TROPOSPHERIC CHEMISTRY:TROPOSPHERIC 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 THE EPA AIR QUALITY STANDARDS, 1999VIOLATING THE EPA AIR QUALITY STANDARDS, 1999

EPA [2001]

124 ppbv84 ppbv

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]

TREND IN THE # SUMMER DAYS TREND IN THE # SUMMER DAYS EXCEEDING 84 ppbv OZONE (8-hour average)EXCEEDING 84 ppbv OZONE (8-hour average)

Lin et al. [2001]

TROPOSPHERIC OZONE AND RADICAL CHEMISTRYTROPOSPHERIC OZONE AND RADICAL CHEMISTRY

?

?

?

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!(we won’t touch it)

Tropopause (8-18 km)Stratospheric ozone

GLOBAL RADIATIVE FORCING OF CLIMATE, GLOBAL RADIATIVE FORCING OF CLIMATE, 1750-present1750-present

IPCC [2001]

Historical records imply a large anthropogenic Historical records imply a large anthropogenic contribution to the present-day ozone backgroundcontribution to the present-day ozone background

at northern midlatitudesat northern midlatitudesOzone trend from European mountain observations, 1870-1990

Preindustrialozone models

}

[Marenco et al.,1994]

1750-2000 radiative forcing from tropospheric ozone1750-2000 radiative forcing from tropospheric ozoneis less well constrained than implied by IPCC 2001 reportis less well constrained than implied by IPCC 2001 report

Standard model:

F = 0.44 W m-2

“Adjusted” model

(lightning and soil NOx decreased,

biogenic hydrocarbons increased):

F = 0.80 W m-2[Mickley et al., 2001]

Global simulation of late 19th century ozone observations with the GISS GCM

8-h daily maximum ozone probability distribution at rural U.S. sites[Lin et al., 2000]

SURFACE OZONE IN U.S. INCLUDES A 20-40 ppbv BACKGROUND SURFACE OZONE IN U.S. INCLUDES A 20-40 ppbv BACKGROUND THAT HAS INCREASED BY ~3 ppbv OVER THE PAST 20 YEARSTHAT HAS INCREASED BY ~3 ppbv OVER THE PAST 20 YEARS

1980-1984 1994-1998

1980-1984

1994-1998

THIS OZONE BACKGROUND IS A SIZABLE INCREMENT THIS OZONE BACKGROUND IS A 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.)

Growth of Asian emissions over the next decades will Growth of Asian emissions over the 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” IPCC scenario: OECD, U.S. 20%, Asia 50%

Modeled increase in mean U.S. surface ozone (ppbv) Modeled increase in mean U.S. surface ozone (ppbv) from tripling of Asian emissions (1985 to 2015)from tripling of Asian emissions (1985 to 2015)

with other emissions held constantwith other emissions held constant

Enough to offset the benefits of 25% reductions in domestic emissions!

Jacob et al. [1999]

OZONE BACKGROUND IS DEPLETED OZONE BACKGROUND IS DEPLETED DURING REGIONAL POLLUTION EPISODESDURING REGIONAL POLLUTION EPISODES

(due to stagnation, ozone deposition and chem. loss)(due to stagnation, ozone deposition and chem. loss)

Background(clean conditions)

O3 vs. (NOy-NOx) At Harvard Forest,

Massachusetts

Background(pollution episodes)

Observed (J.W. Munger)model (GEOS-CHEM)model background

Pollution coordinateFiore et al. [2001]

RANGE OF ASIAN/EUROPEAN POLLUTION RANGE OF ASIAN/EUROPEAN POLLUTION SURFACE OZONE ENHANCEMENTS OVER THE U.S. IN SUMMERSURFACE OZONE ENHANCEMENTS OVER THE U.S. IN SUMMER

determined from a simulation with these emissions shut offdetermined from a simulation with these emissions shut off

ensemble of model results for the U.S., summer 1995ensemble of model results for the U.S., summer 1995

Max enhancements(up to 14 ppbv) occurunder moderatelypolluted conditions(50-70 ppbv ozone)

MAJOR CONCERNIF OZONE STANDARDWERE TO DECREASETO 40 or 60 PPBV

Fiore et al. [2001]

tropical air

Subsidence of Asian pollution+ local production

stagnation

CONCENTRATIONS AND FLUXES OF NORTH CONCENTRATIONS AND FLUXES OF NORTH AMERICAN OZONE IN SURFACE AIR, AMERICAN OZONE IN SURFACE AIR,

GEOS-CHEM MODEL (1997)GEOS-CHEM MODEL (1997)

Li et al. [2001]

APRIL

JULY

L

H

H

L

ORIGIN OF SURFACE OZONE AT BERMUDA IN SPRINGORIGIN OF SURFACE OZONE AT BERMUDA IN SPRING

Li et al. [2001]

Production over U.S. is the dominant source; stratosphere contributes less than 5 ppbv

(S. Oltmans)

