Low frequency (<500 cm⁻¹) contribution to greenhouse gas radiative efficiency

Abstract

Radiative efficiency (RE) is a key climate metric used in the evaluation of a greenhouse gases global warming potential. However, experimental methods are commonly limited to measurements in the spectral region greater than ∼500 cm⁻¹. In this study, density functional theory with the wB97X-D/def2TZVPPD level of theory was employed to calculate the infrared absorption spectra and the contribution of the 0–500 cm⁻¹ spectral region to the total RE for the nearly 800 greenhouse gases, 20 different classes of primarily halogenated compounds, included in the World Meteorological Organization (WMO) Scientific Assessment of Ozone Depletion Annex [1]. In general, the results indicate that the contribution of the low-frequency regime to the total overall RE is not significant, < 2%, with a few exceptions, e.g. several compounds in the hydrocarbon class.

GRAPHICAL ABSTRACT

KEYWORDS:

• Density functional theory
• infrared absorption spectrum
• low-frequency
• global warming potential

Acknowledgements

This work was supported in part by NOAA’s Climate Program Office Atmospheric Chemistry, Carbon Cycle, and Climate Program and NASA’s Atmospheric Composition Program. The authors acknowledge the NOAA Research and Development High Performance Computing Program (http://rdhpcs.noaa.gov) for providing computing and storage resources that contributed to the research results reported within this paper.

Disclosure statement

No potential conflict of interest was reported by the author(s).