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Atmospheric
Research and Analysis (ARA) is an ambient air quality research and
data analysis company dedicated to measuring and monitoring air
quality data in the Southeastern United States. ARA collects
real-time trace gas and fine particulate ambient air quality data
utilizing advanced technologies in support of several studies.
In July 1997, the
Environmental Protection Agency (EPA)
revised the national ambient air quality standards for
ground-level ozone and particulate matter. EPA's action
created a new standard for fine particulate matter. In order to
identify sources of fine particulate |
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matter and to
attribute health effects to specific components, fine Particulate
Matter composition (PM2.5) must be measured as well as its mass.
The Southeastern Aerosol Research and Characterization
(SEARCH) study is a collaboration between
EPRI (Electric Power Research Institute) and Southern Company to
monitor these particles in the atmosphere.
Atmospheric
Research & Analysis, Inc. operates an eight station air quality
monitoring network shown in Figure 1. A typical monitoring station
is pictured in Figure 2.
Figure 2: SEARCH Site in
northwest Georgia
Each of the monitoring stations
contains an array of air quality and meteorology sensors and a
self contained data acquisition system. Objectives of the SEARCH
network include:
- Develop a PM2.5 and Trace Gas
Climatology for 8 Sites
- Understand PM 2.5 Composition
and its Variability
- Track changes in Ozone, its
chemical precursors, and tracer gases over time
- Estimate source contributions
to Ozone and PM 2.5 concentrations
- Test and improve methods for
continuous particulate and trace gas measurements
- Collaborate with State,
Federal, and academic research and monitoring groups
Standard SEARCH
measurements are:
• Discrete Particles (24-hour)
• Continuous Particles (1-min to 1-hr)
• Trace Gases (1-min)
– O3, NO, NO2, NOy, HNO3, SO2, CO, CO2
• Meteorology (1-min)
– Wind speed and direction, Temperature, relative humidity,
barometric pressure, solar radiation and rainfall
• Visibility
High accuracy calibration and auditing of
the on-site meteorological sensors has been problematic in the past. ARA decided to deploy a traveling Paroscientific
MET3A Broadband Meteorological
System as a calibration transfer standard. MET3A was chosen because of its
high accuracy,
reliability, stability,
ease of use, transportability and
high performance pressure
port.
The MET3A is
mounted along with other meteorological sensors at the reference
station and data are collected for several days. A linear
regression analysis is then performed comparing the site sensors
to the MET3A reference station to recalibrate the
on-site meteorological sensors. The MET3A is rotated through each site on a
quarterly basis to audit and calibrate the site sensors.
The use of the
MET3a as an audit and calibration standard allows ARA to report
standard meteorological data from the SEARCH network with greater
accuracy and confidence. |
