· Aerosol are composed of multiple types including urban-industrial sulfates, nitrates and organics (industrial haze), biomass smoke and windblown dust.

· Each type may be considered a different pollutant since it has its own class of sources, aerosol properties and associated with different effects.

· In this sense dust, smoke and haze are aerosol equivalents of the gaseous pollutants, SO_2, NO_x and CO but under the current regulations they are lumped under PM2.5 and PM10.

· This section focuses on the ‘smoke’ portion of the North American aerosol. It will also include discussion of the carbonaceous aerosol in general.

Objectives and Approach to the Analysis

Background

· 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 and 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

o Determines the atmospheric residence time, optical properties

· Chemical – elemental and molecular composition

o Influences optical properties and other effects on health

o Serves as source fingerprint

· Optical – refractive index

o Influences effects on visibility and climate

o Allows detection by remote sensing

Chemical Properties: Detection of Organics is Problematic

Hegg and Hobbs, as part of the TARFOX project conducted airborne organics measurements. They found that the organics fraction of fine mass increases with elevation and the total fine carbon correlates well with the light absorption. Hence, they reason that the carbonations aerosol originated from combustion sources. Smoke from biomass smoke is a plausible source.

Spatio-Temporal Pattern of Carbonaceous Aerosol

Organic and Absorbing Carbon – IMPROVE

Source: IMPROVE, Sisler & Malm

Organics and light absorbing carbon are most abundant in the Southeast

Carbonaceous Aerosol Components

Carbonaceous aerosols (Organics + Light Absorbing Carbon) are most abundant over the East and West Coasts.

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)

o PSO = 20*(K - 0.15*Si – 0.02* Na)

o 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.

· In order to reduce the noise, the daily data were smoothed by a 15-day moving average filter.

Regional Grouping of Sites

· For this work the IMPROVE sites were grouped as follows:

o New England

o Mid-Atlantic

o Central EUS

o Peripheral

· For each region, the seasonality is displayed for:

o Chemical Mass Balance

o Carbonaceous Mass Balance

o “Smoke Organics” Percentiles

New England: Chemical Mass Balance

The concentration of organics and ‘smoke organics’ is low over the Northeast

Mid-Atlantic: Chemical Mass Balance

· At the Mid-Atlantic region, carbonations aerosol are 25-40% of the fine mass

· The seasonality of organics and ‘smoke organics’ is pronounced

· In Washington DC, there is a winter peak that is largely contributed by organics organics and ‘smoke organics’

Central EUS: Chemical Mass Balance

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

· However, several stations show multiple peaks

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.

New England: Carbonaceous Mass Balance

· Carbonaceous aerosols peak in the summer at 2-3 mg/m³.

· At Moosehorn, ‘smoke organics’ exceeds organics.

Mid-Atlantic: Carbonaceous Mass Balance

· The seasonality of carbonaceous aerosol vary

· Shenandoah is strongly summer peaked

· Washington DC and Jefferson have summer and winter peaks

· Dolly Sods and Brigantine are mildly seasonal

·

Except for Jefferson, the ‘smoke organics’ are a small fraction of the total organics

Central EUS: Carbonaceous Mass Balance

· Throughout the Central EUS, the carbonaceous aerosol contributes 4-6 mg/m³

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

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

Peripheral Sites: Carbonaceous Mass Balance

· At the northern peripheral sites, Badlands, Voyageurs and Acadia, the organics range from 1.5 to 4 mg/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.

Semi-Quantitative Satellite and other Observations

Fire Locations and TOMS Smoke Pattern

· Infrared satellite sensors on NOAA polar satellites detect the location of fires under cloud-free conditions

· The daily fire location data are routinely processed by ESA

· In 1998, the highest fire density was over Central America in April-May.

· In July, fires were observed throughout the and particularly in N. Canada.

For April and May 1998, the TOMS satellite data show major plumes of absorbing aerosol (smoke) dispersing from the Central American fires.

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.

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.

Satellite Images if Smoke Plumes over the Southeast

Color SeaWiFS image of the smoke plumes originating from Kentucky, Nov 15, 1999.

Enhanced smoke image

Idaho Fires, August, 2000

Smoke from the major Idaho Fires in August 2000 was tracked through the Absorbing Aerosol Index product from the TOMS ozone sensor.

Smoke Plumes over the Southeast

Satellite detection yields the origin, location, and shape of smoke plumes.

· The influence of smoke is to increase the reflectance at short wavelength (0.4 mm)

· At longer wavelength, the aerosol reflectance is insignificant.

Central American Smoke Events

During a ten-day period, May 7-17, 1998, smoke from numerous widespread fires in Central America drifted northward and caused severe perturbation of the atmospheric environment over parts of Eastern North America. A draft paper describes the impact of the Central American smoke on the on the atmospheric environment of Eastern North America.

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

· The sensor detects low levels of visible night at night.

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 Bay in Canada. The Bext values indicate that the smoke is present at the surface

Smoke Aerosol and Ozone During the Smoke Episode – Inverse Relationship

Extinction Coefficient (visibility)

Surface Ozone

The surface ozone is generally depressed under the smoke cloud.