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\section{Trace \subsection{Trace  Gases} CO is produced globally from four main sources; biomass burning, fossil fuel burning, oxidation of non-methane hydrocarbons (NMHC), and oxidation of methane (CH$_{4}$) \cite{Seiler1987,Novelli1992}. In the southern hemisphere, the distribution of CO is largely affected by biomass burning \cite{Edwards2006,Gloudemans2006}. The main sink of CO in the troposphere is through reaction with the hydroxyl radical (OH). With a relatively long lifetime ranging from 2 weeks to a few months, depending on the levels of OH, CO is it an appropriate indicator of tropospheric pollution and transport \cite{Hough1991,Khalil1983,Holloway2000,Novelli1992}.