Extended Data Fig. 2: Comparison of the most precise model (in isotopic δ notation23) and the simplified model used to include ice data45.
From: Isotopic constraint on the twentieth-century increase in tropospheric ozone
Left, black stars show ∆36 (‘D-36’, in parts per thousand) data in LOCK-IN firn plotted against mean gas ages with uncertainties (±2 s.e.m., calculated using the pooled standard deviation) shown as vertical bars. Lines represent reconstructed atmospheric trends. The preferred scenario is obtained using a SCRIPPS-based O2 trend (see Methods, ‘Δ36 for firn modelling’) and is constrained by LOCK-IN firn data excluding the deepest value. The black and green solid lines show the best-guess trend obtained with the most precise and simplified models, respectively. Long-dashed lines show the uncertainty envelope. Short-dashed lines show the results of the two models when including the probably contaminated deepest data point (most precise model in green, simplified model in black). Right, δ18O18Ocor data (‘d18O18Ocor’, in parts per thousand; see Methods, ‘Δ36 for firn modelling’) in LOCK-IN firn against depth (symbols), compared with model results (lines). The four model simulations only differ in the very deep firn. The deepest data point at 107.65 m, which is probably contaminated (see text), is not shown in the left panel. Its mean gas age is 110 yr, corresponding to 1906 ad.
