APPENDIX A 

Back Trajectories 

Texas and California Maintenance-Only Monitors 

2005-2006 

1997 Ozone NAAQS Exceedance Days 

 

Note 

The attached trajectories were generated by EPA Region 8 using the HYSPLIT 4.9 online 

computer application.1 The HYSPLIT default parameters were used, except for the 

following: Eta Data Assimilation System (EDAS) 40 km meteorological data set; 

duration 72 hours; height at end point1500 m above ground level; end point start time 22 

Coordinated Universal Time (UTC), equivalent to 4:00 pm CST. Exceedance days are 

days of ozone concentrations 85 ppb or above. 

 

1 NOAA ARL READY Website at http://ready.arl.noaa.gov/HYSPLIT.php. NOAA Air Resources Laboratory, 

Silver Spring, MD.
Figure 1.1. Back Trajectories for Dallas CSA Maintenance-Only Ozone Monitors 

NOAA Hysplit Moldel, v4.9 Height: 1500m AGL Start Time: 22:00 UTC Length: 72 hours All days ≥ 85 ppb 2005-2006 
Figure 1.1.a Back Trajectories for Dallas, Hinton Monitor, Site ID 48-113- 0069 

NOAA Hysplit Moldel, v4.9 Height: 1500m AGL Start Time: 22:00 UTC Length: 72 hours All days ≥ 85 ppb 2005-2006 
Figure 1.1.b Back Trajectories for Dallas, Executive Airport Monitor, Site ID 48-113-00

NOAA Hysplit Moldel, v4.9 Height: 1500m AGL Start Time: 22:00 UTC Length: 72 hours All days ≥ 85 ppb 2005-2006 
Figure 1.1.c Back Trajectories for Tarrant, Keller Monitor, Site ID 48-439-2003 

NOAA Hysplit Moldel, v4.9 Height: 1500m AGL Start Time: 22:00 UTC Length: 72 hours All days ≥ 85 ppb 2005-2006 
NOAA Hysplit Moldel, v4.9 

Height: 1500m AGL Start Time: 22:00 UTC Length: 72 hours All days ≥ 85 ppb 2005-2006

Figure 2.1. Back Trajectories for Houston CSA Maintenance-Only Ozone Monitors 
Figure 2.1.a Back Trajectories for Houston, Aldine Monitor, Site ID 48-201-0024 

NOAA Hysplit Moldel, v4.9 Height: 1500m AGL Start Time: 22:00 UTC Length: 72 hours All days ≥ 85 ppb 2005-2006 
Figure 2.1.b Back Trajectories for Houston, Northwest Harris Co. Monitor, Site ID 48-201

NOAA Hysplit Moldel, v4.9 Height: 1500m AGL Start Time: 22:00 UTC Length: 72 hours All days ≥ 85 ppb 2005-2006 
Figure 2.1.c Back Trajectories for Houston, Lynchburg Ferry Monitor, Site ID 48-201-1

NOAA Hysplit Moldel, v4.9 Height: 1500m AGL Start Time: 22:00 UTC Length: 72 hours All days ≥ 85 ppb 2005-2006 
Figure 2.1.d Back Trajectories for Houston, Clinton Monitor, Site ID 48-201-1035 

NOAA Hysplit Moldel, v4.9 Height: 1500m AGL Start Time: 22:00 UTC Length: 72 hours All days ≥ 85 ppb 2005-2006 
Figure 2.1.e Back Trajectories for Houston, Seabrook Friendship Park Monitor, Site ID 48-2

NOAA Hysplit Moldel, v4.9 Height: 1500m AGL Start Time: 22:00 UTC Length: 72 hours All days ≥ 85 ppb 2005-2006 
NOAA Hysplit Moldel, v4.9 

Height: 1500m AGL Start Time: 22:00 UTC Length: 72 hours High O3 days ( ≥ 85 ppb) 2005-2006

Figure 3.1 Back Trajectories for California Maintenance-Only Monitors on High Ozone D

Note: This map combines back trajectories starting at each maintenance monitor on high ozone days. High ozone days include the top one third of the exceedance-days registered each monitor in 2005 and in 2006.
Table 1 

Dallas CSA Maintenance-Only Monitors 

Exceedance-Days/Concentrations for the 1997 8-Hour O3 NAAQS 

2005-2006 

County: Dallas Site Name: Dallas Hinton St. 

Site ID #: 48-113-0069 Lat/Long: 32.819722/-96.860000 

Exceedance 

Date 

Exceedance 

Concentration 

(ppb) 

Exceedance 

Date 

Exceedance 

Concentration 

(ppb) 

