Clark County Regional Ozone Clark County Regional Ozone and Precursor Study and Precursor Study
(CCROPS)(CCROPS)
Robert A. Baxter, CCMRobert A. Baxter, CCM
T&B SystemsT&B Systems
Clark County Air Quality Forum – 03/14/06Clark County Air Quality Forum – 03/14/06
Overview
• Objectives of the Study
• Design of the Measurement Program
• Summary of Enhanced Field Measurements
• Database Description
• Analyses Performed
• Overall Results and Recommendations
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
Measurement Program Design
Clark CountyProject Sponsor
T&B SystemsProgram 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 O3
13 saturation O3
Rawinsonde Ozonesonde Glider O3
Aircraft O3
T&B Systems• Glider O3
UNLV• NOy
• Nitric Acid• PAN• NO2
UCR• Ozone forecasting• Enhanced NOx
• Overall support
Clark County
Measurement Program Design
Period of Operation MeasurementsEntire study period
(May 15 – August 31)
• O3, Met (10 sites)
• Radar, sodars (4 sites)
• NOy, PAN, Nitric Acid
• Joe Neal NOx/NO2 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
Ozone Monitoring Network
Ozone Monitoring Network
Precursor Monitoring Network
Upper-Air Monitoring Network
Field Measurement Enhancements Sodar and Radar Wind Profiler
Field Measurement Enhancements Rawinsondes/Ozonesondes
Field Measurement Enhancements Rawinsondes/Ozonesondes
Field Measurement Enhancements Aircraft
Field Measurement Enhancements Aircraft
July 1 -- Aircraft Flight 0740 PDT Jean Sounding
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PM10 (ug/m3) Ozone (ppb) Temperature (C)
Ozone
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PM10
Field Measurement Enhancements Aircraft
Field Measurement Enhancements Saturation Ozone
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
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?
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?
Ozone Network Coverage
#Sites Season May* June July Aug Totals 5 1996 1 2 1 1 5 6 1997 1 0 0 0 1 6 1998 0 2 6 0 8 13 1999 1 3 2 0 6 15 2000 0 0 1 2 3 15 2001 0 0 0 3 3 15 2002 0 3 1 2 6 15 2003 2 6 2 1 11 15 2004 2 0 1 0 3 14 2005 DAQEM Sites 0 3 5 1 9 10 2005 with Supplemental Sites 0 3 7 1 11 24 2005 including both networks 0 3 7 2 12
*Supplemental Sites fully operational May 15
Ozone Network Coverage
Ozone Network Coverage – July 15
Ozone Transport July 1 - 2
Ozone Transport into Clark CountyJuly 2
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06:41 PDT
Ozone Transport into Clark CountyJuly 2
07:32 PDT
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Ozone Transport into Clark CountyJuly 2
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Ozone Transport into Clark CountyJuly 2
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Ozone Transport into Clark CountyJuly 2
Ozone Transport into Clark CountyBack Trajectory July 2 1500 PDT
Results and RecommendationsNetwork 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
Results and RecommendationsAdditional 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
Results and RecommendationsRecommended 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
Results and RecommendationsRecommended 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
Questions?
Please contact:
Department of Air Quality and Environmental Management (DAQEM)
(702) 455-5942
