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| Titel |
Contribution of ammonium nitrate to aerosol optical depth and direct radiative forcing by aerosols over East Asia |
| VerfasserIn |
R. S. Park, S. Lee, S.-K. Shin, C. H. Song |
| 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. 4 ; Nr. 14, no. 4 (2014-02-27), S.2185-2201 |
| Datensatznummer |
250118429
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| Publikation (Nr.) |
 copernicus.org/acp-14-2185-2014.pdf |
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| Zusammenfassung |
| This study focused on the contribution of ammonium nitrate (NH4NO3)
to aerosol optical depth (AOD) and direct radiative forcing (DRF) by aerosols
over an East Asian domain. In order to evaluate the contribution, chemistry-transport model
(CTM)-estimated AOD was combined with satellite-retrieved AOD, utilizing a data
assimilation technique, over East Asia for the entire year of 2006. Using the
assimilated AOD and CTM-estimated aerosol optical properties, the DRF by
aerosols was estimated over East Asia via a radiative transfer model (RTM).
Both assimilated AOD and estimated DRF values showed relatively good
agreements with AOD and DRF by aerosols from AERONET. Based on these results,
the contributions of NH4NO3 to AOD and DRF by aerosols
(ΦAOD and ΦDRF) were estimated for the four seasons of 2006
over East Asia. Both ΦAOD and ΦDRF showed seasonal
variations over East Asia within the ranges between 4.7% (summer) and
31.3% (winter) and between 4.7% (summer) and 30.7% (winter),
respectively, under clear-sky conditions, showing annual average
contributions of 15.6% and 15.3%. Under all-sky conditions,
ΦDRF varied between 3.6% (summer) and 24.5% (winter), showing
annual average contribution of 12.1% over East Asia. These annual average
contributions of NH4NO3 to AOD and DRF are almost comparable to the
annual average mass fractions of NH4NO3 in PM2.5 and PM10
(17.0% and 14.0%, respectively). ΦAOD and ΦDRF were
even larger in the locations where NH3 and NOx emission rates are
strong, such as the central East China (CEC) region and Sichuan Basin. For
example, under clear-sky conditions, both ΦAOD and ΦDRF
over the CEC region range between 6.9% (summer) and 47.9% (winter) and
between 6.7% (summer) and 47.5% (winter), respectively. Based on this
analysis, it was concluded that both ΦAOD and ΦDRF cannot
be ignored in East Asian air quality and radiative forcing studies,
particularly during winter. |
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