Capturing the crack process of the Antarctic A74 iceberg with Sentinel-1 based offset tracking and radar interferometry techniques

Abstract

In this paper, the crack process of the A74 iceberg is carefully monitored in different aspects by using synthetic aperture radar (SAR) images. First, a offset tracking strategy is designed to retrieve the temporal evolution of the glacier velocity field. Secondly, a signal coherence factor (SCF) is proposed to analyze the interferometric signals. The resulting SCF maps can present a more distinct rupture pattern than the SAR magnitude images, which enables the development of rift to be tracked more precisely. Thirdly, a new approach is proposed to explore the temporal change of the ice flow. Since this approach is based on interferometric phase signals, it is more sensitive than the offset tracking technique. Consequently, the abnormal variation signals associated with the rupture process can be discovered from the experimental results in an earlier stage. The results also show that the area with abnormal signals is almost identical to the region of the calved ice, which demonstrates that the scale of the iceberg might be predicted at least two months before the rupture event. Furthermore, such a consistent pattern may indicate a total alteration of ice characteristics, implying that the complete separation between A74 and BIS is inevitable.

Keywords

• offset tracking
• insar
• change detection
• glacier velocity field
• iceberg rupture