Intercomparability of X&amp;lt;sub&amp;gt;CO&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt;&amp;lt;/sub&amp;gt; and X&amp;lt;sub&amp;gt;CH&amp;lt;sub&amp;gt;4&amp;lt;/sub&amp;gt;&amp;lt;/sub&amp;gt; from the United States TCCON sites
Atmospheric measurement techniques