1. Upper Green River Basin Wyoming Winter Ozone Study WESTAR Oil and Gas Conference September 12, 2007 Cara Keslar Wyoming DEQ - Air Quality Division

2. Introduction  Background  Ozone Monitoring Field Study Design  Field Study Results Jonah 12:00 2/27/06

3. Background

4. Hourly Average Ozone Concentrations February 2005, Jonah Study Periods Slide compliments of NOAA

5. 2005 & 2006 Top 5 8-hour ozone concentrations JonahBoulderDaniel South $ DateppmDateppmDateppm 02/03/050.09802/20/050.08907/08/050.070 02/26/050.08902/03/050.08107/07/050.067 01/24/050.07802/04/050.08007/22/050.066 02/04/050.07602/24/050.08007/11/050.066 02/27/050.07502/19/050.07907/03/050.064 02/27/060.093*04/21/060.08102/25/060.083 02/25/060.081*06/18/060.07905/02/060.076 05/02/060.07105/02/060.07604/21/060.075 06/11/060.07006/01/060.07302/27/060.075 07/15/060.07008/18/060.07206/18/060.073 * Less than 75% data completeness $ Began operation in July 2005

6. Theories on Causes  Monitoring error: Not Likely Checked certifications Additional 3 rd party audits Elevated concentrations at multiple monitors Winter 2006 put Chemiluminescent ozone monitor at Jonah to check for VOC interference and found none  Stratospheric Intrusion: Not Likely Tight inversion and stagnant conditions for several days  Transport: Slight Possibility Other areas had not reported high wintertime conditions

7. Theories on Causes (cont.)  Locally Formed: Most Likely Precursors emitted in area Suspected tight inversion Stagnant conditions High Elevation, sunny, snow cover 2005

8. AQD Response to Ozone Events  Concerns about elevated concentrations Potential for NAAQS violation Health effects on local public More development planned in SW Wyoming  Requested proposals for a special study Ambient and Meteorological Field Study Modeling Study Emission Inventories

9. Ozone Monitoring Field Study

10.  2005 & 2006 meteorological evaluation – forecasting High pressure aloft Light surface winds Snow cover Stable boundary layer UV reflectance  Gather online data from other sources Total columnar ozone GOES temperature profiles  Field Study - February and March 2007 Continuous Measurements Intensive Operating Periods (IOP)

11. Continuous Measurements  Continued and enhanced monitoring at Boulder, Jonah, and Daniel South  CastNet continued collecting ozone data  Airport operations  Profiler Site  Mesonet Meteorology

12. Intensive Operating Periods (IOPs)  Operational forecasts Elevated ozone events likely Trigger Intensive Operating Periods (IOPs)  IOP Measurement Objectives Determine structure of atmosphere during high ozone events: How shallow is the inversion? What does the vertical ozone profile look like? What differences exist between Jonah, Boulder, Daniel? Determine spatial variability of ozone concentrations around Upper Green River Basin Determine VOC and Carbonyl concentrations

13. IOP Measurements  Tetheredsondes and VOC/Carbonyl at Boulder, Jonah and Daniel South  Rawin/ozonesondes at Airport  Mesonet Ozone  Aircraft measurements

14. 2007 Field Study Results Jonah Station and surrounding area 3/17/07 Station

15. Mean 500 mb Wind Speeds Feb-Mar 2005, 2006Feb-Mar 2007 Substantially stronger upper level winds during 2007 field study

16. Mean Surface Temperatures Feb-Mar 2005, 2006Feb-Mar 2007 Warmer temperatures during 2007 field study

17. Jonah 8-Hour O3 March ppb Consistently lower O3 in 2007

18. Jonah O3 and NOx February 8-Hour O3 0 20 40 60 80 100 120 13579111315171921232527 ppb 2005 2006 2007 March 8-Hour O3 0 10 20 30 40 50 60 70 80 135791113151719212325272931 ppb 2005 2006 2007 February 8-Hour NOx 0 20 40 60 80 100 120 140 160 180 13579111315171921232527 ppb 2005 2006 2007 March 8-Hour NOx 0 20 40 60 80 100 120 140 160 135791113151719212325272931 ppb 2005 2006 2007

19. Maximum Ozone Concentration 0 20 40 60 80 100 120 140 Hourly Max8-Hourly MaxHourly Max8-Hourly Max 2005-20062007 Ozone (ppb) Boulder Jonah Daniel

20. Aerial Measurements

21. 17 March Morning Flight Haystack Butte NO titration and elevated PM under inversion

22. 17 March Afternoon Flight Boulder - Low PM - Uniform O3- No inversion

23. Rawinsonde/Ozonesonde MorningAfternoon Inversion O3 depletion below inversion No Inversion 72 ppb O3 layer aloft

24. Ground-level Measurements

25. Hourly Ozone at Selected Sites Ozone depletion due to NO titration O3 at upwind location

26. UV Albedo 2 March: Albedo = 0.81 (snow) 23 March: Albedo = 0.04 (bare ground) Daily Avg. 07:00 – 19:00 MST

27. VOCs: Mean Concentration

28. Median VOC Concentrations: Top Six

29. Median VOC Concentrations: Remainder of Top 21

30. Carbonyl Analysis 12 Samples at Each Site Not Detected Sometimes Detected Detected in all or nearly all samples 2,5- Dimethylbenzaldehyde, Hexaldehyde, Isovaleraldehyde, m,o,p- Tolualdehyde, Propionaldehyde, Valeraldehyde, Buteraldehyde (roughly half of all samples), Crotonaldehyde (2 samples) Acetaldehyde, Acetone, Benzaldehyde, Formaldehyde

31. Formaldehyde 0 1 2 3 4 5 6 7 8 9 0400-07000900-12001400-1700 Time (MST) ppbV Jonah Boulder Daniel Max Min Mean Tentative Conclusions: Several formaldehyde sources near Jonah (high early morning concentrations) Possibility of some midday photochemical production at Boulder Need more sampling!

32. Summary  Weather conditions associated with high ozone events in 2005-2006 did not occur during 2007 Warmer temperatures, lack of snow cover Morning surface inversions did not persist  Observed “background” O3 in 50 – 55 ppb range  Increases in NOx and reduced O3 at Jonah compared to 2005-2006 Need site downwind to observe results of O3 formation  Need more information on VOC/carbonyl

33. Lessons Learned  Difficult to forecast high O3 events  Lack of reliability, and low humidities limited usefulness of profilers  Importance of local personnel to help with troubleshooting equipment, downloading data and coordinating logistics

34. Recommendations for 2008 Field Study  Start operations by mid-January  Maintain wind & temperature obs at 8 mesonet sites (equipment has been purchased)  Allow for potentially more IOPs by limiting cost of each Reduce number of mesonet sites with O3 Eliminate tethersondes Focus on aircraft for horizontal and vertical distributions of ozone, PM, temperature Simplify continuous upper air (SODAR or miniSODAR) Use leftover ozone/rawinsondes More VOC/carbonyl sampling

35. Questions Cara Keslar Field Study Project Manager 307-777-8684 Darla Potter Acting Modeling Study Project Manager 307-777-7346