Simulating Particle Size Distributions over California and Impact on Lung Deposition Fraction

Figures & data

TABLE 1 Summary of Aitken and accumulation mode parameters used for mapping particle emissions to lognormal distributions. Coarse mode parameters not changed in this study

Mode	Scenario^a		% Mass^b	D^c g (nm)	D^d gv (nm)	GSD^e
Aitken	CMAQv4.6	SO^2− 4, NO^− 3, other	0	13	30	1.7
		OC & EC	0.1	13	30	1.7
	Improved Emission		10	25	60	1.7
Accumulation	CMAQv4.6	SO^2− 4, NO^− 3, other	100	70	300	2.0
		OC & EC	99.9	70	300	2.0
	Improved Emission		90	120	280	1.7
^aCMAQv4.6 is standard model; Improved Emission from Elleman and Covert (2010).
^bPercentage of emitted mass apportioned to mode.
^cGeometric mean diameter of particle number-distribution mode.
^dGeometric mean diameter of particle volume-distribution mode.
^eGeometric standard deviation of mode.

FIG. 1 Particle size-distribution observation sites and terrain in California.

FIG. 2 Average observed and modeled mass size distributions for CRPAQS Intensive Operating Period 1 (IOP1). See upper-left FIG. for legend (Obs: Observations; Imp. Emiss.: Improved Emission scenario of Elleman and Covert, 2010). Dashed vertical line indicates aerodynamic diameter of 2.5 μm.

FIG. 3 Same as Figure 2, but for IOP3.

TABLE 2 Observed and modeled PM_2.5 (Angiola and Fresno) or PM_1.8 (other sites) associated with Figs. 2 and 3 (μg m⁻³)

		SO^2− 4		NH^+ 4		NO^− 3		Na^+		Cl^−		OM		EC
Site	Category	IOP1	IOP3	IOP1	IOP3	IOP1	IOP3	IOP1	IOP3	IOP1	IOP3	IOP1	IOP3	IOP1	IOP3
Bodega Bay	Observation	0.79	1.50	0.18	3.64	0.34	7.60	1.77	1.10	3.07	1.80	1.53	4.89	0.23	0.71
	CMAQv4.6	0.53	0.74	0.53	2.44	1.17	7.48	0.02	0.04	0.01	0.04	2.09	3.30	0.44	0.93
	Imp. Emiss.	0.56	0.77	0.56	2.56	1.25	7.88	0.02	0.04	0.01	0.05	2.19	3.49	0.46	0.98
Sacramento/Davis^a	Observation	0.65	0.64	1.19	5.85	2.91	12.93	0.16	0.03	0.15	0.10	5.83	10.05	1.06	1.75
	CMAQv4.6	0.88	0.97	2.31	3.61	6.85	11.20	0.01	0.01	0.01	0.01	5.16	3.11	1.76	1.29
	Imp. Emiss.	0.94	1.04	2.48	3.90	7.36	12.10	0.01	0.01	0.01	0.01	5.56	3.50	1.90	1.45
Modesto	Observation	1.67	2.73	2.87	16.41	5.73	34.15	0.19	0.12	0.32	0.55	9.34	25.34	1.59	3.74
	CMAQv4.6	1.78	3.83	2.96	5.90	7.90	15.38	0.00	0.01	0.01	0.01	4.08	4.95	1.60	2.00
	Imp. Emiss.	1.90	3.92	3.19	6.14	8.57	16.10	0.01	0.01	0.01	0.01	4.47	5.45	1.75	2.20
Fresno	Observation	1.23	2.26	1.69	11.09	3.90	31.85	0.14	0.10	0.18	0.17	23.91	45.79	2.86	4.15
	CMAQv4.6	3.46	4.60	5.36	6.62	14.00	16.89	0.00	0.02	0.01	0.03	6.65	6.44	2.82	2.60
	Imp. Emiss.	3.63	4.74	5.69	6.86	14.91	17.55	0.01	0.03	0.01	0.03	7.09	6.76	3.01	2.73
Angiola	Observation	1.26	3.36	1.83	16.89	4.03	50.02	0.21	0.10	0.41	0.09	13.29	27.65	1.16	2.21
	CMAQv4.6	0.62	0.98	2.98	6.24	9.48	20.23	0.01	0.02	0.02	0.03	1.68	1.92	0.63	0.77
	Imp. Emiss.	0.66	1.00	3.18	6.34	10.10	20.55	0.02	0.02	0.02	0.03	1.84	2.03	0.69	0.81
Bakersfield	Observation	2.12	3.97	4.23	25.92	11.87	53.57	0.08	0.24	0.58	0.32	9.67	24.33	1.59	3.64
	CMAQv4.6	3.22	4.47	4.17	6.84	10.21	17.80	0.01	0.01	0.01	0.02	5.02	4.98	3.30	2.94
	Imp. Emiss.	3.41	4.63	4.45	7.22	10.94	18.90	0.02	0.02	0.02	0.02	5.41	5.34	3.54	3.14
Sequoia	Observation	0.68	0.60	0.89	1.02	1.38	2.33	0.08	0.39	0.09	0.12	2.47	2.35	0.23	0.28
	CMAQv4.6	0.39	0.43	0.41	0.21	0.91	0.18	0.00	0.01	0.00	0.01	0.58	0.44	0.17	0.14
	Imp. Emiss.	0.40	0.42	0.42	0.21	0.96	0.19	0.01	0.01	0.01	0.01	0.62	0.43	0.19	0.14
^aIOP1 values are for Sacramento; IOP3 values are for Davis.

