ICE MARKINGS CAUSED BY GLACIAL DETACHMENTS

The CECs Glaciology Laboratory, , in collaboration with the Institute of Geophysics, Polish Academy of Sciences, and with the Université du Québec à Trois-Rivières, recently published a research paper in the Journal Cold Regions Science and Technology on the spectral properties of ice markings caused by glacial calving.  

Despite major advances in remote sensing and field studies of ice calving, little is known about the temporal distribution of the occurrence of such events. Knowing the exact moment in which they occur is crucial for a better understanding of the processes involved, i.e. whether the nature of calving is for example a chaotic or self-organized critical system. To close this gap, the researcher Micha? P?tlicki from CECs Glaciology Lab with his colleagues proposed a method of estimating the age of calving events of a tidewater glacier using infrared LiDAR point clouds. It is based on a theoretical model that links the measured intensities of LiDAR that depend on the spectral properties of ice in the infrared with a time of exposure of the ice to ablation.

Terrestrial LiDAR scans of the calving front of Fuerza Aerea Glacier (Greenwich Island, South Shetland Islands, Antarctica) were compared with the timing of the ice face exposure by calving events determined from video recordings. The developed model shows that ice aging, as seen by surface reflectivity, follows an exponential decay law in the form inverse to that of snow (Oerlemans and Knap, 1998). The reflectivity of the ice in the infrared increases significantly over time and shows a continuous brightening of the ice surface with aging. It is assumed that the processes of sub-aerial weathering are the main cause of the change. Solar radiation can lead to internal melting of the blue ice and formation of porous weathering crust over a calving scar. Development of weathered or superimposed ice on the calving scars is proposed as the explanation for increase of ice reflectivity with time. However, recent advances in LiDAR technology provide space for improving the model and its effectiveness of glacier calving timing predictions.

Ref.: Podgórski, Julian, P?tlicki, Micha?, Kinnard, Christophe (2018). Revealing recent calving activity of a tidewater glacier with terrestrial LiDAR reflection intensity, Cold Regions Science and Technology, 151, 288-301, doi:10.1016/j.coldregions.2018.03.00