We introduce a novel approach that casts a linear inverse problem for species concentration tomography from spectral data such as those acquired in wavelength modulation spectroscopy or direct absorption spectroscopy. Under isobaric measurement conditions and known plume temperature, our technique leads to a linear well-posed estimation problem for an extended data set derived from the direct absorption spectroscopy measurements. This allows imaging the concentration with enhanced noise

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... ss and spatial resolution that is significantly higher compared to previous methods for the same number of optical paths. We demonstrate the performance of our approach through proof-of-concept simulation for a carbon dioxide tomographic measurement.