Firn- and ice thickness determined by radio echo sounding on two cirque glaciers in Lombardy

Radio echo soundings using dual-frequency 200 and 600 MHz antennas were applied on Suretta and Lupo glacier to investigate glacier thicknesses and firn stratification. On two days in October 2014, tracks of a total length of 2.4 km (Suretta) and 3.1 km (Lupo) were recorded. The post-processing was conducted using the Reflexw software package and consisted of a dewow filtering, bandpass filters, removal of horizontal constant noise and a topography migration together with a compensation for divergence losses. The observed thicknesses along the tracks (mean horizontal resolution of 20 cm) were inter-and extrapolated to the entire glacier areas. Geodetic mass balances Historic topographic maps of Suretta Sud (1962, 1970, 1995, source: Swisstopo) and Lupo glacier (1933, 1962, source: Instituto Geografico Militare) have been scanned and georeferenced. Contour lines were digitized manually and surface DEMs of 2 m resolution were created. By subtracting subsequent DEMs, volume differences could be calculated and transformed into mass changes by assuming a mean density of 0.9. The so derived time series was extended by the existing DEMs from 1982 and 2007.