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Lundi 7 janvier - Mass balance of Icelandic glaciers in variable climate

Par SEMSOU Dernière modification 10/12/2018 11:57
Quand ? Le 07/01/2019,
de 14:00 à 15:00
Où ? salle Coriolis
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Joaquin Belart

Docteur LEGOS - Université d'Islande

 

Mass balance of Icelandic glaciers in variable climate

 

 

Abstract : This thesis focuses on remote sensing techniques to measure geodetic mass balance of Icelandic glaciers from seasonal to decadal time spans and the relationship of mass balance to climate. The data used consists on frame stereo photographs (1945-2000), lidar (2008-2013) and satellite images (2000-present). At seasonal time scales, the winter mass balance of Drangajökull was measured from satellite sub-meter stereo images at the beginning, middle and end of the 2014–2015 winter using data from the Pléiades and WorldView-2 satellites. The results were complemented with in situ snow density measurements and validated with snow thickness measurements. The study concludes that images from the sensors mentioned above may now be used to monitor seasonal mass balance without tedious field logistics. In decadal time scales Eyjafjallajökull was used as test area to develop semi-automated processing chains based on open-source software for processing the stereo imagery, resulting in a 70-year time series of geodetic mass balances. Simple linear regression indicates that most mass balance variations can be related to changes in summer temperature and winter precipitation. It also allows infering the sensitivities of glacier mass balance to these two climatic variables. This processing chain was then applied to 14 Icelandic glaciers and ice caps spatially distributed in all quarters of Iceland. The glaciers of the south and west coasts exhibited the highest decadal variability. This study improves the knowledge of the Icelandic glaciers prior to the 1990‘s and how subsequent warming altered their mass balance.

 

The presentation consists in a remake of Joaquin's PhD defense and will be given in english.

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