Antarctic ozone: Theory and observation [microform]
- Bib ID:
- 3282936
- Format:
- Book and Microform
- Author:
- Salawitch, Ross Jay
- Description:
- 258 p.
- Summary:
-
The amount of ozone observed in October over Antarctica has fallen steadily and precipitously in the last decade. Observational data describing the phenomenology of the Antarctic ozone reduction are reviewed, followed by the presentation of theories that seek to account for the observed ozone reductions while satisfying other available constraints. We begin with a discussion of the thermodynamic properties of solid phases containing HCl and HNO$\sb3$. The presence of clouds in the Antarctic stratosphere, caused be extremely low temperatures during spring, leads to condensation and precipitation of HNO$\sb3$, and condensation and reaction of HCl. Both processes lead to the conversion of unreactive forms of chlorine to chlorine oxides, which participate in a sequence of chemical reactions that consume ozone.
A chemical model that incorporates the influence of cloud catalyzed heterogeneous reactions is compared in detail to the interferometric measurements of HCl, ClNO$\sb3$, HNO$\sb3$, NO$\sb2$, and NO obtained over Antarctica during the spring of 1986 (Farmer et al., 1987). Model results are consistent with observed temporal trends of these species and with trends for total column ozone reported by Stolarski et al. (1986). Loss of ozone is attributed to the catalytic influence of chlorine and bromine radicals, in cycles suggested by McElroy et al. (1986b) and Molina and Molina (1987). Constraints are then placed on the abundance of stratospheric bromine by analysis of observations of OClO over Antarctica during the spring of 1986 (Solomon et al., 1987a). The diurnal variation of OClO is consistent with 16 $\pm$ 4 ppt of stratospheric bromine if a fraction of the overall ClO + BrO reaction proceeds through a channel resulting in the production of BrCl.
Bromine levels in this range would contribute approximately 20% of the total ozone loss. Finally, it is shown that the production of reactive chlorine oxides by heterogeneous processes depends on the initial concentration of HCl relative to the total amount of nitrogen oxides prior to the onset of condensation. Once HCl exceeds a critical value, the end products of the heterogeneous reactions are rapidly converted to chlorine oxide radicals. The onset of Antarctic ozone depletion in the late 1970s may in part reflect growth of HCl levels beyond this threshold.
- Notes:
-
- (UnM)AAI8901637
- Source: Dissertation Abstracts International, Volume: 49-10, Section: B, page: 4370.
- Thesis (Ph.D.)--Harvard University, 1988.
- Reproduction:
- Microfiche. Ann Arbor, Mich.: University Microfilms International.
- Subject:
- Physics, Atmospheric Science
- Other authors/contributors:
- Harvard University
- Copyright:
-
In Copyright
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Copyright status was determined using the following information:
- Material type:
- Literary Dramatic Musical
- Published status:
- Unpublished
- Creation date:
- 1988
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