CAPITA REPORTS AND PAPERS
Below is a list of technical reports relevant to CAPITA. The reports can be physically located on any Web, FTP, or Gopher server.
This is a design document for a general purpose, distributed air quality data exploration and processing system. The system is to (1) facilitate easy access to web-based data servers, (2) allow multidimensional display and navigation through of air quality and meteorological data, and (3) serve as the a host for a rich set of built-in and user-supplied components for data processing and viewing. The data system is envisioned to evolve based on contributions from its users.
Spatial interpolation is frequently applied in estimating air pollutant concentrations. A common interpolation technique is the inverse distance weighted interpolation (1/r^n). Two general factors that influence the interpolation procedure are the type of data used and the "setting" of the interpolation, i.e. the number of stations used and the weighing factor. The data used in this work were hourly ozone concentrations from the EPA's Aerometric Information Retrieval System (AIRS) and Clean Air Status and Trends Network (CASTNet) networks for the eastern U.S. The uncertainty of the interpolation was tested from three perspectives, 1)comparison of the location setting (urban, suburban, rural) influence on the interpolation , 2)analysis of the number of stations used in the interpolation, and 3)evaluation of the effect of adding sites to the data set. The spatial interpolation procedure used performed adequately in estimating ozone concentrations in the eastern half of U.S. with R2 values ranging from 0.6 to 0.85. Using a maximum number of three or four ozone monitoring sites generally produced the best interpolation performance. The addition of CASTNet sites to the AIRS network did not show any substantial improvement in the interpolation results.
The purpose of this report is to present a comparative study of the aerosol light scattering - PM2.5 relationship using existing monitoring data. Light scattering - PM2.5 comparisons were conducted using standard correlation statistics, as well as temporal pattern analysis on yearly, monthly, and daily scales. This report also contains a brief discussion of the criteria by which the alternative monitoring techniques (PM2.5 mass concentration and fine particle light scattering) are to be evaluated as a suitable standard.
Air pollutants are generally measured at monitoring stations such as those comprising the AIRS (Aerometric Information Retrieval System) and IMPROVE (Interagency Monitoring of Protected Visual Environments) networks. In order to determine the concentrations at locations without monitors, some form of extrapolation or interpolation is required. Generally weighted interpolation is applied where the concentrations at surrounding sites are weighted dependent on their relative distance from the new concentration location. This type of interpolation does not account for such concentration dependent factors as elevation or wind direction. This work incorporates elevation into the interpolation scheme. Quarterly U.S. PM10 maps are derived using the new interpolation scheme.
This report describes the methodology used in deriving quarterly and annual fine particle maps for the US. The approach utilizes fine mass (<2.5 µm) concentration data from a 50 station regional monitoring network (IMPROVE/NESCAUM) as the measured "anchor points" for the derived maps. The spatial interpolation beyond the measured PM2.5 data is accomplished with the aid of extinction coefficients (Bext) derived from a 280 station visibility data set. Annual fine mass contour maps are given for 1987-89, 1990-92, and 1992 while quarterly maps are given for 1988-92. The approach uses novel data flow programming techniques for data processing and fusion.
Pollutant concentration data contained in EPA's Aerometric Information Retrieval System (AIRS) are required to be reported in units corrected to standard temperature and pressure (25 C, 760 mm Hg). The EPA is currently evaluating the clinical evidence to support retention of the requirement. This work analyzes the impact of a change from reporting PM10 concentrations at reference conditions to local temperature and pressure. The influence of pressure and temperature individually on the correction was examined over a seasonal time scale. The two correction factors were then combined to produce the total correction facotr and subsequently, the PM10 concentration maps at local conditions. The temperature correction was further inspected for purposes of determining the difference between quarterly and monthly aggregations.
This report covers Year 1 of the work performed by N. V. Gillani & Associates, Inc. (NVGA) under subcontract to Washington University (WU) in the EPA project entitled "Three-dimensional Monte Carlo Module for Interactive Trajectory Analysis". There were two NVGA Tasks in Year 1, as follows: 1. Evaluation of mesoscale meteorological models, including a description of the method of derivation of u', v', w' for use in the CAPITA Monte Carlo model ( as Met Processors 10 based on available met model outputs; and, 2. Review of plume rise formulas for major point sources, and selection of "best" choice for implementation in C-MC.
O estudo climatológico da qualidade do ar e da visibilidade no Grand Canyon tem como objetivo auxiliar a avaliação da extensão e das condições sob as quais a degradação da visibilidade ocorre nesta região, e investigar as interações a longo prazo entre o transporte das massas de ar e as medidas nos locais de amostragem.
