1



## 4 Results for Model Sensitivity Tests

Several sensitivity tests were conducted for both t he July 1999 and the July-August 2000 episodes to see how the model responds to chan ges in input variables. Each of the episodes is five days in duration (ten days tot al for both episodes combined). Descriptions of the sensitivity tests for each epis ode are shown in Table 4-1 (July 1999) and Table 4-2 (July-August 20 00).

Tabulated 1-hour and 8-hour peak ozone concentratio n changes at individual observation stations are provided for each episode in Table 4-3 through Table 4-6. Note that the numbers in these tables represent averaged concentration differences over six days, consisting of the second of two model spin up days plus each five day episode. The initial spin-up day is not used in the calculat ion in order to minimize the effect of initial conditions on the calculated differences. The spatial difference plots for the ozone concentrations at 2pm on the last simulation day fo r each episode are shown in Figure 4-1 through Figure 4-17.

All of the model sensitivity results produce expect ed model responses. One interesting characteristic was noticed for scenarios involving large anthropogenic emission reductions: ozone concentrations near San Francisco Bay increase in some grid cells under scenarios involving large NOx reductions (e.g . Scenario 2). Examination of the results shows that the concentrations in the grid c ells that experience such increases are near background concentration levels under base case conditions. Additionally, the location of the increases that occur under sensitiv ity scenario conditions are in areas that anthropogenic NOx scavenging of incoming backg round ozone would reasonably seem to happen. The San Francisco area is a large urban region near the boundary that is subject to a continual influx of boundary c oncentrations, including ozone. Thus, the ozone concentrations simulated in the Bay under a sensitivity scenario involving zero anthropogenic emissions is higher than in the basecase, since anthropogenic NOx emissions in the basecase that are released into th e Bay scavenge the constant influx of background ozone.2

Table 4-1. Sensitivity tests for for the July 1999 episode. Case Code Details 1999_base Base case 1999_sen1 Modified vertical diffusivity based on la nd use category 1999_sen2 Biogenic emissions only 1999_sen3 No biogenic emissions 1999_sen4 Set lateral ozone boundary conditions to 50 ppb @ 5km 1999_sen5 Set lateral ozone boundary conditions to 90 ppb @ 5km 1999_sen7 Set lateral boundary conditions to 0.1 pp b NO 2 and 0 ppb NO (run with all emissions) 1999_sen8 Set lateral boundary conditions to 0.1 pp b NO 2 and 0 ppb NO (run with biogenic emissions only)

Table 4-2. Sensitivity tests for the July-August 2000 episode.

Case Code Details 2000_noaa_basecase Base case 2000_sen1 No wild fire 2000_sen2 Biogenic emissions only 2000_sen3 Double biogenic emissions 2000_sen4 Set lateral boundary conditions to 0.1 pp b NO 2 and 0 ppb NO (run with all emissions) 2000_sen5 Set lateral boundary conditions to 0.1 pp b NO 2 and 0 ppb NO (run with biogenic emissions only) 2000_sen7 Modified vertical diffusivity based on la nd use category 2000_sen8 Set top ozone boundary conditions to 135 ppb 2000_sen9 Set lateral ozone boundary conditions to 50 ppb @ 5km 2000_sen11 No biogenic emissions 2000_sen12 No mobile source emissions3

Table 4-3. Change in peak 1-hour ozone concentrations at ind ividual observation stations averaged over the second of two model spin up days plus the five day July 1999 episode. Units are in ppb.

