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Forecasting fine particulate matter (PM2.5) across the United States in a changing climate

Forecasting fine particulate matter (PM2.5) across the United States in a changing climate. Loretta J. Mickley. Dominick Spracklen , Jennifer A. Logan, Xu Yue , Amos P.K.A. Tai, Daniel J. Jacob, Rynda C. Hudman. Wildfires in Quebec the same day. Haze over Boston on May 31, 2010.

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Forecasting fine particulate matter (PM2.5) across the United States in a changing climate

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  1. Forecasting fine particulate matter (PM2.5) across the United States in a changing climate Loretta J. Mickley Dominick Spracklen, Jennifer A. Logan, XuYue, Amos P.K.A. Tai, Daniel J. Jacob, Rynda C. Hudman Wildfires in Quebec the same day. Haze over Boston on May 31, 2010

  2. Atmospheric chemistry examines the mix of gases and particles in the atmosphere: • Chemical reactions • Distributions in the atmosphere • Effects on climate and health • Effects of climate on smog Lifetimes in atmospheric chemistry Centuries: SF6, some CFCs Decades: most greenhouse gases: CO2, N2O, . . . 9-10 years: CH4 (methane, precursor to ozone and greenhouse gas) Days-weeks: O3 (ozone), particulate matter (PM, aka aerosols) Seconds: OH, NO Pollution over Hong Kong Air pollution over Hong Kong reached dangerous levels one of every eight days in 2009

  3. Surface ozone and particulate matter are harmful to human health. Number of people living in areas that exceed the national ambient air quality standards (NAAQS) in 2008. Calculated with standard of 0.075 ppm. Proposed new standards will push more areas into non-attainment. Bars on barplot will change with changing emissions of ozone precursors. Climate change could also change the size of these bars, by changing the day-to-day weather.

  4. VOCs -- volatile organic compounds NH3 -- ammonia . . . . . . SO2 -- sulfur dioxide NOx -- nitrogen oxides Life cycle of particulate matter (PM, aerosols) ultra-fine (<0.01 mm) fine (0.01-1 mm) cloud (1-100 mm) precursor gases nucleation cycling coagulation condensation Soup of chemical reactions coarse (1-10 mm) scavenging SO2 SO2 VOCs NOx NOx VOCs VOCs NOx NH3 VOCs NOx VOCs NOx combustion volcanoes agriculture biosphere soil dust sea salt wildfires combustion

  5. . . . . . . Climate change affects many processes. Life cycle of particulate matter (PM, aerosols) ultra-fine (<0.01 mm) fine (0.01-1 mm) cloud (1-100 mm) precursor gases nucleation cycling coagulation condensation Soup of chemical reactions coarse (1-10 mm) faster reactions scavenging Warmer temperatures could increase some emissions. SO2 SO2 VOCs NOx NOx VOCs VOCs NOx NH3 VOCs NOx VOCs NOx combustion volcanoes agriculture biosphere soil dust sea salt wildfires combustion

  6. . . . . . . Transport also important! Life cycle of particulate matter (PM, aerosols) ultra-fine (<0.01 mm) fine (0.01-1 mm) cloud (1-100 mm) precursor gases nucleation cycling coagulation condensation Soup of chemical reactions evaporation coarse (1-10 mm) Warmer temperatures push equilibrium toward gas phase. faster reactions scavenging SO2 SO2 VOCs NOx NOx VOCs VOCs NOx NH3 VOCs NOx VOCs NOx combustion volcanoes agriculture biosphere soil dust sea salt wildfires combustion

  7. Coming climate change will likely affect PM2.5 concentrations. Models disagree on the sign and the magnitude of the impacts Racherla and Adams, 2006 • Response of sulfate PM2.5at the surface to 2000-2050 climate change. • These model results are computationally expensive. • How well do models capture variability in present-day PM2.5? A2 mg m-3 Pye et al., 2009 We need a simple tool that will allow AQ managers to readily calculate the climate penaltyfor PM2.5 air quality across a range of models and scenarios. A1 mg m-3

