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<front>
<journal-meta>
<journal-id journal-id-type="publisher">ANGEO</journal-id>
<journal-title-group>
<journal-title>Annales Geophysicae</journal-title>
<abbrev-journal-title abbrev-type="publisher">ANGEO</abbrev-journal-title>
<abbrev-journal-title abbrev-type="nlm-ta">Ann. Geophys.</abbrev-journal-title>
</journal-title-group>
<issn pub-type="epub">1432-0576</issn>
<publisher><publisher-name>Copernicus Publications</publisher-name>
<publisher-loc>Göttingen, Germany</publisher-loc>
</publisher>
</journal-meta>
<article-meta>
<article-id pub-id-type="doi">10.5194/angeo-23-3727-2005</article-id>
<title-group>
<article-title>Propagation of whistler-mode chorus to low altitudes: divergent ray trajectories and ground accessibility</article-title>
</title-group>
<contrib-group><contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Chum</surname>
<given-names>J.</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>Santolík</surname>
<given-names>O.</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-group><aff id="aff1">
<label>1</label>
<addr-line>Institute of Atmospheric Physics, Bocni II/1401, 14131 Praha 4, Czech Republic</addr-line>
</aff>
<aff id="aff2">
<label>2</label>
<addr-line>Charles University, Faculty of Mathematics and Physics, V Holesovickach 2, 18000 Praha 8, Czech Republic</addr-line>
</aff>
<pub-date pub-type="epub">
<day>23</day>
<month>12</month>
<year>2005</year>
</pub-date>
<volume>23</volume>
<issue>12</issue>
<fpage>3727</fpage>
<lpage>3738</lpage>
<permissions>
<copyright-statement>Copyright: &#x000a9; 2005 J. Chum</copyright-statement>
<copyright-year>2005</copyright-year>
<license license-type="open-access">
<license-p>This work is licensed under the Creative Commons Attribution 3.0 Unported License. To view a copy of this licence, visit <ext-link ext-link-type="uri"  xlink:href="https://creativecommons.org/licenses/by/3.0/">https://creativecommons.org/licenses/by/3.0/</ext-link></license-p>
</license>
</permissions>
<self-uri xlink:href="https://angeo.copernicus.org/articles/23/3727/2005/angeo-23-3727-2005.html">This article is available from https://angeo.copernicus.org/articles/23/3727/2005/angeo-23-3727-2005.html</self-uri>
<self-uri xlink:href="https://angeo.copernicus.org/articles/23/3727/2005/angeo-23-3727-2005.pdf">The full text article is available as a PDF file from https://angeo.copernicus.org/articles/23/3727/2005/angeo-23-3727-2005.pdf</self-uri>
<abstract>
<p>We investigate the ray trajectories of nonductedly propagating lower-band
chorus waves with respect to their initial angle &amp;theta;&lt;sub&gt;0&lt;/sub&gt;, between the wave
vector and ambient magnetic field. Although we consider a wide range of
initial angles &amp;theta;&lt;sub&gt;0&lt;/sub&gt;, in order to be consistent with recent satellite
observations, we pay special attention to the intervals of initial angles
&amp;theta;&lt;sub&gt;0&lt;/sub&gt;, for which the waves propagate along the field lines in the source
region, i.e. we mainly focus on waves generated with &amp;theta&lt;sub&gt;0&lt;/sub&gt; within an
interval close to 0&amp;deg; and on waves generated within an interval close to
the Gendrin angle. We demonstrate that the ray trajectories of waves generated
within an interval close to the Gendrin angle with a wave vector directed
towards the lower L-shells (to the Earth) significantly diverge at the
frequencies typical for the lower-band chorus. Some of these diverging
trajectories reach the topside ionosphere having &amp;theta; close to 0&amp;deg;; thus, a
part of the energy may leak to the ground at higher altitudes where the field
lines have a nearly vertical direction. The waves generated with different
initial angles are reflected. A small variation of the initial wave normal angle
thus very dramatically changes the behaviour of the resulting ray. Although
our approach is rather theoretical, based on the ray tracing simulation, we
show that the initial angle &amp;theta;&lt;sub&gt;0&lt;/sub&gt; of the waves reaching the ionosphere
(possibly ground) is surprisingly close - differs just by several degrees
from the initial angles which fits the observation of magnetospherically
reflected chorus revealed by CLUSTER satellites. We also mention
observations of diverging trajectories on low altitude satellites.</p>
</abstract>
<counts><page-count count="12"/></counts>
</article-meta>
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