Sensitivity Analysis for the Remote Sensing of Methane using the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS)

Abstract:

Methane has a unique absorption signature in the shortwave infrared (SWIR) making it possible to detect methane using imaging spectrometers such as the Airborne Visible-Infrared Imaging Spectrometer (AVIRIS) or next generation version (AVIRIS-NG). Multiple techniques have been developed to identify the methane signal in spectra and map emissions from AVIRIS imagery. The spectral detection approach is applied to reflected radiance and therefore land cover and albedo directly affect the sensitivity of detection techniques to methane enhancement. In this paper, we evaluate the sensitivity of a cluster tuned matched filter and SWIR band ratio for methane detection while varying land cover type and albedo. Sensitivity analysis was performed using a synthetic AVIRIS scene consisting of 30 land cover types, 10 albedo values per type, and 10 methane concentrations distributed above the synthetic scene. We ran the cluster tuned matched filter and SWIR band ratio over the synthetic AVIRIS image and analyzed the results. Findings suggest that the SWIR band ratio is able to successfully detect methane anomalies independent of land cover and albedo while the cluster tuned matched filter is more dependent on the land cover and overall diversity within a scene. These results provide a better understanding of the sensitivity of methane detections over a range of surfaces and albedos. In addition this will also help us to begin to use remote sensing to not only qualitatively map the presence of methane anomalies but also quantitatively estimate methane fluxes.