This study was carried out to establish a visibility and air quality climatology for the Grand Canyon to help evaluate the extent and conditions under which the degradation of visibility occurs in the region, and to investigate long-term relationships between airmass transport and observations at the sampling sites.
A Monte Carlo model for the simulation of regional scale transport, transformation, and dry and wet removal is presented. The model was newly re-designed in a modular framework, separating the emissions, transport and kinetics calculations. The transport module employs a quantized Monte Carlo technique for the simulation of atmospheric boundary layer physics. Kinetic processes are simulated using rate equations where the rate coefficients are dependent upon meteorological variables, and thus vary in space and time. The rate coefficient equations are determined via a tuning process in which simulated values are compared to observed measurements. Results from simulations of SO4^2- and SO4^2- over the eastern US are presented for 1992. Comparisons of simulated daily SO4^2- concentrations to observations had r^2 = 0.35 - 0.83 depending on season and location, while for weekly SO4^2- wet deposition rates r^2 = 0.5 - 0.95. The utility of the model to investigate the source receptor relationship is demonstrated by explicitly examining the role of emission rates, transport, and kinetic processes in the attribution of sulfur dioxide and sulfate at a receptor in Massachusetts during the summer of 1992.
This chapter summarizes the concentrations of particulate matter over the US, including the spatial, temporal, size and chemical aspects. This chapter is aimed to support the quantification of particulate matter effects and to aid the PM standard setting process. The information needs for assessing the major aerosol effects of concern is summarized in Table 6.1. Depending on the effect, different aspects (dimensions) of aerosol concentrations are important. The effects on human health are considered most serious and this chapter is to provide relevant aerosol concentration information to help in quantifying these effects. Concern also exists for aerosol effects on visibility as well as damage to manmade materials.
The National Oceanic and Atmospheric Administration (NOAA) Advanced Very High-Resolution Radiometer (AVHRR) is a polar orbiting satellite that provides information on aerosol distributions based on backscatter radiation measurements that yield a measure of the "radiatively equivalent" aerosol optical thickness (EAOT) over the oceans. Seasonally-composited EAOT data for the period July 1989 to June 1991 reveal many spatially-coherent plume-like patterns that can usually be interpreted in terms of known (or reasonably-hypothesized) sources in association with climatological wind fields.
Tropospheric aerosols are the dispersing agents of many biogeochemically active substances, affect the global climate and interfere with human and electronic vision. Routine satellite monitoring of backscattered solar radiation over the oceans reveals that the highest aerosol signal is near the tropics where wind-blown dust and biomass combustion from Africa and southern Asia produce 5000 km long aerosol plumes. Further aerosol belts of marine origin are observed just north of the equator and at 30-60 latitudes in both hemispheres. The backscattering in the summer hemispheres exceed the winter values by a factor of 5 to 10. Thus, the global tropospheric aerosol is a dynamic collection of independent aerosol regions, with unique sources and temporal pattern.
During the past two years a previous Monte Carlo model was reimplemented onto the IBM-PC platform. This model was designed in a modular framework, separating the emissions, transport and kinetics calculations. The transport module employs a Monte Carlo technique for the simulation of atmospheric boundary layer physics. Kinetic processes are simulated using first order rate equations where the kinetic rate coefficients vary in space and time. The rate coefficients are determined via a tuning process comparing simulated and actual measurements. This paper presents the methodology used to implement the transport and kinetics processes; the architecture of the model addressing data flow and software implementation; and various applications including an initial tuning process for estimation of rate coefficients for the transformation and removal of SO2 and SO4 over the western U.S. during 1992.
Ecosystems consisting of producers, consumers and decomposers provide a metaphor for the flow of man-induced materials. Like the biosphere, humans are responsible for large-scale redistribution of chemicals on earth.
Pollutant concentration data contained in EPA's Aerometric Information Retrieval System (AIRS) are required to be reported in units corrected to standard temperature and pressure (25 C, 760 mm Hg). The EPA is currently evaluating the clinical evidence to support retention of the requirement. This work analyzes the impact of a change from reporting PM10 concentrations at reference conditions to local temperature and pressure. The influence of pressure and temperature individually on the correction was examined over a seasonal time scale. The two correction factors were then combined to produce the total correction facotr and subsequently, the PM10 concentration maps at local conditions. The temperature correction was further inspected for purposes of determining the difference between quarterly and monthly aggregations.
CAPITA REPORTS AND PAPERS