EFFECTS OF TRANSBOUNDARY POLLUTION AND CLIMATE CHANGE ON U.S. AIR QUALITY Daniel J. Jacob with Rokjin J. Park, Lin Zhang, Huiqun Wang, Philippe LeSager, Tzung-May Fu, Noelle E. Selin, Loretta J. Mickley, Shiliang Wu, Eric M. Leibensperger and funding from EPRI, EPA, DOE, NSF, NASA EPRI STARTED IT ALL! Early work spurred major subsequent investment by EPA, NASA, NOAA Cited 127 times as of today (Thompson Science Citation Index) IMPLICATION OF RISING OZONE BACKGROUND FOR MEETING AIR QUALITY STANDARDS ppb Europe AQS (seasonal) U.S. AQS (8-h avg.) U.S. AQS (1-h avg.) Preindustrial ozone background Present-day ozone background at northern midlatitudes Europe AQS (8-h avg.) EPA policy-relevant background (PRB) : U.S. surface ozone concentrations that would be present in absence of North American anthropogenic emissions Increase driven by global NO x, methane PRB RISING ASIAN EMISSIONS AS SEEN FROM SPACE trend in tropospheric NO 2 columns from GOME [Richter et al., 2005] 2006 observations of NO 2 columns from OMI show doubling of Chinese emissions since 2000 [Zhang et al., in prep.] CONSEQUENCES FOR U.S. SURFACE OZONE GEOS-Chem Asian pollution:9 2 Observed: 54 10 GEOS-Chem: 53 8 NASA INTEX-B aircraft/satellite campaign (April-May 2006) Observations (Dan Jaffe, UW) and GEOS-Chem at Mt. Batchelor, Oregon (2,700 m) rise in Asian emissions has increased U.S. surface ozone by 1-2 ppbv in the West (3 ppbv at Mt. Batchelor) Zhang et al., in prep. Mean Asian surface pollution enhancement (GEOS-Chem) 4/17 4/23 4/29 5/5 5/11 ppb U.S. SURFACE OZONE ENHANCEMENTS FROM CANADIAN AND MEXICAN POLLUTION Jun-Aug mean max-8h-avg values from a GEOS-Chem simulation (1 o x1 o resolution) with zero U.S. anthropogenic emissions and with PRB subtracted Wang et al., in prep. Regions of maximum influence: Northeast for Canada Southwest for Mexico Maximum influence in summer for both PRELIMINARY DATA (mask did not remove U.S. offshore emissions) EPISODIC NATURE OF CANADIAN POLLUTION INFLUENCE Jun-Aug 01 time series of max-8h-avg ozone at Unionville, MI Wang et al., in prep. Observations Model (standard) Transboundary PRB Canada + Mexico Unlike PRB, Canadian influence shows large episodes (up to 35 ppb); model is testable with observations for these episodes ** PRELIMINARY DATA ** CANADIAN POLLUTION INFLUENCE: ENSEMBLE VIEW 16 U.S. sites with max Canadian Influence: model vs. obs correlation coefficients are for individual sites Model, ppb Observed, ppb daily max -8h-avg ozone, Jun-Aug 2001 Transboundary pollution Wang et al., in prep. median max ** PRELIMINARY DATA ** maximum Total Canada ELEVATED ORGANIC CARBON (OC) PM IN ASIAN OUTFLOW ACE-Asia aircraft observations offshore from China (spring 2001) Sulfate is scavenged from outflow but not OC Observations show a 1-3 g m -3 OC background missing from model Heald et al. [2005] Contribution to intercontinental pollution? Observed GEOS-Chem NEW MECHANISM FOR OC FORMATION FROM DICARBONYLS Acetylene Aromatics Isoprene Terpenes Acetone Anthropogenic VegetationBiomass burning OH dissolution hydration oxidation oligomerization glyoxal methylglyoxal evaporation secondary organic aerosol (SOA) Lab studies show irreversible uptake of glyoxal and methylglyoxal by aqueous particles and apparent oligomerization This mechanism has now been implemented in GEOS-Chem including detailed gas-phase chemistry of dicarbonyl formation Fu et al., in prep. SIMULATION OF OC PM OVER EASTERN U.S. Water-soluble OC (WSOC) PM observations by Rodney Weber (Georgia Tech) during ICARTT aircraft campaign out of Portsmouth, NH (Jul-Aug 04) Observed Model with dicarbonyl SOA Model without dicarbonyl SOA Boundary layer data (< 2 km) Observed model with dicarbonyl SOA model without dicarbonyl SOA Fu et al., in prep. CONTRIBUTIONS TO N. AMERICAN MERCURY DEPOSITION FROM GLOBAL POOL vs. REGIONAL POLLUTION POOL Hg(0) Hg(II) N. American boundary layer