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<front>
<journal-meta>
<journal-id journal-id-type="publisher">NPG</journal-id>
<journal-title-group>
<journal-title>Nonlinear Processes in Geophysics</journal-title>
<abbrev-journal-title abbrev-type="publisher">NPG</abbrev-journal-title>
<abbrev-journal-title abbrev-type="nlm-ta">Nonlin. Processes Geophys.</abbrev-journal-title>
</journal-title-group>
<issn pub-type="epub">1607-7946</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/npg-18-697-2011</article-id>
<title-group>
<article-title>Dynamical changes of the polar cap potential structure: an information theory approach</article-title>
</title-group>
<contrib-group><contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Coco</surname>
<given-names>I.</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>Consolini</surname>
<given-names>G.</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>Amata</surname>
<given-names>E.</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>Marcucci</surname>
<given-names>M. F.</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>Ambrosino</surname>
<given-names>D.</given-names>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
</contrib>
</contrib-group><aff id="aff1">
<label>1</label>
<addr-line>INAF-Istituto di Fisica dello Spazio Interplanetario, Via Fosso del Cavaliere, 100, 00133 Roma, Italy</addr-line>
</aff>
<pub-date pub-type="epub">
<day>17</day>
<month>10</month>
<year>2011</year>
</pub-date>
<volume>18</volume>
<issue>5</issue>
<fpage>697</fpage>
<lpage>707</lpage>
<permissions>
<copyright-statement>Copyright: &#x000a9; 2011 I. Coco et al.</copyright-statement>
<copyright-year>2011</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://npg.copernicus.org/articles/18/697/2011/npg-18-697-2011.html">This article is available from https://npg.copernicus.org/articles/18/697/2011/npg-18-697-2011.html</self-uri>
<self-uri xlink:href="https://npg.copernicus.org/articles/18/697/2011/npg-18-697-2011.pdf">The full text article is available as a PDF file from https://npg.copernicus.org/articles/18/697/2011/npg-18-697-2011.pdf</self-uri>
<abstract>
<p>Some features, such as vortex structures often observed through a wide spread
of spatial scales, suggest that ionospheric convection is turbulent and
complex in nature. Here, applying concepts from information theory and
complex system physics, we firstly evaluate a pseudo Shannon entropy, &lt;i&gt;H&lt;/i&gt;,
associated with the polar cap potential obtained from the Super Dual Auroral
Radar Network (SuperDARN) and, then, estimate the degree of disorder and the
degree of complexity of ionospheric convection under different Interplanetary
Magnetic Field (IMF) conditions. The aforementioned quantities are computed
starting from time series of the coefficients of the 4th order spherical
harmonics expansion of the polar cap potential for three periods,
characterised by: (i) steady IMF &lt;i&gt;B&lt;sub&gt;z&lt;/sub&gt;&lt;/i&gt; &gt; 0, (ii) steady IMF &lt;i&gt;B&lt;sub&gt;z&lt;/sub&gt;&lt;/i&gt; &lt; 0 and
(iii) a double rotation from negative to positive and then positive to
negative &lt;i&gt;B&lt;sub&gt;z&lt;/sub&gt;&lt;/i&gt;. A neat dynamical topological transition is observed when the
IMF &lt;i&gt;B&lt;sub&gt;z&lt;/sub&gt;&lt;/i&gt; turns from negative to positive and vice versa, pointing toward the
possible occurrence of an order/disorder phase transition, which is the
counterpart of the large scale convection rearrangement and of the increase
of the global coherence. This result has been confirmed by applying the same
analysis to a larger data base of about twenty days of SuperDARN data,
allowing to investigate the role of IMF &lt;i&gt;B&lt;sub&gt;y&lt;/sub&gt;&lt;/i&gt; too.</p>
</abstract>
<counts><page-count count="11"/></counts>
</article-meta>
</front>
<body/>
<back>
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