Air Quality Essay, Research Paper

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.

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 ([email protected])

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 ([email protected])

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 ([email protected])

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 ([email protected])

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 ([email protected])

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 — [email protected]

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 — [email protected]

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 — [email protected]

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 — [email protected]

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 — [email protected]

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 — [email protected]

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 — [email protected]

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).

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.