Grounding and calving cycle of Mertz Ice Tongue revealed by shallow Mertz Bank
A recent study, using remote sensing, provided evidence that a seafloor shoal influenced the 2010 calving event of the Mertz Ice Tongue (MIT), by partially grounding the MIT several years earlier. In this paper, we start by proposing a method to calculate firn air content (FAC) around Mertz from...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2016-09-01
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| Series: | The Cryosphere |
| Online Access: | https://www.the-cryosphere.net/10/2043/2016/tc-10-2043-2016.pdf |
| Summary: | A recent study, using remote sensing, provided evidence that a seafloor shoal
influenced the 2010 calving event of the Mertz Ice Tongue (MIT), by partially
grounding the MIT several years earlier. In this paper, we start by proposing
a method to calculate firn air content (FAC) around Mertz from
seafloor-touching icebergs. Our calculations indicate the FAC around Mertz
region as 4.87 ± 1.31 m. We then design an indirect method of
using freeboard and sea surface height data extracted from ICESat/GLAS, FAC,
and relatively accurate seafloor topography to detect grounding sections of
the MIT between 2002 and 2008 and analyze the process of grounding prior to
the calving event. By synthesizing remote sensing data, we point out that the
grounding position was localized northeast of the Mertz ice front close to
the Mertz Bank. The grounding outlines of the tongue caused by the Mertz Bank
are extracted as well. From 2002 to 2008, the grounding area increased and
the grounding became more pronounced. Additionally, the ice tongue could not
effectively climb over the Mertz Bank in following the upstream ice flow
direction and that is why MIT rotated clockwise after late 2002. Furthermore,
we demonstrate that the area-increasing trend of the MIT changed little after
calving (∼ 36 km<sup>2</sup> a<sup>−1</sup>), thus allowing us to use remote
sensing to estimate the elapsed time until the MIT can reground on and be
bent by the shoal. This period is approximately 70 years. Our observations
suggest that the calving of the MIT is a cyclical process controlled by the
presence of the shallow Mertz Bank location and the flow rate of the tongue.
This calving cycle also explains the cyclic variations in sea-surface
conditions around the Mertz detected by earlier studies. |
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| ISSN: | 1994-0416 1994-0424 |