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| Titel |
Aerosol data over the last 3000 years in seasonal resolution from the Greenland NEEM ice core |
| VerfasserIn |
Daiana Leuenberger, Gideon Gfeller, Simon Schüpbach, Matthias Bigler, Hubertus Fischer |
| Konferenz |
EGU General Assembly 2013
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250079845
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| Zusammenfassung |
| During the field season in summer 2009, the first 600 m (corresponding to 3 kyr b2k (3000
years before A.D. 2000) on the GICC05 timescale) of the Greenland NEEM ice core have
been analysed for a variety of aerosol constituents using Continuous Flow Analysis (CFA).
Here, the records of electric conductivity, sodium (Na+), calcium (Ca2+), particle numbers
of insoluble dust, ammonium (NH4+), nitrate (NO3-) and hydrogen peroxide (H2O2) are
presented with an average effective resolution of 1-2 cm, depending on the component. Since
the annual layer thickness λ amounts to 15cm at minimum sub-annual signals are resolved in
all components over the Holocene period. We achieved to extend the aerosol record over the
early Holocene period except for a large gap over the brittle zone from 5-9 kyr
b2k.
Seasonal variations and extreme events are preserved in great detail and all components.
H2O2 is a reliable proxy for the strength of photochemical processes in the lower atmosphere
and thus shows its minima and maxima at the summer and winter solstice, respectively.
Dust-derived species (insoluble dust, Ca2+) show peak concentrations in early spring and
minima in mid-summer. The marine-derived Na+peaks in mid-winter and is lowest
during early summer. The mean annual variability in concentrations is about 20
ppbw for both Ca2+andNa+. Moreover, it is of the same order of magnitude in
NH4+, butconsiderably larger in NO3- (100 ppbw), both representing continental
biogenic sources peaking in spring and showing minima in autumn. The interpretation
itsclimatic signal is restricted by NO3- undergoing post-depositional redistribution
processes.
Not only is the analysis of impurities in sub-annual resolution crucial for the accurate
dating of the ice core, but also for establishing a detailed chronology of the occurrence of
extreme events such as volcanic eruptions and wildfires. Furthermore, possible changes in the
seasonal variability of aerosol concentrations can be investigated. First results are presented
here. |
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