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Introduction to the SouthEastern Aerosol Research and
Characterization (SEARCH) Network
SEARCH is a comprehensive, multi-pollutant network designed to address
regulatory and scientific questions related to ozone and its precursors,
PM mass and composition, mercury speciation and deposition, wet
deposition of acidity and nutrients and atmospheric visibility. The origins of SEARCH date back to the
early 1990s, when 3 rural ozone and ozone precursor sites were deployed
as part of the Southern Oxidants Study SCION network to understand
regional transport of ozone and its precursors. The highly instrumented 8 site network
was developed as part of a public-private collaboration with EPRI
(Electric Power Research Institute), Southern Company, and other
utilities. Three sites, Centreville, AL, Oak Grove, MS, and Yorkville,
GA, were originally
established to obtain comprehensive, long-term measurements of an
extensive suite of trace gases (O3, NO, NO2, NOy, SO2, and CO) and
meteorology in rural-regional locations.
The
size and scope of SEARCH expanded significantly in the late 1990s to
address questions pertaining to PM2.5 mass, composition and health
effects. Unlike other criteria pollutants such as ozone, fine particles
are comprised of mixtures of many compounds. Therefore, in order to
identify sources of PM2.5 and to attribute health effects to
specific components both the composition and mass of PM2.5 should
be measured. High time resolution measurements are necessary to
understand the dynamic nature of PM and PM precursor sources,
transformations, and sinks.
The scope of SEARCH was increased again in the early 2000s to address
atmospheric mercury. The network
currently extends through Alabama, Florida, Georgia,
and Mississippi,
and currently has produced more than 10 years of data. Along the way, the
SEARCH network as a whole has evolved to provide new and better
measurements; and individual sites have served as platforms for long-term
investigations of health effects and for short-term research campaigns to
address key science questions (e.g., particle nucleation and
photochemical mechanisms). To
date, SEARCH data have been the basis of well over 150 peer-reviewed
scientific publications. SEARCH
data also have been used to constrain and evaluate local, regional,
continental and global-scale atmospheric models, and have proven an
invaluable resource to decisonmakers about the consequences of new,
revised or looming ambient air quality standards.
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