Calvingrate of Kronebreen, Svalbard
Cecilie, Rolstad DenbyProject period: 2007-2010.
Staff: C. Rolstad Denby, and PhD student A.Chapuis.
Radar measurements, calvingfront.
Photo: C. Rolstad
Data of temporal variation of calving event and velocity directly from the calving fronts are very valuable because they inform about calving processes, which are still poorly understood. However, such data are rare, due to the dangers and difficulties connected to measuring. ISPAS Ground based interferometric radar at high temporal rate (2 Hz) has successfully been used in the IPY GLACIODYN project for velocity measurements and monitoring of calving events at Kronebreen, Svalbard for three test seasons (2007, 2008 and 2009). The radar is placed ~4 km from the glacier, and the antenna lobe covers a width of ~700 m of the front. Daily terrestrial optical photogrammetry and continuous visual observation are conducted to facilitate the interpretation of a 116 hour radar data record from August/September 2008. The calving front geometry is extracted from the optical images, and its effect together with the movement of the glacier is identified in a plot of the amplitude of the radar return signal. Detection of calving events is demonstrated by change detection image processing in the radar data set, and 92 % of the total calving events are confirmed from visual observations and registration. Velocities determined from tracking of permanent scatters in the radar data gives an average velocity for the period of 3.2 md-1, and we find in generally good agreement between our measurements and visual observations. In our experimental data set we have observed electromagnetic interference in the radar back scatter data from the calving front, and we explain this to be due to multipath scattering and tidal cycles. The radar has also successfully been tested from Ny-Ålesund research station, 15 km from the glacier front. Continuous radar monitoring of the calving activity of Kronebreen is therefore possible, and seasonal variations can be identified.
Talk in Copenhagen 2009: WWF event at COP15.
Publications:
Chapuis, A., C. Rolstad and R.Norland, 2010. Interpretation of amplitude data from a ground-based radar in combination with terrestrial photogrammetry and visual observations for calving monitoring of Kronebreen, Svalbard. Annals of Glaciology 51 (55) 34-40
Rolstad, C., A. Chapuis and R. Norland. 2009. Electromagnetic interference in ground based interferometric radar data from Kronebreen calving front due to multipath scattering and tidal cycles. Journal of Glaciology 55(193), 943-945.
Rolstad, C., and R. Norland, 2009. Ground based interferometric radar for velocity measurements of the calving front of Kronebreen, Svalbard. Ann. Glaciol. 50(50), 47-54.
Updated: 12.03.12
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Contact: Cecilie Rolstad (cecilie.rolstad@umb.no)