.: The Eurosprite 2005 campaign, in: Proceedings of the 33rd Annual European meeting on Atmospheric Studies by Optical Methods (33AM), edited by Arvelius, J., no. 292 in IRF Scientific Reports, Swedish Inst. of Space Physics, Kiruna, in press, 2008a. %</reference>
		<reference numeration="3" content_type="text"> %Arnone, E., Kero, A., Dinelli, B M., Enell, C.-F., Arnold, N F., Papandrea, % E., Rodger, C J., Carlotti, M., Ridolfi, M., and Turunen, E.: Seeking % sprite-induced signatures in remotely sensed middle atmosphere NO&lt;sub&gt;2&lt;/sub&gt;, % Geophys. Res. Lett., in review, 2008b. </reference>
		<reference numeration="4" content_type="text"> Baehr, J., Schlager, H., Ziereis, H., Stock, P., van Velthoven, P., Busen, R., Ström, J., and Schumann, U.: Aircraft observations of NO, NO$_y$, CO, and O&lt;sub&gt;3&lt;/sub&gt; in the upper troposphere from 60&amp;deg; N to 60&amp;deg; S &amp;ndash; Interhemispheric differences, Geophys. Res. Lett., 30, 1598, doi:10.1029/2003GL016935, 2003. </reference>
		<reference numeration="5" content_type="text"> Balakrishnan, N. and Dalgarno, A.: Nitric oxide production in collisions of hot O($^3P$) atoms with N&lt;sub&gt;2&lt;/sub&gt;, J. Geophys. Res., 108, 1065, doi:10.1029/2002JA009566, 2003. </reference>
		<reference numeration="6" content_type="text"> Banks, P. and Kockarts, G.: Aeronomy, Academic Press Inc., 1973. </reference>
		<reference numeration="7" content_type="text"> Birkeland, K.: Norwegian Aurora Polaris Expedition; 1902&amp;ndash;3, vol 1, H. Aschehoug and Co., Christiania, Norway, 1908. </reference>
		<reference numeration="8" content_type="text"> Brasseur, G P. and Solomon, S.: Aeronomy of the Middle Atmosphere, Springer Verlag, The Netherlands, 2005. </reference>
		<reference numeration="9" content_type="text"> Bucsela, E., Morrill, J., Heavner, M., Siefring, C., Berg, S., Hampton, D., Moudry, D., Wescott, E., and Sentman, D.: N&lt;sub&gt;2&lt;/sub&gt;($B^3\Pi_\mathrmg$) and N$_2^+$($A^2\Pi_\mathrmu$) vibrational distributions observed in sprites, J. Atmos. and Solar-Terr. Phys., 65, 583&amp;ndash;591, 2003. </reference>
		<reference numeration="10" content_type="text"> Callis, L B., Natarajan, M., and Lambeth, J D.: Observed and calculated mesospheric NO, 1992-1997, Geophys. Res. Lett., 29, 1030, doi:10.1029/2001GL013995, 2002. </reference>
		<reference numeration="11" content_type="text"> Chabrillat, S., Kockarts, G., Fonteyn, D., and Brasseur, G.: Impact of molecular diffusion on the CO&lt;sub&gt;2&lt;/sub&gt; distribution and the temperature in the mesosphere, Geophys. Res. Lett., 29, 1729, \doi10.1029/2002GL015309, 2002. </reference>
		<reference numeration="12" content_type="text"> Chern, J L., Hsu, R.-R., Su, H.-T., Mende, S B., Fukunishi, H., Takahashi, Y., and Lee, L C.: Global survey of upper atmospheric transient luminous events on the ROCSAT-2 satellite, J. Atmos. Sol.-Terr. Phy., 65, 647&amp;ndash;659, 2003. </reference>
		<reference numeration="13" content_type="text"> Clilverd, M A., Seppälä, A., Rodger, C J., Verronen, P T., and Thomson, N R.: Ionospheric evidence of thermosphere-to-stratosphere descent of polar NO&lt;sub&gt;x&lt;/sub&gt;, Geophys. Res. Lett., 33, L19811, \doi10.1029/2006GL026727, 2006. </reference>
		<reference numeration="14" content_type="text"> Coppens, F., Berton, R., Bondiou-Clergerie, A., and Gallimberti, I.: Theoretical estimate of NO&lt;sub&gt;x&lt;/sub&gt; production in lightning corona, J.\ Geophys. Res., 103, 10 769&amp;ndash;10 785, 1998. </reference>
