Development of an integrative glacier monitoring system

Glaciers are sensitive indicators of climate change. Mass balance data provide an invaluable base for investigations of global climate change. The proposed glacier monitoring system combines spatially well distributed remote sensing data with automatically acquired and directly measured field data to improve the current glacier monitoring system for Hintereisferner and Kesselwandferner. The applicability of the method to other Alpine glaciers is tested with data from Sonnblickkees (Hohe Tauern) in cooperation with H. Slupetzky from the University of Salzburg (Austria). The glaciological and climatological data base for Hintereisferner and Kesselwandferner is exceptional in view of long time series and high spatial and temporal resolution. Therefore, these two glaciers are chosen as test sites. The data include direct mass balance measurements since 1952 for Hintereisferner and since 1965 for Kesselwandferner, a number of historic maps, annually measured velocity data, climate data from a valley station and annual surface elevation changes. Since 2003, two automatic weather stations on the glacier are recording hourly meteorological data. A web cam provides daily information on cloud and snow cover. Ten very accurate digital elevation models were derived from airborne laser scan data in course of the OMEGA project (2001-2003). In the first project phase, geodetic and directly measured mass balances are verified and consolidated by comparison to measured and modelled flow velocities. The flow velocities are calculated in cooperation with A. Jarosch from the Science Institute of the University of Iceland. The Full-Stokes ice flow model IceFem3D is used to derive the vertical flow velocity with a relative error of 4%. The changes in surface elevation derived from these laser-scan DEMs are compared to the measured and modelled mass balance and velocity data in cooperation with T. Geist and H. Stötter from the Institute for Geography of the University of Innsbruck. From the comparison of the data, test sites are chosen in which the sum of vertical velocities and mass balance is not equal to the changes in surface elevation. In these regions, additional measurements of mass balance, velocity and surface elevation are carried out to find the reason for the deviations. A mass balance model is set up either based on a degree day or an energy balance approach according to the needs identified for improving the accuracy of mass balance in the `critical regions` defined in the previous project phase. At present, three mass balance models are available at the Institute for Meteorology and Geophysics: The degree day model of Hoinkes and Steinacker, the energy balance model of Hofinger and Kuhn and SOMARS of Greuell. One of these models will be selected and adapted for including field and/or remote sensing data using a simple assimilation procedure to reduce errors caused by measurement errors and local effects like snow patches. This integrative mass balance model is validated for Hintereisferner and Kesselwandferner by comparison to the hydrological and geodetic method. The application to other regions in the Alps is tested for Sonnblickkees (Hohe Tauern). The results of the projects are valuable for future developments like real time runoff models for power energy or water resource management or the extrapolation of mass balance data from one directly measured mass balance to nearby glaciers using remote sensing data and sparse field measurements.