Table 1.

Range of the sensitivity forcings/parametrizations. P and L indicate whether the variable is of relevance to ozone production and/or loss, respectively.

	Minimum	Maximum	Descriptions
(1) NOx emissions (P)	0	4	The surface NOx emissions field as a function of latitude and longitude was multiplied by a scaling factor between 0 and 4, to explore the sensitivity of tropospheric ozone to a range of NOx emissions.
(2) CH4 concentrations (P)	0	4	The global-mean CH4 mixing ratio was multiplied by a scaling factor between 0 and 4, to explore the sensitivity of tropospheric ozone to a range of CH4 concentrations.
(3) CO+NMVOC (P) emissions	0	4	As for (1), but the scaling factor was applied to CO and NMVOC emissions simultaneously.
(4) ELEV for NOx and CO+NMVOCs (P)	1	6	Emissions were prescribed on the lowermost 1–6 levels (between the surface and ~2.5 km), to test whether the number of levels is important for tropospheric ozone abundances.
(5) CLEV for CH4 (P)	1	6	CH4 concentrations were prescribed on the lowermost 1–6 levels (between the surface and ~2.5 km), similar to (4).
(6) CMF (P+L)	0.25	1	1 implies clear-sky photolysis, whereas 0 would imply no photolysis. As photolysis rates of 0 do not occur during daytime, we selected a lower bound of 0.25 to represent cloudy sky conditions.
(7) HNO3 washout (L)	0	0.5	To test the sensitivity of tropospheric ozone to HNO3 removal, we removed between 0–50% of tropospheric gas-phase HNO3 at each chemical time step.
(8) N2O5 hydrolysis (L)	0.001	0.3	The probability of N2O5 hydrolysis occurring. Since the default is 0.1, we explored the sensitivity of tropospheric ozone to a range from 0.001–0.3.
(9) O3 dry deposition (L)	0	1	A specific reactivity of 0 stands for a nearly non-reactive gas, while 1 stands for a gas similarly reactive to ozone.