deletions | additions       diff --git a/Problems_with_the_instrument_and__.tex b/Problems_with_the_instrument_and__.tex  index 96522e4..aba35f5 100644  --- a/Problems_with_the_instrument_and__.tex  +++ b/Problems_with_the_instrument_and__.tex 
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\frac{column_{O_2}}{column_{dry air}} = 0.2095  \end{equation}  Retrieved An offset from this value occurs due to spectroscopic biases, and then further retrieved  variations from 0.2095 mol mol$^{-1}$ at TCCON sites must therefore be due to deviations from the expected observed airmass or instrumental problems.   Rearranging equation \ref(eq:o2_dryair2}, we define  \begin{equation}  \label{eq:xair}  X_air = \frac{column_{dry air}}{column_{O_2}} * 0.2095 \approx 1