BACKGROUND AEROSOL CONCENTRATIONS BACKGROUND AEROSOL CONCENTRATIONS ANDAND VISIBILITY DEGRADATION IN THE UNITED VISIBILITY DEGRADATION IN THE UNITED

STATESSTATES

Rokjin Park

• Motivated by EPA Regional Haze Rule

• Quantifying uncontrollable transboundary pollution transport is crucial [Park et al., 2003; 2004]

2nd GEOS-CHEM User’s meeting, April 4, 2005

SIMULATED BASELINE AND BACKGROUND ANNUAL MEAN SIMULATED BASELINE AND BACKGROUND ANNUAL MEAN SULFATE AND NITRATESULFATE AND NITRATE CONCENTRATIONS CONCENTRATIONS (2001) (2001)

BACKGROUND CONC. BASELINE CONC.

SO42-

NO3-

µg m-3

µg m-3

SIMULATED ANNUAL MEAN AEROSOL CONCENTRATIONSSIMULATED ANNUAL MEAN AEROSOL CONCENTRATIONS (2001): OMC, EC, SOIL DUST, SEA SALT(2001): OMC, EC, SOIL DUST, SEA SALT

OMC EC

SEA SALT SOIL DUST

µg m-3

µg m-3

VISIBILITY DEGRADATION STATISTICS IN THE U.S. (2001): VISIBILITY DEGRADATION STATISTICS IN THE U.S. (2001): IMPROVE vs. GEOS-CHEM (1IMPROVE vs. GEOS-CHEM (1oox1x1oo))

Visibility degradation (deciviews): dv = 10ln(bext/10) Aerosol extinction (bext) from sulfate, nitrate, and carbonaceous aerosols:bext = 3f(rh)[sulfate+nitrate] + 4[OMC] + 10[EC] + [soil] + 0.6[CM] + 10.

VISIBILITY DEGRADATION BY SULFATE IN THE SOUTH VISIBILITY DEGRADATION BY SULFATE IN THE SOUTH ATLANTIC AND ITS VARIABILITY: IMPROVE vs. GEOS-CHEMATLANTIC AND ITS VARIABILITY: IMPROVE vs. GEOS-CHEM

GEOS-3 1ox1o PRECIPITATION IN JJA (2001)

TOTAL PRECIPITATION CONVECTIVE PRECIPITATION

AEROSOL WET SCAVENGING IS TOO MUCH IN SUMMER?

PRECIPITATION OVER THE GULF OF MEXICO AND THE SOUTH EASTERN UNITED STATES IS MOSTLY CONVECTIVE PRECIPITATION DURING SUMMER.

mm d-1

mm d-1

PRECIPITATION IN SUMMER (2001): GMAO VS. NCEP / GPCP

VISIBILITY DEGRADATION BY SULFATE IN THE S. WESTERN VISIBILITY DEGRADATION BY SULFATE IN THE S. WESTERN U.S. AND ITS VARIABILITY: IMPROVE vs. GEOS-CHEMU.S. AND ITS VARIABILITY: IMPROVE vs. GEOS-CHEM

Gg S yr-1

GEOS-CHEM: 1.9 Tg S yr-1 BRAVO: 1.3 Tg S yr-1

Courtesy of Dr. Soontae Kim at U. Houston

MEXICAN SULFUR EMISSIONS (1ox1o): GEOS-CHEM (2001) VS. BRAVO (1999)

VISIBILITY DEGRADATION STATISTICS IN THE U.S. VISIBILITY DEGRADATION STATISTICS IN THE U.S. EAST(2001): IMPROVE vs. GEOS-CHEM (1EAST(2001): IMPROVE vs. GEOS-CHEM (1oox1x1oo))

at selected IMPROVE sites in the east (>95oW)FREQUENCY DISTRIBUTION FREQUENCY DISTRIBUTION OF DAILY VISIBILITYOF DAILY VISIBILITYIMPROVE MODEL

IMPROVEMODEL

Visibility extinction (deciviews: dv = 10ln(bext/10) ) from sulfate, nitrate, and carbonaceous aerosols + observed contribution from soil dust and coarse mass (2001)

SIMULATED NATURAL AND BACKGROUND VISIBILITY SIMULATED NATURAL AND BACKGROUND VISIBILITY DEGRADATION STATISTICS IN THE U.S. EASTDEGRADATION STATISTICS IN THE U.S. EAST

DEFINE NATURAL AND BACKGROUND CONCENTRATIONS FROM SENSITIVITYMODEL SIMULATIONS WITH NO GLOBAL AND U.S. ANTHROPOGENIC EMISSIONS, RESPECTIVELY.

FREQUENCY DISTRIBUTION FREQUENCY DISTRIBUTION OF DAILY VISIBILITYOF DAILY VISIBILITYBACKGROUND NATURAL

Uncontrollable anthropogenic contribution from outside U.S.

NO U.S.NO GLOBENO NA

at selected IMPROVE sites in the west (<95oW)

FREQUENCY DISTRIBUTION FREQUENCY DISTRIBUTION OF DAILY VISIBILITYOF DAILY VISIBILITYIMPROVE MODEL

VISIBILITY DEGRADATION STATISTICS IN THE U.S. VISIBILITY DEGRADATION STATISTICS IN THE U.S. NORTHWEST(2001): IMPROVE vs. GEOS-CHEM (1NORTHWEST(2001): IMPROVE vs. GEOS-CHEM (1oox1x1oo))

Successful simulation of low end of pdf increases confidence in ability of modelto describe natural (and transboundary?) signatures

IMPROVEMODEL

SIMULATED NATURAL AND BACKGROUND VISIBILITY SIMULATED NATURAL AND BACKGROUND VISIBILITY DEGRADATION STATISTICS IN THE U.S. WESTDEGRADATION STATISTICS IN THE U.S. WEST

FREQUENCY DISTRIBUTION FREQUENCY DISTRIBUTION OF DAILY VISIBILITYOF DAILY VISIBILITYBACKGROUND NATURAL

NO U.S.NO GLOBENO NA