Figure 1.

Reference frames obtained by Schauer et al. (2016) using two gases with different δ ¹³C (FF and FC), showing the effect of the calculations using the parameters as in Huntington et al. (2009) (a) and the Assonov and Brenninkmeijer (2003) ¹⁷R values and the λ value of Meijer and Li (1998) (b). Note that the differences disappear in Figure 1b. (Reproduced with permission from John Wiley & Sons, Inc.)