Tracking glacial velocity online

Ice masses are in decline across the globe. The speed at which ice is transported into the valley is an indicator for the state of the glacier. Brief periods of acceleration known as surges can also be significant, however, for example if glacial streams become dammed and run the risk of flooding. A team of researchers from FAU has created a web portal which determines the movement of ice in all glaciers outside the major ice sheets, and has provided it free of charge for use by the entire academic community and anyone else who is interested: https://retreat.geographie.uni-erlangen.de/search.

The extent to which glaciers lose ice mass is an indicator of climate change. The causes and processes involved in each individual instance may vary, as may the effects of the loss of ice depending on the region. Different spatial movement patterns can be seen depending on the type of glacier, i.e. whether it calves into an ocean, a lake or onto land. Ice loss can accelerate or decelerate in response to glacier mass flux. The loss of stabilising factors as a result of incidents such as a glacial tongue breaking away from a sub-aquatic moraine can lead to considerable acceleration at the calving front. Researchers require information about the speed the ice is travelling in order to gain a better understanding of these mechanisms and to be able to forecast more accurately the extent of ice discharge into the oceans and the contribution glaciers will make to rising sea levels. Information about the speed the glacier is travelling also acts as an early warning system for potential natural disasters. Consider, for example, the situation which arises if glaciers progress rapidly. Often, this can lead to dangerous surges in water levels in the rivers meltwater feeds into, as witnessed for instance in the Karakoram mountain range in Southern Asia or the Pamir mountains, as well as Alaska, Greenland or Svalbard.

FAU glacier portal provides data about glacial motion

Within the scope of the RETREAT research project funded by the German Aerospace Centre (DLR) and the Federal Ministry of the Economy and Energy (BMWi), the working group led by Prof. Dr. Matthias Braun from the professorship for Geography (Remote Sensing and GIS) have prepared satellite data so that they feed automatically into an online geoinformation system with spatial and graphic search options. The information is available free of charge for the scientific community and anyone else who is interested at https://retreat.geographie.uni-erlangen.de/search.

The portal shows time intervals. The progress of glaciers over several months and years has already been included. Users are not only able to download data. Using an integrated analysis tool they are also able to check data against certain parameters. Alongside services offered by NASA and the US National Snow and Ice Data Center, which offer fewer data in the winter months due to their reliance on optical methods of gathering data, the FAU glacier portal is one of the few portals of its like in the world.

‘Undiscovered treasure’. More than 450 terabytes of satellite data have been analysed.

The web portal has been made possible thanks to modern Earth observation systems such as the radar system on board the two Sentinel 1 satellites in the European COPERNICUS programme. They allow virtually the whole of Earth to be covered with the same geometry on a rotation of between six to twelve days, and are not affected by variations in light or cloud cover. These data have been freely available since 2014. A total of more than 450 terabytes of satellite data have been recorded since 2014 for areas of ice away from the large polar ice sheets in Greenland and the Antarctic.

The FAU researchers used high performance computing (HPC) to help them process such enormous quantities of data. They altered existing algorithms to track ice movements and feed this information into the FAU glacier portal on a weekly basis as part of a fully automated process.

‘I am quite sure there is yet more information and undiscovered treasures to be found in the data. The scope is so large that we have not yet been able to look at all regions in detail,’ explains Prof. Braun. ‘However, we have already been able to track some interesting phenomena, for example ‘surges’ in Spitzbergen, when there are short-term changes to velocity and fluxes in mass which often force the glacial tongue forward.

More functions to be added to the FAU glacier portal

In future, the working group hopes to continue adding to the FAU glacier portal. As part of a DFG project, the researchers are working to track global changes to the height of glaciers. Within the context of the ‘TAPE’ project, funded by the FAU Emerging Fields Initiative, the geographers are working together with the Chair of Pattern Recognition to map glacier fronts more accurately and automatically with the help of processes taken from artificial intelligence. ‘Our vision is to use satellite data in the medium term to derive various state variables for at least the major polar and mountain glaciers and to make this information available centrally to colleagues and anyone else who is interested,’ explains Prof. Braun.

Reference to paper in review in Earth System Science Data: https://doi.org/10.5194/essd-2021-106

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