Remote detection of methane by infrared spectrometry for airborne pipeline surveillance: first results of ground-based measurements

The total length of natural gas pipelines in Germany exceeds 350,000 km. Currently, inspections are performed using hand-held sensors such as flame ionization detectors. Moreover, transmission pipelines are inspected visually from helicopters. In this work, remote detection of methane by passive Fourier-transform infrared (FTIR) spectrometry for pipeline surveillance is investigated. The study focuses on fast measurements in order to enable methane detection from a helicopter during regular inspection flights. Two remote sensing systems are used for the detection of methane: a scanning infrared gas imaging system (SIGIS), which was originally developed for the visualization of pollutant clouds, and a new compact passive scanning remote sensing system. In order to achieve a high spectral rate, which is required due to the movement of the helicopter, measurements are performed at low spectral resolutions. This results in overlapping signatures of methane and other constituents of the atmosphere in the measured spectrum. The spectra are analyzed by a detection algorithm, which includes simultaneous least squares fitting of reference spectra of methane and other atmospheric species. The results of field measurements show that passive remote sensing by FTIR spectrometry is a feasible method for the remote detection of methane.

[1]  Roger J. Combs.  Thermal stability evaluation for passive FTIR spectrometry , 1999 .

[2]  D. Flanigan.  Detection of organic vapors with active and passive sensors: a comparison. , 1986, Applied optics.

[3]  R. Beer.  Remote Sensing by Fourier Transform Spectrometry , 1992 .

[4]  D. Flanigan.  Prediction of the limits of detection of hazardous vapors by passive infrared with the use of modtran. , 1996, Applied optics.

[5]  Roland Harig,et al.  Scanning infrared remote sensing system for identification, visualization, and quantification of airborne pollutants , 2002, SPIE Optics East.

[6]  Roland Harig,et al.  Remote sensing of atmospheric pollution by passive FTIR spectrometry , 1998, Remote Sensing.

[7]  Laurence S. Rothman,et al.  The HITRAN molecular spectroscopic database and HAWKS (HITRAN atmospheric workstation) , 1998, Defense, Security, and Sensing.

[8]  F. X. Kneizys,et al.  FASCODE - Fast Atmospheric Signature Code (Spectral Transmittance and Radiance) , 1978 .

[9]  R. Harig,et al.  Toxic cloud imaging by infrared spectrometry: A scanning FTIR system for identification and visualization , 2001 .

[10]  Peter R. Griffiths,et al.  Fourier Transform spectrometry at low resolution: how low can you go? , 1994, Other Conferences.

[11]  D. Flanigan,et al.  Vapor-detection sensitivity as a function of spectral resolution for a single Lorentzian band. , 1995, Applied optics.

[12]  Roland Harig,et al.  Passive remote sensing of pollutant clouds by FTIR spectrometry: Signal-to-noise ratio as a function of spectral resolution , 2004 .

[13]  Laurence S. Rothman,et al.  Reprint of: The HITRAN molecular spectroscopic database and HAWKS (HITRAN Atmospheric Workstation): 1996 edition , 1998 .

[14]  H Mosebach,et al.  Mobile Fourier-transform infrared spectroscopy monitoring of air pollution. , 1994, Applied optics.

[15]  J. Thériault,et al.  Modeling the responsivity and self-emission of a double-beam Fourier-transform infrared interferometer. , 1999, Applied optics.