Using surface velocities to infer ice thickness and bed topography : A case study a Columbia Glacier, Alaska, USA

• Information about glacier volume and ice thickness distribution is essential for manyglaciological applications, but direct measurements of ice thickness can be diffcult and costly. Wepresent a new method that calculates ice thickness via an estimate of ice fux. We solve the familiarcontinuity equation between adjacent fowlines, which decreases the computational time requiredcompared to a solution on the whole grid. We test the method on Columbia Glacier, a large tidewaterglacier in Alaska, USA, and compare calculated and measured ice thicknesses, with favorable results.This shows the potential of this method for estimating ice thickness distribution of glaciers for whichonly surface data are available. We fnd that both the mean thickness and volume of Columbia Glacierwere approximately halved over the period 1957–2007, from 281m to 143m, and from 294km3to134km3, respectively. Using bedrock slope and considering how waves of thickness change propagatethrough the glacier, we conduct a brief analysis of the instability of Columbia Glacier, which leads usto conclude that the rapid portion of the retreat may be nearing an end.

Ämnesord

NATURVETENSKAP  -- Geovetenskap och miljövetenskap -- Klimatforskning (hsv//swe)

NATURAL SCIENCES  -- Earth and Related Environmental Sciences -- Climate Research (hsv//eng)

Nyckelord

Naturgeografi

Physical Geography

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