Probability analyses of combining background concentrations with model-predicted concentrations

Figures & data

Figure 1. Example tracer array.

Figure 2. Location of Kincaid Power Station and 28 SO₂ monitor locations.

Figure 3. Observed vs. AERMOD predicted hourly SO₂ concentrations fully paired in time and space.

Figure 4. Maximum observed vs. maximum AERMOD predicted hourly SO₂ concentrations paired in time only.

Table 1. Summary of tracer and SO₂ observed outside 90° downwind sector

	Basis:	Maximum per hour			Average per hour			Minimum per hour
Pollutant	Wind direction	99th Percentile observed (10^−9 s/m³)	99th Percentile outside sector (10^−9 s/m³)	Percent hours outside sector >10% hourly max	99th Percentile observed (10^−9 s/m³)	99th Percentile outside sector (10^−9 s/m³)	Percent hours outside sector >10% hourly max	99th Percentile observed (10^−9 s/m³)	99th Percentile outside sector (10^−9 s/m³)	Average observed (10^−9 s/m³)
SF6	National Weather Service	247.2	188.0	60.3%	29.1	23.9	6.5%	0.00	0.00	0.00
	100 m Onsite	247.2	147.3	53.1%	29.1	16.5	3.9%	0.00	0.00	0.00
	10 m Onsite	247.2	116.3	55.7%	29.1	13.0	3.9%	0.00	0.00	0.00
	Basis:	Maximum per hour			Average per hour			Minimum per hour
Pollutant	Wind direction	99th Percentile observed (μg/m³)	99th Percentile outside sector (μg/m³)	Percent hours outside sector >10% hourly max	99th Percentile observed (μg/m³)	99th Percentile outside sector (μg/m³)	Percent hours outside sector >10% hourly max	99th Percentile observed (μg/m³)	99th Percentile outside sector (μg/m³)	Average observed (μg/m³)
SO2	National Weather Service	504.6	366.1	90.8%	77.2	65.9	59.9%	0.00	2.62	0.02
	100 m Onsite	507.3	300.7	90.1%	79.5	57.2	57.8%	0.00	2.62	0.02
	10 m Onsite	507.3	287.6	91.3%	79.5	58.0	58.6%	0.00	0.00	0.02

Table 2. Monitored hourly/seasonal SO₂ background concentrations (μg/m³)

	Season*
Hour of day	Spring (March April May)	Summer (June July August)
1	159	52
2	165	52
3	118	47
4	144	173
5	170	60
6	146	73
7	178	115
8	183	183
9	562	437
10	397	455
11	492	782
12	523	638
13	648	463
14	763	356
15	437	361
16	293	295
17	413	275
18	290	175
19	238	201
20	225	230
21	214	128
22	227	81
23	175	60
24	152	126
*Monitors did not collect winter and autumn data.

Table 3. Summary of total design value concentrations (predicted+background) for the Kincaid SO₂ data set

Background technique	Total concentrations (μg/m^3)
99th Percentile observed max daily 1-hr outside 90-degree sector	1987
Hourly/seasonal	1511
99th Percentile observed max daily minimum 1-hr (anywhere in monitoring network)	879
99th Percentile pairwise combinations with observed max daily 1-hr outside 90-degree sector	1397
99th Percentile pairwise combinations with observed max daily minimum 1-hr (anywhere in monitoring network)	871