Investigations of long-term and seasonal scale variations of flow velocity and frontal position of outlet glaciers in Greenland utilizing multi-temporal Landsat imagery

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For more than a decade, the cryosphere with its glacier regions have been affected by large changes. Many of the outlet glaciers of the Greenland Ice Sheet currently show accelerated flow velocities and a significant surface lowering while sustaining a substantial retreat. In particular, marine-terminating glaciers show a dynamic behavior which is not included in current predictions of the future sea-level change. Thus, the marine-terminating outlet glaciers and their influencing factors at the ice-ocean-boundary are the major research object within the proposal. In the time period between 1972 and 2012 flow velocity fields are available for more than 300 outlet glaciers along the margin of the Greenland Ice Sheet. In addition, information about the frontal position as well as their temporal changes are available for more than 100 glaciers. Within the project term both flow velocity and frontal positions of the glaciers are to be extended using satellite data of Landsat7 and Landsat8. Moreover, satellite data of the Sentinel mission expected to start in 2012 will be incorporated. Long-term and seasonal scale variations of flow velocity and the position of the glacier front as well as their interrelation will be investigated using this large data archive. Special focus will be given on the dynamic processes acting at the ice-ocean boundary. This includes the investigation of the impact of the ice mélange in the proglacial fjord on the stability of the frontal position and on the flow velocity. To analyze regional patterns of synchronous glacier changes information about both the annual cycle of sea-ice formation and sea-surface temperatures derived from MODIS data will be incorporated. In the area of North and Northeast Greenland the long-term evolution of the flow velocity as well as changes of the terminus position for more than four decades will be studied. In particular, the effect of observed long-term changes of the sea ice and fast ice formation on the stability of the glacier front accompanied by an ice shelf will be investigated. All available flow-velocity fields will be used to identify surge events of outlet glaciers and their relation to changes of the frontal position and to changes of the spatial-temporal variability of the flow regime.