5/20/05 .087 8/31/06 .090 

5/21/05 .100 9/1/06 .096 

6/15/05 .104 

6/21/05 .090 

7/02/05 .089 

7/11/05 .087 

7/14/05 .090 

7/29/05 .088 

8/02/05 .089 

8/06/05 .085 

8/22/05 .095 

9/01/05 .098 

County: Dallas Site Name: Dallas Executive Airport 

Site ID #: 48-113-0087 Lat/Long: 32.676667/-96.871944 

5/21/05 .095 6/13/06 .089 

6/15/05 .086 6/27/06 .091 

6/20/05 .085 7/07/06 .088 

6/21/05 .091 8/22/06 .091 

7/06/05 .088 8/31/06 .086 

7/11/05 .088 9/01/06 .095 

7/29/05 .089 

County: Tarrant Site Name: Keller 

Site ID#: 48-439-2003 Lat/Long: 32.922500/-97.281944 

6/15/05 .100 6/03/06 .088 

6/20/05 .094 6/09/06 .097 

6/21/05 .110 6/12/06 .093 

6/22/05 .098 6/14/06 .103 

6/23/05 .085 6/15/06 .085 

7/02/05 .087 6/18/06 .094 

7/08/05 .091 6/28/06 .089 

7/29/05 .085 6/30/06 .087 

7/30/05 .087 7/18/06 .096 

8/01/05 .089 7/19/06 .086 

8/02/05 .115 7/20/06 .090 

9/01/05 .093 7/21/06 .089 

9/02/05 .094 8/18/06 .090 

9/03/05 .086 8/21/06 .087 
9/06/05 .088 8/31/06 .093 

9/08/05 .091 9/01/06 .094 

9/09/05 .098 

9/20/05 .085 

9/22/05 .090 
Table 2 

Houston CSA Maintenance-Only Monitors 

Exceedance-Days/Concentrations for the 1997 8-Hour O3 NAAQS 

2005-2006 

County: Harris Site Name: Aldine 

Site ID #: 48-201-0024 Lat/Long: 29.901111/-95.326111 

Exceedance 

Date 

Exceedance 

Concentration 

(ppb) 

Exceedance 

Date 

Exceedance 

Concentration 

(ppb) 

5/14/05 .098 6/5/06 .100 

5/27/05 .096 6/8/06 .089 

6/2/05 .101 9/1/06 .102 

8/23/05 .086 

10/18/05 .087 

County: Harris Site Name: Northwest Harris Co. 

Site ID #: 48-201-0029 Lat/Long: 30.039444/-95.673889 

5/6/05 .097 4/13/06 .090 

5/27/05 .116 6/5/06 .103 

6/2/05 .094 6/6/06 .086 

6/22/05 .093 6/29/06 .093 

6/23/05 .096 8/31/06 .087 

6/24/05 .091 9/7/06 .087 

6/26/05 .088 9/14/06 .097 

6/27/05 .088 9/27/06 .086 

8/3/05 .087 

County: Harris Site Name: Lynchburg Ferry 

Site ID#: 48-201-1015 Lat/Long: 29.764444-95.077778 

6/2/05 .104 6/4/06 .099 

6/15/05 .088 6/8/06 .089 

8/21/05 .118 6/12/06 .085 

10/18/05 .090 8/17/06 .085 

9/1/06 .111 

9/7/06 .087 

County: Harris Site Name: Clinton 

Site ID#: 48-201-1035 Lat/Long: 29.733611/-95.257500 

8/1/05 .092 6/29/06 .090 

9/5/05 .098 

10/12/05 .088 

10/17/05 .092 

County: Harris Site Name: Seabrook Friendship Park

Site ID#: 48-201-1050 Lat/Long: 29.583056/-95.015556 

4/8/05 .088 6/2/06 .091 

6/2/05 .087 6/4/06 .102 

6/15/05 .086 6/14/06 .086 

6/22/05 .085 9/1/06 .119 

7/28/05 .095 
8/22/05 .107 

8/30/05 .118 

10/18/05 .085 
Table 3 

California Maintenance-Only Monitors 

High Ozone Days/Concentrations 

2005-2006 

County: Sacramento 

Site ID #: 06-067-0006 Lat/Long: 38.6142/-121.3669 

Exceedance 

Date 

Exceedance 

Concentration 

(ppb) 

Exceedance 

Date 

Exceedance 

Concentration 

(ppb) 

7/13/05 .109 7/22/06 .093 

7/14/05 .117 7/23/06 .095 

7/15/05 .106 9/01/06 .095 

7/17/05 .096 9/12/06 .102 

County: Riverside 

Site ID #: 06-065-2002 Lat/Long: 33.7085/-116.2154 

5/23/05 .090 5/12/06 .086 

5/26/05 .091 7/24/06 .090 

6/01/05 .094 

7/01/05 .092 

7/16/05 .095 

8/27/05 .094 

County: Placer 

Site ID#: 06-061-0002 Lat/Long: 38.9378/-121.1039 

5/25/05 .087 6/24/06 .098 

7/01/05 .092 7/18/06 .098 

7/18/05 .096 7/20/06 .094 

7/26/05 .107 7/21/06 .114 

8/03/06 .095 

8/09/06 .093 

9/06/06 .094 

9/13/06 .098 

County: Merced 

Site ID#: 06-047-0003 Lat/Long: 37.2817/-120.4336

7/14/05 .093 6/22/06 .094 

6/23/06 .091 

Note 

High ozone concentration days include the top one third of the ozone exceedances registered on 

each of the 2005-2006 years at each of the four maintenance-only monitors. Dates and 

concentrations are from EPA’s AQS exceedances reports.