CBrF3 (Halon-1301): UV absorption spectrum between 210 and 320 K, atmospheric lifetime, and ozone depletion potential

• CBrF3 (Halon-1301) UV absorption spectrum measurement.
• Evaluation of the absorption spectrum temperature dependence.
• Reduced uncertainty in the model calculated Halon-1301 atmospheric lifetime and ozone depletion potential.

CBrF3 (Halon-1301) is a man-made ozone depleting substance that is a major source of bromine in the Earth’s stratosphere. Halon-1301 is predominantly removed from the atmosphere by UV photolysis in the stratosphere at wavelengths between 200 and 225 nm. The existing level of uncertainty in the Halon-1301 UV absorption spectrum temperature-dependence directly impacts the ability to model stratospheric ozone chemistry and climate change. In this work, the UV absorption spectrum of Halon-1301 between 195 and 235 nm was measured over the temperature range 210–320 K. An empirical parameterization of the spectrum and its temperature dependence is presented. The present results are critically compared with results from previous studies and the current recommendation for use in atmospheric models. A global annually averaged lifetime for Halon-1301 of 74.6 (73.7–75.5) years was calculated using a 2-D atmospheric model and the present results. The range of lifetimes given in parenthesis represents the possible values due solely to the 2σ uncertainty in the Halon-1301 UV spectrum obtained in this work. In addition, the CBrF3 ozone depletion potential was calculated using the 2-D model to be 18.6 (±0.1) using the UV spectrum and 2σ uncertainty from this work.

Figure optionsDownload as PowerPoint slide