Working together for clean airWorking together for clean air
Puget Sound Area Ozone Modeling
NW AIRQUESTDecember 4, 2006
Puget Sound Area Ozone Modeling
NW AIRQUESTDecember 4, 2006
Washington State University
Puget Sound Clean Air Agency
Washington Department of Ecology
Washington State University
Puget Sound Clean Air Agency
Washington Department of Ecology
Overview/DisclaimerOverview/Disclaimer
Presentation will NOT be an in-depth “technical” exploration of the models.
Presentation WILL show how a local agency tapped into local (NW AIRQUEST) modeling resources to help answer internal policy/planning questions.
Presentation will NOT be an in-depth “technical” exploration of the models.
Presentation WILL show how a local agency tapped into local (NW AIRQUEST) modeling resources to help answer internal policy/planning questions.
Background – Ozone Levels in the Puget Sound AreaBackground – Ozone Levels in the Puget Sound Area
Background – Stakeholder charge & Future FactorsBackground – Stakeholder charge & Future Factors
“Although the modeling results demonstrated minimal reductions in ozone concentration as a result of implementing the strategies … … the air quality benefits produced by the strategies could be an important contribution to remaining in attainment.”
“…prudence requires that early identification of any potential impediments to remaining in attainment be vigorously pursued…”
“Although the modeling results demonstrated minimal reductions in ozone concentration as a result of implementing the strategies … … the air quality benefits produced by the strategies could be an important contribution to remaining in attainment.”
“…prudence requires that early identification of any potential impediments to remaining in attainment be vigorously pursued…”
Previous WSU modeling, based on a 1996 ozone event, contributed to stakeholder process and adopted strategies
Low Reid Vapor Pressure (RVP) gasoline
Stage II vapor recovery
Future Factors Moderate population and VMT growth Dramatic growth projected for local ports
Previous WSU modeling, based on a 1996 ozone event, contributed to stakeholder process and adopted strategies
Low Reid Vapor Pressure (RVP) gasoline
Stage II vapor recovery
Future Factors Moderate population and VMT growth Dramatic growth projected for local ports
Objectives and ImprovementsObjectives and Improvements
OBJECTIVES
To determine if the Puget Sound area is likely to remain in attainment in the future, using more updated inventory and methods.
To better understand the impact that low RVP gasoline has on ozone formation in the Puget Sound area.
To better understand ozone formation through sensitivity analyses.
OBJECTIVES
To determine if the Puget Sound area is likely to remain in attainment in the future, using more updated inventory and methods.
To better understand the impact that low RVP gasoline has on ozone formation in the Puget Sound area.
To better understand ozone formation through sensitivity analyses.
IMPROVEMENTS/CHANGES
CMAQ dispersion model (CALGRID used in previous)
MOBILE6 mobile model (MOBILE 5B used in previous)
Land surface model MM5 (simple soil MM5 in previous)
1998 ozone event (1998 concentrations higher than 1996)
1999 emission estimates (1996 NEI)
IMPROVEMENTS/CHANGES
CMAQ dispersion model (CALGRID used in previous)
MOBILE6 mobile model (MOBILE 5B used in previous)
Land surface model MM5 (simple soil MM5 in previous)
1998 ozone event (1998 concentrations higher than 1996)
1999 emission estimates (1996 NEI)
Modeling Project – Process and DesignModeling Project – Process and Design
Emissions Inventory Technical Group PSCAA, Ecology, WSU Inventory based largely on EPA’s 1999 National Emissions
Inventory Exception is non-road mobile (marine)
Base Case Year (1998)
Future Case Year (2015) Two scenarios run, with and without low Reid Vapor Pressure (RVP)
agreements
Sensitivity Runs Runs increasing and decreasing VOC and NOX in different combinations
Emissions Inventory Technical Group PSCAA, Ecology, WSU Inventory based largely on EPA’s 1999 National Emissions
Inventory Exception is non-road mobile (marine)
Base Case Year (1998)
Future Case Year (2015) Two scenarios run, with and without low Reid Vapor Pressure (RVP)
agreements
Sensitivity Runs Runs increasing and decreasing VOC and NOX in different combinations
Emissions Inventory SummaryVOC, NOX emissions reduce 20, 25% Emissions Inventory SummaryVOC, NOX emissions reduce 20, 25%
Emissions Inventory Comparison - 1998 and 2015 Scenarios
0
50
100
150
200
250
300
350
400
450
Area Point Nonroad Onroad Biogenic
Av
era
ge
To
ns
/Da
y
VOC 1998
VOC 2015 Low RVP
VOC 2015 High RVP
NOX 1998
NOX 2015
Inventory for PSCAA Counties - King, Kitsap, Pierce, Snohomish
Results – High Ozone SitesResults – High Ozone Sites
