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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-21-947-2003</article-id>
<title-group>
<article-title>The dependence of cusp ion signatures on the reconnection rate</article-title>
</title-group>
<contrib-group><contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Morley</surname>
<given-names>S. K.</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>Lockwood</surname>
<given-names>M.</given-names>
</name>
<xref ref-type="aff" rid="aff2">
<sup>2</sup>
</xref>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
</contrib>
</contrib-group><aff id="aff1">
<label>1</label>
<addr-line>Department of Physics and Astronomy, University of Southampton, UK</addr-line>
</aff>
<aff id="aff2">
<label>2</label>
<addr-line>Rutherford Appleton Laboratory, Chilton, Oxfordshire, UK</addr-line>
</aff>
<pub-date pub-type="epub">
<day>30</day>
<month>04</month>
<year>2003</year>
</pub-date>
<volume>21</volume>
<issue>4</issue>
<fpage>947</fpage>
<lpage>953</lpage>
<permissions>
<copyright-statement>Copyright: &#x000a9; 2003 S. K. Morley</copyright-statement>
<copyright-year>2003</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>
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<self-uri xlink:href="https://angeo.copernicus.org/articles/21/947/2003/angeo-21-947-2003.pdf">The full text article is available as a PDF file from https://angeo.copernicus.org/articles/21/947/2003/angeo-21-947-2003.pdf</self-uri>
<abstract>
<p>The interpretation of
 structure in cusp ion dispersions is important for helping to understand the
 temporal and spatial structure of magnetopause reconnection.
 &amp;quot;Stepped&amp;quot; and &amp;quot;sawtooth&amp;quot; signatures have been shown to be
 caused by temporal variations in the reconnection rate under the same physical
 conditions for different satellite trajectories. The present paper shows that
 even for a single satellite path, a change in the amplitude of any reconnection
 pulses can alter the observed signature and even turn sawtooth into stepped
 forms and vice versa. On 20 August 1998, the Defense Meteorological Satellite
 Program (DMSP) craft F-14 crossed the cusp just to the south of Longyearbyen,
 returning on the following orbit. The two passes by the DMSP F-14 satellites
 have very similar trajectories and the open-closed field line boundary (OCB)
 crossings, as estimated from the SSJ/4 precipitating particle data and Polar
 UVI images, imply a similarly-shaped polar cap, yet the cusp ion dispersion
 signatures differ substantially. The cusp crossing at 08:54 UT displays a
 stepped ion dispersion previously considered to be typical of a meridional
 pass, whereas the crossing at 10:38 UT is a sawtooth form ion dispersion,
 previously considered typical of a satellite travelling longitudinally with
 respect to the OCB. It is shown that this change in dispersed ion signature is
 likely to be due to a change in the amplitude of the pulses in the reconnection
 rate, causing the stepped signature. Modelling of the low-energy ion cutoff
 under different conditions has reproduced the forms of signature observed.&lt;br&gt;&lt;br&gt;&lt;b&gt;Key words. &lt;/b&gt;Ionosphere (particle
 precipitation) Magnetospheric physics (energetic particles, precipitating,
 magnetopause, cusp and boundary layers)</p>
</abstract>
<counts><page-count count="7"/></counts>
</article-meta>
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