Slow surge of Trapridge Glacier, Yukon Territory, Canada

摘要: [1] Trapridge Glacier, a polythermal surge-type glacier located in the St. Elias Mountains, Yukon Territory, Canada, passed through complete surge cycle between 1951 and 2005. Air photos (1951–1981) ground-based optical surveys (1969–2005) are used to quantify modifications flow geometry that occurred over this period. Yearly averaged records suggest active phase began ∼1980, lasted until ∼2000. The average velocity central area of went from 16 m yr−1 1974 39 1980; it peaked at 42 1984, remained above 25 2001. Over interval, decelerated by steps, 4-year pulses. After particularly vigorous acceleration 1997–1999, gradually slowed presurge velocities. In 2005, was less than 9 yr−1. Digital elevation models generated stereographic analysis air for 1951, 1970, 1972, 1977, 1981. These updated annually using survey data novel implementation Bayesian kriging. course surge, front ice advanced 450 increased 10%, with an associated thinning ice. previous Trapridge starting before 1939 ending led terminus advance ∼1 km. Comparison two surges suggests 1930s started slow progression similar what we observed 1980s 1990s, switched faster mode after 1941. This second never attained recent probably owing lack mass.