ATMOSPHERIC CHEMISTRY:ATMOSPHERIC CHEMISTRY:FROM AIR POLLUTION TO GLOBAL CHANGE AND BACKFROM AIR POLLUTION TO GLOBAL CHANGE AND BACK

Daniel J. Jacob

NUMBER OF PEOPLE LIVING IN U.S. COUNTIES NUMBER OF PEOPLE LIVING IN U.S. COUNTIES VIOLATING NATIONAL AIR QUALITY STANDARDS, 1999VIOLATING NATIONAL AIR QUALITY STANDARDS, 1999

EPA [2001]

124 ppbv84 ppbv

Carbon monoxide (CO)

Lead

Nitrogen dioxide

Ozone (O3)

Particles < 10 m(PM10)

Particles < 2.5 m(PM2.5)

Sulfur dioxide(SO2)

Any pollutant

MEAN NUMBER OF SUMMER DAYS (1980-1998) MEAN NUMBER OF SUMMER DAYS (1980-1998) EXCEEDING THE U.S. OZONE AIR QUALITY STANDARD EXCEEDING THE U.S. OZONE AIR QUALITY STANDARD

(84 ppbv, 8-hour average)(84 ppbv, 8-hour average)

EPA/AIRS data [Lin et al., 2001]

SOURCES OF TROPOSPHERIC OZONESOURCES OF TROPOSPHERIC OZONE

?

?

?

Fires Biosphere Humanactivity

Lightning

Ocean physicschemistrybiology

Nitrogen oxides (NOx) CO, Hydrocarbons

hOzone (O3)

h, H2OHydroxyl (OH)

The Pacman of the atmosphere!

Complex non-linear chemistry

Tropopause (8-18 km)Stratospheric ozone

STRATOSPHERE

TROPOSPHERE

O2 + h

LARGE-SCALE POLLUTION IN THE TROPICS:LARGE-SCALE POLLUTION IN THE TROPICS:BIOMASS BURNINGBIOMASS BURNING

•

R. Husar

TRANSPACIFIC TRANSPORT OF ASIAN DUSTTRANSPACIFIC TRANSPORT OF ASIAN DUST

April 1998 event

CLIMATE FORCING BY AIR POLLUTANTSCLIMATE FORCING BY AIR POLLUTANTS

GLOBAL RADIATIVE FORCING OF CLIMATE, 1750-present [IPCC, 2001]GLOBAL RADIATIVE FORCING OF CLIMATE, 1750-present [IPCC, 2001]

POLLUTANT-RELATED

BLACK CARBON: A MAJOR “GREENHOUSE” AEROSOLBLACK CARBON: A MAJOR “GREENHOUSE” AEROSOL

Chin et al. [2000]

DIESEL

DOMESTICCOAL BURNING

BIOMASSBURNING

INCREASE IN TROPOSPHERIC OZONE BACKGROUNDINCREASE IN TROPOSPHERIC OZONE BACKGROUNDFROM INTERCONTINENTAL TRANSPORT OF POLLUTIONFROM 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 PRESENT OZONE BACKGROUND IS SIZABLE INCREMENT TOWARDS VIOLATION OF U.S. AIR QUALITY STANDARDSTOWARDS VIOLATION OF U.S. AIR QUALITY STANDARDS

(even more so in Europe!)(even more so in Europe!)

0 20 40 60 80 100 120 ppbv

Europe(seasonal)

U.S.(8-h avg.)

U.S.(1-h avg.)

preindustrial presentbackground

Europe (8-h avg.)

EFFECT OF NORTH AMERICAN SOURCESEFFECT OF NORTH AMERICAN SOURCESON EXCEEDANCES OF EUROPEAN AIR QUALITY ON EXCEEDANCES OF EUROPEAN AIR QUALITY

STANDARD (55 ppbv, 8-h average)STANDARD (55 ppbv, 8-h average)

GEOS-CHEM modelresults, summer 1997

Number of exceedance days(out of 92)

# of exceedance days thatwould not have happenedin absence of U.S. emissions

Li et al. [2002]

Growth of Asian emissions over next decades will Growth of Asian emissions over next decades will increase role of background for ozone air quality in U.S.increase role of background for ozone air quality in U.S.

