Table 3.

Aerosol light extinction (Mm⁻¹) for average of 20% most impaired days in 2011 at Mesa Verde National Park: Comparison of EPA natural extinction to modeled U.S. background (U. S. natural plus international, USB) extinction using three global models, MOZART, GEOS-Chem, and AM3, for boundary conditions and zero U.S. emissions for the CAMx continental U.S. modeling domain.

Scenario	AmmSO4	AmmNO3	Organic carbon mass	Elemental carbon	Fine soil	Coarse mass	Sea salt	Totalb
USB MOZART a	2.97	0.08	2.11	0.34	0.10	0.29	0.39	6.29
USB GEOS-Chem a	3.06	0.16	2.31	0.26	0.48	0.78	0.43	7.48
USB AM3 a	1.74	0.32	2.47	0.28	0.19	0.39	0.35	5.73
EPA natural	0.96	0.89	2.27	0.28	0.75	1.71	0.10	6.97

^aZero out U.S. anthropogenic in CAMx simulation.

^bExcluding Rayleigh light scattering.