Extended Data Fig. 1: Histogram of the measured D/H and 18O/16O isotope ratios, as well as their relation with the water vapour mixing ratio and temperature.
From: Isotopic fractionation of water and its photolytic products in the atmosphere of Mars
Only the points with uncertainties of D/H < 1 VSMOW and 18O/16O < 0.13 VSMOW are shown. The black dashed lines on the histogram plots represent typical measurement uncertainties, centred at D/H = 4.9 ± 0.4 VSMOW and 18O/16O = 1.14 ± 0.11 VSMOW. The colour of the points on the plots in the middle and right columns represents the density of measured points. The red cross in the temperature panels represents the most frequently measured value of the isotope ratios at temperatures > 180 K, which we take as the average non-fractionated isotope ratios in the Martian atmosphere.
