Response of Kongsvegen glacier (Svalbard) to climate change

Compared to other glaciers in the world, Svalbard glaciers are still fairly close to balance (IPCC 2007). Such is rather exceptional as the Arctic is overall prone to outstanding effects in response to observed and predicted climate change on the other hand. This motivates enhanced investigation of key glaciers in these areas in order to reveal the environmental conditions and the processes behind their peculiar development. Thus the overall aim of this proposal is to enhance the knowledge about the mass and energy balance of a typical Svalbard glacier in response to regional climate changes during the last decades. The approach is based on numerical modelling supported by field measurements and remote sensing derivatives. The glacier Kongsvegen is considered as a test bed for these investigations. This glacier is located in northwestern Spitzbergen (Svalbard) and is representative for the majority of Svalbard glaciers. It is a surge-type glacier with a well developed polythermal structure and formation of super-imposed ice, respectively. Mass balance data are available since 1987 and multidisciplinary data from various projects provide a background for the planned investigations. Numerical glacier mass- and energy balance models are state of the art tools to investigate the complex interaction between climate and glacier development. These models will be used in local and spatially distributed modes aiming at investigation of crucial near surface processes and longer-term response to regional climate forcing, respectively. Meteorological and glaciological field work is necessary to gather data about the environmental parameters along the glacier. During a complete annual cycle specific measurements will be conducted at reference sites in the ablation and accumulation area of Kongsvegen glacier. Particular emphasis will be given to the role of snow micro- structure in context of super-imposed ice formation. Based on this, an enhanced process understanding can be achieved and locally set up mass and energy balance models can be tested and improved. Further, these locally calibrated mass balance models will be applied all over the glacier in order to investigate the mass and energy balance of the whole glacier. In this context the comparative skill of different data sets and methods to provide spatially distributed data for initialisation and forcing of the model input will be investigated firstly. This involves the use of direct observations along the glacier (spatially interpolated), more or less scarce and remote climate data (upscaled) or atmospheric model output data (downscaled). In the latter context, high- resolution (2km) atmospheric model output from different regional climate models will be used. An optimized model will be used for or studying the mass and energy balance of the whole glacier and its response to regional climate change, finally.

Project FWF I 369-B17 aimed at investigation of the meteorological and glaciological conditions, as well as of the energy- and mass balance of an Arctic glacier (Kongsvegen, Svalbard) and their interaction with regional weather conditions. The focus was on near-surface processes thus mainly concerning the atmospheric boundary layer and the underlying snow and ice layers. The investigations are based on data from a temporary network of automatic weather stations, detailed observations of the snow structure and process-oriented numerical simulations employing specifically adapted snow cover models. At a prevailingly considered site close to the equilibrium line of the glacier, the measured mass balance was overall negative during the decade 2001-2010, which was supported by a correspondingly positive surface energy budget. This was found to be representative for the total glacier but interannual variability is large. The latter is strongly related to synoptically-induced warming events, which can lead to intermittent melt all over the glacier even during polar winter. The associated melt water partly refreezes, thereby significantly changing the structure and the thermal regime of the near surface snow/ice layers. These processes essentially contribute to the poly-thermal nature of Kongsvegen, which is typical for many other glaciers in the Arctic.The overall positive energy balance is mostly due to input from turbulent fluxes fo heat and moisture towards the surface, which overcompensate the negative radiation budget. Comparison of directly measured and modeled turbulent fluxes reveals overall agreement while demonstrating critical issues and directions for improvement of corresponding parameterizations on the other hand. For example, the role of advection and gravity waves on turbulent flow was investigated thereby.Further studies addressed better quantification of the uncertainty inherent to state of the art snow modeling applying a special Monte-Carlo simulation strategy. The results show which input data or parameterizations have the most critical influences and indicate corresponding directions for improvement. The project also investigated the skill of a representative weather forecast model advancing improved modeling of high-resolution meteorological conditions in Arctic glacier environments. Project work finally contributed to several studies on the regional mass balance of all glaciers in Svalbard during the last decade and developments of major ice caps in the Russian Arctic, respectively.The project was embedded in an international ESF-PolarCLIMATE network (www.svalglac.eu) and contributed to six publications in peer-reviewed science journals. Infrastructure established within this project is still operational and fosters new research ideas and cooperation.