Watching glaciers move

Recent investigations, such as this recent article in Science, present evidence that the world’s glaciers are retreating. How melting glaciers will affect sea levels and river systems and how quickly these changes might happen are still unknown.

Monitoring glaciers in inaccessible areas prone to extreme weather and long periods of darkness (such as the Arctic) was difficult before the era of satellites. Now, however, we can track their evolution: radar satellites can “penetrate” cloud cover and the dark and offer frequent and systematic coverage of these areas.

At TRE ALTAMIRA we have recently concluded a project for monitoring the displacement of glaciers in Northern Russia using images from radar satellites. In one area, over 30 m of displacement was measured in one month. The results show how the displacement increased towards the coast.

Accumulated displacement rates in the period of study (1 month).

Accumulated displacement rates in the period of study (1 month).

Such rapid movement rates exceed those observable with SAR interferometry (suitable for detecting motion rates from millimetric to centimetric). To overcome this limitation we have developed an advanced technique for detecting movement rates up to 10 m/month. This technique, called Rapid Motion Tracking (RMT), compares the position of a patch of the radar image within a set of images acquired at different times over the same area. RMT provides displacement measurements in two directions: North-South and East-West.

Our analysis in Northern Russia was also compared with results obtained from buoy measurements. The results showed a good fit for all measurements, as can be observed in the image below, where the cumulative displacement measured from the buoys is represented in blue and those from the nearest satellite points in green and red.

glacier-time-series

Knowledge of glacier acceleration/deceleration is valuable for refining numerical models to help predict their behaviour, a step torwards a better understanding of how glaciers will respond to climate change.