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AQ Cycles Re-examined: Shifting of the Bermuda High and Changes in Regional Ozone Patterns

AQ Cycles Re-examined: Shifting of the Bermuda High and Changes in Regional Ozone Patterns. Duc Nguyen, Senior Meteorologist Michael Woodman, Chief Air Quality Measurements, Modeling and Analysis Division Ambient Air Monitoring Program

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AQ Cycles Re-examined: Shifting of the Bermuda High and Changes in Regional Ozone Patterns

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  1. AQ Cycles Re-examined:Shifting of the Bermuda High and Changes in Regional Ozone Patterns Duc Nguyen, Senior MeteorologistMichael Woodman, ChiefAir Quality Measurements, Modeling and Analysis DivisionAmbient Air Monitoring Program Presented at:2010 National Air Quality ConferencesRaleigh, NCMarch 18, 2010

  2. Outline • Ozone Exceedance Days and 90  F Cycle • Ozone Season NOx Emissions • Air Quality (AQ) Cycles • Pre/Post Adjustments for AQ Improvements • Estimate Magnitude of AQ Improvements • Bermuda High and Regional Ozone Patterns • Outlook for 2010 • Summary

  3. 3 years 5 years 3 years 4 years 4 years 3 years 5 years Maryland 8-Hour Ozone Exceedances Daysvs. ≥ 90 F Days ? *2009 data are preliminary.

  4. ? ? Ozone Exceedance Days and 90 F Cycle • Standardized departure of Maryland’s 8-hour ozone exceedance days (OEDs) and 90 deg F days at BWI follow a periodic cycle through 2002. Correlation is 0.67 • OEDs are consistently below normal since 2002 (indicating air quality improvements) regardless of temperature data. • Nguyen & Wooodman (2008) showed that the air quality improvements were driven by effective control strategies.

  5. Controls in Action …Ozone Season NOx Emissions • Compared to 1990 emissions, ozone season NOx emissions cut by 62% in 2003-2004. • By 2008, NOx emissions decreased by 75%. Figures extracted from EPA’s NOx Budget Trading Program 2008 Progress Report.

  6. Ozone Season NOx Emissions by State NOx SIP CallHelp LEVELING Upwind NOx Emissions! Map created by Maryland Department of the Environment using data extracted from Clean Air Markets - Data and Maps website.

  7. Characteristics of AQ Cycle EXCEEDANCE TENDENCY UPPER-LEVELPRESSURE/HEIGHT CORESSPONDINGSFC TEMPERATURE These characteristics can be observed spatially and temporally. Remark

  8. Higher Pressure~ Above Normal Counts About Normal Pressure~ Some Above& Some Below Year 3 Lower Pressure~ Below Normal Counts Year 2 Year 1 Air Quality Cycle (2000-2002) • Normal (Air Quality): 10-year (1993-2002) • Normal (Meteorology): 30-year (1971-2000) • Months: Jun-Aug This cycle has all the classic characteristics described on previous slide! Maps created using data extracted from AIRNowTech and ESRL PSDPlotting and Analysis. Some preliminary AQ data were used in the analysis.

  9. Slightly Below Normal & Normal PressureBUT Many Below Normal Counts Higher PressureBUT Many Below Normal Counts Relationshipstartingto break … Normal & Higher PressureBUT Many Below Normal Counts Lower Pressure~ Below Normal Counts Slightly Lower Pressure~ Below Normal Counts Air Quality Cycle (2003-2007) Relationship broke down … Analysis in 2007 indicated that air quality improvements have been driven by effective control strategies (e.g. NOx SIP Call)! Maps created using data extracted from AIRNowTech and ESRL PSDPlotting and Analysis. Some preliminary AQ data were used in the analysis.

  10. Pre/Post NOx SIP Call OEDs(Baltimore, MD MSA) Pre NOx SIP Call OEDs Post NOx SIP Call OEDs *2009 data are preliminary.

  11. Pre/Post NOx SIP Call OEDs(Washington, DC-MD-VA-WV MSA) Pre NOx SIP Call OEDs Post NOx SIP Call OEDs *2009 data are preliminary.

  12. Pre/Post NOx SIP Call OEDs(Philadelphia, PA-NJ MSA) Pre NOx SIP Call OEDs Post NOx SIP Call OEDs *2009 data are preliminary.

  13. Pre/Post NOx SIP Call OEDs(Boston, MA-NH MSA) Periphery of I-95 Ozone Plume *2009 data are preliminary.

  14. Pre/Post NOx SIP Call OEDs(Columbus, OH MSA) Upwind of Maryland and OTC States *2009 data are preliminary.

  15. Slightly Below Normal & Above Normal Pressure~ Normal and Above Normal Counts Higher Pressure~ Above Normal Counts Relationshipis now intact! Normal & Above Normal Pressure~ Normal/BelowNormal (North)Above Normal (South) Lower Pressure~ Below Normal Counts Slightly Lower Pressurebut Some Normal& Above NormalCounts Air Quality Cycle (2003-2007)(Adjusted for Recent Data) Relationship is restored after adjustments for recent data … Next Step: Compare ozone exceedances pre/post NOx SIP Call to estimate its effectiveness. Maps created using data extracted from AIRNowTech and ESRL PSDPlotting and Analysis. Some preliminary AQ data were used in the analysis.

  16. Air Quality ImprovementsPre/Post NOx SIP Call (1 of 2) • Similar meteorology between 2004 and 2009 allows us to estimate the minimum benefits for the NOx SIP Call. • Substantial number of MSAs observe OEDs improve by one category.(i.e “Normal”  “Below Normal”  “Well Below Normal”

  17. Air Quality ImprovementsPre/Post NOx SIP Call (2 of 2) • East of Mississippi experienced reduction of 30% or more in OEDs (highest reductions in rural settings). • 7 MSAs increase in OEDs but small averages and mainly located west of Mississippi. • Need another round of EMISSION REDUCTIONS to help OTC states and major cities attainnew stringent ozone standard. Maps were created using preliminary data extracted from AIRNowTech.

