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| Titel |
Incorporation of advanced aerosol activation treatments into CESM/CAM5: model evaluation and impacts on aerosol indirect effects |
| VerfasserIn |
B. Gantt, J. He, X. Zhang, Y. Zhang, A. Nenes |
| 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. 14 ; Nr. 14, no. 14 (2014-07-24), S.7485-7497 |
| Datensatznummer |
250118902
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| Publikation (Nr.) |
 copernicus.org/acp-14-7485-2014.pdf |
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| Zusammenfassung |
| One of the greatest sources of uncertainty in the science of anthropogenic
climate change is from aerosol–cloud interactions. The activation of
aerosols into cloud droplets is a direct microphysical linkage between
aerosols and clouds; parameterizations of this process link aerosol with
cloud condensation nuclei (CCN) and the resulting indirect effects. Small
differences between parameterizations can have a large impact on the
spatiotemporal distributions of activated aerosols and the resulting cloud
properties. In this work, we incorporate a series of aerosol activation
schemes into the Community Atmosphere Model version 5.1.1 within the
Community Earth System Model version 1.0.5 (CESM/CAM5) which include factors
such as insoluble aerosol adsorption and giant cloud condensation nuclei
(CCN) activation kinetics to understand their individual impacts on
global-scale cloud droplet number concentration (CDNC). Compared to the
existing activation scheme in CESM/CAM5, this series of activation schemes
increase the computation time by ~10% but leads to
predicted CDNC in better agreement with satellite-derived/in situ values in
many regions with high CDNC but in worse agreement for some regions with low
CDNC. Large percentage changes in predicted CDNC occur over desert and
oceanic regions, owing to the enhanced activation of dust from insoluble
aerosol adsorption and reduced activation of sea spray aerosol after
accounting for giant CCN activation kinetics. Comparison of CESM/CAM5
predictions against satellite-derived cloud optical thickness and liquid
water path shows that the updated activation schemes generally improve the
low biases. Globally, the incorporation of all updated schemes leads to an
average increase in column CDNC of 150% and an increase (more negative)
in shortwave cloud forcing of 12%. With the improvement of
model-predicted CDNCs and better agreement with most satellite-derived cloud
properties in many regions, the inclusion of these aerosol activation
processes should result in better predictions of radiative forcing from
aerosol–cloud interactions. |
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