Table 2. Second-order, cross-term sensitivities of the
reactivity L-CH4 relative to critical species (NOx, O3,
CH4, CO) calculated in pair combinations. Results here
are from ATom-1 and the Pacific basin (54°S-60°N). The single +10%
sensitivities calculated for individual species, S(X+10%), are shown in
italics along the diagonal. The doubly signed (i.e., ++ or –)
off-diagonal values represent the additional change in sensitivity due
to the coupling of the two species: S(X+10% & Y+10%) – S(X+10%) –
S(Y+10%). When the 2nd-order is small (only the
O3 x CO term here), the coupled perturbation is simply
the sum of the two individual ones. Atom-1 results for other
reactivities (P-O3, L-O3) and the Atlantic basin are given in
Supplemental Table S3.