SEN1 SEN2 SEN3 SEN4 SEN5 SEN7 SEN8 ANGI 1.0 -30.1 -5.2 -2.1 4.6 -0.1 -30.4 ARV 0.6 -42.8 -4.7 -3.2 6.3 -0.1 -43.1 BAC 1.9 -31.3 -4.5 -2.8 5.7 -0.1 -31.5 BGS 3.7 -29.0 -5.2 -2.7 5.6 -0.1 -29.3 BTI 0.6 -30.2 -11.9 -2.2 7.7 -0.2 -30.5 CCD 2.0 -26.3 -15.6 -2.3 9.1 -0.2 -26.5 CLO 1.2 -54.5 -10.1 -1.8 4.0 -0.1 -54.8 CUS 0.8 -46.3 -11.3 -2.0 4.1 -0.1 -46.5 DVS 2.0 -39.0 -9.9 -1.9 5.5 -0.1 -39.2 EDS 1.0 -46.3 -7.2 -3.3 6.6 -0.1 -46.6 ELK 1.2 -41.8 -9.5 -2.1 5.5 -0.1 -42.0 FCW 1.9 -45.2 -19.4 -1.8 10.3 -0.1 -45.4 FLN 0.7 -66.0 -19.8 -2.0 5.7 -0.1 -66.2 FSD 2.2 -46.9 -9.3 -1.9 4.3 -0.1 -47.1 FSF 2.3 -45.9 -9.7 -2.0 4.4 -0.1 -46.1 FSS 0.9 -41.7 -8.2 -2.0 4.4 -0.1 -41.9 GNBY 0.9 -53.8 -14.3 -2.0 5.3 -0.1 -54.1 HAN 1.2 -34.6 -6.6 -1.9 4.4 -0.1 -34.9 KETC 0.8 -31.1 -5.8 -2.0 4.3 -0.1 -31.3 KRE 0.6 -35.5 -16.4 -2.5 8.6 -0.2 -35.7 KRV 0.4 -38.7 -5.7 -1.9 3.7 -0.1 -38.9 LAMB 0.6 -41.0 -12.2 -1.8 6.3 -0.1 -41.2 LDUB 1.6 -42.1 -25.6 -2.4 9.8 -0.2 -42.3 LVF 1.5 -48.7 -25.2 -2.6 8.8 -0.1 -48.9 LVR1 1.5 -48.7 -25.2 -2.6 8.8 -0.1 -48.9 M14 1.9 -45.7 -12.9 -2.0 5.7 -0.1 -45.8 M29 0.8 -35.6 -6.8 -2.1 4.6 -0.1 -35.8 MCKI 0.5 -25.1 -4.1 -2.8 6.0 -0.2 -25.4 MCS 0.6 -26.6 -3.6 -3.1 6.2 -0.1 -26.9 MRA 1.3 -45.4 -9.9 -2.2 4.8 -0.1 -45.6 NAP 0.7 -36.9 -10.0 -1.7 7.5 -0.1 -37.1 NAT 1.2 -41.4 -10.5 -1.8 4.8 -0.1 -41.6 OLD 1.4 -33.9 -4.7 -2.5 5.4 -0.1 -34.2 PBG 0.4 -30.0 -12.9 -2.3 7.9 -0.2 -30.2 PCP 0.7 -42.0 -10.2 -2.2 5.3 -0.1 -42.2 PGN 0.8 -52.0 -12.4 -1.9 4.1 -0.1 -52.2 PGV 1.8 -37.4 -8.9 -1.9 5.4 -0.2 -37.6 PLR 0.9 -47.2 -7.6 -1.9 4.0 -0.1 -47.4 RED 1.9 -36.9 -16.5 -1.1 11.1 -0.2 -37.2 ROC 1.2 -43.7 -11.1 -2.0 5.4 -0.1 -43.9 ROS 2.1 -43.9 -12.6 -1.8 5.1 -0.1 -44.1 S13 3.0 -36.8 -11.1 -1.9 5.1 -0.1 -37.1 SDP 2.1 -45.9 -14.6 -2.0 6.0 -0.1 -46.1 SFA 5.5 11.0 -5.3 1.4 16.4 -0.2 10.8 SHA 0.8 -28.9 -4.7 -2.5 5.2 -0.1 -29.2 SJ4 3.4 -45.9 -21.4 -2.0 9.1 -0.1 -46.1 SLU 0.7 -59.0 -15.1 -1.9 5.7 -0.1 -59.2 SMAP 1.3 -54.9 -17.8 -2.4 7.4 -0.1 -55.1 SNH 1.1 -41.6 -11.7 -2.1 5.7 -0.2 -41.9 SOH 4.1 -27.5 -12.8 -2.2 6.2 -0.1 -27.7 SOM 0.8 -46.9 -13.5 -2.1 5.8 -0.1 -47.1 SRF 2.7 -23.2 -7.7 -1.8 8.5 -0.2 -23.5 SRL 1.1 -25.2 -12.1 -1.5 9.1 -0.1 -25.5 SUNO 1.1 -53.2 -25.8 -2.3 9.4 -0.2 -53.4 TPP 1.1 -45.4 -15.1 -2.3 6.4 -0.1 -45.6 TSM 1.3 -50.8 -13.0 -2.0 5.4 -0.1 -51.0 VCS 1.1 -36.7 -6.3 -2.1 4.0 -0.1 -36.9 VJO 1.6 -33.7 -13.5 -1.8 7.7 -0.1 -34.0 WLN 1.7 -35.8 -9.7 -1.9 5.7 -0.2 -36.14

Table 4-4. Change in 8-hour ozone concentrations at individu al observation stations averaged over the second of two model spin up days plus the five day July 1999 episode. Units are in ppb.

