 |
| Titel |
Simulation of stratospheric water vapor trends: impact on stratospheric ozone chemistry |
| VerfasserIn |
A. Stenke, V. Grewe |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1680-7316
|
| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 5, no. 5 ; Nr. 5, no. 5 (2005-05-31), S.1257-1272 |
| Datensatznummer |
250002808
|
| Publikation (Nr.) |
 copernicus.org/acp-5-1257-2005.pdf |
|
|
|
|
|
| Zusammenfassung |
| A transient model simulation of the 40-year time period 1960 to 1999
with the coupled climate-chemistry model (CCM) ECHAM4.L39(DLR)/CHEM shows a
stratospheric water vapor increase over the last two decades of
0.7 ppmv and, additionally, a short-term increase after major
volcanic eruptions. Furthermore, a long-term decrease in global
total ozone as well as a short-term ozone decline in the tropics
after volcanic eruptions are modeled. In order to understand the
resulting effects of the water vapor changes on lower stratospheric
ozone chemistry, different perturbation simulations were performed
with the CCM ECHAM4.L39(DLR)/CHEM feeding the water vapor perturbations only to the
chemistry part. Two different long-term perturbations of lower
stratospheric water vapor, +1 ppmv and +5 ppmv, and a
short-term perturbation of +2 ppmv with an e-folding time of
two months were applied. An additional stratospheric water vapor
amount of 1 ppmv results in a 5–10% OH increase in
the tropical lower stratosphere between 100 and 30 hPa. As a
direct consequence of the OH increase the ozone destruction by the
HOx cycle becomes 6.4% more effective. Coupling processes
between the HOx-family and the NOx/ClOx-family also affect the
ozone destruction by other catalytic reaction cycles. The NOx cycle
becomes 1.6% less effective, whereas the effectiveness of
the ClOx cycle is again slightly enhanced. A long-term water vapor
increase does not only affect gas-phase chemistry, but also
heterogeneous ozone chemistry in polar regions. The model results
indicate an enhanced heterogeneous ozone depletion during antarctic
spring due to a longer PSC existence period. In contrast, PSC formation in
the northern hemisphere polar vortex and therefore heterogeneous
ozone depletion during arctic spring are not affected by the water
vapor increase, because of the less PSC activity. Finally, this
study shows that 10% of the global total ozone decline in
the transient model run can be explained by the modeled water vapor
increase, but the simulated tropical ozone decrease after volcanic
eruptions is caused dynamically rather than chemically. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|