  8. Effects of wildfires on air quality in cities in Western US • Hayman fire, June 8-22, 2002 • 56,000 ha burned • 30 miles from Denver and Colorado Springs Worst ever air quality in Denver June 9, 2002 June 8, 2002 PM10 = 372 μg/m3 PM2.5 = 200 μg/m3 Standard = 35 µg/m3 PM10 = 40 μg/m3 PM2.5 = 10 μg/m3 Colorado Dept. of Public Health and Environment Vedal et al., 2006

  9. Fires are increasing in North America Area burned in Canada has increased since the 1960s, correlated with temperature increase. obs temperature area burned Gillett et al., 2004 5 yr means 1960 2000 Increased fire frequency over the western U.S. since 1970, related to warmer temperatures and earlier snow melt. 1970 2000 Westerling et al., 2007

  10. Two constellations of studies Sensitivity of PM2.5 to changing meteorology in the East. Sensitivity of wildfires to changing climate in the West and the consequences for PM2.5. First, a few slides on chemistry + climate models.

  11. Basic working of climate models All climate models depend on basic physics to describe motions and thermodynamics of the atmosphere: E.g., vertical structure of pressure is described by hydrostatic equation Climate models also depend on parameterizations for many processes. E.g., microphysics of cloud droplet formation, vegetation processes. Output Climate model Input Physics + Parameterized processes Tilt of earth, geography, greenhouse gas content Weather + Climate

  12. Simulations of future climate depend on the path of socio-economic development. Global mean surface temperature anomalies Different scenarios follow different socio-economic paths for developed and developing countries. A2 = heavy fossil fuel B1 = alternative fuels A1B = mix of fossil + alternative fuels IPCC 2007

  13. IPCC AR4 models show increasing temperatures across North America by 2100 in A1B scenario. Change in surface temperatures in 2100, relative to present-day. Results for precipitation changes are not so clear. IPCC, 2007

  14. winds Winds carry pollutants to other boxes. Emissions + chemistry calculated within box How 3-D chemistry models work. particulate matter (PM) and ozone pollution emissions transport dilution chemistry population GEOS-Chemchemical transport model: Global 3-D model describes the transport and chemical evolution of atmospheric pollutants Meteorology from a climate model

  15. Two constellations of studies Sensitivity of PM2.5 to changing meteorology in the East. Sensitivity of wildfires to changing climate in the West and the consequences for PM2.5.

  16. Surface ozone levels are sensitive to cold-front passage. Are particles also sensitive to cold-front passage? Leibensperger et al., 2008

  17. Meteorology affects surface concentrations of PM2.5. Observed correlations of PM2.5 with meteorological variables. 1998-2008 meteorology + EPA-AQS observations Multiple linear regression coefficients for total PM2.5on meteorological variables. Units: μg m-3 D-1 (p-value < 0.05) Increases in total PM2.5 on a stagnant day vs. a non-stagnant day. Mean PM2.5 is 2.6 μg m-3greater on a stagnant day Tai et al. 2010

  18. 2000-2050 climate change leads to increases in annual mean PM2.5 across much of the Eastern US. We used Principal Component Analysis to define the main meteorological modes driving PM2.5 variability over the US. Models show increased duration of stagnation in the East, with corresponding increases in annual mean PM2.5. This approach could provide a useful tool to assess climate penalty on PM2.5. We use observed relationships + climate models, no chemistry models. Change in annual mean PM2.5 concentrations in 2050s relative to present-day mg m-3 Tai et al., ms.

  19. How do we predict fires in a future climate?We don’t have a good mechanistic approach for modeling wildfires. + Relationship between observed meteorology + area burned Future area burned Future meteorology 1970 2000

  20. Predictions of area burned are made for large eco-regions for the fire season ERM RMF PNW NMS CCS In each region, identify the meteorological variables that best predict area burned using stepwise linear regression. DSW We find that the most important predictors for wildfires in the West are temperature, relative humidity, and precipitation. Ecoregions are aggregates of those in Bailey et al. (1994)

  21. Regression matches observed area burned, except for California coastal shrub Data Fit Fit depends on relative humidity the previous summer Spracklen et al., 2009; Yueet al., ms.