2015 ozone levels lower than 1998 at highest ozone sites High or low RVP gasoline made small difference in 2015 levels, less than 0.3 ppb at a monitor Poor model performance on second and third day of event
2015 ozone levels lower than 1998 at highest ozone sites High or low RVP gasoline made small difference in 2015 levels, less than 0.3 ppb at a monitor Poor model performance on second and third day of event
1-hour ozone at Enumclaw. Red = 1998 observations, blue = 1998 model, green = 2015 model (low RVP)
Results – “Urban Core” SitesResults – “Urban Core” Sites
Beacon Hill, near urban core, showed higher concentrations, in 2015 than 1998 Higher concentrations moving closer to urban area
Ozone/NOX ratios increasing from 1998 to 2015, smaller band “VOC-limited”
Not important for attainment status, but may potentially have public health implication
Beacon Hill, near urban core, showed higher concentrations, in 2015 than 1998 Higher concentrations moving closer to urban area
Ozone/NOX ratios increasing from 1998 to 2015, smaller band “VOC-limited”
Not important for attainment status, but may potentially have public health implication
1-hour ozone at Beacon Hill. Red = 1998 observations, blue = 1998 model, green = 2015 model
Results – Low RVP AgreementResults – Low RVP Agreement
Difference between 2015 “high” and “low” RVP scenarios less than 1 ppb
At individual monitoring sites, the difference is less than 0.3 ppb
Results – Sensitivity Analyses (based on 1998)Results – Sensitivity Analyses (based on 1998)
Reducing VOC (with NOX
constant or increasing) yields most optimal ozone reductions
Reducing VOC (with NOX
constant or increasing) yields most optimal ozone reductions
UncertaintiesUncertainties
Uncertainties in emissions inventory and projections Uncertainties in meteorological and dispersion
modeling Under-prediction in second, third day of event
Future uncertainties Lower future ozone NAAQS? “Background” concentrations from developing
countries Climate change effect?
Uncertainties in emissions inventory and projections Uncertainties in meteorological and dispersion
modeling Under-prediction in second, third day of event
Future uncertainties Lower future ozone NAAQS? “Background” concentrations from developing
countries Climate change effect?
Results – Objectives Met?Results – Objectives Met?
Modeling confirms previous results. The Puget Sound area is likely to remain in attainment in future years (with the current standard).
Voluntary low RVP gasoline will make little difference as cleaner cars are incorporated into the fleet in future years.
The region is “VOC limited.” VOC emissions reductions contribute to lower ozone concentrations. (caveat – sensitivity runs based on 1998 scenario).
Modeling confirms previous results. The Puget Sound area is likely to remain in attainment in future years (with the current standard).
Voluntary low RVP gasoline will make little difference as cleaner cars are incorporated into the fleet in future years.
The region is “VOC limited.” VOC emissions reductions contribute to lower ozone concentrations. (caveat – sensitivity runs based on 1998 scenario).
Post-Model Discussions/Input…Post-Model Discussions/Input…
Results inform PSCAA Programs
Voluntary Low Reid Vapor Pressure (RVP) gasoline in summer months
Vapor recovery (Stage II)
Results inform PSCAA Programs
Voluntary Low Reid Vapor Pressure (RVP) gasoline in summer months
Vapor recovery (Stage II)
Continuous Improvement
Possible model “metrics” (in addition to EPA’s guidance)
Model improvements
Continuous Improvement
Possible model “metrics” (in addition to EPA’s guidance)
Model improvements
Acknowledgements and QuestionsAcknowledgements and Questions
Many thanks to all who contributed:
Washington State Department of Ecology
Washington State University
Region 10 Environmental Protection Agency
Puget Sound Regional Council
Puget Sound Clean Air Agency
Many thanks to all who contributed:
Washington State Department of Ecology
Washington State University
Region 10 Environmental Protection Agency
Puget Sound Regional Council
Puget Sound Clean Air Agency
Results – Pack ForestResults – Pack Forest
1-hour ozone at Pack Forest. Red = 1998 observations, blue = 1998 model, green = 2015 model (low RVP)
Results – Model PerformanceResults – Model Performance
Overall, CMAQ model performance statistics met EPA guidance 1-hour mean normalized bias and error of -3% and 21% (guidance is 15%,
35%) 8-hour normalized bias of 1% (matched cell) and 9% (5 x 5 cells)
Very good agreement at Pack Forest Under-prediction at Enumclaw sites
Likely due to meteorology and over-prediction of planetary boundary layer Negative bias around 15% When include surrounding cells, negative bias around 10%
Scatter diagram, quantile-quantile plot show good agreement between observed and predicted
MM5 modeling generally shows an index of agreement ~0.8 for wind speed, direction, temperature, and humidity.
