Carbonaceous Aerosol and Smoke over the Eastern US

Objectives and Approach to the AnalysisBackground

• There is considerable evidence that smoke from biomass fires constitutes a significant component of the aerosol over North America, particularly in the PM2.5 size range.

• However, both the recent and previous research results on smoke are fragmented, and uneven in spatial, temporal an compositional coverage.

• An integrated assessment of the North American smoke using the rich literature and the most recent data would be most desirable.

Objectives • Explore qualitatively the spatio-temporal and chemical pattern of smoke over North America• Characterize spatio-temporal features of smoke dust from the different sources

Approach• Integrate data from surface and satellite observations • Combine spatial, temporal and compositional analysis• Invite the community to actively particulate in conducting this open, integrative analysis

Status (May 2001) • Recent data from several satellite and surface sensors were analyzed and presented graphically• The data and knowledge from the literature has not yet been incorporated • An open discussion and interaction with the community is to begin in June 2001

Applications of this Work

NARSTO-PM Assessment. NARSTO is conducting a PM Assessment for North America. This work supports the NARSTO PM Assessment process.

Monitoring Network Design/Evaluation. EPA is implementing an extensive monitoring network for speciated PM sampling. This work supports the design and performance-evaluation of the new network.

MODELS-3 Evaluation. EPA’s MODELS-3/CMAQ is a sophisticated high resolution, regional-scale modeling system designed to simulate and investigate gaseous and fine pattern over the US. This work supports the evaluation and further development of the model.

Regional Haze Management. In response to the new haze regulations, Regional Planning Organizations (RPOs, Central States, Northeast OTC, Western States ) have been set up for haze management. This work is to provide background information to be used by the RPOs.

Smoke Physical, Chemical and Optical Properties

• Physical - size distribution and shape– Determines the atmospheric residence time, optical properties

• Chemical – elemental and molecular composition– Influences optical properties and other effects on health– Serves as source fingerprint

• Optical – refractive index– Influences effects on visibility and climate– Allows detection by remote sensing

Cumulative Seasonal PM2.5 Composition

• PM2.5 chemical components were calculated based on the CIRA methodology

• In addition, the the organics were (tentatively) further separated as Primary Smoke Organics (red) and Remainder organics (purple)

PSO = 20*(K - 0.15*Si – 0.02* Na) Remainder Org = Organics - PSO

• Also, the ‘Unknown’ mass (white area) is the difference between the gravimetrically measured and the chemically reconstructed PM2.5.

• The daily chemical composition was aggregated over the available IMPROVE data range (1988-99) to retain the seasonal structure.

• I order to reduce the noise the daily data were smoothed by a 15-day moving average filter.

Shenandoah

Central EUS: Chemical Mass Balance

• The pattern of the Central EUS is similar to the Mid-Atlantic region

• However, several stations show multiple peaks

Upper Buffalo Mammoth Cave Shining Rock

G.Smoky Mtn.Sipsy

Peripheral Sites: Chemical Mass Balance• Eastern N. America is

surrounded by aerosol source regions such as Sahara and Central America.

• As a consequence, the PM concentration at the ‘edges’ ranges between 4-15 ug/m3; much of it originating outside.

• The chemical composition of the inflow varies by location and season.

• At the Everglades, organics, ‘smoke organics’ and LAC dominate over sulfate and fine dust

• Sahara dust, and smoke from Central America and W. US/Canada are the main contributions to Everglades, FL, and Big Bend, TX.

Badlands(scale 0-15 ug/m3)

Big Bend(scale 0-15 ug/m3)

Voyageurs(scale 0-15 ug/m3)

Acadia

Everglades

Central EUS: Carbonaceous Mass Balance

• Throughout the Central EUS, the carbonaceous aerosol contributes 4-6 g/m3

• There is a 50% seasonal variation with a summer peak

• ‘Smoke Organics’ constitute 20-30% of the total organics

Upper Buffalo Mammoth Cave Shining Rock

G.Smoky Mtn.Sipsy

Badlands(scale 0-15 ug/m3)

Peripheral Sites: Carbonaceous Mass Balance• At the northern

peripheral sites, Badlands, Voyageurs and Acadia, the organics range from 1.5 to 4 g/m3

• At Big Bend the organics show a spring peak, with a majority of ‘smoke organics’. This indicates biomass smoke origin.

• At the Everglades, the fall peak is due to organics, while ‘smoke organics’ light absorption is present throughout the year.

Big Bend(scale 0-15 ug/m3)

Voyageurs(scale 0-15 ug/m3)

Acadia (scale 0-15 ug/m3)

Everglades (scale 0-15 ug/m3)

May 15, 98

• Fire locations detected by the Defense Meteorological Satellite Program (DMSP) sensor.

• The sensor detects low levels of visible night at night

Smoke from Central American Fires

• Satellite image of color SeaWiFS data, contours of TOMS satellite data (green) and surface extinction coefficient, Bext

• The smoke plume extends from Guatemala to Hudson May in Canada

• The Bext values indicate that the smoke is present at the surface

St. Louis – Atlanta, Dec 1998

During the fall season, fires and biomass smoke can be observed throughout the southeastern US.

During a St. Louis – Atlanta flight, December 1998 over a dozen biomass smoke plumes were photographed (right).

Satellites now allow detection of fire locations through out the world.

For example, in December 1998, the fires recorded by the ESA IONIA Program are indicated below

Astronaut Photos

• On a single day, an astronaut photo of North Carolina reveals over a dozen individual smoke plumes. These are presumed to be biomass fires.

Smoke Plumes over the Southeast• Satellite detection yields the origin and location is the

shape of smoke plumes

R 0.68 m

G 0.55 m

B 0.41 m

0.41 m

0.87 m

• The influence of the smoke is to increase the reflectance ant short wavelength (0.4 m) • At longer wavelength, the aerosol reflectance is insignificant.

Smoke Aerosol and Ozone During the Smoke Episode – Inverse Relationship

The surface ozone is generally depressed under the smoke cloud

Extinction Coefficient (visibility)

Surface Ozone

Hourly PM10 During the Smoke Event

Hourly PM10 concentration pattern at six eastern US locations during May 1998.

Smoke Composition at Big Bend, TX

Daily average light scattering coefficient and chemically speciated fine mass concentration for the IMPROVE monitoring site at Big Bend, TX, May 1998.

Central American Smoke Pattern, April, 2000

The May major 1998 Central American smoke event was not a unique phenomenon. On April 25, 2000, the intense smoke plume was similar to the ’98 event. The plume covers part of Florida.