<?xml version='1.0' encoding='utf-8'?>
<oai_dc:dc xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:oai_dc="http://www.openarchives.org/OAI/2.0/oai_dc/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.openarchives.org/OAI/2.0/oai_dc/ http://www.openarchives.org/OAI/2.0/oai_dc.xsd">
  <dc:contributor>Jeffrey J. Love</dc:contributor>
  <dc:contributor>J.L. Gannon</dc:contributor>
  <dc:creator>G. L. Siscoe</dc:creator>
  <dc:date>2012</dc:date>
  <dc:description>&lt;p&gt;&lt;span&gt;Love and Gannon (2009) discovered that statistically, over a fifty year period the difference in the dawn and dusk disturbance‐field&amp;nbsp;&lt;/span&gt;&lt;i&gt;H&lt;/i&gt;&lt;span&gt;&amp;nbsp;component at low latitudes (hourly averaged) is linearly proportional to&amp;nbsp;&lt;/span&gt;&lt;i&gt;Dst.&lt;/i&gt;&lt;span&gt;&amp;nbsp;If the difference is designated by&amp;nbsp;&lt;/span&gt;&lt;i&gt;δ&lt;/i&gt;&lt;sub&gt;&lt;i&gt;DD&lt;/i&gt;&lt;/sub&gt;&lt;span&gt;&amp;nbsp;in units of nT/R&lt;/span&gt;&lt;sub&gt;E&lt;/sub&gt;&lt;span&gt;, then the Love‐Gannon (L‐G) relation is&amp;nbsp;&lt;/span&gt;&lt;i&gt;δ&lt;/i&gt;&lt;sub&gt;&lt;i&gt;DD&lt;/i&gt;&lt;/sub&gt;&lt;span&gt;&amp;nbsp;=&amp;nbsp;&lt;/span&gt;&lt;i&gt;−&lt;/i&gt;&lt;span&gt;0.2&amp;nbsp;&lt;/span&gt;&lt;i&gt;Dst.&lt;/i&gt;&lt;span&gt;&amp;nbsp;At any time departures from the relation can be large. Nonetheless, the relation is evident for all values of&amp;nbsp;&lt;/span&gt;&lt;i&gt;Dst&lt;/i&gt;&lt;span&gt;&amp;nbsp;and persists throughout magnetic storms, both the main phase and the recovery phase. The Love‐Gannon discovery presents a problem to current understanding of the relation between the causes of&amp;nbsp;&lt;/span&gt;&lt;i&gt;δ&lt;/i&gt;&lt;sub&gt;&lt;i&gt;DD&lt;/i&gt;&lt;/sub&gt;&lt;span&gt;&amp;nbsp;and&amp;nbsp;&lt;/span&gt;&lt;i&gt;Dst&lt;/i&gt;&lt;span&gt;&amp;nbsp;because the dawn dusk asymmetry in the disturbance field is presumably governed by a long‐established magnetosphere‐ionosphere coupling theory which predicts a characteristic time scale (the shielding time) of less than an hour whereas the characteristic time scale for&amp;nbsp;&lt;/span&gt;&lt;i&gt;Dst&lt;/i&gt;&lt;span&gt;&amp;nbsp;(the ring current decay time) is more like ten hours. Thus, without forcing both time scales toward each other to the limits of their ranges, a linear proportionality between&amp;nbsp;&lt;/span&gt;&lt;i&gt;δ&lt;/i&gt;&lt;sub&gt;&lt;i&gt;DD&lt;/i&gt;&lt;/sub&gt;&lt;span&gt;&amp;nbsp;and&amp;nbsp;&lt;/span&gt;&lt;i&gt;Dst&lt;/i&gt;&lt;span&gt;&amp;nbsp;cannot be derived from the current understanding of the causes of the asymmetry and the ring current. This conclusion is the paper's main contribution. In addition, we attempt to get around the conflict of time scales by looking at other possibilities for generating&amp;nbsp;&lt;/span&gt;&lt;i&gt;δ&lt;/i&gt;&lt;sub&gt;&lt;i&gt;DD&lt;/i&gt;&lt;/sub&gt;&lt;span&gt;&amp;nbsp;that depend directly on the ring current. The most promising of these is the possibility that the ring current decay mechanism creates a quasi‐permanent, local‐time modification of the ring current compared to what it would be in the absence of the decay mechanism and that this modification causes a field‐aligned current that closes through the ionosphere and generates the asymmetry&amp;nbsp;&lt;/span&gt;&lt;i&gt;δ&lt;/i&gt;&lt;sub&gt;&lt;i&gt;DD&lt;/i&gt;&lt;/sub&gt;&lt;span&gt;. This idea has the virtue of coupling the asymmetry directly to the ring current and of accounting for the persistence of the L‐G proportionality through the recovery phase of magnetic storms.&lt;/span&gt;&lt;/p&gt;</dc:description>
  <dc:format>application/pdf</dc:format>
  <dc:identifier>10.1029/2012JA017879</dc:identifier>
  <dc:language>en</dc:language>
  <dc:publisher>AGU</dc:publisher>
  <dc:title>Problem of the Love‐Gannon relation between the asymmetric disturbance field and Dst</dc:title>
  <dc:type>article</dc:type>
</oai_dc:dc>