Publication Date:
2019-12-03
Description:
Ice shelves strongly interact with coastal Antarctic sea ice and the associated ecosystem by creating
conditions favorable to the formation of a sub-ice platelet layer. The close investigation of this phenomenon
and its seasonal evolution remains a challenge due to logistical constraints and a lack of suitable
methodology. In this study, we characterize the seasonal cycle of Antarctic fast ice adjacent to the Ekstr€om
Ice Shelf in the eastern Weddell Sea. We used a thermistor chain with the additional ability to record the
temperature response induced by cyclic heating of resistors embedded in the chain. Vertical sea-ice temperature
and heating profiles obtained daily between November 2012 and February 2014 were analyzed to
determine sea-ice and snow evolution, and to calculate the basal energy budget. The residual heat flux
translated into an ice-volume fraction in the platelet layer of 0.18+-0.09, which we reproduced by a independent
model simulation and agrees with earlier results. Manual drillings revealed an average annual
platelet-layer thickness increase of at least 4 m, and an annual maximum thickness of 10 m beneath
second-year sea ice. The oceanic contribution dominated the total sea-ice production during the study,
effectively accounting for up to 70% of second-year sea-ice growth. In summer, an oceanic heat flux of 21
Wm-2 led to a partial thinning of the platelet layer. Our results further show that the active heating
method, in contrast to the acoustic sounding approach, is well suited to derive the fast-ice mass balance in
regions influenced by ocean/ice-shelf interaction, as it allows subdiurnal monitoring of the platelet-layer
thickness.
Repository Name:
EPIC Alfred Wegener Institut
Type:
Article
,
isiRev
Format:
application/pdf
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