Calibration and field testing of cavity ring-down laser spectrometers measuring CH&amp;lt;sub&amp;gt;4&amp;lt;/sub&amp;gt;, CO&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt;, and &amp;lt;i&amp;gt;δ&amp;lt;/i&amp;gt;&amp;lt;sup&amp;gt;13&amp;lt;/sup&amp;gt;CH&amp;lt;sub&amp;gt;4&amp;lt;/sub&amp;gt; deployed on towers in the Marcellus Shale region
Atmospheric measurement techniques