Fig. 1.
Schematic illustrating possible metrics for NOx emissions that lead to perturbations of both ozone and methane. Shown are the cases of a discrete pulse emission of NOx (a-c) and a sustained emission change (d-f). (a and d) The evolution of the concentrations of NOx, ozone, and methane. (b and e) The net (ozone plus methane) RF (the individual ozone and methane RFs follow the curves for the burden in a and d) and the parameters that can be used for climate metrics. The absolute GWP (AGWP) is the time-integrated RF over some time horizon (H). The degree of compensation between the ozone and methane RFs depends on the value of H. The RF at some time H could also be used in a metric. (c and f) The global-mean surface-temperature change in response to the RF from b and e. The absolute global temperature potential (AGTP) at some time H is another possible metric.