WORKSHOP ON CLIMATE CHANGE AND AIR QUALITYWORKSHOP ON CLIMATE CHANGE AND AIR QUALITY: part I: : part I: Intercontinental transport and climatic effects of pollutants Intercontinental transport and climatic effects of pollutants

OBJECTIVE:

• Define a near-term (-2003) research strategy for EPA/OAQPS to1. Better understand the role of intercontinental transport in affecting

ozone and PM air quality;2. Better understand the global/regional climate forcing of air

pollutants (BC, OC, sulfate, ozone);3. Enable an integrated appproach to assess the combined air quality

and climatic implications of changes in anthropogenic emissions. • Develop a longer-term program for integrating intercontinental transport

and climatic forcing issues in EPA’s regulatory strategy

Dust transport over the Pacific, April 21-25, 1998.

R. Husar

Asian Dust Cloud Over North AmericaAsian Dust Cloud Over North America

GOES Satellite Image PM10 West Coast

R. Husar

OZONE TREND AT EUROPEAN MOUNTAIN SITES, 1870-1990OZONE TREND AT EUROPEAN MOUNTAIN SITES, 1870-1990

Preindustrialozone models

}

Marenco et al. [1994]

SURFACE OZONE BACKGROUND PRODUCED OUTSIDE SURFACE OZONE BACKGROUND PRODUCED OUTSIDE NORTH AMERICA IS A SIZABLE INCREMENT TOWARDS NORTH AMERICA IS A SIZABLE INCREMENT TOWARDS

VIOLATION OF U.S. AIR QUALITY STANDARDSVIOLATION 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.)

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

IPCC [2001]

Aerosol Effect on Surface ReflectanceAerosol Effect on Surface Reflectance

• Aerosols add to the reflectance and sometimes reduce the reflectance of surface objects• Aerosols always diminish the contrast between dark a bright surface objects• They change the color of surface objects• Haze adds a bluish while dust adds yellowish tint to the surface color of surface objects.

Future SOFuture SO22 emissions in Asia are likely to be much emissions in Asia are likely to be much

lower than the latest IPCC forecastslower than the latest IPCC forecasts

Indexed trends in greenhouse-gas emissions in Indexed trends in greenhouse-gas emissions in ChinaChina

The net effect of theseemission changes on global

mean temperatures is anINCREASE, due to the

dominant effect ofthe sulfate aerosol

M.Z. Jacobson

PRIORITY QUESTIONS AND STRATEGIES FOR PHASE IIPRIORITY QUESTIONS AND STRATEGIES FOR PHASE IIOF EPA/OAQPS INITIATIVE, 2002-2003OF EPA/OAQPS INITIATIVE, 2002-2003

1. How will changing anthropogenic emissions outside North America enhance background ozone and PM concentrations in the U.S., and the ability of the U.S. to meet the NAAQS?• Need improved 2000 global, gridded emission inventories for ozone and PM

precursors partitioned by source sector• Need policy-relevant 2020 emission projections• Need nested global regional model• Need to determine the PM background levels contributed by intercontinental

transport

2. How will changes in emissions of PM, PM precursors, and ozone precursors, in the U.S. and in the rest of the world, contribute to climate change?• Need GCM calculations of climate response for selected policy-relevant

emission projections, develop approach for linearizing the dependence of climate response on the perturbation

3. How do U.S emissions affect the ability of countries in Europe and Asia to meet their air quality objectives?

GOING BEYOND 2003: SOME PRIORITY ISSUESGOING BEYOND 2003: SOME PRIORITY ISSUES

– Link to air quality objectives outside North America through different nested model strategies

– Use observations from satellites and aircraft field campaigns to

• Test model estimates of intercontinental transport

• Improve emission estimates (esp. fires, megacities)

– Better define errors and error covariances in emission inventories towards improving these estimates through inversion models.

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, FLUXES, BUDGETSCONCENTRATIONS, FLUXES, BUDGETS

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