Industrial smokestack plume emissions were remotely measured with a midwave infrared (1800-3000 cm(-1)) imaging Fourier-transform spectrometer operating at moderate spatial (128 × 64 with 19.4 × 19.4 cm(2) per pixel) and high spectral (0.25 cm(-1)) resolution over a 20 min period. Strong emissions from CO(2), H(2)O, SO(2), NO, HCl, and CO were observed. A single-layer plume radiative transfer model was used to estimate temperature T and effluent column densities q(i) for each pixel's spectrum immediately above the smokestack exit. Across the stack, temperature was uniform with T = 396.3 ± 1.3 K (mean ± stdev), and each q(i) varied in accordance with the plume path length defined by its cylindrical geometry. Estimated CO(2) and SO(2) volume fractions of 8.6 ± 0.4% and 380 ± 23 ppm(v), respectively, compared favorably with in situ measurements of 9.40 ± 0.03% and 383 ± 2 ppm(v). Total in situ NO(x) concentration (NO + NO(2)) was reported at 120 ± 1 ppm(v). While NO(2) was not spectrally detected, NO was remotely observed with a concentration of 104 ± 7 ppm(v). Concentration estimates for the unmonitored species CO, HCl, and H(2)O were 14.4 ± 0.3 ppm(v), 88 ± 1 ppm(v), and 4.7 ± 0.1%, respectively.

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The Telops Hyper-Cam midwave (InSb 1.5-5.5 μm) imaging Fourier-transform spectrometer observed the plume from a coal-burning power plant smokestack. From a distance of 600 meters, the plume was captured on a 128 × 64 pixel sub-window of the focal-plane array with each pixel imaging a 19.5 × 19.5 cm 2 region. Asymmetric interferograms were collected with long side and short side maximal optical path differences of 2.4 cm and 0.9 cm, respectively. Interferograms were recorded for each scan direction. The plume was strongly emissive across 1800-3000 cm −1 , and raw spectra revealed emissions from CO 2 , CO, H 2 O, NO, SO 2 , and HCl. A complete description of the instrument calibration and lineshape modeling is presented, including a simple and computationally efficient method of averaging spectra from forwardand reverse-scan interferograms that avoids the need to model a complex instrument lineshape. A simple radiative transfer model is developed to interpret the spectrum between 2565 ≤ν ≤ 3000 cm −1 . Examination of the HCl spectrum demonstrates exceptional agreement between the data and an ideal instrument lineshape. For a pixel immediately above the stack exit, the plume temperature is estimated to be 399.6 ± 0.6 K with an SO 2 concentration of 376 ± 10 ppm v , and these values agree well with in situ measurements of 407.0 ± 0.2 K and 383 ± 2 ppm v , respectively.

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