SEN1 SEN2 SEN3 SEN4 SEN5 SEN7 SEN8 ANGI 1.0 -29.4 -4.9 -2.1 4.5 -0.1 -29.6 ARV 0.6 -37.9 -4.2 -3.2 6.2 -0.1 -38.1 BAC 1.9 -28.7 -4.6 -2.7 5.6 -0.1 -29.0 BGS 3.5 -23.5 -5.2 -2.8 5.7 -0.1 -23.8 BTI 0.5 -27.7 -10.4 -2.1 7.7 -0.2 -27.9 CCD 1.9 -19.8 -13.5 -2.2 8.9 -0.2 -20.0 CLO 1.4 -44.9 -8.6 -2.0 4.2 -0.1 -45.2 CUS 0.9 -46.4 -11.0 -2.0 4.2 -0.1 -46.6 DVS 1.8 -35.6 -9.2 -1.9 6.1 -0.1 -35.9 EDS 1.0 -36.3 -5.9 -3.2 6.1 -0.1 -36.5 ELK 0.9 -36.3 -8.0 -1.9 5.9 -0.1 -36.5 FCW 1.4 -29.2 -14.8 -1.7 10.2 -0.2 -29.4 FLN 0.9 -56.9 -16.6 -2.1 5.9 -0.1 -57.1 FSD 2.1 -39.5 -8.6 -2.0 4.4 -0.1 -39.8 FSF 2.5 -39.3 -8.8 -2.0 4.3 -0.1 -39.5 FSS 0.9 -38.5 -7.6 -2.0 4.3 -0.1 -38.7 GNBY 0.8 -46.2 -12.2 -2.0 5.5 -0.1 -46.4 HAN 1.2 -32.3 -5.9 -2.0 4.3 -0.1 -32.6 KETC 0.6 -29.6 -5.5 -1.9 4.1 -0.1 -29.8 KRE 0.5 -28.4 -13.1 -2.4 8.6 -0.2 -28.7 KRV 0.4 -32.1 -4.5 -2.1 3.9 -0.1 -32.3 LAMB 0.6 -35.4 -9.4 -2.0 7.1 -0.2 -35.6 LDUB 1.7 -28.3 -17.3 -2.1 9.3 -0.1 -28.5 LVF 1.5 -31.9 -15.0 -2.4 8.6 -0.2 -32.1 LVR1 1.5 -31.9 -15.0 -2.4 8.6 -0.2 -32.1 M14 2.0 -40.2 -12.8 -2.1 6.2 -0.1 -40.4 M29 0.9 -35.0 -6.6 -2.1 4.4 -0.1 -35.2 MCKI 0.5 -25.1 -3.9 -3.0 5.9 -0.2 -25.4 MCS 0.5 -25.5 -3.4 -3.4 6.5 -0.2 -25.7 MRA 1.2 -41.8 -9.1 -2.2 5.1 -0.1 -42.0 NAP 0.7 -26.7 -7.2 -1.8 8.5 -0.2 -26.9 NAT 0.9 -35.8 -7.8 -2.0 5.9 -0.2 -36.0 OLD 1.4 -30.6 -4.7 -2.7 5.4 -0.1 -30.8 PBG 0.5 -24.8 -11.1 -2.1 8.1 -0.2 -25.0 PCP 0.9 -34.9 -8.3 -2.2 5.5 -0.1 -35.1 PGN 1.0 -48.6 -10.1 -1.9 4.1 -0.1 -48.8 PGV 0.8 -33.0 -6.7 -2.0 5.5 -0.1 -33.2 PLR 0.8 -40.8 -7.0 -2.0 4.3 -0.1 -41.0 RED 1.6 -21.1 -11.1 -1.2 10.8 -0.2 -21.4 ROC 1.0 -37.0 -8.8 -2.0 5.3 -0.1 -37.3 ROS 1.2 -35.4 -8.6 -2.1 5.5 -0.2 -35.6 S13 2.8 -32.8 -9.5 -2.0 6.0 -0.1 -33.1 SDP 2.0 -39.8 -12.7 -2.2 6.2 -0.2 -40.0 SFA 4.3 19.5 -3.2 0.1 12.5 -0.1 19.3 SHA 0.9 -28.3 -4.5 -2.4 5.2 -0.1 -28.5 SJ4 2.9 -28.4 -17.3 -2.0 8.8 -0.1 -28.6 SLU 0.7 -52.9 -13.5 -2.1 6.0 -0.1 -53.1 SMAP 1.0 -43.2 -14.3 -2.5 7.1 -0.2 -43.4 SNH 0.7 -34.2 -7.6 -2.1 5.7 -0.2 -34.4 SOH 3.9 -25.9 -11.8 -2.0 6.4 -0.1 -26.1 SOM 0.7 -41.3 -12.3 -2.1 6.4 -0.1 -41.5 SRF 2.4 -15.1 -5.6 -1.8 9.2 -0.2 -15.4 SRL 1.0 -16.3 -7.8 -1.8 9.8 -0.2 -16.6 SUNO 1.0 -36.2 -17.1 -2.2 9.2 -0.2 -36.4 TPP 0.9 -34.9 -11.2 -2.2 6.8 -0.1 -35.1 TSM 1.4 -44.4 -12.3 -2.1 6.0 -0.1 -44.6 VCS 0.9 -34.9 -5.4 -2.2 4.3 -0.1 -35.1 VJO 1.3 -22.8 -10.6 -1.8 8.9 -0.2 -23.0 WLN 2.0 -31.2 -8.7 -1.9 6.1 -0.2 -31.45