FIG. 4 Time series of observed and modeled number concentration (number cm^–3) for particles with diameter > 9 nm at Fresno for 12/8/00–1/31/01.

FIG. 5 Average diurnal number-concentration (number cm⁻³) profile at Fresno associated with time series in Figure 4.

FIG. 6 Average observed and modeled number size distributions at Fresno for 12/8/00–1/31/01 for (A) 7:00–8:00 PST, (B) 20:00–21:00 PST, and (C) all hours.

TABLE 3 Average peak-concentration diameter (nm) for particle number size distributions. Both wet and dry diameters are given for modeled distributions

	Bakersfield (All Hours)	Modesto (All Hours)	Fresno (All Hours)	Fresno (7–8 PST)	Fresno (20–21 PST)
Observation	79	79	78	35	78
CMAQv4.6 (wet)	118	131	120	143	114
CMAQv4.6 (dry)	76	80	76	76	75
Imp. Emiss. (wet)	34	43	40	42	40
Imp. Emiss. (dry)	25	31	30	28	30

FIG. 7 Average observed and modeled number size distributions at Modesto (1/4/01–1/7/01) and Bakersfield (1/4/01–1/5/01).

FIG. 8 Average modeled deposition fraction in the 5-lobe symmetric lung geometry as a function of airway generation number for average particle number size distributions in Figures 6c and 7. Average particle number concentration (number cm^–3) is given in parenthesis in the legend for the following diameter ranges (nm): 5–1000 for model, 9–392 for observations at Fresno, and 16–764 for observations at Modesto and Bakersfield. “H” indicates extrathoracic region; generation 1 is trachea.

FIG. 9 Observed (Zhu et al. 2004) and modeled particle number size distributions near Highway 710, LA in January. Observations are from 2002; model results are from 2001. Numbered labels indicate distance from roadway in meters, Bkgrd corresponds to background location, and Imp. Emiss. is Improved Emission scenario of Elleman and Covert (2010).

FIG. 10 Average modeled deposition fraction in the 5-lobe symmetric lung geometry as a function of airway generation number for particle number size distributions in FIG. 9. Average particle number concentration (number cm^–3) is given in parenthesis in the legend for the following diameter ranges (nm): 5–1000 for model, 6–225 for observations. “H” indicates extrathoracic region; generation 1 is trachea.

Elleman , R. A. and Covert , D. S. 2010 . Aerosol Size Distribution Modeling with the Community Multiscale Air Quality Modeling System in the Pacific Northwest: 3. Size Distribution of Particles Emitted into a Mesoscale Model . J. Geophys. Res. , 115 : D3 doi: 10.1029/2009JD012401

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