Overall, CMAQ model performance statistics met EPA guidance 1-hour mean normalized bias and error of -3% and 21% (guidance is 15%,
35%) 8-hour normalized bias of 1% (matched cell) and 9% (5 x 5 cells)
Very good agreement at Pack Forest Under-prediction at Enumclaw sites
Likely due to meteorology and over-prediction of planetary boundary layer Negative bias around 15% When include surrounding cells, negative bias around 10%
Scatter diagram, quantile-quantile plot show good agreement between observed and predicted
MM5 modeling generally shows an index of agreement ~0.8 for wind speed, direction, temperature, and humidity.
Results – Test of Future AttainmentWeyerhauser Mill, Lake Sammamish, Pack ForestResults – Test of Future AttainmentWeyerhauser Mill, Lake Sammamish, Pack Forest
Designed to take model uncertainty account, using model in a relative sense. Very Conservative as it takes 5 years into account.
1) Calculate current design values (DVC) based on 4th high 8-hour concentrations
2) Calculate the relative reduction factor from modeling
RRF = average 2015 8 hour maxaverage 1998 8 hour max
3) Calculate future design value = DVC * RRF
SITE RRF Future Design Value
WM 0.90 68 ppbLS 0.97 58 ppbPF 0.94 68 ppb
Designed to take model uncertainty account, using model in a relative sense. Very Conservative as it takes 5 years into account.
1) Calculate current design values (DVC) based on 4th high 8-hour concentrations
2) Calculate the relative reduction factor from modeling
RRF = average 2015 8 hour maxaverage 1998 8 hour max
3) Calculate future design value = DVC * RRF
SITE RRF Future Design Value
WM 0.90 68 ppbLS 0.97 58 ppbPF 0.94 68 ppb
Results – Sensitivity AnalysesResults – Sensitivity Analyses
8-hr 26-Jul 27-Jul 28-Jul ppm ppm ppm Base 0.093 0.096 0.077 No area 0.088 0.088 0.071 No biogenic 0.075 0.075 0.053 No on-road 0.088 0.084 0.070 No on-road VOC 0.088 0.083 0.067 No on-road NOX 0.105 0.098 0.082 No non-road 0.084 0.086 0.074 No non-road VOC 0.080 0.085 0.070 No non-road NOX 0.103 0.098 0.082 No point 0.095 0.095 0.076 % change from 1998 base No area -5% -8% -8% No biogenic -19% -22% -31% No on-road -5% -13% -9% No on-road VOC -5% -14% -13% No on-road NOX 13% 2% 6% No non-road -10% -10% -4% No non-road VOC -14% -11% -9% No non-road NOX 11% 2% 6% No point 2% -1% -1%
8-Hour Ozone Standard Exceeded with Entire Source Categories Removed
Emissions Inventory SummaryTotal VOCs estimated to decrease ~ 20%Emissions Inventory SummaryTotal VOCs estimated to decrease ~ 20%
VOC Sources 1998
Area, 142, 15%
Point, 16, 2%
Nonroad, 147, 16%
Onroad, 223, 24%
Biogenic, 410, 43%
TOTAL 938 Tons/Day VOC Sources 2015 ("high RVP" scenario)
Area, 158, 21%
Point, 16, 2%
Nonroad, 83, 11%
Onroad, 81, 11%
Biogenic, 410, 55%
TOTAL 748 Tons/Day
Inventory for PSCAA Counties - King, Kitsap, Pierce, Snohomish
Total 950 tons/day
Total 750 tons/day
Emissions Inventory SummaryNOX Emissions Estimated to Decrease ~25%Emissions Inventory SummaryNOX Emissions Estimated to Decrease ~25%
NOX Sources 1998
Onroad, 290, 55%
Biogenic, 2, 0%Area, 14, 3%
Point, 24, 5%
Nonroad, 195, 37%
TOTAL 525 Tons/Day NOX Sources 2015
Nonroad, 266, 68%
Onroad, 93, 23%
Biogenic, 2, 0%Area, 13, 3%
Point, 24, 6%
TOTAL 398 Tons/Day
Inventory for PSCAA Counties - King, Kitsap, Pierce, Snohomish Total 400 Tons/Day