Stratospheric ozone depletion: A review of concepts and history

Abstract

Abstract. Stratospheric ozone depletion through catalytic chemistry involving man-made chlorofluorocarbons is an area of focus in the study of geophysics and one of the global environmental issues of the twentieth century. This review presents a brief history of the science of ozone depletion and describes a conceptual framework to explain the key processes involved, with a focus on chemistry. Observations that may be considered as evidence (fingerprints) of ozone depletion due to chlorofluorocarbons are explored, and the related gas phase and surface chemistry is described. Observations of ozone and of chlorine-related trace gases near 40 km provide evidence that gas phase chemistry has indeed currently depleted about 10% of the stratospheric ozone there as predicted, and the vertical and horizontal structures of this depletion are fingerprints for that process.

A decadal satellite record of gravity wave activity in the lower stratosphere to study polar stratospheric cloud formation

“…The particles provide the surface area for heterogeneous reactions that catalyze the conversion of chlorine from reservoir gases like ClONO 2 and HCl into active chlorine radicals, which accelerate ozone loss in the polar lower stratosphere in late winter and spring (Solomon et al, 1986;Solomon, 1999). Furthermore, the sedimentation of large cloud particles containing HNO 3 leads to the denitrification of the stratosphere, which in turn decreases NO 2 concentrations, increases ClO / ClONO 2 ratios, and accelerates chlorinecatalyzed ozone loss (Toon et al, 1986).…”

A multi-wavelength classification method for polar stratospheric cloud types using infrared limb spectra

“…Polar stratospheric clouds (PSCs) play an essential role in the depletion of stratospheric ozone (Solomon, 1999). Although they have been explored for more than 30 years, there are still many unanswered questions that limit our ability to predict R. Spang et al: A multi-wavelength classification method for polar stratospheric cloud types the formation and surface area of different PSCs and, consequently, the prediction of future polar ozone loss rates in a changing climate system.…”

“…The simpler schemes are frequently based on nitric acid trihydrate (NAT), although it is known that heterogeneous chemistry on super-cooled ternary solution (STS) and on cold binary aerosol particles probably dominates polar chlorine activations (e.g. Solomon, 1999;Drdla and Müller, 2012). The models usually do not include comprehensive microphysical modules to describe the evolution of different types of PSCs over the winter.…”

The Case of the Weak N−X Bond: Ab Initio, Semi-Experimental, and Experimental Equilibrium Structures of XNO (X = H, F, Cl, OH) and FNO2

“…Because the N-X bond is known to be weak, these species are easily photolyzed, yielding the radicals X (F, Cl, HO) that are important contributors to the depletion of the ozone layer. 1 HONO plays an important role in chemical dynamics and reaction kinetics studies. 3 HNO has been indicated 4 to have biological activity, joining NO and its oxidized congeners as small "inorganic" molecules vital for life.…”