Mineral Dust Variability in Antarctic Ice for Different Climate Conditions - Integrated Analysis of Interglacial Climate Dynamics (INTERDYNAMIC) - page 82

Approximately two thirds of the increase in dust deposition over Antarctica for
the mid-Holocene and Eemian is attributed to enhanced Southern Hemisphere dust
emissions (Fig. 2 c), predominantly from the Australian source (not shown).
Atmospheric transport ef

ciency (described by the number of air mass trajectories
originating above the Southern Hemisphere grid points with dust emissions and
reaching Antarctica within 10 days) is shown in Fig. 2 d. Slightly increased transport
ef ciency in 6 and 126 ka BP causes the remaining one third of the increase in dust

deposition in Antarctica. In general, the annual cycle of emission and the ef

ciency
of the atmosphere to transport dust particles to Antarctica are out of phase for the
considered time slices. In the LGM simulation, dust deposition over Antarctica is
signi cantly increased due to 2.6 times higher Southern Hemisphere dust emis-

sions, doubled atmospheric transport ef ciency and 30 % weaker precipitation over

the Southern Ocean (not shown).
The ice core reconstruction cannot pinpoint the absolute season of dust input to
the Antarctic ice during the LGM, but it can pinpoint the onset of the decoupling of
transport and emission. A shift between the maxima of dust concentration and size
suggests that a different seasonality of dust emission and transport intensity may
have contributed to the dust variability over T1. The different phasing of intense
transport and high dust concentration in the ice starts very early during T1 ( 19 ka

BP, Fig. 1 ) simultaneously with the onset of the decrease in dust concentration. The
changes in the seasonality of dust concentration in the ice obtained by the model
support this

*

finding.
According to the ice cores, for the whole EAP the same dust provenance
(southern South America) is dominant during the glacial, whereas during the
Holocene different source regions could be detected in different areas of the EAP.
For the Indian sector of the EAP Australia plays a major role. For the Atlantic sector
some contributions from other sources outside the South American continent could
be detected. However, the major contribution originates from southern South
America. The South American dust sources are dominant until 15 ka BP. From that
time on contributions from sources outside South America can be detected (Wegner
et al. 2012 ). At that time the dust concentration in Antarctic ice cores are almost on
Holocene levels. The model suggests a major in fl uence of South America to EDML

during the Holocene (not shown).

References

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Merkel U, Ramstein G, Valdes P, Weber SL, Yu Y, Zhao Y (2007) Results of PMIP2 coupled
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