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Infrared Degenerate Four-wave Mixing with Upconversion Detection for Quantitative Gas Sensing
Published on: March 22, 2019
Developing and evaluating techniques for localizing pollutant emission sources with open-path Fourier transform
Chang-Fu Wu1, Ching-Hui Chen, Shih-Ying Chang
1Department of Public Health and Institute of Occupational Medicine and Industrial Hygiene, National Taiwan University, Taipei, Taiwan, Republic of China. changfu@ntu.edu.tw
Journal of the Air & Waste Management Association (1995)
|October 23, 2008
Summary
Two methods using open-path Fourier transform infrared (OP-FTIR) spectroscopy were evaluated for localizing pollutant emission sources. Both simulation and field tests showed comparable performance, with one method being easier to implement.
Area of Science:
- Environmental Science
- Analytical Chemistry
- Spectroscopy
Background:
- Accurate localization of pollutant emission sources is crucial for environmental monitoring and regulatory compliance.
- Open-path Fourier transform infrared (OP-FTIR) spectroscopy offers a non-invasive method for detecting and quantifying atmospheric pollutants over extended paths.
Purpose of the Study:
- To evaluate and compare two distinct approaches for localizing pollutant emission sources using OP-FTIR data.
- To assess the performance of these methods through both simulated data and field experiments.
Main Methods:
- Developed and simulated two source localization algorithms: one combining Smooth Basis Function Minimization (SBFM) with wind data, and another using Monte Carlo sampling.
- Investigated the impact of different basis functions (beta, Weibull, normal) within the SBFM algorithm on peak location accuracy.
- Conducted field experiments releasing two tracer gases and collecting OP-FTIR data downwind.
Main Results:
- Simulation studies indicated that beta and Weibull basis functions in SBFM were generally better for plumes within the monitoring line, while the normal function performed better for symmetric or spread plumes.
- In field tests, the first approach achieved source localization within a 0.25- to 0.5-probability area when peak location uncertainty was considered.
- The second, Monte Carlo-based approach was simpler to implement and yielded comparable results, with estimated source locations within 10 m of the actual sources.
Conclusions:
- Both evaluated OP-FTIR-based methods are viable for pollutant source localization, with the Monte Carlo approach offering ease of implementation and satisfactory performance.
- The choice of basis function in SBFM is critical and depends on plume characteristics relative to the OP-FTIR path.
- Accurate source localization is achievable with OP-FTIR, contributing to effective environmental management strategies.
