Cluster Analysis of Air Quality Data for CCOS Study … CCOS...Cluster Analysis of Air Quality Data...
Transcript of Cluster Analysis of Air Quality Data for CCOS Study … CCOS...Cluster Analysis of Air Quality Data...
Cluster Analysis of Air Quality Data for CCOS Study Domain
Scott BeaverAhmet Palazoglu, P.I.University of California, Davis
Dept. Chemical Engineering & Materials Science
CCOS Technical Committee MeetingCal/EPA Building, 1001 I St., Sacramento, CA
Thursday 31 March 2007
Department of Chemical Engineering and Materials Science
Overview• Project: Cluster Analysis for CCOS Domain
I. Intra-basin analyses: wind patterns & synoptic regimesII. Inter-basin meteorological response of O3 levels
• Intra-basin analyses:– Completed Bay Area analysis
• Strong synoptic influence; seabreeze cycles
– Preliminary North SJV wind field clustering• Synoptic & ventilation effects
– Preliminary Central SJV wind field clustering• Synoptic & mesoscale (Fresno eddy) effects
– Preliminary South SJV wind field clustering• Synoptic effects; mesoscale variability difficult to capture
– Initial Sacramento Valley & Mountain Counties analysis
• Future work and recommendations
Department of Chemical Engineering and Materials Science
Cluster Analysis for CCOS• Scope of 2-year project
I. Intra-basin wind field cluster analyses– Requires continuous, hourly surface wind data– Days grouped by diurnal wind field patterns– Reveals synoptic and mesoscale flow regimes
II. Inter-basin analysis
• Study Domain– 6 CCOS air basins
• San Francisco Bay Area• SJV: split into North, Central, & South• Sacramento Valley• Mountain Counties
– 1996-2004 ozone seasons (1 May – 31 October)
Department of Chemical Engineering and Materials Science
SFBA: 4 clusters for 976 days1
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Department of Chemical Engineering and Materials Science
*Beaver and Palazoglu, 2006: Cluster analysis of hourly wind measurements to reveal synoptic regimes affecting air quality. Journal of Applied Meteorology and Climatology, 45, 1710—26.
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SFBA clusters = synoptic regimes
Department of Chemical Engineering and Materials Science
H
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V2V1
Onshore High: 353 d, 13% episodes Offshore High: 86 d, 13% episodes
Weaker Trough: 309 d, 0% episodes Deeper Trough: 309 d, 0% episodes
*Beaver, Palazoglu and Tanrikulu, 2007: Cluster sequencing to analyze synoptic transitions affecting regional ozone. Journal of Applied Meteorology and Climatology, in press.
Synoptic Transition Probabilities• R transitions rapidly to H
– Severe, multi-day episodes– Reverse H�R does not occur– Polar low may “save” SFBA from episode
• Persistence of H indicates stability– Displaced by sufficiently deep trough (e.g. V2)– Bulk of episodes during persistent H
• Transitions from V1 & V2 driven by global met.– Troughs may persist for long periods; low O3 levels– Transition to H or R will occur unless O3 season ends
Department of Chemical Engineering and Materials Science
Wind Speed Errors at Tracy
Department of Chemical Engineering and Materials Science
1996—1999 are similar to 2001—2004.
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Tracy-Patterson Rd. -- Wind Direction Hourly Distribution
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Wind Direction Errors at Tracy
Department of Chemical Engineering and Materials Science
1996—1999 are similar to 2001—2003.
Gantt chart for N-SJV
Department of Chemical Engineering and Materials Science
Yellow = 1 Nov—30 Apr winter data (not clustered)Blue = clustered stations (included in Total)Red = non-clustered stations (excluded from Total)
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Department of Chemical Engineering and Materials Science
H: 179 days, 42%
H H
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R: 264 days, 19%H/V: 212 days, 25%
V2: 108 days, 6%V1: 299 days, 12%
N-SJV 0900 PST Wind Field
Department of Chemical Engineering and Materials Science
Magenta: Carquinez Strait— Ft. Funston, Pt. San Pablo, Suisun, Bethel Is.
