ATMOSPHERIC CHEMISTRY: FROM AIR POLLUTION TO GLOBAL CHANGE
ATMOSPHERIC CHEMISTRY: FROM AIR POLLUTION TO GLOBAL CHANGE AND BACK Daniel J. Jacob NUMBER OF PEOPLE LIVING IN U.S. COUNTIES VIOLATING NATIONAL AIR QUALITY STANDARDS, 1999 Carbon monoxide (CO) EPA  Lead Nitrogen dioxide Ozone (O3)
Particles < 10 m (PM10) Particles < 2.5 m (PM2.5) Sulfur dioxide (SO2) Any pollutant 124 ppbv 84 ppbv MEAN NUMBER OF SUMMER DAYS (1980-1998) EXCEEDING THE U.S. OZONE AIR QUALITY STANDARD (84 ppbv, 8-hour average)
EPA/AIRS data [Lin et al., 2001] SOURCES OF TROPOSPHERIC OZONE O2 + h Stratospheric ozone Tropopause (8-18 km) STRATOSPHERE TROPOSPHERE ? Complex non-linear chemistry
Lightning Nitrogen oxides (NOx) h Ozone (O ) h, H2O Hydroxyl (OH) 3 CO, Hydrocarbons The Pacman of ? ? the atmosphere! Fires
Biosphere Human activity Ocean physics chemistry biology LARGE-SCALE POLLUTION IN THE TROPICS: BIOMASS BURNING TRANSPACIFIC TRANSPORT OF ASIAN DUST
April 1998 event R. Husar CLIMATE FORCING BY AIR POLLUTANTS GLOBAL RADIATIVE FORCING OF CLIMATE, 1750-present [IPCC, 2001] POLLUTANT-RELATED BLACK CARBON: A MAJOR GREENHOUSE AEROSOL DIESEL DOMESTIC COAL BURNING BIOMASS
BURNING Chin et al.  INCREASE IN TROPOSPHERIC OZONE BACKGROUND FROM INTERCONTINENTAL TRANSPORT OF POLLUTION 1870-1990 ozone trend at European mountain sites [Marenco et al.,1994] Preindustrial ozone assumed in IPCC models } PRESENT OZONE BACKGROUND IS SIZABLE INCREMENT TOWARDS VIOLATION OF U.S. AIR QUALITY STANDARDS
(even more so in Europe!) Europe (8-h avg.) Europe (seasonal) 0 20 preindustrial 40 present background
U.S. (8-h avg.) 60 80 U.S. (1-h avg.) 100 120 ppbv
EFFECT OF NORTH AMERICAN SOURCES ON EXCEEDANCES OF EUROPEAN AIR QUALITY STANDARD (55 ppbv, 8-h average) GEOS-CHEM model results, summer 1997 Number of exceedance days (out of 92) # of exceedance days that would not have happened in absence of U.S. emissions Li et al. 
Growth of Asian emissions over next decades will increase role of background for ozone air quality in U.S. Anthropogenic NOx emissions [IPCC, 2001] 2000 2020 Optimistic IPCC scenario: OECD, U.S. down 20% Asia up 50% 109 atoms N cm-2 s-1 WHAT DOES THE FUTURE HOLD?
Future emission scenarios from IPCC  NOx A1, A2, B1, B2: different socioeconomic story lines A2: dirty world SO2 B2: clean world FUTURE EMISSIONS MAY BE LESS THAN PRESENT FORECASTS IF PUSH IS MADE FOR ENERGY EFFICIENCY AND AIR QUALITY IN DEVELOPING WORLD
Streets et al.  GETTING A BIG BANG FOR THE BUCK: controlling methane emissions A 50% reduction in anthropogenic methane emissions would: yield a fast negative global radiation forcing of 0.37 W m-2 (-0.30 W m-2 from methane, -0.07 W m-2 from ozone) decrease the incidence of ozone > 80 ppbv in surface air over U.S. by more than 50% [A.M. Fiore, GEOS-CHEM model results, 2002] Recent methane trend Historical methane trend
IPCC PROJECTION OF FUTURE METHANE EMISSIONS Can we try to decrease methane emissions instead? FUTURE MONITORING OF EMISSIONS BY INVERSE MODELING OF ATMOSPHERIC OBSERVATIONS Assimilated meteorological data 3-D CHEMICAL TRANSPORT MODEL OBSERVATIONS surface satellite
aircraft INVERSE MODEL OPTIMIZED EMISSIONS Aerosol and chemical processes A PRIORI EMISSIONS (from process model)
GLOBAL MAPPING OF NOx EMISSIONS FROM SPACE: GOME observations of nitrogen dioxide (July 1996) Martin et al.  GOME GEOS-CHEM model NASA/TRACE-P AIRCRAFT MISSION TO THE PACIFIC RIM (MARCH-APRIL 2001) Quantifying the export of Asian pollution 50 N 40 N
Satellite data: 30 N MOPITT (CO) TOMS (ozone) SEAWIFS, 20 N TOMS (aerosols) Latitude 3-D chemical transport model forecasts 10 N
DC-8 and P-3 aircraft DC-8 Flights P-3B Flights 0N 110 E 120 E 130 E 140 E 150 E
160 E Longitude Flight tracks were designed to optimize model testing and satellite validation INTEGRATION OF AIRCRAFT, SATELLITES, AND MODELS: quantifying the Asian dust source in TRACE-P Dust forecast for 3/21/01 (Carmichael, U. Iowa) DC8 flight track and TOMS absorbing aerosol index DC-8 flight track
SEAWIFS aerosol optical depth SEAWIFS visible image FUTURE SATELLITE MEASUREMENTS OF TROPOSPHERIC CHEMISTRY TERRA ENVISAT AURA MODIS/ MISR
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