NF3: UV absorption spectrum temperature dependence and the atmospheric and climate forcing implications

Nitrogen trifluoride, NF3, is an atmospherically persistent greenhouse gas that is primarily removed by UV photolysis and reaction with O(1D) atoms. In this work, the NF3 gas-phase UV absorption spectrum, σ(λ,T), was measured at 16 wavelengths between 184.95 and 250 nm at temperatures between 212 and 296 K. A significant spectrum temperature dependence was observed in the wavelength region most relevant to atmospheric photolysis (200-220 nm) with a decrease in σ(210 nm,T) of ~45% between 296 and 212 K. Atmospheric photolysis rates and global annually averaged lifetimes of NF3 were calculated using the Goddard Space Flight Center (GSFC) 2D model and the σ(λ,T) parameterization developed in this work. Including the UV absorption spectrum temperature dependence increased the stratospheric photolysis lifetime from 610 to 762 years and the total global lifetime from 484 to 585 years; the NF3 global warming potentials (GWPs) on the 20-, 100-, and 500-year time horizons increased <0.3, 1.1, and 6.5% to 13300, 17700, and 19700, respectively.