Table 4-5. Change in peak 1-hour ozone concentrations at ind ividual observation stations averaged over the second of two model spin up days plus the five day July - August 2000 episode. Units are in ppb.

SEN1 SEN2 SEN3 SEN4 SEN5 SEN7 SEN8 SEN9 SEN11 SEN1 2 ANGI -0.6 -45.3 5.5 -0.2 -45.7 0.6 1.2 -1.7 -9.5 -1 3.4 ARV -1.5 -54.9 5.7 -0.2 -55.3 0.4 1.4 -2.1 -9.3 -14 .9 BAC -0.9 -44.3 5.2 -0.2 -44.7 0.8 1.1 -1.6 -10.0 -1 1.4 BGS -1.2 -41.0 4.9 -0.2 -41.5 2.2 1.1 -1.6 -11.8 -8 .7 BTI 0.0 -61.2 14.2 -0.2 -61.7 0.3 1.1 -1.2 -21.2 -8 .2 CCD 0.0 -39.4 12.3 -0.2 -39.7 1.1 1.0 0.1 -18.7 -0. 2 CLO -0.3 -63.5 10.0 -0.2 -63.9 0.5 1.0 -1.5 -16.9 - 18.9 CUS -0.1 -44.2 -0.1 -0.2 -44.7 0.6 1.5 -1.9 -14.6 - 19.4 DVS 0.0 -52.0 7.4 -0.2 -52.4 0.9 0.9 -1.3 -17.2 -14 .4 EDS -1.4 -53.6 6.2 -0.2 -54.0 0.5 1.2 -1.9 -11.6 -9 .9 ELK 0.0 -54.9 8.1 -0.2 -55.4 0.5 0.9 -1.2 -14.8 -14 .7 FCW -0.1 -36.2 9.4 -0.2 -36.6 0.9 0.9 0.9 -12.6 -3. 0 FLN -0.1 -56.6 6.7 -0.2 -57.1 0.8 1.3 -1.7 -17.8 -1 9.3 FSD -0.4 -56.9 9.5 -0.2 -57.3 1.3 1.1 -1.5 -15.1 -1 4.6 FSF -0.3 -52.3 9.6 -0.2 -52.7 1.4 1.0 -1.4 -14.3 -1 2.6 FSS -0.2 -51.7 7.3 -0.2 -52.1 0.7 1.0 -1.5 -11.5 -1 5.4 GNBY -0.1 -46.9 7.4 -0.2 -47.3 1.3 1.4 -2.0 -14.5 - 14.1 HAN -0.3 -48.9 6.6 -0.2 -49.4 0.7 1.0 -1.7 -10.9 -1 3.9 KETC -0.5 -38.5 4.7 -0.2 -39.0 0.4 1.2 -1.8 -8.3 -1 0.0 KRE -0.1 -51.0 13.8 -0.3 -51.4 0.3 1.0 -0.3 -22.7 - 4.3 KRV -0.6 -52.3 4.4 -0.2 -52.7 0.4 1.4 -1.8 -10.9 -1 7.9 LAMB 0.1 -59.6 10.3 -0.2 -60.0 0.5 0.9 -0.8 -15.6 - 12.6 LDUB -0.1 -33.7 12.1 -0.3 -34.1 0.9 0.8 0.7 -14.7 1 .5 LVF -0.1 -46.8 13.7 -0.3 -47.2 1.1 1.0 -0.1 -18.9 - 4.0 LVR1 -0.1 -46.8 13.7 -0.3 -47.2 1.1 1.0 -0.1 -18.9 -4.0 M14 -0.1 -53.2 10.2 -0.2 -53.7 2.1 1.0 -1.2 -14.4 - 10.4 M29 -0.2 -50.0 5.7 -0.2 -50.4 1.0 0.9 -1.5 -11.4 -1 6.1 MCKI -0.6 -40.6 4.7 -0.2 -41.0 0.3 1.1 -1.8 -8.0 -1 1.5 MCS -0.8 -41.8 4.4 -0.2 -42.3 0.3 1.2 -2.0 -7.7 -11 .7 MRA -0.1 -55.7 7.2 -0.2 -56.1 1.1 1.0 -1.4 -14.0 -1 5.1 NAP 0.1 -41.8 6.5 -0.2 -42.2 0.5 0.7 0.1 -11.6 -11. 