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Geodesy and Glaciology

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Climate variability and glacier evolution of Fedchenko Glacier, Pamir Mountains

High altitude precipitation and the related accumulation rates on the glaciers are variables with the highest uncertainties, when it comes to assessing the status of the cryosphere in High Mountain Asia (HMA). While ice melt in the lower regions can be modelled to a rather satisfying accuracy by using reanalysis data, combined with meteorological information from valley stations, the knowledge about accumulation at high elevations is still poorly constrained. We propose an integrated study, which combines novel field observations with state of the art analysis of remote sensing observations to feed into regional climate models and detailed modelling of the snow and firn conditions. The outcome will answer urgent questions at different levels on spatial and temporal scales, focussing on Fedchenko Glacier in the Pamir Mountains for the local investigations, but extending the model results to the entire Pamir region. Temporally high resolved information will be gained about the evolution of the firnlayering and the effect of surface melt on compaction, percolation and layer preservation. The regional accumulation distribution across the most significant elevation ranges will be reconstructed and used as input for mass flux estimates across the equilibrium line. These investigations will contribute to characterising the mass balance situation of the glaciers. Considering an extended scale in space and time will allow us to analyse the temporal evolution of the glacier accumulation for a larger region, also in the view of the stability of the Pamir-Karakoram anomaly, indicating more stable recent mass balance conditions across large parts of the Pamir Mountains. To do so, a regional climate model, already developed by the French counterpart of this project, will be configured to produce a centennial atmospheric reanalysis covering the period 1900-present over the whole HMA area. The model will be calibrated using both local and satellite observational data, to finally produce a reanalysis data set for the respective period. This will allow us to investigate the variability of both the climate and the cryosphere from daily to centennial timescales, a way to interpret the local observations with a regional and centennial view. Besides new insights into the processes involved in the climatic transformation across the accumulation regions, this study will also provide important information on the stability and representativeness of climate information potentially stored in the upper Fedchenko Glacier. This is of special importance, as a new project of scientific partners secured funding for the retrieval of a deep ice core from the Fedchenko Glacier accumulation region. Our results will help to improve the interpretation of the core sample analysis and integrate this information in a larger picture of the recent evolution of the high altitude precipitation history.

The project is funded by the German Research Foundation (DFG).

Project title: Combining glaciological field surveys, REmote sensing and regional Climate modelling to Analyze the variability of accumulation in the Pamir mountains

Project manager: Dr. Christoph Mayer

Cooperation Partners: Dr. Fanny Brun; Dr. Patrick Ginot; Dr. Martin Ménégoz; Dr. Patrick Wagnon

Completed projects:

Recent climate variability and glacier evolution in Central Asia - a case study at the accumulation zone of Fedchenko Glacier in the Pamir

The glaciers of the central Pamir in Central Asia seem to be much less affected by globally observed climatic changes than the glaciers in many other mountain regions. Remote sensing studies indicate that the glaciers in the central Pamir in particular have gained mass during the last decade. However, these indications are contradictory and not evenly distributed throughout the region.

In this research project, we are investigating the recent climate development and accumulation variability in the main accumulation area of the Fedchenko Glacier in the Pamir Mountains using combined geophysical and glaciological measurements. The Fedchenko Glacier is one of the largest mountain glaciers on earth and has, with 125 km³ of ice, about the same volume as all Alpine glaciers combined. The main accumulation basin is located at an altitude of more than 5100 m above sea level and forms one of the largest accumulation areas in the entire region. Detailed ground penetrating radar measurements are carried out to document the spatial and temporal variability of snow accumulation. These results are combined with data from snow pits and shallow firn cores for validating and extracting additional climate parameters, mainly the temperature signal. On this basis, the climate evolution over the last decades can be studied and correlated with the long-term observation series of the weather stations from the past.

Additional measurements of ice thickness distribution, surface deformation and ice velocities are used to determine the spatially distributed mass flux and compare it with the accumulation distribution. These measurements allow an ideal site for future ice core deep drilling to be identified, which could provide new insights into climate variability in Central Asia. The combination of these different measurements and the available climate data forms the basis for an evaluation of the sensitivity of glacier response to individual climate parameters. For the first time, the sensitivity of the accumulation zone to climatic variations can be evaluated on the basis of field data, in combination with remote sensing data and meteorological information. This analysis will significantly improve the understanding of the observed glacier changes in the Pamir Mountains in a climatic context.

The project was funded from 2015 to 2018 by the German Research Foundation (DFG).

Projektleiterin: Dr. Astrid Lambrecht