Low-frequency radar sounding of temperate ice masses in Southern Alaska

We present the Warm Ice Sounding Explorer (WISE), a low-frequency (2.5 MHz) radar for the sounding of temperate ice. WISE deployment in southern Alaska in 2008 and 2012 provides comprehensive measurements of glacier thickness, reveals deep valleys beneath glaciers and the full extent of zones grounded below sea level. The east branch of Columbia Glacier is deeper that its main branch and remains below sea level 20 km farther inland. Ice is 1000 m deep on Tazlina Glacier. On Bering glacier, two sills separate three deep bed depressions (>1200 m) that coincide with the dynamic balance lines during surges. The piedmont lobe of Malaspina Glacier and the lower reaches of Hubbard Glacier are entirely grounded below sea level 40 and 10 km, respectively, from their termini. Knowledge of ice thickness in these regions helps better understand their glacier dynamics, mass balance, and impact on sea level.