Hg(0) emission (53%) Hg(II) Global pool (lifetime ~ 1 y) Regional pollution pool Hg(II) emission (RGM 33%. Hg(P) 14%) reduction External anthropogenic Oceans Land N. America accounts for only 7% of global anthro. emission (2000) NORTH AMERICA cycling and re-emission GEOS-Chem GLOBAL 3-D ATM-LAND-OCEAN MODEL FOR MERCURY Inventories in Mg Rates in Mg y -1 Selin et al. [submitted] Accounts for coupling between atmospheric and surface reservoirs on short-term to centurial time scales SIMULATION OF U.S. MERCURY DEPOSITION NETWORK (MDN) DATA Seasonal variation vs. latitude Observations Model Model (N.Amer. sources) Annual mean wet deposition fluxes, : observations = circles, model = background Selin et al., in prep. Major contribution to mercury deposition from subsidence and scavenging of Hg(II) from global pool SOURCE ATTRIBUTION FOR U.S. MERCURY DEPOSITION % contribution of N. American sources to annual total mercury deposition Natural (32%) North American anthropogenic (20%) Rest of world anthropogenic (31%) half cycled through ocean on annual time scale Legacy anthropogenic re-emitted from soil on centurial time scale (16%) Selin et al., in prep. OBSERVED DEPENDENCE OF AIR QUALITY ON WEATHER WARNS OF POTENTIALLY LARGE EFFECT OF CLIMATE CHANGE Interannual variability of exceedances of ozone NAAQS in the Northeast # summer days with 8-hour ozone > 84 ppbv, average for 257 northeast U.S. AIRS sites 1988, hottest of record Ozone is strongly correlated with temperature in observations (R 2 ~ 0.5); reflects (1) chemistry, (2) biogenic VOC emissions, (3) association with stagnation Lin et al. [2001] 1992, coldest on record (Pinatubo) PROJECTING EFFECT OF CLIMATE CHANGE ON OZONE AIR QUALITY USING OBSERVED OZONE-TEMPERATURE CORRELATIONS Probability of max 8-h O 3 > 84 ppbv vs. daily max. temperature Projected T change for northeast U.S. in simulated with ensemble of downscaled GCMs for different scenarios [IPCC, 2007] T = 3K Probability of ozone AQS exceedance Temperature, K Probability of exceedance doubles By 2025, T = 1-3 K depending on model and scenario; use statistical approach at right to infer increased probability of ozone exceedance for a given region or city assuming nothing else changes. Effect is large! Lin et al. [2001] Northeast Los Angeles Southeast Lin et al., in prep. COMPREHENSIVE MODEL APPROACH FOR INVESTIGATING EFFECT OF CLIMATE CHANGE ON AIR QUALITY Global climate model (GCM) Global chemical transport model (CTM) for ozone-PM Regional climate model (RCM) Regional CTM for ozone-PM boundary conditions input meteorology input meteorology boundary conditions IPCC future emission scenario greenhouse gases ozone-PM precursors internal EPA project (CIRAQ) and several EPA-STAR projects EPA-STAR GLOBAL CHANGE AND AIR POLLUTION (GCAP) PROJECT GISS GCM 3 GEOS-Chem global CTM MM-5 RCM CMAQ regional CTM boundary conditions input meteorology input meteorology boundary conditions IPCC emission scenario greenhouse gases ozone-PM precursors Applied to global change simulations with IPCC SRES A1 scenario; compare 2050 climate (GCM , 3-y averages) to 2000 ( ) D.J. Jacob and L.J. Mickley (Harvard), J.H. Seinfeld (Caltech), D. Rind (NASA/GISS), D.G. Streets (ANL), J. Fu (U. Tenn.), D. Byun (U. Houston) EMISSIONS OF OZONE PRECURSORS (A1) GlobalUnited States 2000 emissions % change, emissions% change, NO x, Tg N y -1 Anthropogenic Lightning Soils (natural) % +18% +8% % +21% +11% NMVOCs, Tg C y -1 Anthropogenic Biogenic % +23% % +23% CO, Tg y %87-47% Methane, ppbv (+37%) Wu et al. [in press] Global increase in anthropogenic emissions but 40-50% decreases in U.S. Climate-driven increases in natural NO x, NMVOC emissions CHANGES IN SUMMER MEAN 8-h AVG. DAILY MAXMUM OZONE FROM CHANGES IN CLIMATE AND GLOBAL EMISSIONS Models agree that climate change will decrease background ozone but will increase surface ozone in U.S, with effects ranging from