A new study using Copernicus Sentinel-1 data found that glaciers feeding the George VI Ice Shelf speed up by approximately 15% during the Antarctic summer. This is the first time seasonal cycles have been detected on land ice flowing into ice shelves in Antarctica.
Although it is common for ice flow in the Arctic regions to speed up during summer, scientists had previously assumed that ice in Antarctica wasn’t subject to the same seasonal movements. This was partly because temperatures remain below freezing for most of the year, but also due to the lack of adequate monitoring of ice flow over the continent’s ice margins.
Before the detailed measurements of ice speed made possible by Sentinel-1 satellites, scientists who wanted to study short-term variations in Antarctic-wide ice flow relied on data collected by optical satellites such as NASA’s Landsat 8.
The advantage of radar for remote sensing is that it can image Earth’s surface through rain, cloud, day and night. This is also useful for studying areas in long periods of darkness.
The reasons for these seasonal changes are not clear. They could be caused by surface meltwater reaching the base of the ice, acting as a lubricant, or it could be the result of relatively warm ocean water melting the ice from below, thinning the floating ice and allowing upstream glaciers to move faster.