Air Quality
Today, the air quality aspect of ARL
research is by far the dominant theme, but
distinctions among the themes
remain somewhat vague. For example, the models
developed for emergency
response purposes are among those used for air quality
prediction. The Air
Quality and Dispersion theme is one of the strongest ties
that binds ARL's
components together. ARL is not heavily involved in the pure
science of the
business. Instead, ARL focusses on the need to assemble
integrated
understanding and models from all available sources, to develop
the
capability to predict changes in air quality that will follow changes
in
emissions, or that will occur as a result of meteorological factors. ARL
air
quality research extends to studies of atmospheric deposition essentially
the
coupling between the atmospheric pollutant environment and the surface
below.
ARL now operates the only research-grade deposition monitoring
network in the
nation: AIRMoN (the Atmospheric Integrated Research Monitoring
Network).
Programs. Air Quality and Deposition Modeling Air quality
models have demanded
this kind of coupling for a considerable time. As a
result, there are now
well-developed descriptions of PBL processes in use in
air quality models. ARL
research products are now receiving a wider audience,
within the mesoscale
modeling community at large. It is recognized that
modern models are invariably
data assimilative, and that modern monitoring
programs require coupled modeling
activities for data interpretation. Model
development programs are supported by
a vigorous physical modeling program,
located at Research Triangle Park, NC. ARL
operates one of the nation's major
fluid modeling facilities, at which studies
are conducted on the effects of
mountains, buildings, and other surface
obstacles on atmospheric flow
patterns. Integrated Monitoring, and AIRMoN The
Atmospheric Integrated
Research Monitoring Network is an atmospheric component
to the overall
national integrated monitoring initiative that is currently
evolving. AIRMoN
has two principal components: wet and dry deposition. ARL
presently focuses
its research attention on ? the measurement of
precipitation chemistry with
fine time resolution (AIRMoN-wet), ? the
development of systems for measuring
deposition, both wet and dry, ? the
measurement of dry deposition using
micrometeorological methods (AIRMoN-dry),
? the development of techniques for
assessing air-surface exchange in
areas (such as specific watersheds) where
intensive studies are not feasible,
and ? the extension of local measurements
and knowledge to describe areal
average exchange in numerical models.
Aerosols and visibility ARL specializes in
the geochemical cycling of
atmospheric aerosols, particularly the particulate
component. Research groups
in ARL concentrate on (a) the injection of dust and
soil particles into the
atmosphere, (b) the transport of particles through the
atmosphere, © the
production of aerosol particles in the air by chemical
reactions, (d) the
scavenging of airborne particles by clouds and their
subsequent deposition in
precipitation, (e) the dry deposition of particles as
air moves across
different landscapes, and (f) the assembly of numerical models.
Specific
topics include ? the injection of dust and soil particles into
the
atmosphere, ? the long-range transport of particles through the
atmosphere, ?
the production of aerosol particles in the air by chemical
reactions, ? the
scavenging of airborne particles by clouds and their
subsequent deposition in
precipitation, and ? the dry deposition of
particles as air moves across
different landscapes. International ARL serves as
the leader of the U.S.
multi-agency effort to impose formalized and uniform
quality assurance
programs on the many national air quality and deposition
monitoring networks
that are operational around the globe. How are ozone
concentrations
calculated with Hysplit? Ozone is then calculated from the
photostationary
state equation. The IER solution is used in the operational
Hysplit ozone
calculation. The pollutant particles are tracked and air
concentrations for
each species are computed each advection time step following
the usual
lagrangian approaches. At the conclusion of the advection step the
GRS
differential equations are solved on the concentration grid (Eulerian
solution),
and the change of concentration of each pollutant species is
applied to the
pollutant mass on the particles that contributed concentration
to each grid
cell. -Eulerian chemistry solution on the grid dc/dt =
{Equations 1 - 7} 1) ROC
+ hv -* RP + ROC Nitric oxide-ozone titration
reaction 5) RP + RP -* RP k5 =
10200 Sink for nitrogen dioxide to stable
gaseous nitrates What is the
Integrated Empirical Rate Model? Time
Integrated on the particle (Lagrangian):
Algebraic solution on the grid
(Eulerian): Smog product = ozone produced and
oxidized nitric oxide
Photostationary state balances formation and destruction
of ozone Definition
of NOx Air-Surface Exchange Heat, Momentum, Water, and CO2
Transfer at
the Earth Surface Presently, ARL focuses its attention on the
development of
systems for measuring fluxes at specific locations, and the
extension of
local measurements and understanding to describe areal average
exchange in
numerical models. Improving NOAA's prediction capabilities requires
this
understanding. ARL's internal model developments are arranged to be in
close
association with the field work. Tower Studies. Dennis Baldocchi
(baldocchi@atdd.noaa.gov)
Three ARL groups (Oak Ridge, Research Triangle
Park, and Silver Spring) are
currently working with portable eddy flux
systems, based upon original ARL
developments. The system is specifically
designed to provide uninterrupted
monitoring of momentum, heat, water vapor,
and carbon dioxide fluxes. Walker
Branch watershed flux studies have
recently been extended in an exploration of
the flux contributions of the
forest floor and the trees themselves. Experience
gained in this effort will
be important for anticipated surface-layer model
testing and evaluation
studies (under NOAA/GEWEX/GCIP). At Research Triangle
Park, and in
cooperation with Oak Ridge, a separate portable flux-measuring
system was
developed, this time designed for direct measurement of trace gas
fluxes but
relying on measurement of the standard micrometeorological quantities
for
quality assurance. The system provides for direct eddy
correlation
measurements of sulfur dioxide, ozone, and carbon dioxide fluxes,
and of nitric
acid by filter pack gradient analysis, as well as the important
components of
the surface energy budget. The Mobile Flux Platform, and GPS.