0 NAT 0.0 -45.5 6.4 -0.3 -45.9 0.7 1.0 -1.7 -13.6 -14 .0 OLD -1.0 -43.3 4.7 -0.2 -43.7 0.8 1.1 -1.5 -9.1 -11 .9 PBG 0.0 -51.2 12.2 -0.3 -51.6 0.4 1.0 -0.7 -17.4 -6 .2 PCP -0.2 -42.7 4.1 -0.2 -43.1 0.6 0.9 -1.4 -10.0 -1 5.4 PGN -0.2 -41.2 -1.7 -0.3 -41.6 1.4 1.5 -2.1 -13.4 - 18.7 PGV 0.1 -43.0 4.5 -0.2 -43.5 0.7 1.2 -1.8 -12.2 -13 .6 PLR -0.5 -71.2 8.6 -0.2 -71.7 0.4 1.0 -1.4 -15.3 -2 3.6 RED 0.0 -19.6 4.9 -0.2 -20.0 1.0 0.7 1.6 -6.5 0.3 ROC -0.1 -45.2 4.3 -0.3 -45.7 0.8 1.4 -2.2 -14.7 -1 5.5 ROS 0.0 -46.6 5.7 -0.3 -47.1 0.8 1.4 -2.1 -16.5 -15 .9 S13 0.0 -47.8 9.8 -0.2 -48.2 1.8 1.0 -1.3 -18.0 -13 .9 SDP -0.1 -57.2 11.8 -0.2 -57.7 1.3 1.1 -1.6 -22.9 - 16.1 SFA 0.0 10.4 -2.0 -0.2 10.0 2.1 0.4 8.5 -1.2 3.4 SHA -0.7 -42.1 5.0 -0.2 -42.6 0.5 1.1 -1.5 -8.7 -11 .5 SJ4 -0.1 -33.4 10.2 -0.3 -33.8 2.0 1.0 0.0 -15.6 -0 .7 SLU -0.1 -73.6 13.4 -0.2 -74.1 0.3 1.1 -1.5 -26.7 - 21.3 SMAP -0.1 -40.6 5.9 -0.2 -41.0 0.7 0.9 -0.9 -12.8 - 11.4 SNH 0.0 -47.1 7.3 -0.3 -47.6 0.6 1.3 -2.1 -14.7 -14 .7 SOH -0.1 -47.6 10.6 -0.2 -48.0 2.8 1.0 -1.4 -17.0 - 9.6 SOM -0.1 -59.1 10.6 -0.2 -59.5 0.6 0.9 -1.2 -17.2 - 11.9 SRF 0.0 -18.5 1.5 -0.2 -18.9 1.4 0.7 0.5 -6.1 -6.8 SRL 0.0 -24.4 6.8 -0.2 -24.7 0.6 0.7 1.1 -8.8 -6.1 SUNO -0.1 -43.7 11.5 -0.3 -44.1 0.7 1.0 0.3 -15.3 - 4.6 TPP -0.1 -60.6 14.3 -0.2 -61.0 0.5 1.1 -1.5 -20.5 - 12.3 TSM 0.0 -56.4 9.0 -0.2 -56.8 1.5 0.9 -1.2 -15.8 -12 .8 VCS -0.7 -60.1 6.7 -0.2 -60.5 0.8 1.2 -1.6 -12.2 -1 8.2 VJO 0.0 -32.9 7.0 -0.2 -33.3 0.8 0.7 0.3 -10.5 -5.4 WLN 0.3 -41.8 4.2 -0.2 -42.3 1.1 1.1 -1.6 -12.9 -13 .06

Table 4-6. Change in 8-hour ozone concentrations at individu al observation stations averaged over the second of two model spin up days plus the five day July - August 2000 episode. Units are in ppb.

