Columbia Glacier Photogrammetry

该提案被推荐为探索性研究（SGER）的小额拨款，以记录阿拉斯加哥伦比亚冰川因快速崩解而持续退缩的情况。冰川目前正以每年约1.67公里的速度退缩。这种快速的退缩伴随着每天高达34米（米）的流动速度，使它成为现在世界上移动最快的冰川。自1982年以来，自18世纪中叶以来，冰川终点已经退缩了超过12公里，向海方向（10-15公里）变薄了大约200米。在接下来的9个月里，冰川的退缩模式和速度可能会发生重大变化，因为冰川的终点会穿过一个限制其流动的裂缝。未来几个月的活动可能会为哥伦比亚冰川的长期命运提供重要线索，因为冰川床位于海平面以下的水道上。最近的计算表明，取决于水流速度是保持目前的快速速度还是适度下降，在海平面以下的冰川部分（最低的25公里，冰体积约为8 × 1010立方米）将在5至20年内通过漂浮或崩解而消失。主要研究人员正在继续分析1999年和2000年的摄影测量数据，并将于2001年9月向OPP/ANS提交一份建议。然而，目前的终点位置和新计算的冰下地形可能意味着冰川正处于退缩的关键状态，并且在2001年底之前可能发生重大事件。这笔资金将允许他们在2001年继续进行航拍，因为终点站将进入更深的水域，并通过一个主要的横向收缩，届时可能会发生重大变化。

ABSTRACTPfefferOPP-01-21399This proposal is being recommended as a Small Grant for Exploratory Research (SGER) to document to continuing retreat of the Columbia Glacier, Alaska by rapid calving . The Glacier is presently retreating at a rate of approximately 1.67 kilometers (Km) per year. This rapid retreat has been accompanied by flow speeds up to 34 meters (m) per day, making it now the world's fastest-moving glacier. Since 1982, the glacier terminus has retreated more than 12 Km since the mid-eighteenth century and thinned seaward (10-15 kilometers) by approximately 200 m.Significant changes may be occurring in the glacier's pattern and speed of retreat during the next nine months as the glacier terminus passes through a gap which confines its flow. The activities over the next few months may provide important clues about the longer-term fate of Columbia Glacier as the retreat progresses up the channel where the glacier bed lies below sea-level. Recent calculations suggest that, depending on whether flow speeds continue at their present fast rate or decline moderately, the portion of the glacier grounded below sea level (the lowermost 25 km, with an ice volume of ca. 8 x 1010 m3) will be removed by flotation or calving within 5 to 20 years.The Principal Investigators are continuing their analysis of photogrammetric data from 1999 and 2000, and will submit a proposal to OPP/ANS in September 2001. However, the present terminus position and newly calculated subglacial topography may mean that that the glacier is at a critical state in its retreat, and that significant events may occur before the end of 2001. The funds will allow them to continue the aerial photography through 2001 when important changes may occur as the terminus enters deeper water and passes a major lateral constriction.