Blue: Altamont Pass— Kregor Peak, TracyRed: Pacheco Pass— Los BanosBlack: SJV floor
H H/VR V1 V2Increasing marine ventilation: R < H < H/V < V1 < V2
N-SJV Seasonal Distribution
Department of Chemical Engineering and Materials Science
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Department of Chemical Engineering and Materials Science
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Altamont Pass Wind Distribution
Department of Chemical Engineering and Materials Science
0800PST Wind Distribution
H (164 d)
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N-SJV Synoptic Sequencing
• α = 0.05– R H/V disfavored– Clusters occur in different seasons (trivial result)
• α = 0.15– R H favored
– H H/V favored
– H/ V V favored
– V R favored
• Compare to Bay Area– Transitions significant at α < 0.02– Stronger synoptic influence than N-SJV
Annual Biases in Wind Direction
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2000—02 are ~15o more westerly than other years.
Upslope/Downslope Cycle
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Department of Chemical Engineering and Materials Science
Wind direction at SLAMS Sequoia monitor for 20 days during 2003.
Flow switches from easterly to westerly.
Daytime upslope flows; nighttime drainage flows
Diurnal cycle largely captures local effects.
Signal is not well modeled by clustering algorithm.
Gantt chart for C-SJV
Department of Chemical Engineering and Materials Science
Magenta: stations with annual biases
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Department of Chemical Engineering and Materials Science
H: 203 days
H H R
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R: 341 daysH/V: 169 days
V/I: 378 daysV: 279 days
IV?
C-SJV 8-hr O3 Exceedances
Department of Chemical Engineering and Materials Science
H RH/VV/IV
Ventilated regime episodes favor Sequoia.
Anti-cyclonic regime episodes favor SJV floor.
Percentage of days in each cluster that are 8-hr O3 exceedances
279 d 378 d 169 d 203 d 341 dTotal 40% 32% 64% 92% 59%SJV floor 29% 17% 34% 84% 52% Parlier 20% 15% 28% 73% 43% Clovis 18% 6% 12% 62% 33%
Sequoia 25% 25% 57% 64% 33%SJV floor & Sequoia 14% 10% 27% 56% 26%
C-SJV Seasonal Distribution
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Department of Chemical Engineering and Materials Science
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C-SJV Synoptic Sequencing
• Direct transitions between H, R, and Voccur infrequently
• H/V and V/I are “intermediate” states– C-SJV is buffered from synoptic effects
– Synoptic transitions have less effect on O3levels than for N-SJV (than for Bay Area)
• Mesoscale effects important for C-SJV
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The Fresno Eddy
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Magenta: Carquinez Strait— Ft. Funston, Pt. San Pablo, SuisunBlue: Altamont Pass— Kregor Peak, TracyRed: Pacheco Pass— Los BanosCyan: Parkfield (west) & Sequoia (east)Yellow: Carrizo Plain
R H/VH V V/IDecreasing eddy strength: H > R > H/V > V > V/I
Eddy Strength and O3 Levels
Department of Chemical Engineering and Materials Science
Strong eddyNo/weak eddy
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Parlier southerly wind component at 0900 PST (m/s)
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Department of Chemical Engineering and Materials Science
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Eddy (296 d)R H/V V V/IH
Eddy Strength & Marine Ventilation
Within each regime, enhanced marine ventilation can suppress eddy formation
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Department of Chemical Engineering and Materials Science
H/V: 206 days, 64%
H H R
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R: 373 days, 62%H: 354 days, 58%
V/I: 317 days, 22%V: 160 days, 36%
I?V
Department of Chemical Engineering and Materials Science
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S-SJV Seasonal Distribution
Progress
Department of Chemical Engineering and Materials Science
Non-contracted quality assurance is a critical but time consuming step which has delayed Phase I progress.
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San Francisco Bay Area X X X X X X XSJV North X X X \ \ XSJV Central X X X \ \ XSJV South X X \ \Sacramento Valley XMountain Counties X
Phase I Phase II
Recommendations• Transport analysis for identified met regimes using a
(back-trajectory) transport model.– Transport through gaps in Coastal Range– Transport patterns from major source areas
• NOx/VOC ratio and O3 sensitivity– Role of meteorology
• El Nino effects• Wild fire analysis• Vertical analysis
– Visalia profiler– Limited soundings?
• AQM performance evaluation• … and others from project work plan ???
Department of Chemical Engineering and Materials Science