SEN1 SEN2 SEN3 SEN4 SEN5 SEN7 SEN8 SEN9 SEN11 SEN1 2 ANGI -0.7 -42.2 4.7 -0.2 -42.6 0.5 1.1 -1.6 -8.5 -1 1.4 ARV -1.3 -48.2 4.7 -0.2 -48.7 0.4 1.3 -2.2 -8.0 -12 .6 BAC -1.1 -41.0 4.7 -0.2 -41.4 1.0 1.2 -1.8 -9.1 -8. 9 BGS -1.2 -35.5 3.8 -0.2 -35.9 2.4 1.3 -1.8 -11.0 -6 .4 BTI 0.0 -45.6 9.0 -0.2 -46.0 0.4 0.8 -0.7 -15.0 -7. 4 CCD 0.0 -25.5 8.6 -0.2 -25.9 1.0 0.8 0.4 -15.9 0.2 CLO -0.4 -53.7 7.8 -0.2 -54.1 1.1 1.2 -1.7 -13.9 -1 3.6 CUS -0.1 -41.4 -0.1 -0.3 -41.8 0.9 1.5 -2.1 -14.0 - 17.7 DVS -0.1 -42.9 6.1 -0.2 -43.3 1.4 0.9 -1.1 -14.6 -1 0.7 EDS -1.5 -45.9 5.1 -0.2 -46.3 0.7 1.3 -1.9 -10.3 -8 .3 ELK 0.1 -47.1 6.0 -0.2 -47.5 0.6 0.8 -1.1 -12.8 -12 .3 FCW -0.1 -22.8 6.3 -0.2 -23.2 0.7 0.8 1.0 -10.0 0.3 FLN -0.1 -47.1 4.9 -0.2 -47.6 1.0 1.3 -1.8 -15.4 -1 5.0 FSD -0.4 -49.8 8.2 -0.2 -50.2 1.5 1.1 -1.6 -13.9 -1 0.7 FSF -0.3 -48.1 8.0 -0.2 -48.5 1.7 1.1 -1.7 -13.4 -9 .7 FSS -0.2 -49.9 6.4 -0.2 -50.3 0.7 1.1 -1.6 -11.7 -1 3.6 GNBY -0.1 -42.3 4.0 -0.2 -42.7 0.9 1.4 -1.9 -13.5 - 12.9 HAN -0.4 -44.4 5.5 -0.2 -44.8 0.8 1.0 -1.6 -9.8 -10 .9 KETC -0.4 -38.2 4.3 -0.2 -38.6 0.5 1.1 -1.8 -8.0 -9 .6 KRE 0.0 -36.8 10.6 -0.3 -37.2 0.4 0.9 -0.2 -17.5 -3 .5 KRV -0.8 -46.9 2.8 -0.2 -47.3 0.6 1.5 -1.8 -9.6 -14 .6 LAMB 0.1 -43.3 6.3 -0.2 -43.6 0.3 0.8 -0.5 -12.2 -1 0.0 LDUB 0.0 -21.8 7.6 -0.2 -22.2 1.0 0.8 0.6 -11.0 2.7 LVF -0.1 -32.5 9.4 -0.3 -32.9 1.0 1.0 -0.3 -14.9 -1 .5 LVR1 -0.1 -32.5 9.4 -0.3 -32.9 1.0 1.0 -0.3 -14.9 - 1.5 M14 -0.1 -46.4 9.3 -0.2 -46.8 1.9 1.0 -1.3 -14.4 -7 .3 M29 -0.2 -48.1 4.9 -0.2 -48.5 0.8 1.0 -1.5 -10.9 -1 3.9 MCKI -0.4 -39.9 4.6 -0.2 -40.3 0.3 1.1 -1.8 -8.0 -1 0.8 MCS -0.8 -40.2 3.9 -0.2 -40.7 0.3 1.2 -2.0 -7.1 -10 .4 MRA -0.1 -48.4 6.7 -0.2 -48.8 1.1 1.0 -1.3 -12.9 -1 1.7 NAP 0.0 -27.3 4.0 -0.2 -27.6 0.4 0.7 0.7 -7.6 -6.0 NAT 0.1 -41.8 5.3 -0.2 -42.2 0.6 1.1 -1.6 -12.3 -11 .2 OLD -1.1 -40.4 4.5 -0.2 -40.8 1.1 1.2 -1.8 -8.8 -9. 2 PBG 0.0 -37.9 8.6 -0.2 -38.3 0.3 0.8 -0.3 -14.0 -5. 4 PCP -0.2 -36.2 3.8 -0.2 -36.5 0.5 0.8 -1.1 -8.7 -12 .6 PGN -0.1 -38.3 -3.1 -0.3 -38.7 1.5 1.5 -2.0 -12.0 - 17.2 PGV 0.1 -38.7 3.4 -0.2 -39.2 0.7 1.2 -1.8 -11.0 -11 .7 PLR -0.6 -58.7 6.9 -0.2 -59.1 0.7 1.0 -1.4 -13.0 -1 6.2 RED 0.0 -11.5 3.4 -0.2 -11.9 0.9 0.7 2.0 -5.4 1.9 ROC -0.1 -40.9 3.9 -0.2 -41.3 1.0 1.4 -2.0 -13.2 -1 2.5 ROS -0.1 -40.9 4.3 -0.2 -41.3 1.0 1.3 -1.9 -13.5 -1 2.6 S13 0.1 -39.1 8.3 -0.2 -39.5 2.1 1.1 -1.4 -15.0 -8. 2 SDP 0.0 -45.9 10.1 -0.2 -46.3 1.6 1.2 -1.6 -17.9 -9 .7 SFA 0.0 16.4 -1.5 -0.2 16.0 1.4 0.3 6.0 -2.1 5.8 SHA -0.9 -40.9 4.7 -0.2 -41.3 0.6 1.1 -1.6 -8.4 -10 .5 SJ4 0.0 -19.9 6.4 -0.3 -20.3 1.7 0.9 0.0 -12.6 1.7 SLU 0.0 -53.6 8.6 -0.2 -54.0 0.6 1.1 -1.5 -18.0 -14 .2 SMAP -0.1 -32.0 4.2 -0.2 -32.4 0.5 0.9 -1.0 -9.7 -8 .7 SNH 0.0 -41.8 5.0 -0.2 -42.3 0.7 1.3 -1.9 -13.1 -12 .3 SOH 0.0 -36.7 9.3 -0.2 -37.1 2.6 0.9 -1.2 -14.9 -5. 9 SOM -0.1 -51.4 9.5 -0.2 -51.8 0.8 0.9 -1.2 -16.6 -9 .1 SRF 0.0 -11.6 1.0 -0.2 -11.9 1.2 0.7 0.9 -4.8 -2.3 SRL 0.0 -15.7 3.5 -0.3 -16.0 0.6 0.7 1.4 -5.3 -3.0 SUNO -0.1 -30.6 7.6 -0.3 -30.9 0.7 0.9 0.2 -11.9 -1 .9 TPP -0.1 -44.3 9.5 -0.2 -44.7 0.4 0.9 -1.0 -14.7 -9 .4 TSM -0.1 -48.7 9.4 -0.2 -49.1 2.3 1.0 -1.2 -15.1 -8 .4 VCS -0.8 -53.2 5.5 -0.2 -53.6 0.6 1.2 -1.5 -10.9 -1 4.9 VJO 0.0 -21.0 4.6 -0.2 -21.3 0.7 0.7 1.0 -7.8 -2.2 WLN -0.2 -37.3 4.1 -0.2 -37.7 1.4 1.1 -1.5 -12.4 -1 0.57

