Comment on “Effects of Cosmic Rays on Atmospheric Chlorofluorocarbon Dissociation and Ozone Depletion”

Cosmic-ray-driven electron-induced reactions of halogenated molecules adsorbed on ice surfaces: Implications for atmospheric ozone depletion and global climate change

“…Atmospheric chemists have concerns about how CFCs and other halogenated molecules could be adsorbed on ice particles in PSCs [128]. However, it is known to surface scientists that although CFCs are not sticky to the static surfaces of H 2 O ice at the stratospheric temperature under the vacuum condition, dynamical and other physical properties of ice surfaces under polar stratospheric conditions can make a drastic difference, causing adsorption, diffusion and trapping of molecules into ice.…”

“…In current content of atmospheric chemistry, "air descending" is attributed to be responsible for the concentration decreases of CFCs and some photo-inactive "tracer" gases such as N 2 O and CH 4 , and thus any physical/chemical processes for CFCs are excluded for the winter polar stratosphere [37,128]. However, two major problems with this assignment must be addressed.…”

Impact of Cosmic Rays on Stratospheric Chlorine Chemistry and Ozone Depletion

“…They suggest that the physical basis of these observations is dissociative electron attachment (DEA) to CFC on the surface of PSC particles, due to cosmic-ray radiation that causes CFC-11 and CFC-12 to be rapidly destroyed in the winter polar stratosphere at altitudes below 20 km. This view has been criticized by the argument that the observed CFC distribution in the stratosphere can be explained by known transport and chemical processes [11,12]. Furthermore, it was questioned whether a correlation actually exists between the observed ozone loss and cosmic-ray activity [11] and what the impact of DEAinduced degradation of CFC would be on estimates of the recovery of the ozone hole [12].…”

“…This view has been criticized by the argument that the observed CFC distribution in the stratosphere can be explained by known transport and chemical processes [11,12]. Furthermore, it was questioned whether a correlation actually exists between the observed ozone loss and cosmic-ray activity [11] and what the impact of DEAinduced degradation of CFC would be on estimates of the recovery of the ozone hole [12]. Here, the question of a relation between PSC occurrence, cosmic-ray flux, CFC degradation, and stratospheric ozone depletion is revisited.…”

Comment on “Resonant dissociative electron transfer of the presolvated electron to CCl4 in liquid: Direct observation and lifetime of the CCl4∗− transition state” [J. Chem. Phys. 128, 041102 (2008)]

“…The importance of DEA for stratospheric polar ozone loss is indeed put forward in several papers, 4-6 but this view was criticized on the basis of the argument that no significant correlation exists between polar column ozone levels and cosmic ray intensity, 12,13 and that both observed CFC distributions and observed CFC-N 2 O correlations in the polar stratosphere are inconsistent with a destruction of CFC on PSC surfaces by DEA. [12][13][14] Furthermore, model calculations of polar ozone chemistry implementing 13 the mechanism of CFC destruction of Lu and Sanche 6 demonstrated that this mechanism can only have a limited impact on polar chemical ozone loss. However, DEA-induced destruction of HCl on PSC surfaces potentially has some influence on stratospheric polar chlorine chemistry.…”