Prediction of Future North American Air Quality

Transcription

1 Prediction of Future North American Air Quality Gabriele Pfister, Stacy Walters, Mary Barth, Jean-Francois Lamarque, John Wong Atmospheric Chemistry Division, NESL/NCAR Greg Holland, James Done, Cindy Bruyere Meteorological Mesoscale Division, NESL/NCAR Jerome Fast, Po-Lun Ma Pacific Northwest Laboratory, PNNL

2 Objectives Emission controls in the U.S. have lead to significant reductions in air pollution, but many regions in the country still experience levels of pollutants above national health standards Average number of days (%) during May-Sep and when the 8-hour ozone NAAQS of 75 ppbv was exceeded. (EPA Monitoring Network)

3 Objectives There is growing recognition that development of optimal control strategies for key pollutants (O 3, PM2.5) requires assessment of potential future climate conditions and their influence on the attainment of air quality objectives

4 Δ Surface O 3 (%) over CA Steiner et al., 2006 Objectives There is growing recognition that development of optimal control strategies for key pollutants (O 3, PM2.5) requires assessment of potential future climate conditions and their influence on the attainment of air quality objectives Global trop. O 3 Burden (Young et al., 2013) Tai et al., 2012 Eastern U.S. (Hogrefe et al., 2004) Increased temperatures & stagnation events Changes in clouds and solar insolation Increased methane enhanced O 3 background Feedbacks of climate on biogenic & fire emissions Changes in anthropogenic emissions

5 Objectives There is growing recognition that development of optimal control strategies for key pollutants (O 3, PM2.5) requires assessment of potential future climate conditions and their influence on the attainment of air quality objectives Limitations of past studies: Coarse resolution Limited number of years Wu et al., 2008 Courtesy: NOAA

6 Objectives High Resolution Regional Chemistry-Climate Simulations Future changes in weather and air quality over North America Effects of changing emissions and changing climate on AQ Feedbacks between chemistry and climate Differences in climate metrics when downscaling from global or larger scale simulations with different physics Sensitivity of predictions to initial conditions NSF EASM - Developing a Next-Generation Approach to Regional Climate Prediction at High Resolution (PI Greg Holland) NCAR ASD - Accelerated Scientific Discovery Proposal 2012 (PI Gabriele Pfister)

7 Regional CTM WRF-Chem Weather Research and Forecasting Model with Chemistry Fully coupled regional chemical transport model Embedded in WRF Variety of Chemical Schemes (incl. RADM2, RACM, CBMZ, MOZART-4, ) Different Aerosol schemes (bulk, modal), sectional) Biogenic emission schemes (incl. MEGAN) Photolysis Schemes (incl. TUV, FTUV) Online dry deposition (incl. Wesely) Main WRF-Chem Website: NCAR/ACD WRF-Chem Website: MOZART, WRF-Chem and EPA Network Surface O 3 June 19-30, 2008

8 WRF-Chem NRCM-Chem 13 years present ( ) and future ( ) Season: 1 April 1 Oct 12 x 12 km 2 (697 x 394); 51 vertical levels (up to 10 hpa) Gas-Phase Scheme: Reduced Hydrocarbon Scheme (40 species) Aerosols: Modal Aerosol Model (MAM; 33 species, +SOA) Direct/indirect aerosol effects CAM-5 microphysics and PBL Scheme IPCC A2 Climate Scenario, RCP8.5 Emission Scenario Simulation Period Climate Emissions IC & BC Chemistry SIM PRES Present Present 2000 Present REDHC/MAM SIM FUT Future Future 2050 Future REDHC/MAM SIM FUT_EMIS Future Future 2000 Future REDHC/MAM SIM MET Future Future - Future - 10 years + 3 years/simulation with initial start date changed

9 NRCM-Chem - IC & BC Meteorological Initial & Boundary Conditions Downscaled from 36 x 36 km 2 [Done et al., 2012] 36 x 36 km 2 Done et al. (2012), NCAR/TN-490+STR, 28pp. 12 x 12 km 2

10 NRCM-Chem Downscaling Meteorology NRCM 36 km x 36 km NRCM-Chem 12 km x 12 km Mean JJA 2 m for Present

11 NRCM-Chem Downscaling Meteorology NRCM 36 km x 36 km NRCM-Chem 12 km x 12 km Mean JJA 2 m for Present

12 NRCM-Chem Downscaling Meteorology NRCM 36 km x 36 km NRCM-Chem 12 km x 12 km Mean JJA 2 m for Future

13 NRCM-Chem - IC & BC Chemical Initial and Lateral Boundary Conditions CAM-Chem RCP 8.5 [Lamarque et al., 2011); Monthly means for 2000 and 2050 Upper Chemical Boundary Conditions for O 3, N 2 O, CO,... Lamarque et al., Climatic Change, 2011.

