More than a decade ago, scientists began monitoring the developments of a large crack in the Larsen C ice shelf in Antarctica. In mid-July, one of the largest icebergs ever recorded broke free from it, leaving the area at its lowest recorded extent. This giant iceberg, known as A68, is estimated to cover an area of around 6,000 sq km. Since the ice shelf is already floating, the newly calved iceberg didn’t affect sea level. However, it changed the outline of the Antarctic Peninsula forever and it could bring further consequences. Water currents and winds might eventually push the A68 iceberg north of the Antarctic where it could become a hazard to shipping. Additionally, as the Iceberg A68 moves away into the Weddell Sea, it will expose around 6,000 square kilometres of sea floor that have been shielded by ice for up to 120,000 years, presenting an exceptional chance to study the ecosystem beneath before the loss of the ice causes it to change.
Antarctica contains about 60 per cent of the Earth’s fresh water rooted into its massive ice sheet. Ice shelves hold back the glaciers behind them, regulating the speed at which they flow into the ocean. Understanding how ice shelves melt can help scientists improve estimations of how the Antarctic ice sheet will respond to a warming ocean and contribute to sea level rise. It also will shape up global models of ocean circulation by providing a better projection of the amount of fresh water ice shelf melting adds to Antarctic coastal waters.
But, how can we timely monitor such a remote place, with extreme weather and poor light conditions, as Antarctica? Satellite data has proved to be one of the most cost-effective tools so far.
Synergistic tipping and cueing to understand Larsen C Ice Shelf’s evolution
Following the recent developments in Antarctica, Deimos Imaging launched a campaign to monitor the Larsen C ice shelf and the freshly calved A68 iceberg with Deimos-1 and Deimos-2. It is specially complicated to get pictures of Antarctica in July and August because of its long winter nights and the frequent cloud cover. Scientist had to rely mainly on polar satellites such as Sentinel-1, which use radar to see through dense cloud cover and regardless light conditions. Nonetheless, Deimos Imaging managed to capture exclusive optical imagery with Deimos-1 and Deimos-2.
Deimos-1 was specifically designed to timely monitor vast regions, thanks to its very wide 650-km wide swath. Additionally, Deimos-2 very-high resolution data is a key source of information to detect changes in incredible detail that complement ground assessment information, without the costs and risks of having people on the field. Thanks to the very high revisit frequency of both sensors, 2 days average revisit time worldwide for Deimos-2 and 3 days for Deimos-1, a synergistic use of both sensors ensures a remarkable capacity of imaging the Earth’s surface cloud-free.
The images captured over Antarctica’s Larsen C Ice Shelf since the calving of the Iceberg A68, allowed to perform a change detection and a multitemporal comparison of the berg’s trajectory.
In this campaign, a synergistic tipping and queuing was carried out, collecting information and coordinating activities between Deimos Imaging’s sensors. Thanks to its wide swath and high revisit time, Deimos-1 pinpointed where the main developments were going on in the Larsen C ice shelf and its surroundings; then, this information was used to task the very-high-resolution Deimos-2 over the identified areas, to get much more detailed imagery that allowed a very accurate measurement of the crack’s extension. This procedure of tipping and cueing was applied reversely too, when Deimos-2 captured a fraction of a large area and thereupon Deimos-1 was tasked to cover its whole extent.
The ability to record a sequence of images over time at different spatial resolution and the utilization of the tipping and cueing technique are especially useful for environmental monitoring and change detection. In this case, it enabled to track and capture the most relevant developments, both in context and in detail of the changes in Antarctica’s Larsen C Ice Shelf.