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| Titel |
A global model simulation of present and future nitrate aerosols and their direct radiative forcing of climate |
| VerfasserIn |
D. A. Hauglustaine, Y. Balkanski, M. Schulz |
| 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 ; 14, no. 20 ; Nr. 14, no. 20 (2014-10-21), S.11031-11063 |
| Datensatznummer |
250119110
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| Publikation (Nr.) |
 copernicus.org/acp-14-11031-2014.pdf |
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| Zusammenfassung |
| The ammonia cycle and nitrate particle formation are introduced into the
LMDz-INCA (Laboratoire de Météorologie
Dynamique, version 4 – INteraction with Chemistry and
Aerosols, version 3) global model. An important aspect of this new model is that both
fine nitrate particle formation in the accumulation mode and coarse nitrate
forming on existing dust and sea-salt particles are considered. The model
simulates distributions of nitrates and related species in agreement with
previous studies and observations. The calculated present-day total nitrate
direct radiative forcing since the pre-industrial is −0.056 W m−2.
This forcing corresponds to 18% of the sulfate forcing. Fine particles
largely dominate the nitrate forcing, representing close to 90% of this
value. The model has been used to investigate the future changes in nitrates
and direct radiative forcing of climate based on snapshot simulations for the
four representative concentration pathway (RCP) scenarios and for the 2030,
2050, and 2100 time horizons. Due to a decrease in fossil fuel emissions in
the future, the concentration of most of the species involved in the
nitrate–ammonium–sulfate system drop by 2100 except for ammonia, which
originates from agricultural practices and for which emissions significantly
increase in the future. Despite the decrease of nitrate surface levels in
Europe and North America, the global burden of accumulation mode nitrates
increases by up to a factor of 2.6 in 2100. This increase in ammonium nitrate
in the future arises despite decreasing NOx emissions due to
increased availability of ammonia to form ammonium nitrate. The total aerosol
direct forcing decreases from its present-day value of −0.234 W m−2
to a range of −0.070 to −0.130 W m−2 in 2100 based on the
considered scenario. The direct forcing decreases for all aerosols except for
nitrates, for which the direct negative forcing increases to a range of
−0.060 to −0.115 W m−2 in 2100. Including nitrates in the
radiative forcing calculations increases the total direct forcing of aerosols
by a factor of 1.3 in 2000, by a factor of 1.7–2.6 in 2030, by 1.9–4.8 in
2050, and by 6.4–8.6 in 2100. These results show that the agricultural emissions
of ammonia will play a key role in the future mitigation of climate change,
with nitrates becoming the dominant contributor to the anthropogenic aerosol
optical depth during the second half of the 21st century and significantly
increasing the calculated aerosol direct forcing. This significant increase
in the influence that nitrate exerts on climate in the future will at the
same time affect regional air quality and nitrogen deposition to the
ecosystem. |
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