A two-dimensional model with coupled dynamics, radiative transfer, and photochemistry 2. Assessment of the response of stratospheric ozone to increased levels of CO{sub 2}, N{sub 2}O, CH{sub 4}, and CFC
- Havard Univ., Cambridge, MA (United States)
- Atmospheric and Environmental Research, Inc., Cambridge, MA (United States)
The impact of increased levels of carbon dioxide (CO{sub 2}), chlorofluorocarbons (CFCs), and other trace gases on stratospheric ozone is investigated with an interactive, two-dimensional model of gas phase chemistry, dynamics, and radiation. The scenarios considered are (1) a doubling of the CO{sub 2} concentration, (2) increases of CFCs, (3) CFC increases combined with increases of nitrous oxide (N{sub 2}O) and methane CH{sub 4}, and (4) the simultaneous increase of CO{sub 2}, CFCs, N{sub 2}O, and CH{sub 4}. The radiative feedback and the effect of temperature and circulation changes are studied for each scenario. For the double CO{sub 2} calculations the tropospheric warming was specified. The CO{sub 2} doubling leads to a 3.1% increase in the global ozone content. Doubling of the CO{sub 2} concentrations would lead to a maximum cooling of about 12{degrees}C at 45 km if the ozone concentration were held fixed. The cooling of the stratosphere leads to an ozone increase with an associated increase in solar heating, reducing the maximum temperature drop by about 3{degrees}C. The CFC increase from continuous emissions at 1985 rate causes a 4.5% loss of ozone. For the combined perturbation a net loss of 1.3% is calculated. The structure of the perturbations shows a north-south asymmetry. Ozone losses (when expressed in terms of percent changes) are generally larger in the high latitudes of the southern hemisphere as a result of the eddy mixing being smaller than in the northern hemisphere. Increase of chlorine leads to ozone losses above 30 km altitude where the radiative feedback results in a cooler temperature and an ozone recovery of about one quarter of the losses predicted with a noninteractive model. In all the cases, changes in circulation are small. In the chlorine case, circulation changes reduce the calculated column depletion by about one tenth compared to offline calculations. 19 refs., 12 figs., 1 tab.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 160382
- Journal Information:
- Journal of Geophysical Research, Vol. 98, Issue D11; Other Information: PBD: 20 Nov 1993
- Country of Publication:
- United States
- Language:
- English
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