First results of the RAGMAC glacier elevation change intercomparison exercise

The intercomparison exercise by the IACS Working Group on Regional Assessments of Glacier Mass Change (RAGMAC) aims to provide an overview of good practises as well as spread of different processing approaches for assessing glacier volume changes from geodetic methods. It is composed of two experiments with mandatory and optional tasks. Participants are encouraged to contribute to all tasks.

Experiment 1 targets a comparison of spaceborne elevation changes to high-quality, high-resolution airborne data (either from laser scanning or aerial photogrammetry) as well as to in-situ surface glacier mass balance data. Test sites are Aletsch Glacier and Hintereisferner in the Alps as well as Vertisen in Norway. The expected outcome of the first experiment (with validation data) is to see how the participants account for the mismatch between DEM acquisition dates and to assess quantitatively the divergence between estimates as a function of this mismatch.

Experiment 2 is setup for regions (Northern Patagonian Icefield, Karakoram, Franz Joseph Land) where not direct validation data is available. The challenge posed here is on the intercomparison and influence of different processing steps and approaches on the elevation and volume change results. Observation periods are pre-defined and participants deliver different versions of the processing results.

The presentation will provide an overview of the exercise and the experiments and outline first results of the endeavour.