1− R² vs. mole fraction (0 = pure CO₂, 1 = pure H₂O) for three species for the pre-equinox and the two post-equinox time periods. The dashed curves show a parabolic fit to peaks in 1 − R². These fits provide an indication of the uncertainties in the range of mole fractions that produce the best fit (corresponding to the maximum correlation, i.e., the lowest 1 − R², see Livadiotis & McComas 2013; Livadiotis 2007). Post-equinox, HCN correlates best with pure H₂O. Pre- and post-equinox, C₂H₆ correlates best with CO₂ because addition of H₂O either makesthe correlation worse or does not change the correlation. CH₄ is clearly different pre- and post-equinox. Pre-equinox, this species correlates better with pure H₂O, but post equinox, the correlation is best with pure CO₂. HCN pre-equinox is the only species that has a better correlation with a mix of CO₂ and H₂O.