On the potential of GPS tracking of fjord ice features for remote sensing validation

Negrel, Jean; Gerland, Sebastian; Doulgeris, Anthony Paul; Lauknes, Tom Rune; Rouyet, Line


Event: Polar Ice, Polar Climate, Polar Change, Remote sensing and modeling advances in understanding the cryosphere (Boulder, Colorado)

Date: 14. August 2017 –19. August 2017

Organiser: International Glaciological Society

The climate change in the Arctic induces strong modification in precipitations and freezing regimes. In this framework the monitoring of young thin ice is a key question. But young thinnest ice is also the most challenging to investigate, both in the field, because scientist cannot always step on it to sample it, and from satellites, as the low signal to noise ratio makes it difficult to distinguish from open water. To monitor the changes, satellite remote sensing techniques remain better to in situ work in cost, spatial and temporal sampling, and consistency of the data collected. However, fieldwork remains crucial for the mandatory validation of this data.

In April 2016 an Arctic fieldwork campaign was conducted at Kongsfjorden, Svalbard. This campaign was carried out in the framework of the Norwegian Polar Institute’s long-term monitoring of Svalbard fjord ice, in collaboration with the Center for Integrated Remote Sensing and Forecasting for Arctic operations (CIRFA).
This campaign has been the opportunity to combine various techniques to record the fjord ice properties ranging from the local field sampling (coring and thickness drilling) to the broader ground (Ku band ground radar sweeping the fjord every two minutes) and satellite radar remote sensing (acquisition of four Radarsat-2 high resolution quad-pol scenes) of the fjord. The combination of the various techniques offers an opportunity to cross-validate all the data collected and investigate the capacities and limits of each.

The constant tracking of the small boat used to go on the field with hand-held GPS offered a good opportunity to assess the limits of radar identification of small icebergs and thin ice. A total of 17 icebergs and the tracking of 2 thin ice edges have been achieved over the week of fieldwork. The comparison with the classification of the Radarsat-2 scenes presented contrasted but encouraging results on the ice edge.