Articles | Volume 9, issue 6
Research article
26 Nov 2015
Research article |  | 26 Nov 2015

Revealing glacier flow and surge dynamics from animated satellite image sequences: examples from the Karakoram

F. Paul

Abstract. Although animated images are very popular on the internet, they have so far found only limited use for glaciological applications. With long time series of satellite images becoming increasingly available and glaciers being well recognized for their rapid changes and variable flow dynamics, animated sequences of multiple satellite images reveal glacier dynamics in a time-lapse mode, making the otherwise slow changes of glacier movement visible and understandable to the wider public. For this study, animated image sequences were created for four regions in the central Karakoram mountain range over a 25-year time period (1990–2015) from freely available image quick-looks of orthorectified Landsat scenes. The animations play automatically in a web browser and reveal highly complex patterns of glacier flow and surge dynamics that are difficult to obtain by other methods. In contrast to other regions, surging glaciers in the Karakoram are often small (10 km2 or less), steep, debris-free, and advance for several years to decades at relatively low annual rates (about 100 m a−1). These characteristics overlap with those of non-surge-type glaciers, making a clear identification difficult. However, as in other regions, the surging glaciers in the central Karakoram also show sudden increases of flow velocity and mass waves travelling down glacier. The surges of individual glaciers are generally out of phase, indicating a limited climatic control on their dynamics. On the other hand, nearly all other glaciers in the region are either stable or slightly advancing, indicating balanced or even positive mass budgets over the past few decades.

Short summary
This study uses animations of freely available Landsat images (acquired over 25 years) to reveal glacier flow and surge dynamics in the central Karakoram. The animations provide a holistic view on the timing and variability of glacier dynamics that is hard to obtain by other more quantitative methods. Among others, the study reveals that most surging glaciers are comparably small, steep and debris-free, with a wide range of advance rates and durations, overlapping with non-surge-type glaciers.