Figure 4-1. Modified vertical diffusivity based on land use c ategory

(July 1999, Scenario 1)

Regionally, the effect of this change is small (les s than 1 ppb in most areas). In urban areas, the enhanced mixing increases the ozone conc entration by ~2-4 ppb. In San Francisco, the increase is higher probably due to the higher density of urban coverage.8

Figure 4-2. Biogenic emissions only.

(July 1999, Scenario 2)

The purpose for this run is to generally assess the influence of anthropogenic emission sources on ozone formation. Totally eliminating an thrpogenic emissions from the simulations greatly reduces ozone concentrations, p articularly downwind of large urban areas. The maximum reduction is around 80 ppb. Ozon e concentrations near San Francisco increase by about 14 ppb; however, the ba secase concentrations are near background and the location of the increase occurs within grid cells that anthropogenic NOx scavenging of ozone occurs.9

Figure 4-3. No biogenic emissions.

(July 1999, Scenario 3)

When biogenic emissions are excluded, the simulated ozone concentrations across the entire domain generally decrease, with a maximum de crease occurring downwind ofand around major urban areas. The impact of this sc enario around Fresno and Bakersfield appears to be less in 1999 than in 2000

.10

Figure 4-4. Set lateral ozone boundary conditions to 50 ppb @ 5km.

(July 1999, Scenario 4)

In this sensitivity run, the boundary condition for ozone was set to be a constant of 50 ppb (i.e. held constant from the surface up to 5 km above the surface). The base case uses a variable boundary condition where the l ower boundary condition for ozone over water near the surface is 25 ppb and gradually increases as a function of height. The largest impact of this scenario occurs over the ocean near the domain boundary, where the concentrations are increased by about ~25 ppb.11

Figure 4-5. Set lateral ozone boundary conditions to 90 ppb @ 5km.

