Publication Date:
2019-07-17
Description:
ABSTRACT. We investigated the large-scale (10–1000m) and small-scale (mm–cm) variations in size,
number and arrangement of air bubbles in the EPICA Dronning Maud Land (EDML) (Antarctica) ice
core, down to the end of the bubble/hydrate transition (BHT) zone. On the large scale, the bubble
number density shows a general correlation with the palaeo-temperature proxy,
d18O, and the dust concentration, which means that in Holocene ice there are fewer bubbles than in glacial ice. Small-scale variations in bubble number and size were identified and compared. Above the BHT zone there exists a strong anticorrelation between bubble number density and mean bubble size. In glacial ice, layers of
high number density and small bubble size are linked with layers with high impurity content, identified
as cloudy bands. Therefore, we regard impurities as a controlling factor for the formation and
distribution of bubbles in glacial ice. The anticorrelation inverts in the middle of the BHT zone. In the
lower part of the BHT zone, bubble-free layers exist that are also associated with cloudy bands. The high
contrast in bubble number density in glacial ice, induced by the impurities, indicates a much more
pronounced layering in glacial firn than in modern firn.
Repository Name:
EPIC Alfred Wegener Institut
Type:
Article
,
isiRev
Format:
application/pdf
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