Flow dynamics and iceberg calving rates of Devon Ice Cap, Nunavut, Canada
Flow dynamics and iceberg calving rates of Devon Ice Cap, Nunavut, Canada
复制标题
DOI：
10.3189/172756505781829430
复制
发表时间：
2005-01-01
影响因子：
3.4
通讯作者：
Benham, TJ
中科院分区：
文献类型：
--
作者：
Burgess, DO;Sharp, MJ;Benham, TJ
利用干涉合成孔径雷达(InSAR)测绘了加拿大努纳武特德文冰帽的表面速度场。西区和东南区使用升空欧洲遥感卫星1号和2号(ERS-1/-2)串联模式数据，东北区使用3天重复通过的ERS-1图像。对RADARSAT 1图像使用斑点跟踪程序，以获得贝尔彻冰川(一个主要的崩解锋面)末端的表面速度，在那里发生了ERS数据之间的去相关性。InSAR的数据突出了冰帽东西两侧的冰流动力学的显著反差。主要南北分水岭以西的冰运动以相对均匀的“席状”流为主，但三条快速流动的出口冰川在冰盖边缘以外延伸14-23公里，也排干了这一地区的水。从东部边缘向内陆延伸长达60公里的几个出口冰川排干了冰帽的东侧。根据驱动应力(在十个冰层厚度的长度尺度上平均)和表面速度与冰层厚度的比率之间的关系，对主要的冰流状态进行了分类。绘制的流态分布图似乎描绘了冰盖底部滑动的空间范围。冰面上流动条纹的出现与流动状态之间的密切关系支持了这一点，在流动状态中，基面滑动被发现是冰川运动的一个重要组成部分。冰山的崩解率是使用测量的表面速度和从航空无线电回波探测得出的冰厚度计算出来的。1960年至1999年间崩解的冰量估计为20.5+/-4.7千米(3)(或0.57千米(3)年(-1))。大约%的损失发生在东部边缘地区。最大的单一来源是贝尔彻冰川，它占解冻冰总量的50%左右。
The surface velocity field of Devon Ice Cap, Nunavut, Canada, was mapped using interferometric synthetic aperture radar (InSAR). Ascending European Remote-sensing Satellite 1 and 2 (ERS-1/-2) tandem mode data were used for the western and southeast sectors, and 3 day repeat pass ERS-1 imagery for the northeast sector. Speckle-tracking procedures were used with RADARSAT 1 imagery to obtain surface velocities over the terminus of Belcher Glacier (a major calving front) where decorrelation between ERS data occurred. The InSAR data highlight a significant contrast in ice-flow dynamics between the east and west sides of the ice cap. Ice movement west of the main north-south divide is dominated by relatively uniform 'sheet' flow, but three fast-flowing outlet glaciers that extend 14-23 km beyond the ice-cap margin also drain this region. Several outlet glaciers that extend up to 60 km inland from the eastern margin drain the eastern side of the ice cap. The dominant ice-flow regimes were classified based on the relationship between the driving stress (averaged over a length scale of ten ice thicknesses) and the ratio of surface velocity to ice thickness. The mapped distribution of flow regimes appears to depict the spatial extent of basal sliding across the ice cap. This is supported by a close relationship between the occurrence of flow stripes on the ice surface and flow regimes where basal sliding was found to be an important component of the glacier motion. iceberg calving rates were computed using measured surface velocities and ice thicknesses derived from airborne radio-echo sounding. The volume of ice calved between 1960 and 1999 was estimated to be 20.5 +/- 4.7 km(3) (or 0.57 km(3) a(-1)). Approximately 89% of this loss occurred along the eastern margin. The largest single source is Belcher Glacier, which accounts for similar to 50% of the total amount of ice calved.