(July 1999, Scenario 5)

In this sensitivity run, the boundary condition for ozone is set to a constant of 90 ppb (i.e. held constant from the surface up to 5km abov e the surface). The base case uses a variable boundary condition, where the lower bounda ry condition for ozone over water near the surface is 25 ppb and gradually increases as a function of height. The largest impact of this scenario occurs over the ocean, wher e the concentrations are increased near the domain boundary by about ~65 ppb.12

Figure 4-6. Set lateral boundary conditions to 0.1ppb NO 2 and 0 ppb NO (run with all emissions). (July 1999, Scenario 7)

No significant impact was noticed using this modifi ed boundary condition.13

Figure 4-7. Set lateral boundary conditions to 0.1ppb NO 2 and 0 ppb NO (run with biogenic emissions only). (July 1999, Scenario 8)

The majority of the changes in this scenario are du e to excluding anthropogenic emissions, which is expected given the results from Scenario 7 and Scenario 2.14

Figure 4-8. No wild fire emissions.

(July-August 2000, Scenario 1)

When wild fire emissions are removed, ozone is redu ced in areas immediately surrounding the location of the fires. The largest impact occurs in the southern part of the modeling domain around a large wildfire.15

Figure 4-9. Biogenic emissions only.

(July-August 2000, Scenario 2)

The purpose for this run is to generally assess the influence of anthropogenic emissions. Totally eliminating anthrpogenic emissio ns from the simulations greatly reduces ozone concentrations, particularly in regio ns downwind of large urban areas. The maximum reduction is around 100 ppb. As with t he equivalent July 1999 sensitivity run, ozone concentrations near San Francisco increa se. However, as mentioned in the discussion of the 1999 sensitivity results, the bas ecase concentrations are near background and the location of the increase occurs within grid cells in which anthropogenic NOx scavenging of ozone occurs.16

Figure 4-10. Double biogenic emissions.

(July-August 2000, Scenario 3)

The purpose of this simulation is to see how sensit ive the model is to large perturbations in biogenic emissions. Doubling the b iogenic emissions increases ozone concentrations in most areas. The maximum increase (~30 ppb) occurs in areas that are downwind of the San Francisco/Bay area. Within the mountain areas, where biogenic emissions are abundant and NO x emissions are low, adding additional biogenic VOC emissions reduces the ozone concentrat ion by around ~10 ppb. This is due to the fact that additional VOC acts mainly as chain terminators in the photochemical reactions.17

Figure 4-11. Set lateral boundary conditions to 0.1 ppb NO 2 and 0 ppb NO (run with all emissions). (July-August 2000, Scenario 4)

The impact of NO x

boundary conditions on the predicted ozone is smal l, yielding less than one ppb difference in ozone concentrations.18

Figure 4-12. Set lateral boundary conditions to 0.1 ppb NO 2 and 0 ppb NO (run with biogenic emissions only). (July-August 2000, Scena rio 5)

The majority of the changes in this scenario are du e to excluding anthropogenic emissions.19

Figure 4-13. Using ENVIRON’s kvpatch to modify the minimal ver tical diffusivity value for the first 100 meters above the surface. (July- August 2000, Scenario 7)

Regionally, the effect of this change on predicted ozone concentrations is quite small (less than 1 ppb) in most areas of the modeling dom ain. In urban areas, the enhanced mixing seems to increase the ozone concentration by ~2 ppb. In downtown San Francisco, the increase is higher due to the higher density of urban coverage.20

Figure 4-14. Set top ozone boundary conditions to 135 ppb.

(July-August 2000, Scenario 8)

The largest vertical ozone concentration measured i n the study is around 135 ppb and was used to develop the ozone vertical profile. It seems that the predicted ozone concentrations are not significantly affected by th e modeling domain top ozone boundary concentration. The maximum impact is in th e elevated regions of the model domain. The increase of ozone concentrations in the Valley is less than 2 ppb, while near the foothills the increase is ~5 ppb.21

Figure 4-15. Set lateral ozone boundary conditions to 50 ppb @ 5km.

(July-August 2000, Scenario 9)

In this sensitivity run, the boundary condition for ozone was set to be a constant of 50 ppb from the surface up to 5km above surface. In the base case, the lateral ozone boundary condition consists of a lower boundary co ndition for ozone over water near the surface (25 ppb) and gradually increases as a f unction of height. The largest impact of this sensitivity scenario occurs over the ocean, where the concentrations are increased by about ~25 ppb.22

Figure 4-16. No biogenic emissions.

(July-August 2000, Scenario 11)

When biogenic emissions are removed, the model-simu lated ozone concentrations generally decrease, with maximum decreases occurrin g downwind from- and around major urban areas.23

Figure 4-17. No mobile source emissions.

(July-August 2000, Scenario 12)

When all of the mobile source emissions are removed from the model simulation, peak ozone concentrations in the Sacramento and Fresno a rea decrease significantly while a slight increase is seen in the Bakersfield region. Ozone concentrations slightly increase in the Bay Area. This is due to fact that less ozon e is titrated because of the removal of a significant source of NO x emissions.