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

STANDARD (55 ppbv, 8-h average)STANDARD (55 ppbv, 8-h average)GEOS-CHEM modelresults, summer 1997

Number of violation days(out of 92)

# of violation days thatwould not have beenin absence of N.American emissions

Li et al. [2001]

OZONE DATA AT MACE HEAD, IRELANDOZONE DATA AT MACE HEAD, IRELAND

Observed[Symmonds]

GEOS-CHEMmodel

N.America pollutionevents in model

Time series, Mar-Aug 1997

Model vs. observedstats, 1993-1997

Li et al. [2001]

FORECASTING TRANSATLANTIC TRANSPORT OF FORECASTING TRANSATLANTIC TRANSPORT OF NORTH AMERICAN POLLUTION TO EUROPE FROM THENORTH AMERICAN POLLUTION TO EUROPE FROM THE

NORTH ATLANTIC OSCILLATION (NAO) INDEXNORTH ATLANTIC OSCILLATION (NAO) INDEX

NAO IndexNorth American ozone pollution enhancementAt Mace Head, Ireland (GEOS-CHEM model)

r = 0.57

NAO index = normalized surface P anomaly between Iceland and Azores

Li et al.[2001]

SURFACE OZONE ENHANCEMENTS CAUSED BYSURFACE OZONE ENHANCEMENTS CAUSED BY

ANTHROPOGENIC EMISSIONS FROM DIFFERENT CONTINENTSANTHROPOGENIC EMISSIONS FROM DIFFERENT CONTINENTS GEOS-CHEMmodel, July 1997

North America

Europe

Asia

Li et al. [2001]

QUANTIFYING INTERCONTINENTAL TRANSPORTQUANTIFYING INTERCONTINENTAL TRANSPORTTHROUGH INTEGRATION OF OBSERVATIONS AND MODELSTHROUGH INTEGRATION OF OBSERVATIONS AND MODELS

3-D CHEMICAL TRACER MODELS

INTERCONTINENTAL TRANSPORT:INTERCONTINENTAL TRANSPORT:CONCENTRATIONS AND FLUXESCONCENTRATIONS AND FLUXES

SATELLITE OBSERVATIONSGlobal and continuous but few species, low resolution

AIRCRAFT OBSERVATIONSHigh resolution, targeted flights

provide critical snapshots for model testing

SURFACE OBSERVATIONShigh resolution but spatially limited

Source/sinkinventories

Assimilated meteorological

data

Chemical and aerosolprocesses

TRAnsport and Chemical Evolution over the Pacific TRAnsport and Chemical Evolution over the Pacific (TRACE-P)(TRACE-P)

A two-aircraft NASA mission over the western Pacific in March-April 2001A two-aircraft NASA mission over the western Pacific in March-April 2001to quantify Asian chemical outflow to the Pacific and its relationship to sources:to quantify Asian chemical outflow to the Pacific and its relationship to sources:

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

• long-lived greemhouse gases• ozone and precursors• aerosols and precursors

CENTRAL IDEA BEHIND TRACE-P:CENTRAL IDEA BEHIND TRACE-P:DEVELOP AN OBSERVATIONAL STRATEGY DEVELOP AN OBSERVATIONAL STRATEGY

FOR “TOP-DOWN” QUANTIFICATION OF SOURCES FOR “TOP-DOWN” QUANTIFICATION OF SOURCES

0

100

200

300

400

500

600

700

800

900

1991 1993 1995 1997 1999

CO2 emissionfrom China, Tgyr-1

Can we test such “bottom-up”emission estimates using atmospheric observations?

Latest China report to Energy Information Administrationclaims a decrease of CO2 emissions after 1997.

TRACE-P EXECUTIONTRACE-P EXECUTION

Emissions-Fossil fuel-Biomass burning-Biosphere, dust

Long-range transport fromEurope, N. America, Africa

ASIA PACIFIC

P-3

Satellite datain near-real time:MOPITTTOMSSEAWIFSAVHRRLIS

DC-8

3D chemical model forecasts: - ECHAM - GEOS-CHEM - Iowa/Kyushu - Meso-NH -LaRC/U. Wisconsin

FLIGHTPLANNING

Boundary layerchemical/aerosolprocessing

ASIANOUTFLOW

Stratosphericintrusions

PACIFIC

CARBON MONOXIDE CONCENTRATIONS IN TRACE-PCARBON MONOXIDE CONCENTRATIONS IN TRACE-PHigh concentrations from fossil fuel combusion, biofuels, and biomass burning

Biomassfires

40

30

20

10

160150140130120110100

14

12

10

8

6

4

2

Perchlorethylene (pptv)

>15

HONG KONG

TOKYO

<1

Distribution of Perchlorethylene (C2Cl4) Measured During TRACE P

Don Blake, UCI

Symbol size 1/altitude

CC22ClCl44 CONCENTRATIONS MEASURED IN TRACE-P CONCENTRATIONS MEASURED IN TRACE-PC2Cl4(dry cleaning) is an anthropogenic pollution tracer

