Rainer Prinz

Seventy‐six years of mean mass balance rates derived from recent and re‐evaluated ice volume measurements on tropical Lewis Glacier, Mount Kenya

[1] Lewis Glacier on Mt Kenya has a unique history of detailed study, making it among the best documented tropical glaciers. Here we present (i) a new ice volume determination based on a bedrock DEM constructed from GPR data acquisition and (ii) the glacier’s mean mass balance rates over the last 76 years derived from volume and area estimates based on seven historical maps and the newly determined bedrock topography. Total ice volume in 2010 was 1.90 ± 0.30 × 10 6 m 3 with a mean (maximum) ice depth of 18 ± 3 m (45 ± 3 m), which is one order of magnitude larger than previously published values. In 2010, the glacier had lost 90% (79%) of its 1934 glacier volume (area), with the highest rates of ice volume loss occurring around the turn of the century. Computed mean mass balance rates, covering the whole period of glaciological surveys of Lewis Glacier, provide the longest record of tropical glacier change and show that the mean mass balance rate varies consistently with global estimates, but the magnitude is always more negative than in other regions. Citation: Prinz, R., A. Fischer, L. Nicholson, and G. Kaser (2011), Seventy‐six years of mean mass balance rates derived from recent and re‐evaluated ice volume measurements on tropical Lewis Glacier, Mount Kenya, Geophys. Res. Lett., 38, L20502, doi:10.1029/2011GL049208.

KU- and X-band backscatter analysis and SWE retrieval for Alpine snow

Spatial and temporal characteristics of Ku- and X-band backscatter signatures of Alpine snow are discussed and related to in situ snow observations. The radar data have been acquired with the airborne SnowSAR sensor over three test sites in the Austrian Alps during the AlpSAR campaign in winter 2012/13. An example for inversion of backscatter images in terms of snow water equivalent (SWE) is presented. The backscatter signatures of three test sites in different elevation zones show significant differences in terms of mean values and temporal trends during the winter season. These variations can be attributed to snow structure and to properties of the medium below the snow pack.

Mapping the snow line altitude for large glacier samples from multitemporal Landsat imagery

The cryosphere of mountain regions is highly sensitive to climate change. This is particularly evident in region wide retreat of glaciers and reduced snow coverage in mountain areas. Snow cover is an important parameter in the glacier mass but also energy balance as it controls the energy fluxes on the glaciers surface and protects the glacier from melt. Monitoring snow cover and the snow line altitude of a glacier through remote sensing data near the end of the ablation season may be considered roughly representative for the equilibrium line altitude on Alpine glaciers which is a useful indicator of the annual mass balance. The aim of this study is to develop an automated tool to retrieve information related to glacier mass balance based on multitemporal satellite imagery and an already existing glacier inventory. The method is developed in the Ötztal Alps where reliable in-situ data are available for several glaciers for a period longer than 30 years. The results show a clear rise of the snow line altitude, which is in agreement with the equilibrium line altitude observed in the field. Nevertheless, the retrieved snow lines by remote sensing imagery are generally too low (> 200 m difference). Part of this underestimate is likely due to the mapping method or the usage of a present DEM which is not representative for historical snow line altitudes. After a proper validation of the current methodology, it can subsequently transferred to other regions in the world.