Velocity Measurements On Daugaard-Jensen Gletscher, Scoresby Sund, East Greenland
Velocity Measurements On Daugaard-Jensen Gletscher, Scoresby Sund, East Greenland
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东格陵兰岛斯科斯比湾 Daugaard-Jensen Gletscher 的速度测量
DOI：
10.3189/s0260305500001336
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发表时间：
1986
影响因子：
2.9
通讯作者：
O. Olesen
中科院分区：
文献类型：
--
作者：
N. Reeh;O. Olesen
东格陵兰岛的Daugaard-Jensen Gletscher是格陵兰冰盖的一个快速移动的出口冰川，其表面移动是通过经纬仪测量确定的，使用基岩观测站的交叉点，每天一次或两次，为期十天。在大约三个星期的间隔期间，又恢复了三天的观测方案，以便计算“长期”平均速度，作为研究2-10天时间尺度上速度波动的参考。各种方法的分析非同步经纬仪测量快速移动的冰川进行了讨论，和以前报道的大速度波动进行了严格审查。它的结论是，在研究的时间尺度上，速度在Daugaard-詹森Gletscher的锋面区域波动高达15%。然而，有一次，观察到速度增加超过50%，持续约7.5小时。这一事件被推断为冰下排水系统的水压突然增加的结果，这是由冰川前缘后面的冰坝湖的水龙头引起的。更温和的速度波动最有可能也是由于冰下水力系统的变化。
The surface movement of Daugaard-Jensen Gletscher, East Greenland, a fast-moving outlet glacier from the Greenland ice sheet, was determined by means of theodolite measurements, using intersections from observation stations on bedrock, once or twice a day, during a ten-day period. With a gap of about three weeks, the observation programme was resumed for another three days which allowed “long term” mean velocities to be calculated, as references for a study of velocity fluctuations on time scales in the range 2–10 days. Various methods of analysing non-synchronous theodolite measurements on fast-moving glaciers are discussed, and previously-reported large velocity fluctuations are critically reviewed. It is concluded that, on the time scales studied, velocities in the frontal region of Daugaard-Jensen Gletscher fluctuate by up to 15%. However, on one occasion, a velocity increase of more than 50% was observed, lasting for about 7.5 hours. This event is inferred to be the result of a sudden increase in the water pressure of the subglacial drainage system, caused by the tapping of an ice-dammed lake behind the glacier front. The more moderate velocity fluctuations are most likely also due to changes of the subglacial hydraulic system.