CORRELATIONS BETWEEN SPECIES (here COCORRELATIONS BETWEEN SPECIES (here CO22:CO):CO)

OFFERED QUANTITATIVE INFORMATION ON SOURCES IN TRACE-POFFERED QUANTITATIVE INFORMATION ON SOURCES IN TRACE-P

CO from G.W. SachseCO2 from M.A. Avery

PRELIMINARY GLOBAL (GEOS-CHEM) 3-D MODEL PRELIMINARY GLOBAL (GEOS-CHEM) 3-D MODEL ANALYSIS OF TRACE-P OBSERVATIONS ANALYSIS OF TRACE-P OBSERVATIONS

Mat Evans,Harvard

SATELLITE MEASUREMENTS SATELLITE MEASUREMENTS OF TROPOSPHERIC CHEMISTRYOF TROPOSPHERIC CHEMISTRY

ATMOSPHERIC COLUMNS OF NOATMOSPHERIC COLUMNS OF NO2 2 AND FORMALDEHYDE (HCHO) AND FORMALDEHYDE (HCHO)

MEASURED FROM MEASURED FROM GOMEGOME BY SOLAR BACKSCATTERBY SOLAR BACKSCATTERALLOW MAPPING OF NOALLOW MAPPING OF NOxx AND HYDROCARBON EMISSIONS AND HYDROCARBON EMISSIONS

Emission

NOh (420 nm)

O3, RO2

NO2

HNO3

1 day

NITROGEN OXIDES (NOx) NON-METHANE HYDROCARBONS

Emission

NMHC

OHHCHOh (340 nm)

hoursCO

hours

BOUNDARYLAYER

~ 2 km

Tropospheric NO2 column ~ ENOx

Tropospheric HCHO column ~ ENMHC

Deposition

GOME

IMPROVED RETRIEVAL OF TROPOSPHERIC NOIMPROVED RETRIEVAL OF TROPOSPHERIC NO2 2 FROM GOME FROM GOME

(errors (errors in 10in 101515 molecules cm molecules cm-2-2))

GOME SPECTRUM (423-451 nm)

SLANT NO2 COLUMN

TROPOSPHERIC SLANT NO2 COLUMN

TROPOSPHERIC NO2 COLUMN

Fit spectrum

Remove stratospheric contribution, diffuser plate artifact

Use Central Pacific GOME data with:•HALOE to test strat zonal invariance•PEM-Tropics, GEOS-CHEM 3-D model to treat tropospheric residual

Apply AMF to convert slant column to vertical column

Use radiative transfer model with:• local vertical shape factors from GEOS-CHEM• local cloud information from CRAG

Martin et al. [2001]

CAN WE USE GOME TO ESTIMATE NOCAN WE USE GOME TO ESTIMATE NOx x EMISSIONS?EMISSIONS?

TEST IN U.S. WHERE GOOD TEST IN U.S. WHERE GOOD A PRIORI A PRIORI EXISTS EXISTSComparison of GOME retrieval (July 1996) to GEOS-CHEM model fields

using EPA emission inventory for NOx

GOME

GEOS-CHEM(EPA emissions)

BIAS = +3%

R = 0.79

Martin et al. [2001]

GOME RETRIEVAL OF TROPOSPHERIC NOGOME RETRIEVAL OF TROPOSPHERIC NO22

vs. GEOS-CHEM SIMULATION (July 1996)vs. GEOS-CHEM SIMULATION (July 1996)

GEIA emissionsscaled to 1996

Martin et al. [2001]

FORMALDEHYDE COLUMNS FROM GOME:FORMALDEHYDE COLUMNS FROM GOME:July 1996 meansJuly 1996 means

BIOGENIC ISOPRENE IS THE MAIN SOURCE OF HCHO IN U.S. IN SUMMER

Palmer et al. [2001a]

GOME DETECTS THE ISOPRENE “VOLCANO” GOME DETECTS THE ISOPRENE “VOLCANO” IN THE OZARKSIN THE OZARKS

Palmer et al. [2001b]

DEPENDENCE OF GOME HCHO COLUMNSDEPENDENCE OF GOME HCHO COLUMNSOVER THE OZARKS ON SURFACE AIR TEMPERATUREOVER THE OZARKS ON SURFACE AIR TEMPERATURE

Temperature dependenceof isoprene emission (GEIA)

Palmer et al. [2001b]

MAPPING OF ISOPRENE MAPPING OF ISOPRENE EMISSIONS FOR JULY 1996 EMISSIONS FOR JULY 1996 BY SCALING OF GOME BY SCALING OF GOME FORMALDEHYDE COLUMNS FORMALDEHYDE COLUMNS [Palmer et al., 2001b][Palmer et al., 2001b]

GEIA (IGAC inventory)

BEIS2(official EPA inventory)

GOME

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