		<reference numeration="15" content_type="text"> CPAT and Kinema Software: The Siglo data base, http://www.siglo-kinema.com. </reference>
		<reference numeration="16" content_type="text"> Crutzen, P J., Isaksen, I. S A., and Reid, G C.: Solar Proton Events: Stratospheric Sources of Nitric Oxide, Science, 189, 457&amp;ndash;458, 1975. </reference>
		<reference numeration="17" content_type="text"> Cummer, S A., Jaugey, N., Li, J., Lyons, W A., Nelson, T E., and Gerken, E A.: Submillisecond imaging of sprite development and structure, Geophys.\ Res. Lett., 33, L04104, doi:10.1029/2005GL024969, 2006. </reference>
		<reference numeration="18" content_type="text"> Fischer, H., Birk, M., Blom, C., Carli, B., Carlotti, M., von Clarmann, T., Delbouille, L., Dudhia, A., Ehhalt, D., Endemann, M., Flaud, J M., Gessner, R., Kleinert, A., Koopmann, R., Langen, J., López-Puertas, M., Mosner, P., Nett, H., Oelhaf, H., Perron, G., Remedios, J., Ridolfi, M., Stiller, G., and Zander, R.: MIPAS: an instrument for atmospheric and climate research, Atmos. Chem. Phys. Discuss., 7, 8795&amp;ndash;8893, 2007. </reference>
		<reference numeration="19" content_type="text"> Franz, R C., Nemzek, R J., and Winckler, J R.: Television Image of a Large Upward Electrical Discharge Above a Thunderstorm System, Science, 249, 48&amp;ndash;51, 1990. </reference>
		<reference numeration="20" content_type="text"> Fukunishi, H., Takahashi, Y., Kubota, M., and Sakanoi, K.: Elves: Lightning induced transient luminous events in the lower ionosphere,, Geophys. Res.\ Lett., 23, 2157&amp;ndash;2160, \doi10.1029/96GL01979, 1996. </reference>
		<reference numeration="21" content_type="text"> Funke, B., López-Puertas, M., von Clarmann, T., Stiller, G P., Fischer, H., Glatthor, N., Grabowski, U., Höpfner, M., Kellmann, S., Kiefer, M., Linden, A., Mengistu~Tsidu, G., Milz, M., Steck, T., and Wang, D Y.: Retrieval of stratospheric NO$_x$ from 5.3 and 6.2 μm nonlocal thermodynamic equilibrium emissions measured by Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) on Envisat, J. Geophys.\ Res., 110, D09302, doi:10.1029/2004JD005225, 2005. </reference>
		<reference numeration="22" content_type="text"> Gerken, E A. and Inan, U S.: Observations of decameter-scale morphologies in sprites, J. Atmos. Sol.-Terr. Phy., 65, 567&amp;ndash;572, 2003. </reference>
		<reference numeration="23" content_type="text"> Gerken, E A., Inan, U S., and Barrington-Leigh, C P.: Telescopic imaging of sprites, Geophys. Res. Lett., 27, 2637&amp;ndash;2640, 2000. </reference>
		<reference numeration="24" content_type="text"> Gilmore, F R., Laher, R R., and Espy, P J.: Franck-Condon Factors, r-Centroids, Electronic transition Moments, and Einstein Coefficients for many Nitrogen and oxygen Band Systems, J. Phys. Chem. Ref. Data, 21, 1005&amp;ndash;1107, 1992. </reference>
		<reference numeration="25" content_type="text"> Hedin, A E.: Extension of the MSIS Thermospheric Model into the Middle and Lower Atmosphere, J. Geophys. Res., 96, 1159&amp;ndash;1172, 1991. </reference>
		<reference numeration="26" content_type="text"> Hiraki, Y., Tong, L., Fukunishi, H., Nanbu, K., Kasai, Y., and Ichimura, A.: Generation of metastable oxygen atom O($^1$D) in sprite halos, Geophys.\ Res. Lett., 31, L14105, doi:10.1029/2004GL020048, 2004. </reference>
		<reference numeration="27" content_type="text"> Huntrieser, H., Schlager, H., Roiger, A., Lichtenstern, M., Schumann, U., Kurz, C., Brunner, D., Schwierz, C., Richter, A., and Stohl, A.: Lightning-produced NOx over Brazil during TROCCINOX: Airborne measurements in tropical and subtropical thunderstorms and the importance of mesoscale convective systems, Atmos. Chem. Phys., 7, 2987&amp;ndash;3013, 2007. </reference>
