Air Quality
The atmospheric boundary layer plays a key role in air quality: wind
transports pollutants from their various sources, turbulence mixes and
dilutes pollution, boundary layer cumulus clouds vent pollution into the
free troposphere, and temperature and humidity levels in the boundary layer
affect chemical reactions and the rates at which many dangerous compounds
are formed. Without accurate meteorological models, especially within the
boundary layer, it would be impossible to forecast air quality reliably.
Methods
The Boundary Layer Team has been involved in numerous air quality field programs.
Our role has been to deploy meteorological instruments, collect data, run meteorological models,
and evaluate the models using the instruments we deploy. The most
important instrumentation deployed for characterizing the boundary layer
and its role on air quality are wind profiling radars, which identify transport
directions and speeds and determine the depth of turbulent mixing in the
convective boundary layer. Other instruments deployed include surface
meteorological stations (temperature, humidity, wind speed and direction,
pressure, solar radiation, and soil temperature and humidity); sodars;
cloud radars; and turbulent heat and moisture flux systems.
Activities & Outcomes
Modeling-related research has focused on using high-resolution weather models.
Science questions addressed are the ability of these models to accurately simulate flow in complex terrain; to
correctly follow the growth of the convective boundary layer; and to assess
the impact of observations from networks of boundary layer profilers on
improving the analyzed wind fields. Meteorological simulations produced by the
boundary layer team were used by the California Air Resources Board to
develop their State Implementation Plan to meet EPA regulations on allowed
ozone concentrations. We have worked on using
Large Eddy Simulation (LES) models to address issues surrounding turbulent
mixing within the boundary layer.
Evaluation of operational and research air quality models is another
important area of research. In past field campaigns we have developed a
real-time model evaluation web site, which incorporates meteorological
observations, surface chemistry observations, and coupled (meteorology +
chemistry) air quality forecast information. Analysis of these data sets
has focused on the impact of meteorology on air quality, and especially on
the impact of meteorological forecast errors on pollution concentration
forecast errors.
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Scientists aboard a NOAA research ship deploy a balloon carrying an ozonesonde—which measures ozone in the atmosphere—that rises up to 70,000 feet and sends back the data to ground stations. |
MM5 simulation of winds in CA during a high ozone episode from the CCOS field campaign. Elevations greater than 100m are blacked out to highlight flow within the Central Valley. |
Click images for more details |
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