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| Titel |
An improved dust emission model – Part 2: Evaluation in the Community Earth System Model, with implications for the use of dust source functions |
| VerfasserIn |
J. F. Kok, S. Albani, N. M. Mahowald, D. S. Ward |
| 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. 23 ; Nr. 14, no. 23 (2014-12-09), S.13043-13061 |
| Datensatznummer |
250119224
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| Publikation (Nr.) |
 copernicus.org/acp-14-13043-2014.pdf |
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| Zusammenfassung |
| The complex nature of mineral dust aerosol emission makes it a difficult
process to represent accurately in weather and climate models. Indeed,
results in the companion paper indicate that many large-scale models
underestimate the dust flux's sensitivity to the soil's threshold friction
velocity for erosion. We hypothesize that this finding explains why many dust
cycle simulations are improved by using an empirical dust source function
that shifts emissions towards the world's most erodible regions. Here, we
both test this hypothesis and evaluate the performance of the new dust
emission parameterization presented in the companion paper. We do so by
implementing the new emission scheme into the Community Earth System Model
(CESM) and comparing the resulting dust cycle simulations against an array of
measurements. We find that the new scheme shifts emissions towards the
world's most erodible regions in a manner that is strikingly similar to the
effect of implementing a widely used source function based on satellite
observations of dust source regions. Furthermore, model comparisons against
aerosol optical depth measurements show that the new physically based scheme
produces a statistically significant improvement in CESM's representation of
dust emission, which exceeds the improvement produced by implementing a
source function. These results indicate that the need to use an empirical
source function is eliminated, at least in CESM, by the additional physics in
the new scheme, and in particular by its increased sensitivity to the soil's
threshold friction velocity. Since the threshold friction velocity is
affected by climate changes, our results further suggest that many
large-scale models underestimate the global dust cycle's climate sensitivity. |
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