Citation:

EDER, B. K., J. E. Sickles II, AND D. S. SHADWICK. A PRINCIPAL COMPONENT ANALYSIS OF THE CLEAN AIR STATUS AND TRENDS NETWORK (CASTNET) AIR CONCENTRATION DATA. Presented at Air & Waste Management Association Environmental Conference, Oakabrook, IL, October 04 - 05, 2005.

Impact/Purpose:

The framework of accountability is based on measuring environmental outcomes using an integrated environmental assessment model - - assessing and documenting relationships between emissions, air quality, atmospheric deposition, and effects to public health and ecosystems. Work in AMD will focus on relating changes in emissions to changes in environmental conditions prospectively, and the retrospective attribution of observable improvements in environmental conditions to specific emission control strategies.

1.Emission reductions observed in ambient air and atmospheric deposition

Since the 1990 Clean Air Act Amendments, a greater number of stationary sources of SO2 and NOx emissions have installed continuous emissions monitoring systems. Improved systems for tracking emissions from mobile sources have also been developed. At this level, an accountability framework provides a bridge between measured emission reductions and changes in the ambient environment. Resources under this initiative would be applied to analyze specific primary and transformed emission products in ambient air and in atmospheric deposition (e.g., nitrogen oxide, particle nitrate) over relevant geographic areas.

2.Predicted air quality and atmospheric deposition improvements

Resources would be applied to enhance the predictive capability to address whether emissions reductions have resulted in the expected improvements in air quality and deposition, for example:

Reduced ozone, PM2.5 concentrations

Reduced deposition of NOx transformations (e.g., wet and dry deposition of nitrate)

Diagnostic species (e.g., peroxides, nitric acid, ammonia) useful for model evaluations and interpreting dynamic changes in the atmosphere associated emissions reductions

In addition to assessing whether the improvements have occurred, this would also entail assessing whether these improvements can be attributed to specific emission control strategies.This team's objective is to research and develop analytical tools that will quantify the effect of regional NOx emission reductions on ambient air quality, thus providing a measure of control stategy accountability.

Description:

The spatial and temporal variability of ambient air concentrations of SO₂, SO₄^2-, NO₃, HNO₃, and NH₄⁺ obtained from EPA's CASTNet was examined using an objective, statistically based technique called rotated principal component analysis. This analysis, which covered most of the time period from 2 January 1990 through 31 December 2002 has allowed for the identification and subsequent characterization of homogeneous "influence regimes" associated with each of the species. This identification of homogeneity across sites has added to the "weight of evidence" supporting regionality of behavior of species, which have historically been difficult to estimate and understand because of complicating factors - both meteorological and chemical.

Record Details:

Record Type:DOCUMENT( PRESENTATION/ EXTENDED ABSTRACT)

Product Published Date:10/04/2005

Record Last Revised:10/30/2006

Record ID: 143123

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Acronyms:

Title :A PRINCIPAL COMPONENT ANALYSIS OF THE CLEAN AIR STATUS AND TRENDS NETWORK (CASTNET) AIR CONCENTRATION DATA

Version :1.0

Acronym :CASTNET

Acronym Meaning :Clean Air Status and Trends Network