POSTDOCTORAL & EARLY CAREER RESEARCHER EXCHANGE – REPORT
ANDREW TEDSTONE – UNIVERSITY OF EDINBURGH
EXCHANGE TO UNIVERSITÉ SAVOIE-MONT BLANC, ANNECY, FRANCE – JANUARY 2015
I was awarded a PECRE grant in order to visit the Université Savoie-Mont Blanc (Annecy, French
Alps), during October 2014 and January 2015, to collaborate with Amaury Dehecq. As part of his
PhD, Dehecq developed a processing strategy to extract estimates of glacial ice motion from pairs of
optical satellite images separated by some time period, through the tracking of distinct features in
the images as they move by glacier flow. This strategy was developed in order to investigate
Himalayan glacier dynamics, taking advantage of the release of unprecedented volumes of Landsat
satellite imagery which have recently become available from the United States Geological Survey
and European Space Agency for the first time.
To more fully exploit the potential of processing strategy to examine inter-annual trends in the flow
of the world’s glaciers, I used my PECRE grant to extract ice motion estimates for the landterminating margins of the south-west Greenland Ice Sheet from 1985 to 2014. During the exchange
Dehecq showed me how to undertake the processing, and we then make collaborative
modifications and undertook testing to the underlying code which enabled me to successfully apply
the strategy to the Greenland Ice Sheet.
My research has shown that the margins of the south-west Greenland Ice Sheet have slowed down
since 2002, a period in which surface meltwater production has risen substantially. This is important
because previous studies (e.g. Zwally et al, 2002, Science; Parizek & Alley, 2004, QSR) suggested that
the input of more surface meltwater to the ice sheet bed would result in a net speed-up of ice sheet
motion, by reducing the friction between the ice and its underlying bed – not the slowdown which
has been identified through this research.
I have first-authored a paper on the findings which stem from this successful PECRE grant, and on
which collaborators including Dehecq are co-authors. The paper is currently under review with
Nature.
June 2015