  18. Below Normal Pressure~ Normal/BelowNormal Counts Well Below Normal Pressure~ Mostly BelowNormal Counts Cycle Since 2008 • Data suggest that 2008 and 2009 were the beginning of a new cycle consisting of 2 beginning low years. • This information is crucial for seasonal AQ outlook for 2010 (i.e., likely to be normal or above normal counts). Maps created using data extracted from AIRNowTech and ESRL PSDPlotting and Analysis. Some preliminary AQ data were used in the analysis.

  19. Large-Scale Circulations • Large-scale circulation creates strong subsidence around 30° N. • Subsidence creates semi-permanent Subtropical highs at the surface around the globe. • Over the Atlantic Ocean, it’s referred to as “Azores / Bermuda High.” • Strength of High increases with height. Source: http://www.suu.edu/faculty/colberg/Hazards/Weather/04_GlobalWind.swf

  20. Bermuda High: Classic Mid-Atlantic Air Pollution Weather

  21. Bermuda Highis Responsible for WindFlow & PollutionTransport Patternsin Marylandand the Mid-Atlantic. Shifting of Bermuda HighDuring Low vs High Ozone Seasons

  22. Outlook for 2010 (1 of 2) • Latest ENCEP coupled forecast system (CFS) predicts weak Warm ENSO (El Niño) conditions to persist through 2010 summer. • Various other models also predict weak warm ENSO or normal conditions through 2010 summer. • If forecasts verify the Mid-Atlantic region will likely be experiencing normal or above normal temperatures and/or dry conditions during the 2010 summer air quality season. Sources: NCDC ENSO Diagnostic Discussion | CFS Seasonal Climate ForecastsIRI ENSO Quicklook

  23. Outlook for 2010 (2 of 2) • CDC outlooks calls for warmer than normal temperatures through summer of 2010. • AQ Cycle suggests high probability of normal or above normal OEDs for 2010. • Much of the Eastern United States (Northeast, Mid-Atlantic, and Ohio River Valley) should experience an increase in OEDs (above normal counts for 8-hour ozone exceedances) in 2010. • The benefits of the regional NOx control program and Maryland Healthy Air Act should offset this increase. Source: CDC Three-Month Outlooks

  24. Summary (1 of 2) • Maryland OEDs can be broken down into 3-5 year periods, trending with the 90 degree days cycle to minimize the year-to-year fluctuations in meteorology. OEDs by each period showed continuous improvements. Significant improvements are observed after implementation of a large-scale multi-state NOx control program (NOx SIP Call). • As much as 30-90% reductions in OEDs are observed in MSAs across the eastern U.S post NOx SIP Call. • Significant AQ improvements require that AQ Cycle post 2002 be adjusted for trends in regional ozone patterns. • Shifting of the Bermuda high creates fluctuations in seasonal weather patterns and combined with reduced emissions causes changes in regional ozone patterns. • At the surface, the Appalachian lee-side trough is enhanced along the I-95 corridor during high pollution years, indicating short and mid-range transport patterns from south/southwest are pronounced. • The enhanced trough line is associated with Maryland OEDs and potentially the development of the Nocturnal Low Level Jet (NLLJ).

  25. Summary (2 of 2) • Shifting of the Bermuda high creates an anomaloushigh over the upwind states (Plains, Great Lakes and Midwest) during high pollution years. • On average, the anomalous high is 3.5 deg F warmer for a column of air from the surface to 850-mb level and results in high ozone production in upwind states. • The enhanced ozone concentrations during high pollution years in the Mid-Atlantic and Northeast are driven by local pollutant sources and to a greater extend transported pollution. • Maryland and other northeastern states need another round of broad regional control programs on top of local controls to attain a more stringent 8-hour standard!

  26. Contact Duc NguyenSenior Meteorologist Ambient Air Monitoring ProgramAir and Radiation Management Administration dnguyen@mde.state.md.us410-537-3275 Maryland Department of the Environment1800 Washington Boulevard | Baltimore, MD 21230410-537-3000 | TTY Users: 1-800-735-2258www.mde.state.md.usMartin O’Malley, Governor | Anthony G. Brown, Lt. Governor | Shari T. Wilson, Secretary

  27. References • AIRNowTech – National real-time repository of real-time air quality data provided by EPA AIRNow program (http://www.airnowtech.org). • CFS Seasonal Climate Forecasts web site (http://www.cpc.noaa.gov/products/people/wwang/cfs_fcst/). • Clean Air Markets - Data and Maps web site (http://camddataandmaps.epa.gov/gdm/). • Climate Prediction Center: Three-Month Outlooks web site: (http://www.cpc.noaa.gov/products/predictions/90day/). • Global wind animation (http://www.suu.edu/faculty/colberg/Hazards/Weather/04_GlobalWind.swf). • IRI ENSO Quicklook web site (http://iri.columbia.edu/climate/ENSO/currentinfo/QuickLook.html). • Interactive plotting and analysis pages by ESRL / PSD / CDC (http://www.esrl.noaa.gov/psd/cgi-bin/data/getpage.pl). • NOx Budget Trading Program 2008 Progress Reports by EPA (http://www.epa.gov/AIRMARKET/progress/nbp08.html). • Nguyen & Woodman (2008). Air Quality Variability in Maryland due to Climate Cycles and Emissions. Retrieved from AIRNow NAQ web site: http://www.epa.gov/airnow/2008conference/Forecasting/Tuesday/nguyen_aqvariability.pdf.

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