109 atoms N cm-2 s-1

AnthropogenicNOx emissions[IPCC, 2001]

2000

2020

“Optimistic” IPCCscenario:OECD, U.S. down 20%Asia up 50%

WHAT DOES THE FUTURE HOLD?WHAT DOES THE FUTURE HOLD?Future emission scenarios from IPCC [2001] Future emission scenarios from IPCC [2001]

A1, A2, B1, B2: different socioeconomic story lines

A2: “dirty world”

B2: “clean world”

NOx

SO2

FUTURE EMISSIONS MAY BE LESS THAN PRESENT FUTURE EMISSIONS MAY BE LESS THAN PRESENT FORECASTS IF PUSH IS MADE FOR ENERGY EFFICIENCY FORECASTS IF PUSH IS MADE FOR ENERGY EFFICIENCY

AND AIR QUALITY IN DEVELOPING WORLDAND AIR QUALITY IN DEVELOPING WORLD

Streets et al. [2001]

GETTING A BIG BANG FOR THE BUCK:GETTING A BIG BANG FOR THE BUCK:controlling methane emissionscontrolling 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]

Historical methane trend

Recent methane trend

IPCC PROJECTION OF FUTURE METHANE EMISSIONSIPCC PROJECTION OF FUTURE METHANE EMISSIONS

Can we try to decrease methane emissions instead?

FUTURE MONITORING OF EMISSIONS FUTURE MONITORING OF EMISSIONS BY INVERSE MODELING OF ATMOSPHERIC OBSERVATIONSBY INVERSE MODELING OF ATMOSPHERIC OBSERVATIONS

3-D CHEMICAL TRANSPORT MODEL

Assimilated meteorological

data

Aerosoland chemical

processes

OPTIMIZED EMISSIONS

A PRIORI EMISSIONS

(from process model)INVERSE MODEL

OBSERVATIONS• surface• satellite• aircraft

GLOBAL MAPPING OF NOGLOBAL MAPPING OF NOx x EMISSIONS FROM SPACE:EMISSIONS FROM SPACE:

GOME observations of nitrogen dioxide (July 1996)GOME observations of nitrogen dioxide (July 1996)Martin et al. [2002]

GOME

GEOS-CHEMmodel

110 E 120 E 130 E 140 E 150 E 160 E

Longitude

0 N

10 N

20 N

30 N

40 N

50 N

Lat

itu

de

DC-8 FlightsP-3B Flights

NASA/TRACE-P AIRCRAFT MISSION TO THE PACIFIC RIMNASA/TRACE-P AIRCRAFT MISSION TO THE PACIFIC RIM(MARCH-APRIL 2001)(MARCH-APRIL 2001)

Quantifying the export of Asian pollutionQuantifying the export of Asian pollution

DC-8 and P-3 aircraft

Satellite data:MOPITT (CO)TOMS (ozone)SEAWIFS, TOMS (aerosols)

3-D chemical transportmodel forecasts

Flight tracks were designed to optimize model testing and satellite validation

DC-8flight track

INTEGRATION OF AIRCRAFT, SATELLITES, AND MODELS:INTEGRATION OF AIRCRAFT, SATELLITES, AND MODELS:quantifying the Asian dust source in TRACE-Pquantifying the Asian dust source in TRACE-P

Dust forecast for 3/21/01 (Carmichael, U. Iowa) DC8 flight track and TOMS absorbing aerosol index

SEAWIFS aerosol optical depth SEAWIFS visible image

2002 2002 2004 2004 2004 2004 2004

FUTURE SATELLITE MEASUREMENTS FUTURE SATELLITE MEASUREMENTS OF TROPOSPHERIC CHEMISTRYOF TROPOSPHERIC CHEMISTRY

MODIS/MISR

TERRA ENVISAT AURA