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

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

Background

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

2005 & 2006 Top 5 8-hour ozone concentrations JonahBoulderDaniel South $ DateppmDateppmDateppm 02/03/ /20/ /08/ /26/ /03/ /07/ /24/ /04/ /22/ /04/ /24/ /11/ /27/ /19/ /03/ /27/ *04/21/ /25/ /25/ *06/18/ /02/ /02/ /02/ /21/ /11/ /01/ /27/ /15/ /18/ /18/ * Less than 75% data completeness $ Began operation in July 2005

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

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

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

Ozone Monitoring Field Study

 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)

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

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

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

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

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

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

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

Jonah O3 and NOx February 8-Hour O ppb March 8-Hour O ppb February 8-Hour NOx ppb March 8-Hour NOx ppb

Maximum Ozone Concentration Hourly Max8-Hourly MaxHourly Max8-Hourly Max Ozone (ppb) Boulder Jonah Daniel

Aerial Measurements

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

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

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

Ground-level Measurements

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

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

VOCs: Mean Concentration

Median VOC Concentrations: Top Six

Median VOC Concentrations: Remainder of Top 21

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

Formaldehyde 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!

Summary  Weather conditions associated with high ozone events in 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 Need site downwind to observe results of O3 formation  Need more information on VOC/carbonyl

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

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

Questions Cara Keslar Field Study Project Manager Darla Potter Acting Modeling Study Project Manager