Rescue, Documentation and Re-analysis of Swiss Glacier Monitoring Data

Abstract:

Long-term glacier monitoring in Switzerland has resulted in some of the longest and most complete data series globally. Point mass balance observations, starting in the 19th century, are the backbone of the monitoring as they represent the raw and original data demonstrating the response of surface accumulation and melt to changes in climate forcing. However, little attention has so far been devoted to the careful documentation of the raw point mass balance measurements, including an assessment of their sources and an estimate of their quality. Yet accurate metadata are highly important for homogenisation of the in-situ measurements and subsequent analysis of the long-term series.

For compiling and documenting raw point mass balance data acquired in Switzerland, a complete re-assessment of all individual measurements from pre-existing digital sources, published reports, unpublished documents, field notes, as well as meta-knowledge of the observers has been performed. A newly developed system of indicators allows attributing quality measures and further information on data acquisition, sources and observers for single measurements.

At this stage, data series for about 60 individual glaciers are available, corresponding to almost 60.000 point observations. The data comprise three types of point measurements: 55 series of annual mass balance, 46 series for winter snow accumulation, and 46 series with intermediate observations (daily to sub-seasonal). All previously available point mass balance observations have been re-assessed and documented, but a significant amount of additional data has been discovered and digitized summing up to 68 new data series, adding more than 20.000 point measurements.

Many of the previous observations were not traceable, and their quality was mostly unknown. The quality-checked and updated original data permits the re-analysis of consistent time series of glacier-wide mass balance allowing further interpretation of the climate change impacts on Swiss glaciers.