Antarctic tabular icebergs are important active components in the ice sheet-ice shelf-ocean system.Seafloor topography is the key factor that affects the drifting and grounding of icebergs,but it has not been fully investigated.This study analyzes the impact of seafloor topography on the drifting and grounding of Antarctic tabular icebergs using Bedmap-2 datasets and iceberg route tracking data from Brigham Young University.The results highlight the following points.(1) The quantitative distributions of iceberg grounding events and the tracking points of grounded icebergs are mainly affected by iceberg draft and reach their peak values in sea water with depths between 200 m and 300 m.The peak tracking point number and linear velocity of free-drifting icebergs are found in the Antarctic Slope Front(water depth of approximately 500 m).(2) The area of possible grounding regions of small-scale icebergs calved from ice shelf fronts accounts for 28%of the sea area at water depths less than 2000 m outside the Antarctic coastline periphery(3.62 million km2).Their spatial distribution is mainly around East Antarctica and the Antarctic Peninsula.The area of possible grounding regions of large tabular icebergs with long axes larger than 18.5 km(in water depths of less than 800 m) accounts for 74%of the sea area.(3) The iceberg drifting velocity is positively correlated with ocean depth in areas where the depth is less than 2000 m(R=0.85,P<0.01).This result confirms the effect of water depth variations induced by seafloor topography fluctuations on iceberg drifting velocity.
The Amery Ice Shelf is the largest ice shelf in East Antarctica. It drains continental ice from an area of more than one million square kilometres through a section of coastline that represents approximately 2% of the total circumference of the Antarctic continent. In this study, we used a time series of ENVISAT ASAR images from 2004-2012 and flow lines derived from surface velocity data to monitor the changes in 12 tributaries of the Amery Ice Shelf front. The results show that the Amery Ice Shelf has been expanding and that the rates of expansion differ across the shelf. The highest average annual rate of advance from 2004-2012 was 3.36 m＇d-1 and the lowest rate was 1.65 m.d-1. The rates in 2009 and 2010 were generally lower than those in other years. There was a low correlation between the rate of expansion and the atmospheric temperature recorded at a nearby research station, however the mechanism of the relationship was complex. This study shows that the expansion of the Amery Ice Shelf is slowing down, reflecting a changing trend in climate and ice conditions in East Antarctica.
Owing to global warming,frequent ice shelf disintegration and rapid acceleration of inland ice flow have occurred in recent decades,which impacts the Antarctic mass balance and the global sea level[1].These events are closely linked to atmospheric and oceanic processes.The prolonged melt season and larger extent of melt ponds on the ice shelf surface[2],as well as enhanced basal melting caused by warmer sea water[3],will induce crevasses that
