Grantee Research Project Results
1999 Progress Report: Orthogonal Background Suppression Technique for EPA's Field Infrared Data Processing
EPA Grant Number: R825366Title: Orthogonal Background Suppression Technique for EPA's Field Infrared Data Processing
Investigators: Blatherwick, R. D.
Institution: University of Denver
EPA Project Officer: Hahn, Intaek
Project Period: October 1, 1996 through September 30, 1999 (Extended to September 30, 2000)
Project Period Covered by this Report: October 1, 1998 through September 30, 1999
Project Amount: $248,743
RFA: Analytical and Monitoring Methods (1996) RFA Text | Recipients Lists
Research Category: Water , Land and Waste Management , Air , Ecological Indicators/Assessment/Restoration , Environmental Statistics
Objective:
This project is intended to develop methods and user-friendly tools that can be used to extract information on pollutant gases from FTIR spectra obtained at field sites having highly variable concentrations of background water vapor.Progress Summary:
During the reporting period, work continued on the investigation and development of methods of identifying and quantifying gaseous pollutants from infrared spectral data recorded at field sites. The mathematical technique of singular value decomposition (SVD), which had been studied in the previous reporting period, was further investigated and techniques developed for generating orthogonal vectors from the infrared spectra of potential pollutants. These vectors can then be used to identify and quantify pollutant gases by the vector operation of evaluating the scalar product (or "dot product") between the orthogonal vector and a field spectrum. If there is none of the suspected pollutant in the field spectrum, then the scalar product is zero, or nearly zero, and if the pollutant spectral signature is in the field data, then the magnitude of the scalar product is proportional to the amount of pollutant present.An additional technique, model matching, also was investigated. In this technique, one uses a computer model to generate synthetic spectral data that match the field data. By comparing the model to the field spectra, spectral signatures arising from pollutant gases present in the field data, but not included in the model, can be isolated for further investigation and identification. This method is somewhat more traditional than the SVD method discussed above, but it is much more time consuming and computationally intensive. However, it has the advantage that it does not require a large set of pollutant-free background data, as is generally required for the SVD technique.
Future Activities:
During the next 3 months, we will record and process a set of infrared laboratory spectra of water vapor at several different temperatures and use the results to validate (to the extent possible) the existing molecular line parameter data used in the computer modeling of the atmospheric spectrum of this important molecule.Journal Articles:
No journal articles submitted with this report: View all 1 publications for this projectSupplemental Keywords:
principal component factor analysis, line-by-line radiative transfer model., RFA, Scientific Discipline, Air, Toxics, Ecosystem Protection/Environmental Exposure & Risk, Environmental Chemistry, Chemistry, HAPS, Monitoring/Modeling, tropospheric ozone, Engineering, environmental monitoring, orthogonal background suppression, remote sensing, ambient particle properties, field portable monitoring, ambient air, spectroscopic studies, air quality data, analytical chemistry, FTIR, carbon dioxide, spectroscopic, atmospheric monitoring, water vapor, measurement methods , aerosol analyzers, atmospheric chemistry, Fourier transform infraredProgress and Final Reports:
Original AbstractThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.