		<reference numeration="28" content_type="text"> Ignaccolo, M., Farges, T., Mika, A., Allin, T H., Chanrion, O., Blanc, E., Fraser-Smith, A C., and Füllekrug, M.: The Planetary Rate of Sprite Events, Geophys. Res. Lett., 33, L11808, \doi10.1029/2005GL025502, 2006. </reference>
		<reference numeration="29" content_type="text"> Liu, N., Pasko, V P., Burkhardt, D H., Frey, H U., Mende, S B., Su, H.-T., Chen, A B., Hsu, R.-R., Lee, L.-C., Fukunishi, H., and Takahashi, Y.: Comparison of results from sprite streamer modeling with spectrophotometric measurements by ISUAL instrument on FORMOSAT-2 satellite, Geophys. Res. Lett., 33, L01101, \doi10.1029/2005GL024243, 2006. </reference>
		<reference numeration="30" content_type="text"> Lyons, W A.: The meteorology of transient luminous events &amp;ndash;- an introduction and overview, in: Sprites, Elves and Intense Lightning Discharges, edited by Füllekrug, M., Mareev, E A., and Rycroft, M J., vol. 225 of \em NATO Science Series II. Mathematics, physics and chemistry\/, pp. 19&amp;ndash;56, Springer Verlag, ISBN 1-4020-4628-6, 2006. </reference>
		<reference numeration="31" content_type="text"> Mende, S., Rairden, R., Swenson, G., and Lyons, A.: Sprite spectra; N&lt;sub&gt;2&lt;/sub&gt; 1 PG band identification, Geophys. Res. Lett., 22, 2633&amp;ndash;2636, 1995. </reference>
		<reference numeration="32" content_type="text"> Mende, S B., Frey, H U., Hsu, R R., Su, H T., Chen, A B., Lee, L C., Sentman, D D., Takahashi, Y., and Fukunishi, H.: D region ionization by lightning-induced electromagnetic pulses, J. Geophys. Res., 110, A11312, doi:10.1029/2005JA011064, 2005. </reference>
		<reference numeration="33" content_type="text"> Miller, S L.: A Production of Amino Acids Under Possible Primitive Earth Conditions, Science, 117, 528&amp;ndash;529, 1953. </reference>
		<reference numeration="34" content_type="text"> Mishin, E.: Ozone layer perturbation by a single blue jet, Geophys. Res.\ Lett., 24, 1919&amp;ndash;1922, 1997. </reference>
		<reference numeration="35" content_type="text"> Morrill, J S., Bucsela, E J., Pasko, V P., Berg, S L., Heavner, M J., Moudry, D R., Benesch, W M., Wescott, E M., and Sentman, D D.: Time resolved N&lt;sub&gt;2&lt;/sub&gt; triplet state vibrational populations and emissions associated with red sprites, J. Atmos. Sol.-Terr. Phy., 60, 811&amp;ndash;829, 1998. </reference>
		<reference numeration="36" content_type="text"> Neubert, T.: On Sprites and Their Exotic Kin, Science, 300, 747&amp;ndash;749, 2003. </reference>
		<reference numeration="37" content_type="text"> Noxon, J F.: Atmospheric nitrogen fixation by lightning, Geophys. Res.\ Lett., 3, 463&amp;ndash;465, 1976. </reference>
		<reference numeration="38" content_type="text"> Oparin, A I.: The origin of life, Dover, New York, 1952. </reference>
		<reference numeration="39" content_type="text"> Pasko, V P.: Red sprite discharges in the atmosphere at high altitude: the molecular physics and the similarity with laboratory discharges, Plasma Sources Sci. Technol., 16, S13&amp;ndash;S29, \doi10.1088/0963-0252/16/1/S02, 2007. </reference>
		<reference numeration="40" content_type="text"> Pavlov, A V. and Buonsanto, M J.: Using steady state vibrational temperatures to model effects of N$_2^*$ on calculations of electron densities, J.\ Geophys. Res., 101, 26 941&amp;ndash;26 946, \doi10.1029/96JA02734, 1996. </reference>