Ron Dobosy (dobosy@atdd.noaa.gov)
During 1994, the use of new Global
Positioning System (GPS) technology was
evaluated, and the newest available
GPS systems were adopted. The systems
developed for aircraft eddy flux use
have now been fitted to one of NOAA's two
Twin Otter aircraft. Large-Area
Exchange Tim Crawford (crawford@atdd.noaa.gov)
The Oak Ridge group has
frequently deployed both tower and aircraft eddy
correlation systems during
studies of areal fluxes over a heterogenous surfaces,
in real-world studies
of how well flat-earth formulations apply in real
situations. Analysis of
tower eddy correlation fluxes of heat and moisture
displayed differences in
the fluxes among alfalfa, corn, and wheat crops; during
daytime,
transpiration rates differed by 20% to 50%. Measurements of momentum,
heat,
and moisture fluxes from the ATDD Long-EZ research airplane were analyzed
to
quantify spatial variabilities in the fluxes. Carbon Dioxide. Tilden Meyers
(meyers@atdd.noaa.gov)
Continuous eddy correlation measurement of CO2
flux over the Walker Branch (Oak
Ridge) forest have continued since 1993.
The eddy flux measurement of CO2
exchange is now a mature technology. (See
discussion above -- "Tower
Studies".) Air-surface exchange has been
studied extensively in classical
investigations that focus on revealing the
processes involved. Winston Luke (winston.luke@noaa.gov)
The importance
of accurate air-surface flux formulation in numerical models is
now widely
acknowledged. Atmospheric Loadings to Coastal Ecosystems
Regulatory
strategies that fail to recognize that part of the problem arises
from
atmospheric deposition will not work as expected. The ARL Role
Measurement and
modeling of atmospheric deposition are long-standing ARL
specialties. east
coast, from Maine to Florida. ARL is leading a large part
of the integrated
research effort focusing on this issue. Leadership of the
Chesapeake Bay Air
Subcommittee Contact -- richard.valigura@noaa.gov The
Chesapeake Bay Program (CBP)
is a multi-agency program of targeted scientific
research and integrated
assessment, which has been instrumental in alerting
policy makers to the need to
couple air and water issues in their
decision-making processes. Characterizing
the East and Gulf Coast Atmospheric
Resource Contact -- bruce.hicks@noaa.gov It
is clear that emissions from the
"airshed" that serves as a regional
origin of air pollutants affecting the
Chesapeake Bay also influence other
coastal ecosystems. east coast estuarine
and coastal ecosystems would benefit as
well. Research Grade Monitoring of
Deposition in the Coastal Zone Contact --
richard.artz@noaa.gov The
atmospheric deposition that affects east coast
ecosystems is very poorly
measured. For dry deposition, there are very few data
points. The NOAA
Atmospheric Integrated Research Monitoring Network (AIRMoN) has
constituted a
framework for exploring methods for quantifying the actual
deposition
loadings to the Chesapeake Bay watershed. ARL is currently operating
several
AIRMoN stations in the watershed -- State College, PA, is a long-term
site
where both wet and dry deposition are being studied. Modeling Deposition
to
the Coastal Zone at Regional Scales Contact -- rdennis@hpcc.epa.gov The
Regional
Acid Deposition Model (RADM) has been adopted as the modeling
workhorse of the
east coast estuarine regulatory community. The results
indicate that grid sizes
*2 km may be necessary to resolve the effects of the
Bay on atmospheric dry
deposition (but not wet). Estimating Air-Water
Exchange of Nitric Acid in
Coastal Areas Contact --
richard.valigura@noaa.gov A project was successfully
undertaken which, i)
developed and evaluated an iterative bulk exchange model to
estimate
air-water exchange of heat, water and momentum from buoy data, and ii)
used
the model outputs to estimate air-water transfer rates of nitric acid
(HNO3).
Natural emissions of Oxidant precursors: Validation of techniques
and
Assessment (NOVA) Contact -- winston.luke@noaa.gov Historically, NOx
emissions
from soils have been estimated using chamber, or enclosure,
techniques, whereby
the measured rate of increase of [NO] within the chamber
used to derive an
estimate of the NO emission flux from the underlying soil
surface. Mercury
Deposition Contact -- meyers@atdd.noaa.gov ARL
researchers at Oak Ridge (a
collaboration between ATDD and Oak Ridge National
Laboratory) have been working
on techniques to measure the deposition of
mercury directly. More recently,
field studies have been conducted in
southern Florida, where mercury originating
from sugar farming practices is
suspected to be affecting coastal ecosystem
viability. Research Plans
Linkages within NOAA The ARL coastal studies program
is strongly linked with
the NOAA Chesapeake Bay Office of the National Marine
Fisheries Service.
The work is also tied to the NOAA Coastal Ocean Program, and
to coastal
activities of the National Ocean Service. The Chesapeake Bay
Air
Subcommittee (led by ARL) serves as an interface with all federal
agencies
involved in related research (EPA, DOD, DOE, DOI, DOA, NASA,
Smithsonian) as
well as with the air and water environmental components of
each of the states in
the Chesapeake Bay region (Delaware, New York,
Pennsylvania, Maryland, Virginia,
District of Columbia, West Virginia).
The NPS Air Resources Division synthesizes
information acquired through the
NPS air quality research and monitoring
programs, disseminates the
information to park personnel and managers, and works
with park personnel to
develop air quality related interpretive goals, themes,
projects and
activities. NPS interpretive programs serve to educate the park
visitor about
air resource by: Describing statutory authorities which help the
NPS
protect air resources. In 1983, barely a half dozen parks were using
air
quality information in interpretive/educational programs.