High-Accuracy Near-Infrared Carbon Dioxide Intensity Measurements to Support Remote Sensing

Abstract

Two cavity ring-down spectrometers were employed to accurately measure line intensities in a series of near-infrared carbon dioxide bands including (30012) ← (00001), (30013) ← (00001), and (30014) ← (00001) near 1.6 μm. Relative combined standard uncertainties for these band intensities were less than 0.1% and showed significant, percent-level deviations with respect to many existing spectroscopic databases (although close agreement was observed with the HITRAN 2016 database in the (30013) ← (00001) and (30014) ← (00001) bands). Further, the resulting line intensities were utilized in Total Carbon Column Observing Network retrievals and led to significantly reduced biases in the (30012) ← (00001) and (30013) ← (00001) bands. These results indicate that refinements of spectroscopic databases are required to meet the accuracy targets of both ground- and satellite-based remote sensing missions.