		<reference numeration="41" content_type="text"> Peterson, H., Bailey, M., Hallett, J., and Beasley, W.: NOx Production in Simulated Blue Jets, Sprites, and TLE Discharges, AGU Fall Meeting Abstracts, pp. A990, 2005. </reference>
		<reference numeration="42" content_type="text"> Piper, L G., Caledonia, G E., and Kennealy, J P.: Rate constants for deactivation of N&lt;sub&gt;2&lt;/sub&gt;(A,$\nu&apos;=0,1$) by O&lt;sub&gt;2&lt;/sub&gt;, J. Chem. Phys., 74, 2888&amp;ndash;2895, 1981a. </reference>
		<reference numeration="43" content_type="text"> Piper, L G., Caledonia, G E., and Kennealy, J P.: Rate constants for deactivation of N&lt;sub&gt;2&lt;/sub&gt;($A^3§igma_u^+,\nu=0,1$) by O, J. Chem. Phys., 75, 2847&amp;ndash;2852, 1981b. </reference>
		<reference numeration="44" content_type="text"> Pitchford, L C., Oneil, S V., and J R Rumble, J.: Extended Boltzmann analysis of electron swarm experiments, Phys. Rev. A, 23, 294&amp;ndash;304, 1981. </reference>
		<reference numeration="45" content_type="text"> Press, W H., Teukolsky, S A., Vetterling, W T., and Flannery, B P.: Numerical Recipes in C, Cambridge University Press, second edn., 1992. </reference>
		<reference numeration="46" content_type="text"> Price, C.: Global thunderstorm activity, in: Sprites, Elves and Intense Lightning Discharges, edited by: Füllekrug, M., Mareev, E A., and Rycroft, M J., vol. 225 of \em NATO Science Series II. Mathematics, physics and chemistry\/, Springer Verlag, ISBN 1-4020-4628-6, 2006. </reference>
		<reference numeration="47" content_type="text"> Rakov, V A. and Uman, M A.: Lightning, Physics and Effects, Cambridge University Press, ISBN: 0-521-58327-6, 2003. </reference>
		<reference numeration="48" content_type="text"> Randel, W., Udelhofen, P., Fleming, E., Geller, M., Gelman, M., Hamilton, K., Karoly, D., Ortland, D., Pawson, S., Swinbank, R., Wu, F., Baldwin, M., Chanin, M.-L., Keckhut, P., Labitzke, K., Remsberg, E., Simmons, A., and Wu, D.: The SPARC Intercomparison of Middle-Atmosphere Climatologies, J. Climate, 17, 986&amp;ndash;1003, 2004. </reference>
		<reference numeration="49" content_type="text"> Schumann, U. and Huntrieser, H.: The global lightning-induced nitrogen oxides source, Atmos. Chem. Phys., 7, 3823&amp;ndash;3907, 2007. </reference>
		<reference numeration="50" content_type="text"> Sentman, D D., Wescott, E M., Osborne, D L., Hampton, D L., and Heavner, M J.: Preliminary results from the Sprites94 aircraft campaign: 1. Red sprites, Geophys. Res. Lett., 22, 1205&amp;ndash;1208, 1995. </reference>
		<reference numeration="51" content_type="text"> Seppälä, A., Clilverd, M A., and Rodger, C J.: NO&lt;sub&gt;x&lt;/sub&gt; enhancements in the middle atmosphere: The relative significance of Solar Proton Events and the Aurora as a source, J. Geophys. Res., 112, D23303, doi:10.1029/2006JD008326, 2007. </reference>
		<reference numeration="52" content_type="text"> Shimazaki, T.: Minor Constituents in the Middle Atmosphere, no 6 in Developments in Earth and Planetary Physics, D. Reidel Publishing Company, 1984. </reference>
		<reference numeration="53" content_type="text"> Slanger, T G. and Black, G.: Quenching of O($^1$S) by O&lt;sub&gt;2&lt;/sub&gt;(a$^1\Delta_g$), Geophys. Res. Lett., 8, 535&amp;ndash;538, 1981. </reference>
		<reference numeration="54" content_type="text"> Stenbaek-Nielsen, H.-C., McHarg, M G., Kammae, T., and Sentman, D D.: Observed Emission Rates in Sprite Streamer Heads, Geophys. Res. Lett., 34(11), L11105, doi:10.1029/2007GL029881, 2007. </reference>
