Spatial distribution of atmospheric CO2 absorption detected around 2 µm on the reflectance spectra derived from Hyperion images

This study explores the detectability of atmospheric carbon dioxide (CO₂) absorption at the short wave infrared bands of Hyperion EO-1 hyperspectral images. Two CO₂ absorption bands at around 2.002–2.012 and 2.052 µm, respectively, were identified on the reflectance spectra derived from the images. Considering the principle of differential optical absorption spectroscopy (DOAS) and assuming the O₂-A band around 0.762 µm as reference, the spatial variation of the column density was estimated for Kolkata, a region around 22° 31′ N 88° 21′ E. The ratio of the individual absorption depth of CO₂ to that of O₂, instead of the ratio of their column density, was found to be more suitable to express the spatial distribution of CO₂ concentration over short distance, of the order of metres. The methodology was validated with Orbiting Carbon Observatory-2 (OCO-2) data. The work suggests the inclusion of 2–3 narrowband channels corresponding to O₂-A and CO₂ absorptions in future moderate resolution multispectral sensors in order to facilitate the monitoring of atmospheric CO₂.