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April 2008 Ozone Events in Connecticut

April 2008 Ozone Events in Connecticut. Michael Geigert CTDEP. Ozone Exceedances from April 2008 (from the EPA Region 1 Web Site).

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April 2008 Ozone Events in Connecticut

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  1. April 2008 Ozone Events in Connecticut Michael Geigert CTDEP

  2. Ozone Exceedances from April 2008 (from the EPA Region 1 Web Site) Four States in New England recorded violations of the new ozone standard during this period. The highest 8-hour ozone average was recorded at the Cornwall site in Connecticut (1600 ft).

  3. Characteristics of the April 18-19 Event • Light wind flow that becomes southeast by April 19 • High solar intensity and low humidity • Surfaces temperatures in the lower 80’s • Models under predicted event for New England • Low pressure stalled over the Atlantic and over the Midwest

  4. Satellite for April 18th

  5. Satellite for April 19th

  6. Evaluation of CMAQ performance for April 2008 NE U.S. AQ Event Jeff McQueen, Marina Tsidulko, Pius Lee, Brad Ferrier, Eric Rogers, Mike Ek, … 9/6/2014 The following slides are part of a NCEP Analysis that I requested from Paula Davidson regarding the under prediction of the NOAA model during the April ozone events in New England.

  7. CMAQ daily max O3 April 18-19, 2008 8-hr max 18Apr2008 • O3 (Prod run) Exceedences captured: DC/VA/NC • Underprediction in MD, PA, NJ, NY by as much as 25 ppb • O3 (Prod run) Exceedences captured: MD/DE/PA • Underprediction in S. New England by as much as 25 ppb

  8. NE US33h Forecast Temperatures 21 UTC Saturday April 19, 2008 NAM 12 km RTMA 5 km • NAM Temperatures • Well predicted over Mid-Atlantic • Too cold by 4-8°C from N. PA thru New England

  9. NAM vs RTMA Dewpoint T21 UTC April 19, 2008 RTMA Td NAM 12 km 33h Forecast • NY, MA, CT, VT, NH • NAM: +9 to +12 C • RTMA: -3 to +6 C

  10. April 23, 2008 Case 30h 2 m Temperature: NAM-RTMA • 8 hr max exceedences missed in CT-MA • Cold Bias: -4  -6

  11. NAM/NAM-y North East AreaTemperature/TD ErrorApril 13-23, 2008 30 hour (18 UTC) forecast bias Temp : -2.5; TD: +5 Diurnal Forecast rmse/bias

  12. Summary Mid-Atlantic: April 19, 2008 • CMAQ captured observed 8h ozone exceedances over Mid Atlantic. • NAM predicted Mid-Atlantic temperatures well. Southern New England 4/18, 4/19, 4/23 • CMAQ under-estimated 8h-avg ozone concentrations; 75-ppb exceedances missed on 4/18 and 4/23 • NAM is too cool and moist by as much as 4-8°C over New England • NAM Downward SW flux is comparable to NESDIS product • Sensible Heat Fluxes too low over clear skies On-going work • Checking emissions– no obvious issues, but looking at biogenic VOCs • LSM team looking into vegetation greenness fraction • Launcher run with weekly updated greenness rather than climatology

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