The slow-growing tooth of the Amery Ice Shelf from 2004 to 2012

摘要

The Loose Tooth rift system is an active rift system located at the front of the Amery Ice Shelf, Antarctica, which is expected to calve and produce a large iceberg in the near future. A time series of Envisat advanced synthetic aperture radar (ASAR) images from February 2004 to February 2012 has been used here to observe the system. The results show that both the west (T1) and east (T2) rifts propagated rapidly over 9 years at average rates of 4.49 and 2.53md~(-1), respectively. The rift system will not break during 2012-15 as previously projected, unless unforeseen events occur. Additionally, it was found that the heading direction of T1 turned dramatically in 2009-10. However, most surprising is that the propagation rates of both rifts have shown a decreasing trend since 2005, which might be due to increasing thickness of melange ice filling in the rifts. Other environmental factors (e.g. wind forcing and air tempera-ture) may influence the rift motion by changing the melange ice thickness and other properties.