		<reference numeration="55" content_type="text"> Su, H T., Hsu, R R., Chen, A B., Wang, Y C., Hsiao, W S., Lai, W C., Lee, L C., Sato, M., and Fukunishi, H.: Gigantic jets between a thundercloud and the ionosphere, Nature, 423, 974&amp;ndash;976, 2003. </reference>
		<reference numeration="56" content_type="text"> Swider, W.: Atmospheric formation of NO from N&lt;sub&gt;2&lt;/sub&gt;(A$^3§igma$), Geophys.\ Res. Lett., 3, 335&amp;ndash;337, 1976. </reference>
		<reference numeration="57" content_type="text"> Thomas, J M. and Kaufman, F.: Rate constants of the reactions of metastable N&lt;sub&gt;2&lt;/sub&gt;($A^3§igma_u^+$) in ν=0,1,2, and 3 with ground state O&lt;sub&gt;2&lt;/sub&gt; and O, J. Chem. Phys., 83, 2900&amp;ndash;2903, 1985. </reference>
		<reference numeration="58" content_type="text"> Thomas, J M., Kaufman, F., and Golde, M F.: Rate constants for electronic quenching of N&lt;sub&gt;2&lt;/sub&gt;($A^3§igma_u^+, \nu=0-6$) by O&lt;sub&gt;2&lt;/sub&gt;, NO, CO, N&lt;sub&gt;2&lt;/sub&gt;O, and C&lt;sub&gt;2&lt;/sub&gt;H&lt;sub&gt;4&lt;/sub&gt;, J. Chem. Phys., 86, 6885&amp;ndash;6892, 1987. </reference>
		<reference numeration="59" content_type="text"> Tobiska, W., Woods, T., Eparvier, F., Viereck, R., Floyd, L., Bouwer, D., Rottman, G., and White, O.: The SOLAR2000 empirical solar irradiance model and forecast tool, J. Atmos. Sol.-Terr. Phy., 62, 1233&amp;ndash;1250, 2000. </reference>
		<reference numeration="60" content_type="text"> Turunen, E., Matveinen, H., Tolvanen, J., and Ranta, H.: D-Region Ion Chemistry Model, in: STEP Handbook of Ionospheric Models, edited by Schunk, R W., pp. 1&amp;ndash;25, Scientific Committee on Solar-Terrestrial Physics, 1996. </reference>
		<reference numeration="61" content_type="text"> Verronen, P., Turunen, E., Ulich, T., and Kyrölä, E.: Modelling the effects of the October 1989 solar proton event on mesospheric odd nitrogen using a detailed ion and neutral chemistry model, Ann. Geophys., 20, 1967&amp;ndash;1976, 2002. </reference>
		<reference numeration="62" content_type="text"> Verronen, P T.: Ionosphere-atmosphere interaction during solar proton events, Ph.D. thesis, Finnish Meteorological Institute, Helsinki, Finland, http://ethesis.helsinki.fi/, ISBN: 951-697-650-6, 2006. </reference>
		<reference numeration="63" content_type="text"> Verronen, P T., Seppälä, A., Clilverd, M A., Rodger, C J., Kyrölä, E., Enell, C.-F., Ulich, T., and Turunen, E.: Diurnal variation of ozone depletion during the October&amp;ndash;November 2003 solar proton event, J. Geophys. Res., 110, A09S32, doi:10.1029/2004JA010932, 2005. </reference>
		<reference numeration="64" content_type="text"> Vitt, F M. and Jackman, C H.: A comparison of sources of odd nitrogen production from 1974 through 1993 in the Earth&apos;s middle atmosphere as calculated using a two-dimensional model, J. Geophys. Res., 101, 6729&amp;ndash;6739, 1996. </reference>
		<reference numeration="65" content_type="text"> Vitt, F M., Armstrong, T P., Cravens, T E., Dreschhoff, G. A M., Jackman, C H., and Laird, C M.: Computed contributions to odd nitrogen concentrations in the Earth&apos;s polar middle atmosphere by energetic charged particles, J. Atmos. Sol.-Terr. Phy., 62, 669&amp;ndash;683, 2000a. </reference>
		<reference numeration="66" content_type="text"> Vitt, F M., Cravens, T E., and Jackman, C H.: A two-dimensional model of thermospheric nitric oxide sources and their contributions to the middle atmospheric chemical balance, J. Atmos. Sol.-Terr. Phy., 62, 653&amp;ndash;667, 2000b. </reference>
	</references>
</article>
