Understanding the influence of turbulence in imaging Fourier transform spectroscopy of smokestack plumes

Jennifer L. Massman; Kevin C. Gross

doi:10.1117/12.883197

20 May 2011 Understanding the influence of turbulence in imaging Fourier transform spectroscopy of smokestack plumes

Jennifer L. Massman, Kevin C. Gross

Proceedings Volume 8048, Algorithms and Technologies for Multispectral, Hyperspectral, and Ultraspectral Imagery XVII; 80480A (2011) https://doi.org/10.1117/12.883197
Event: SPIE Defense, Security, and Sensing, 2011, Orlando, Florida, United States

Abstract

A Telops Hyper-Cam Fourier-transform spectrometer (IFTS) was used to collect infrared hyper-spectral imagery of the smokestack plume from a coal-burning power facility to assess the influence of turbulence on spectral retrieval of temperature (T) and pollutant concentrations (C_i ). The mid-wave (1.5-5.5 μm) system features a 320x256 InSb focal-plane array with a 326 μrad instantaneous field-of-view (IFOV). The line-of-sight distance to the 76mtall smokestack exit was 350m(11.4 x 11.4 cm² IFOV). Approximately 5000 interferogram cubes were collected in 30 minutes on a 128x128 pixel window corresponding to a spectral resolution of 20 cm^-1. Radiance fluctuations due to plume turbulence were observed on a time scale much shorter than hyper-spectral image acquisition rate, suggesting scene change artifacts (SCA) would be present in the Fourier-transformed spectra. Time-averaging the spectra minimized SCA magnitudes, but accurate T and C_i retrieval requires a priori knowledge of the statistical distribution of temperature and other stochastic flow field parameters. A method of quantile sorting in interferogram space prior to Fourier-transformation is presented and used to identify turbulence throughout the plume. Immediately above the stack exit, T and CO₂ concentration estimates from the median spectrum are 395 K and 6%, respectively, which compare well to in situ measurements. Turbulence is small above the stack exit and introduced systematic errors in T and C_i on the order of 0.5 K and 0.01%, respectively. In some plume locations, turbulent fluctuations introduced errors in T and C_i on the order of 8 K and 1%, respectively. While more complicated radiance fluctuations precluded straightforward retrieval of the temperature probability distribution, the results demonstrate the utility of additional information content associated with multiple interferogram quantiles and suggest IFTS may find use as a tool for non-intrusive flow field analysis.

Citation Download Citation

Jennifer L. Massman and Kevin C. Gross "Understanding the influence of turbulence in imaging Fourier transform spectroscopy of smokestack plumes", Proc. SPIE 8048, Algorithms and Technologies for Multispectral, Hyperspectral, and Ultraspectral Imagery XVII, 80480A (20 May 2011); https://doi.org/10.1117/12.883197

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available