Revised UV absorption spectra, ozone depletion potentials, and global warming potentials for the ozone‐depleting substances CF2Br2, CF2ClBr, and CF2BrCF2Br

Abstract

The contribution of Halons, bromine‐containing haloalkanes, to stratospheric ozone depletion is highly dependent on their atmospheric lifetime, which is primarily determined by UV photolysis. In this work, UV absorption cross‐sections of the ozone‐depleting substances CF2Br2 (Halon‐1202), CF2ClBr (Halon‐1211), and CF2BrCF2Br (Halon‐2402) were measured between 300 and 350 nm over the temperature range 210–296 K using cavity ring‐down spectroscopy. Rayleigh scattering cross‐sections were also determined and utilized in the cross‐section determination. Spectra parameterizations are presented and 2‐D atmospheric model calculations were used to determine global annually averaged atmospheric lifetimes of 2.52, 16.4, and 28.3 years, ozone depletion potentials (ODPs) of 1.95, 8.1, and 18.4, global warming potentials (GWPs) of 175, 1940, and 2270 (100‐year time horizon), and associated uncertainties for CF2Br2, CF2ClBr, and CF2BrCF2Br, respectively. The revised lifetimes, ODPs, and GWPs differ from values currently reported in international assessments to evaluate ozone recovery and climate change.