Ice Shelf Water-influenced Fast Ice and Sub-Ice Platelet Layer Thickness
Distributions beside the Campbell Ice Tongue in Terra Nova Bay,
Antarctica
Abstract
Prior to the present study, no dedicated in situ measurement of the
thickness distributions of fast ice and the sub-ice platelet layer,
formed by supercooled Ice Shelf Water in the near-surface ocean, had
been carried out in Terra Nova Bay. Previous studies have recognised the
biological importance of the sub-ice platelet layer observed beneath
fast ice beside the Campbell Ice Tongue. Furthermore, a recent airborne
survey of fast ice in the western Ross Sea implied that smaller ice
bodies (ice tongues and outlet glaciers) contribute to the formation of
supercooled Ice Shelf Water. With the objective of inferring source
regions and circulation of Ice Shelf Water, we measured fast ice and
sub-ice platelet layer thickness distributions near the Campbell Ice
Tongue in late spring of 2021, using drill hole surveys and
high-resolution ground-based electromagnetic induction soundings. We
observed thicker fast ice and sub-ice platelet layer near the ice tongue
with very thick and narrow sub-ice platelet layer maxima identifying
highly channelled outflow of supercooled Ice Shelf Water from beneath
the ice tongue through ice mélange, subglacial formations, and grounded
regions. We conclude that a significant volume of supercooled Ice Shelf
Water is locally sourced from the Campbell Ice Tongue through basal
melting and affirm that the icescape in north Terra Nova Bay results
from a complex interplay of glacial morphology, bathymetry, polynya
dynamics, and ocean circulation.