Grounding and Calving Cycle of Mertz Ice Tongue Revealed by Shallow Mertz Bank

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Date: Jan. 21, 2016
From: The Cryosphere(Vol. 10, Issue 1)
Publisher: Copernicus GmbH
Document Type: Brief article; Report
Length: 317 words

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Abstract :

A recent study, using remote sensing, provided some 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 propose 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 design an indirect method of using freeboard and sea level data extracted from ICESat/GLAS, FAC, and highly accurate seafloor topography to detect grounding sections of the MIT between 2002 and 2008 and analyze the process of grounding before the calving. By synthesizing remote sensing data, we point out that the grounding position was just 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, however the length is only limited in several kilometers since late 2002. From 2002 to 2008, the grounding area increased and the grounding became more pronounced. Additionally, the ice tongue could not 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 /a), thus allowing us to use remote sensing to estimate the elapsed time until the MIT can reground on the shoal. This time period is approximately 70 years. The calving of MIT can be repeatable because of the shallow Mertz Bank and the calving cycle of the MIT explains the cycle of sea-surface condition change around Mertz. Keywords: Mertz Ice Tongue, Firn air content, iceberg grounding, Mertz Bank, iceberg scouring, calving cycle.

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Gale Document Number: GALE|A482095731