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| Titel |
The response of surface ozone to climate change over the Eastern United States |
| VerfasserIn |
P. N. Racherla, P. J. Adams |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 8, no. 4 ; Nr. 8, no. 4 (2008-02-22), S.871-885 |
| Datensatznummer |
250005672
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| Publikation (Nr.) |
 copernicus.org/acp-8-871-2008.pdf |
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| Zusammenfassung |
| We investigate the response of surface ozone (O3) to future
climate change in the eastern United States by performing
simulations corresponding to present (1990s) and future (2050s)
climates using an integrated model of global climate, tropospheric
gas-phase chemistry, and aerosols. A future climate has been imposed
using ocean boundary conditions corresponding to the IPCC SRES A2
scenario for the 2050s decade. Present-day anthropogenic emissions
and CO2/CH4 mixing ratios have been used in both
simulations while climate-sensitive emissions were allowed to vary
with the simulated climate. The severity and frequency of O3
episodes in the eastern U.S. increased due to future climate change,
primarily as a result of increased O3 chemical production. The
95th percentile O3 mixing ratio increased by 5 ppbv and the
largest frequency increase occured in the 80–90 ppbv range; the US
EPA's current 8-h ozone primary standard is 80 ppbv. The
increased O3 chemical production is due to increases in: 1)
natural isoprene emissions; 2) hydroperoxy radical concentrations
resulting from increased water vapor concentrations; and, 3) NOx
concentrations resulting from reduced PAN. The most substantial and
statistically significant (p<0.05) increases in episode
frequency occurred over the southeast and midatlantic U.S., largely
as a result of 20% higher annual-average natural isoprene
emissions. These results suggest a lengthening of the O3 season
over the eastern U.S. in a future climate to include late spring and
early fall months. Increased chemical production and shorter average
lifetime are two consistent features of the seasonal response of
surface O3, with increased dry deposition loss rates contributing
most to the reduced lifetime in all seasons except summer.
Significant interannual variability is observed in the frequency of
O3 episodes and we find that it is necessary to utilize 5 years
or more of simulation data in order to separate the effects of
interannual variability and climate change on O3 episodes in the
eastern United States. |
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