<?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>Timothy N. Titus</dc:contributor>
  <dc:creator>Thomas H. Prettyman</dc:creator>
  <dc:date>2004</dc:date>
  <dc:description>&lt;div class="article-section__content en main"&gt;&lt;p&gt;The northern and southern seasonal polar caps of Mars are formed in the polar night, during their respective autumn and winter seasons, by the condensation of atmospheric CO&lt;sub&gt;2&lt;/sub&gt;directly to the solid phase as ice, snow, and possibly frost. During spring and summer, the seasonal ice sublimes, returning CO&lt;sub&gt;2&lt;/sub&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;to the atmosphere. The caps advance and recede in response to seasonal variations in solar insolation, extending as far as 40° from the poles, and have been noted by telescopic observers since the 17th century Roughly 25% of the atmosphere, which is 95% CO&lt;sub&gt;2&lt;/sub&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;by volume, is cycled into and out of the seasonal caps. The CO&lt;sub&gt;2&lt;/sub&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;cycle dominates atmospheric circulation on Mars, and must be thoroughly understood in order to answer fundamental questions about climate history and the global distribution of near‐surface water.&lt;/p&gt;&lt;/div&gt;</dc:description>
  <dc:format>application/pdf</dc:format>
  <dc:identifier>10.1029/2004EO410005</dc:identifier>
  <dc:language>en</dc:language>
  <dc:publisher>American Geophysical Union</dc:publisher>
  <dc:title>Exploring Martian polar atmospheric circulation and surface interactions</dc:title>
  <dc:type>article</dc:type>
</oai_dc:dc>