Reducing Uncertainties of Molecular Line Intensities Via Cavity Ring-Down Spectroscopy Measurements and Ab Initio Calculations

Abstract

Remote sensing applications require accurate, precise, and traceable measurement science to meet demanding mission goals. Advances in laboratory spectroscopy and molecular line shapes have impressively reduced the uncertainty in satellite, aircraft, and ground-based field campaigns. This has enabled observation of spatially and temporally resolved trends of species such as CO 2 . However, the ambitious requirements of modern remote sensing missions place great demands on laboratory measurements and require state-of-the-art measurement science. Here we present some recent advances in frequency stabilized cavity ring-down spectroscopy (FS-CRDS) measurements of molecular line intensities of carbon dioxide, carbon monoxide, and water. These results are compared to existing spectroscopic databases and reveal that refinements are necessary to meet the accuracy targets for both ground-based and satellite-based remote sensing missions. These results are also compared to ab initio calculations, which may provide a route to directly link molecular absorptions measurements to the SI, without using calibrated gas reference mixtures or artifact standards.