New GPS-based method can measure daily ice loss in Greenland

As Greenland’s ice sheet melts, which it has increasingly in recent years, the underlying rocks move slightly.

This happens because the pressure of the ice sheet above decreases and the land below rises. This elevation change can be measured and translated into how much ice is disappearing from Greenland’s ice sheet and how fast it’s happening. Now, researchers at the Technical University of Denmark (DTU) have developed a method based on this principle, which for the first time allows daily monitoring of snowmelt.

„This is the first time we can measure total ice mass loss on a day-to-day basis. For example, satellite gravity measurements show mass loss every month. Other methods only provide one estimate per year. This means we can’t. explains Valentina Barletta, senior researcher at DTU Space.

He led the work on the new innovative system, which was just now Published Inside Geophysical Research Letters.

Based on data from the past 20 years, Greenland is losing an average of 5 cubic kilometers of ice per week. This is equivalent to draining Denmark’s largest lake, Arresø, 40 times a week.

The new GPS method represents a significant advance in tracking ice mass loss in Greenland and understanding the processes behind ice melting. As a result, the UN on climate change Organizations such as the Intergovernmental Panel on Climate Change (IPCC) can obtain better estimates of future ice sheet melting and the contribution of meltwater to global sea level rise.

The measurements could be used for flood warnings in Greenland

The new system and estimates of ice loss can also be used for practical purposes, such as warning residents of Greenland if large amounts of meltwater are suddenly released.

„By calculating daily changes in ice mass, we can monitor the melting period and warn local people if rivers are at risk of flooding. For example, in 2012, the bridge collapsed in Kangerlussuaq, also known as Søndre Strømfjord. With the new GPS-based system, we can predict if such events are imminent. better tracking,” explains DTU aerospace professor Shafaqat Abbas Khan, who contributed to the development of the new method.

Data provided by state measuring stations in Greenland

Measurements are made using the Danish state’s GNET, which consists of 61 GNSS stations located around Greenland.

GNSS stands for Global Navigation Satellite System and includes the American GPS system and the European Galileo. With GNSS technology, movements in bedrock over time can be detected with sub-millimeter accuracy.

„We are happy that the data from GNET stations will be used more widely and give us new opportunities to accurately monitor climate change in Greenland. For example, with the new measurement system developed by DTU. Therefore, we are making great efforts to maintain and improve these measurement stations,” says a from the Ministry of Climate, Energy and Utilities. Participating is Malte Nordmann Winter-Dahl, project manager for GNET at the Danish Geodata Agency.

SDFI owns GNET, which works in collaboration with DTU.

So far, researchers and the IPCC have generally used three different methods to measure ice mass loss:

• Changes in gravity, measured by NASA’s Grace satellites, can be converted into mass changes and ice loss
• Direct changes in ice height measured by altimetry satellites
• Measuring ice movements by satellite and how much ice streams change over time. The faster the ice moves into the ocean, the more ice is lost from the ice sheet.

The research and the new method have been developed in collaboration with DTU Computing Center located at DTU Space and DTU Computing Centre. The center’s expertise and computing power are critical to handling large volumes of GPS data and running simulations in the project.