Abstract

Horseshoe Valley (80°18S, 81°22W) is a 30 km wide glaciated valley at the south-eastern end of Ellsworth Mountains draining into the Hercules inlet, Ronne Ice Shelf. The ice at Horseshoe Valley has been considered stable; now we use Global Positioning System (GPS) measurements obtained between 1996 and 2006 to investigate ice elevation change and mass balance. Comparison of surface heights on a profile across Horseshoe Valley reveals a slight but significant elevation increase of 0.04 m a-1 ± 0.002 m a -1. The blue ice area of Patriot Hills (~13 km2) at the mount of Horseshoe Valley shows large interannual variability in area, with a maximum extent in 1997, an exceptionally warm summer, but no clear multi-year trend, and an elevation increase of 0.05 m a-1 in eight years, which agrees with the result from Horseshoe Valley. © Antarctic Science Ltd 2009.