Spatio-temporal Analysis Of Ice Flow Velocity And Surface Structures Variations On The Getz Ice Shelf,Antarctica

The Getz Ice Shelf,the westernmost ice shelf in Amundsen sea,sector provides the largest source of meltwater to the Southern Ocean.Many glaciological processes,such as grounding line retreat,ice-shelf thinning,and mass balance are different between parts in Amundsen Sea and Ross Sea.Getz F Ice Shelf is located at the boundary between those parts.It is important to investigate the flow dynamics of the Getz F Ice Shelf in response to atmospheric and oceanic changes in the context of climate change.In this study,we derived the time series of flow velocities over the Getz F Ice Shelf during 2000-2017 by applying a semi-automated image matching method to multi-sensor satellite images.The utilized satellite images include Landsat 7 ETM+ and Landsat 8 OLI images.In addition,we mapped the crevasse structures over the Getz ice shelf area in 2000 and 2017 and analyzed the spatial and temporal variation of flow velocity with ice shelf front retreat,surface melting intensity and crevasse structures.The core conclusions are as follows:(1)The ice velocity over the Getz ice shelf is faster in the middle,low on both sides,increasing from upstream to down stream.The western flow is higher than the east flow.The difference between east and west is mainly due to the weakening of the Antarctic circulation from west to east.The ice velocity over the Getz ice shelf has been significantly different in time and space in recent 17 years.he Getz E ice shelf has accelerated significantly(by an average of about 68% a year),so the coastline extends far out.The Getz F ice shelf has an average annual velocity increase of about 9%.With the exception of the Getz E and Getz F ice shelves,ice velocity declined significantly over a 17-year period.The annual average velocity declines of the Getz A ice shelf ?Getz B ice shelf?Getz D ice shelf were about 16%,17% and 18%,respectively.The maximum ice velocity remained Getz E>Getz F>Getz D>Getz B>Getz A for 17 years.The spatial and temporal variation of ice velocity in ice shelf is closely related to ocean current movement,topography and coastline structure.(2)The surface structure of the ice shelf is closely related to the change of ice velocity and reflects the stability of the ice shelf.The Getz E ice shelves and Getz F ice shelves,which are in the accelerating stage and have the highest veloctity,have the densest crevasse distribution and the largest change at the front of the ice shelf.Due to the action of ocean currents,they are the most unstable part of the Getz ice shelf,which are more prone to disintegration in the future due to the acceleration of their outwardextending front end.The crevasses of both Getz A and Getz D ice shelves developed laterally,and the front of the ice shelf retreated to a certain extent.The Getz A ice shelf may have been thinned and fractured by warm water entering the bottom channel.The Getz D ice shelf may have been fractured by the impact of seawater on the bay's topography.The crevasses of Getz B ice shelf are dense and short,which cross to form suture zone and are not easy to fracture.