Extreme &amp;lt;sup&amp;gt;13&amp;lt;/sup&amp;gt;C depletion of CCl&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt;F&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt; in firn air samples from NEEM, Greenland
Atmospheric chemistry and physics