CONCEPTUAL MODEL OF ORGANIC PM FORMATION
Project No. A-60
Leaders: J. C. Ball
R. S. MacArthur
Scope and Objective
This project will (1) develop a conceptual
model of atmospheric organic PM formation based on data from comprehensive
measurement programs (supersites and others), (2) relate this conceptual model
to our understanding of organic PM based on laboratory and theoretical analyses
(i.e., results from A-59), and (3) identify the major processes missing in
current models that are of atmospheric importance in the United States.
Current Status and Future Program
Under Project A-59, Atmospheric and
Environmental Research (AER) assessed the current state-of-the-science for
secondary organic aerosol (SOA) formation. The literature review results
suggest that many pathways for SOA formation are currently missing or crudely
represented in current models of atmospheric PM. Project A-59 further
investigated those new SOA formation pathways and assessed their potential
atmospheric importance with some preliminary modeling. On the ambient
measurement side, a large body of information on atmospheric organic PM has
recently become available via the supersite program and other special studies.
Such data are being analyzed to some extent. However, there is a need to
integrate the current knowledge gained from (1) laboratory and theoretical
studies of SOA formation and (2) advanced measurement programs of organic PM
(both primary and secondary) and to use the resulting information to improve
current PM models.
The project will: (1) review relevant data from
supersites and other special studies using results of previous data analyses to
the extent possible, (2) develop a conceptual model of organic PM formation
(e.g., diurnal profiles; dependence on meteorological variables such as solar
radiation, relative humidity and temperature; chemical characteristics;
correlations with other variables such as other pollutant concentrations), (3)
provide a scientific basis for this conceptual model based on current knowledge
of organic PM, (4) identify the major deficiencies in terms of scientific
formulation in current PM, and (5) develop a set of recommendations to remediate
those deficiencies.
This project was a
new start in late 2006 and is being conducted by AER as a follow-on study. The
committee elected to commit budget from 2006 to begin the effort, with
additional funds supplied in 2007. A draft journal article for Part 1 of the
project has been approved by the committee for submission to the journal.
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