1. Clark County Regional Ozone and Precursor Study (CCROPS) Robert A. Baxter, CCM T&B Systems Clark County Air Quality Forum – 03/14/06

2. Overview Objectives of the Study Design of the Measurement Program Summary of Enhanced Field Measurements Database Description Analyses Performed Overall Results and Recommendations

3. Objectives Obtain a data set to help understand the origin of ozone and precursors Assess the adequacy of the Clark County monitoring network to measure peak ozone Obtain a data set of known quality for model validation Generate a database for current and future SIP development Provide recommendations for future research to support modeling of ozone

4. Measurement Program Design Clark County Project Sponsor T&B Systems Program Management Upper air winds Sodar Radar Wind Profiler Doppler reanalysis Rawinsonde and Pibal (NOAA) Boundary ozone DRI (south) VOCs DRI (north) Field coordination Ozone forecasting Data management Quality assurance Measurements 10 supplemental O 3 13 saturation O 3 Rawinsonde Ozonesonde Glider O 3 Aircraft O 3 T&B Systems Glider O 3 UNLV NO y Nitric Acid PAN NO 2 UCR Ozone forecasting Enhanced NO x Overall support Clark County

5. Measurement Program Design Period of OperationMeasurements Entire study period (May 15 – August 31) O 3, Met (10 sites) Radar, sodars (4 sites) NO y, PAN, Nitric Acid Joe Neal NO x /NO 2 addition Intensive Operational Periods (four 1- to 2-week periods) Upper-air meteorology using rawinsondes at 1 site Continuous ozone at up to 13 saturation sites Episodic Operations (1- to 3-day forecasted periods) VOC at 3 sites, 4 samples/day Upper-air ozone 3/day Upper-air ozone using 2 aircraft Pibal/rawinsondes at various sites

6. Ozone Monitoring Network

8. Precursor Monitoring Network

9. Upper-Air Monitoring Network

10. Field Measurement Enhancements Sodar and Radar Wind Profiler

11. Field Measurement Enhancements Rawinsondes/Ozonesondes

13. Field Measurement Enhancements Aircraft

16. Field Measurement Enhancements Saturation Ozone

17. CCROPS Database Goal was to produce a validated and documented database in a standard format that was detailed, flexible and easy to use Relational database in MS Access Contains both enhanced and DAQEM data Predefined information in tables Data quality flags for all reported variables Metadata files containing key operational and data quality information and Measurement Quality Objectives (MQOs) –Accuracy, precision, lower quantifilable limit, resolution, completeness –Site pictures and location information –Data processing procedures –Data limitations

18. Data Analyses How well does the existing DAQEM monitoring network measure the maximum ozone exposure in Clark County? How well does the existing DAQEM monitoring station at Jean represent ozone background levels in Southern Nevada and the Las Vegas Valley? What are ozone levels aloft; and is day-to-day carryover an important feature? Is the three-dimensional wind field in the Las Vegas Valley uniform or dominated by local terrain features? How representative is the NOAA sounding at Desert Rock of the boundary layer in the Las Vegas Valley? How well does the CART ozone forecast model perform in an operational mode? Can we distinguish the relative contributions from transport and local emissions to the total ozone burden in Clark County?

19. Data Analyses How well does the existing DAQEM monitoring network measure the maximum ozone exposure in Clark County? How well does the existing DAQEM monitoring station at Jean represent ozone background levels in Southern Nevada and the Las Vegas Valley? What are ozone levels aloft; and is day-to-day carryover an important feature? Is the three-dimensional wind field in the Las Vegas Valley uniform or dominated by local terrain features? How representative is the NOAA sounding at Desert Rock of the boundary layer in the Las Vegas Valley? How well does the CART ozone forecast model perform in an operational mode? Can we distinguish the relative contributions from transport and local emissions to the total ozone burden in Clark County?

20. Ozone Network Coverage

22. Ozone Network Coverage – July 15

23. Ozone Transport July 1 - 2

24. Ozone Transport into Clark County July 2 06:41 PDT

25. Ozone Transport into Clark County July 2 07:32 PDT

26. Ozone Transport into Clark County July 2 10:14 PDT

27. Ozone Transport into Clark County July 2 10:40 PDT

28. Ozone Transport into Clark County July 2

29. Ozone Transport into Clark County Back Trajectory July 2 1500 PDT

30. Results and Recommendations Network Changes City Center Ozone site adversely impacted by local emissions and should be discontinued Permanent sites for Paiute and Indian Springs areas should be established Short term summer study for Sunset Park region recommended to learn more about the saturation site findings

31. Results and Recommendations Additional Considerations Additional monitoring in the foothills Short term summer monitoring for Craig Ranch region Monitoring at one of the two CCROPS ridge top sites to aid in understanding of nighttime ozone aloft and daily forecasting

32. Results and Recommendations Recommended Analyses Select candidate modeling periods and perform detailed descriptive analyses – local vs. transport Further analyze critical features driving the exceedances Examine hourly timing of ozone peaks within the extended network, characterize with respect to the “conceptual model” Quantify the Las Vegas urban area contribution

33. Results and Recommendations Recommended Analyses (cont.) Integrate the VOC and nitrogen species data into the analyses to determine the extent of reaction and major source contribution Examine downwind impacts to the northeast Examine in more detail the interbasin transport routes using data from the California networks Investigate in detail the wildfire impacts and extent of the smoke plume using PM and ozone network data Update and refine the existing CART model and forecasting protocol

34. Questions? Please contact: Department of Air Quality and Environmental Management (DAQEM) (702) 455-5942