Air Quality



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Air Quality & Dispersion
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.

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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

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