Using ground based high resolution photography for seasonal snow and ice dynamics (Austre Lovénbreen, Svalbard, 79°N)
Résumé
As is the case in many regions, arctic glaciers are reliable indicators of global climate changes. Within this context, the observed ev olutions are becoming faster and more unpre- dictable. Snow and ice dynamics are directly affected, and following processes becomes challenging: some fast but key events can be missed since they are short but significant. Such observations have been made in the Austre Lovénbreen basin (Spitsbergen, Norway - 79°N) during the Hydro-sensor-FlOWS program. In order to perform long term daily monitoring of the glacier basin behaviour aimed at a local scale understanding of the phenomena driving the glacier evolution, satellite imagery is insuf- ficient, both due to cost and availability issues as well as insufficient spatial and time resolu- tions. In this context, automated digital cameras were installed around the glacier basin, and are considered as the best solution to our monitoring problem. Despite data losses due to rough weather conditions and control electronics failure, a sufficient dataset was gathered to assess the snow coverage of the glacier as a function of time. The 6 camera stations ori- ented so as to observe the glacier itself provide a surface coverage of 96%. Furthermore, geometric corrections of the pictures, using reference points located on the glacier using GPS receivers, yield a quantitative information from initially qualitative images. Projecting the resulting mosaic on a GIS allows for the precise monitoring of ice-related processes, and especially the snow coverage evolution over time. This presentation summarizes our current understanding of such dynamics, based on the analys is of daily mosaiques of images allow- ing for the observation of both long term ev olution on the seasonal scale and the short term events on the week scale. Such results will be demonstrated one typical full hydrological season (April to October 2009), from which further analysis of the phenomena occurring downstream (hydrology) can be considered.