  22. GISS GCM meteorological output used to project future area burned, emissions and changes in air quality changing greenhouse gases (A1B scenario) GISS climate model 1950 2000 2025 2050 2075 2100 Spin-up archive met fields from climate model Area Burned Regressions GEOS-CHEM Global chemistry model Predict Area Burned 50% increase in biomass consumption by wildfires over the western United States for 2045-2054, relative to present-day. Calculate emissions

  23. Effect of future fires in a future climate on organic carbon in the western U.S. May-October change in OC Change in organic carbon (OC) by 2050s, relative to present-day (5 year mean) Organic carbon particles increase by 40% by 2050. Black carbon increases by 20%. For OC, most of increase is from fire emissions, some is from higher biogenic emissions in a warmer climate. Spracklen et al., JGR, 2009

  24. Results shown so far were driven by one climate model. But models show large variation in response to changing greenhouse gases. Results from IPCC AR4 ensemble of climate models: warmer, drier, less humid. Changes in meteorology by 2050s, relative to present-day, for JJA Temp Precip RMF ERM Rel Humidity PNW, Pacific Northwest CCS, California Coastal Shrub DSW, Desert Southwest NMS, Nevada /Semi-desert RMF, Rocky Mountain Forest ERM, East Rockies/ Plains. PNW NMS CCS DSW Yue et al., ms.

  25. 1986-2000 2051-2065 Wildfires in western US are predicted to increase by ~60% by 2050s. +40% 1986 2065 Obs +20% Median of models spread of models doubling Area burned (ha) The GCMs cannot match year to year variability, but match the mean area burned fairly well in present-day. +60% RMF ERM PNW +70% NMS CCS DSW +60% Yue et al., ms.

  26. Median GCM results show an increase in area burned in all regions. Median changes: 40-70% increase in forested regions 60% increase in grasslands Doubling in Southwest Ratio of 2050s area burned / present-day area burned Forest Forest median Ratio of 2050s / present-day RMF ERM PNW NMS Pacific Northwest Desert Southwest Eastern Rockies Rocky Mountains CCS Nevada Mountains DSW California Coastal Shrub Yue et al., ms.

  27. Organic particles increase in future atmosphere over the western U.S. in summer, especially during extreme events. Cumulative probability of daily mean concentrations of organic particles Change in OC in ~2050s, relative to present-day 2050s doubling Present-day • Rocky Mountains • April-October. Yue et al., ms.

  28. How do we improve fire predictions in S. California? The largest fires in CA are associated with Santa Ana events. Fire plumes (Oct. 2007) Composite Santa Ana winds Need finely resolved wind fields to capture Santa Ana in meteorological record. Hughes and Hall (2010)

  29. Area burned Improving predictions of area burned in Southern California. • Parameterize area burned as function of: • Temperature • Relative humidity • Precipitation • Large-scale pressure differences • Divide up southern California into 3 smaller ecoregions. Fire data from a suite of sources. Surface pressure anomalies Yue et al., ms.

  30. Seasonality of fires in Southern California South-West Cal. area Fire regions num. fires Central Western Cal. Largest area burned in SW California. October peak associated with the Santa Ana winds, which are underestimated by large scale models as they lack the detailed topography: need large-scale approach Sierra Nevada

  31. New parameterization predicts yearly variability and seasonality in south west California Southwest CA R2=0.64 Seasonality Area burned in ~2050 / Present-day Area burned in Southern California increases 20-100% by 2050s relative to present-day. Two approaches used in each ecoregion. R P R P R Sierra Nevada Central California South westCalifornia Yue et al., ms.

  32. Conclusions Models show increased duration of stagnation in future atmosphere, with corresponding increases in annual mean PM2.5. Wildfire activity in the West can be predicted with meteorological variables. Area burned by wildfires may double in some regions in the western US by 2050s. By 2050s, mean summertime organic carbon particles could increase 40-70%, with doubling during extreme events.

  33. Future regional predictions for meteorology in A1B 2100 atmosphere show large variation across North America. Percent change in 2100 precipitation relative to present-day JJA Annual DJF Number of models showing increasing precipitation most models few models IPCC 2007

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