14 NRCM-Chem - Emissions IPCC RCP 8.5 Scenario: NO x emissions reduced by -60% over domain (-10% globally) by 2050 Domain Totals for JJA

15 NRCM-Chem - Emissions IPCC RCP 8.5 Scenario (8.5 W m-2 radiative forcing by 2100) NO x emissions reduced by -60% over domain (-10% globally) by 2050 Global 0.5 IPCC emissions used in CAM-Chem re-grid in 2 x 2 segments to 0.1 using EDGAR-4.1 # spatial distribution mass-conserving mapping to NRCM-Chem domain Global Emissions 0.5 NRCM-Chem 12 km EPA NEI km->12km #

16 NRCM-Chem - Emissions Fire Emissions: NCAR Fire Model FINN 10-year Climatology Same for Present & Future NO Fire Emissions - Time Series Biogenic Emissions: Online MEGAN No change in land cover/use Radiation and T dependence LAI, TS and PAR climatology for plant history Isoprene Emissions, July present

17 Present Time Surface Ozone Evaluation Daytime JJA Surface Ozone Nighttime NRCM-Chem: 13 years present time AQS Surface Ozone Monitoring Sites, (

18 Present Time Surface Ozone Evaluation JJA Surface Ozone Average Diurnal Cycle

19 Prediction of Future Surface Ozone Present Future Climate + Future Anth. Emissions MD8hr

20 Prediction of Future Surface Ozone Present Future Climate + Present Anth. Emissions MD8hr

21 Prediction of Future Surface Ozone Present Future Climate + Emissions Future Climate Only MD8hr

22 Days with Ozone - NAAQS Exceedances MD8hr > 75 ppbv Present MD8hr > 65 ppbv Future (Climate + Emissions) -99% Future (Climate Only) -98% +64% +45%

23 Meteorological Drivers 2m Temperature (Present) Daily Mean 2m Temperature (Future-Present) 13-year JJA Average Individual daily mean values 30 C 40 C Daytime, Confidence Level: 95%

24 Future-Present Present Meteorological Drivers Heat Index (HI) Temperature (K) & Rel. Humidity (%) Heat Index Days Shown are Daily Mean T & RH, # HI days in JJA HI Day = Day with HI min > 80 F and HI max <105 F

25 Meteorological Drivers Isoprene emissions (Present) Daily Total Isoprene Emissions (Future-Present) TgC (Present) Daytime Solar Radiation (Future-Present) Confidence Level: 95%

26 Meteorological Drivers Rainfall (Present) JJA Total Rainfall (Future-Present) 13-year JJA Average JJA Rainfall Totals for each year Confidence Level: 75%

27 Meteorological Drivers Wind & Solar Radiation (Present) Daily Mean Wind Speed (Future-Present) (Present) Ventilation Index (unvented hours/day) (Future-Present)

28 Global and Regional Predictions

29 Long Range Transport and Background Ozone CAM-Chem Present Time Surface Ozone (16-22 UTC) Future - Present

30 Predictions: Global Regional NRCM-Chem JJA - Present Surface Afternoon Ozone CAM-Chem UTC

31 Predictions: Global Regional NRCM-Chem JJA Future-Present Surface Afternoon Ozone CAM-Chem UTC

32 Global and Regional Predictions Present Future-Present NRCM-Chem CAM-Chem

33 Conclusions and Next Steps Reducing surface Ozone over the U.S. can be achieved by strong emission reductions, while the impacts of climate act to increase surface ozone by 2050 in parts due to increased temperature, solar radiation and stagnation events and higher background levels. Albeit biases in absolute values, global and regional models predicts similar changes on the larger scale. Locally, however, differences can be significant. Much more to look into: Future Changes in Air Quality Impacts of Climate and Emissions Future Changes in Climate and Weather Extreme Events Dynamical Downscaling of Meteorology and Chemistry Chemistry-Climate Feedbacks Sensitivity to Initial Conditions etc. etc. etc.

34 QUESTIONS / SUGGESTIONS