1 

4 Results for Model Sensitivity Tests 

Several sensitivity tests were conducted for both the July 1999 and the July-August 

2000 episodes to see how the model responds to changes in input variables. Each of 

the episodes is five days in duration (ten days total for both episodes combined). 

Descriptions of the sensitivity tests for each episode are shown in 

Table 4-1 (July 1999) and Table 4-2 (July-August 2000). 

Tabulated 1-hour and 8-hour peak ozone concentration 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 calculation 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 for each episode are shown in 

Figure 4-1 through Figure 4-17. 

All of the model sensitivity results produce expected 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 cells that experience such increases 

are near background concentration levels under basecase conditions. Additionally, the 

location of the increases that occur under sensitivity scenario conditions are in areas 

that anthropogenic NOx scavenging of incoming background 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 concentrations, 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 the 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 land 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 ppb NO2and 0 ppb NO 

(run with all emissions) 

1999_sen8 Set lateral boundary conditions to 0.1 ppb NO2and 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 ppb NO2and 0 ppb NO 

(run with all emissions) 

2000_sen5 Set lateral boundary conditions to 0.1 ppb NO2and 0 ppb NO 

(run with biogenic emissions only) 

2000_sen7 Modified vertical diffusivity based on land 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 emissions 
3 

Table 4-3. Change in peak 1-hour ozone concentrations at individual 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 -36.1 
4 

Table 4-4. Change in 8-hour ozone concentrations at individual 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 -31.4 
5 

Table 4-5. Change in peak 1-hour ozone concentrations at individual 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 SEN12 

ANGI -0.6 -45.3 5.5 -0.2 -45.7 0.6 1.2 -1.7 -9.5 -13.4 

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 -11.4 

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 -19.3 

FSD -0.4 -56.9 9.5 -0.2 -57.3 1.3 1.1 -1.5 -15.1 -14.6 

FSF -0.3 -52.3 9.6 -0.2 -52.7 1.4 1.0 -1.4 -14.3 -12.6 

FSS -0.2 -51.7 7.3 -0.2 -52.1 0.7 1.0 -1.5 -11.5 -15.4 

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 -13.9 

KETC -0.5 -38.5 4.7 -0.2 -39.0 0.4 1.2 -1.8 -8.3 -10.0 

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 -17.9 

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 -16.1 

MCKI -0.6 -40.6 4.7 -0.2 -41.0 0.3 1.1 -1.8 -8.0 -11.5 

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 -15.1 

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 -15.4 

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 -23.6 

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 -15.5 

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 -18.2 

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 -13.0 
6 

Table 4-6. Change in 8-hour ozone concentrations at individual 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 SEN12 

ANGI -0.7 -42.2 4.7 -0.2 -42.6 0.5 1.1 -1.6 -8.5 -11.4 

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 -13.6 

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 -10.7 

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 -15.0 

FSD -0.4 -49.8 8.2 -0.2 -50.2 1.5 1.1 -1.6 -13.9 -10.7 

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 -13.6 

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 -10.0 

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 -13.9 

MCKI -0.4 -39.9 4.6 -0.2 -40.3 0.3 1.1 -1.8 -8.0 -10.8 

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 -11.7 

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 -16.2 

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 -12.5 

ROS -0.1 -40.9 4.3 -0.2 -41.3 1.0 1.3 -1.9 -13.5 -12.6 

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 -14.9 

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 -10.5 
7 

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

(July 1999, Scenario 1) 

Regionally, the effect of this change is small (less than 1 ppb in most areas). In urban 

areas, the enhanced mixing increases the ozone concentration 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 anthrpogenic emissions from the 

simulations greatly reduces ozone concentrations, particularly downwind of large urban 

areas. The maximum reduction is around 80 ppb. Ozone concentrations near San 

Francisco increase by about 14 ppb; however, the basecase 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 decrease occurring downwind ofand around major urban areas. The impact of this scenario 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 5km above the surface). The base 

case uses a variable boundary condition where the lower 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 above the surface). The base case uses a 

variable boundary condition, where the lower 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, where the concentrations are increased 

near the domain boundary by about ~65 ppb. 
12 

Figure 4-6. Set lateral boundary conditions to 0.1ppb NO2and 0 ppb NO (run with all 

emissions). (July 1999, Scenario 7) 

No significant impact was noticed using this modified boundary condition. 
13 

Figure 4-7. Set lateral boundary conditions to 0.1ppb NO2and 0 ppb NO (run with 

biogenic emissions only). (July 1999, Scenario 8) 

The majority of the changes in this scenario are due 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 reduced 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 emissions from the simulations greatly 

reduces ozone concentrations, particularly in regions downwind of large urban areas. 

The maximum reduction is around 100 ppb. As with the equivalent July 1999 sensitivity 

run, ozone concentrations near San Francisco increase. However, as mentioned in the 

discussion of the 1999 sensitivity results, the basecase 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 sensitive the model is to large 

perturbations in biogenic emissions. Doubling the biogenic 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 NOx emissions are low, adding additional 

biogenic VOC emissions reduces the ozone concentration 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 NO2and 0 ppb NO (run with all 

emissions). (July-August 2000, Scenario 4) 

The impact of NOx boundary conditions on the predicted ozone is small, yielding less 

than one ppb difference in ozone concentrations. 
18 

Figure 4-12. Set lateral boundary conditions to 0.1 ppb NO2 and 0 ppb NO (run with 

biogenic emissions only). (July-August 2000, Scenario 5) 

The majority of the changes in this scenario are due to excluding anthropogenic 

emissions. 
19 

Figure 4-13. Using ENVIRON’s kvpatch to modify the minimal vertical 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 domain. 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 in 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 the modeling domain top ozone 

boundary concentration. The maximum impact is in the 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 condition for ozone over water near 

the surface (25 ppb) and gradually increases as a function 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-simulated ozone concentrations 

generally decrease, with maximum decreases occurring 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 area 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 ozone is titrated because of the removal of 

a significant source of NOx emissions.