Getting fascinated by CryoSat results in first


517 opinions

Since its launch more than 12 years ago, the European Space Agency’s CryoSat ice mission has wowed it with its sheer technological and scientific superiority. This fascinating Earth Explorer satellite has brought back a wealth of information that has transformed our understanding of Earth’s ice and how it responds to climate change. However, in some circumstances, being dazzled isn’t a good thing, particularly when it comes to measuring sea ice height from space during the summer.

a paper Posted in temper nature It describes how scientists have now found an ingenious way to remove the nagging problem of fascination from surface meltwater to produce the first year-round continuous altimetry measurements of sea ice thickness in the Arctic Ocean.

As one of the most dynamic components of the Earth’s climate system, sea ice naturally turns wax and fades with the seasons, but the general trend is one of rapid deterioration as a result of climate warming.

Floating ice not only plays an essential role in the polar environment, but also plays an essential role in global climate. For example, its white surface reflects more sunlight into space than a dark ocean, acts as a buffer between ocean water and air, and helps drive global ocean circulation patterns. They also support indigenous communities and are vital for wildlife above and below water.

To understand exactly how much ice the Arctic Ocean is losing, measurements of ice extent and ice thickness are required to calculate the actual loss in terms of volume.

Jack Landy, from UiT Arctic University in Norway, said, “Arctic ice is melting faster than ever. We need to know the thickness of sea ice, to reduce safety risks for businesses and shipping, but also to make future climate projections.”

Summer meltwater pools on sea ice in the Arctic Ocean

Satellites have already been used to estimate ice thickness since the 1980s, but these measures are more reliable during the winter, from October to March, when the ice and snow are cold and dry.

During the summer, a large area of ​​Arctic sea ice melts, and as the climate changes, the amount remaining by September tends to be less over the years.

However, the thickness of summer ice is the most difficult to measure from space. This is because pools of melt water can build up on the surface of the ice resulting in inaccuracies in satellite data.

Dr Landy stated, “In the summer months, satellite instruments can be dazzled by melt water that collects on the surface of sea ice, which means they are unable to distinguish between melting ice and the open water surface between sea ice floes.”

This issue of fascination also complicates how scientists interpret data from the CryoSat mission.

Measuring the buoyancy of sea ice

CryoSat carries a specialized radar altimeter that measures the height of ice protruding above the water, and this ice thickness can be calculated.

Trust in satellite data is absolutely fundamental to climate science research, so it is initially funded by ESA’s Living Planet Fellowship Program And then by the Natural Environment Research Council in the UK and the Research Council in Norway, a team led by Dr Landy looked at how to solve this problem of fascination.

they ResultsPosted today in temper naturedescribe how to harness artificial intelligence and apply it to CryoSat data to produce the first record of pan-Arctic sea ice thickness, for the whole year, for a decade, twice a month for 2011-2020.

Dr. Landy explained: “Our international team used artificial intelligence techniques to check if CryoSat was looking at melting sea ice or the ocean surface between pontoons, then we used radar simulation models to make sure that CryoSat was measuring sea ice thickness correctly.”

“By comparing new satellite data with on-site observations from Arctic fieldwork campaigns, we discovered that CryoSat can indeed accurately measure the thickness of sea ice during the summer. The data revealed that sea ice volume is shrinking by 80% every summer in the Arctic, From about 23,000 km3 at the end of winter to about 4,000 km at the end of summer.

Climate models predict that the Arctic Ocean has lost about three-quarters of its summer sea ice since the 1980s. Our new observations confirm that over the past decade, the amount of summer sea ice has been as low as models predicted.”

Sea ice fish all year round from CryoSat

According to Dr Michel Tsamados of University College London, the findings are of great importance to our understanding of weather and climate. “When we use the new ice thickness data in advanced numerical prediction models, it will improve our short-term forecasts of mid-latitude weather and long-term forecasts that show the climate we will have in the future.”

In addition to advancing climate science, these new findings will also have important practical uses. For example, it leads to a safer corridor in the Arctic for marine traffic, especially in the summer.

Summer thaw has significantly increased shipping in recent years, particularly in the Barents Sea and near Svalbard. However, before determining their course, ships need accurate information about where the ice is and how thick it is.

The Norwegian Meteorological Institute provides sea ​​ice forecast for Arctic but lacks observations in the Arctic of sea ice thickness during the summer months.

Measuring Arctic sea ice thickness for validation

“Using new satellite data, we can finally make predictions of sea ice based on ice density, not only for winter, but also for summer. This increases the safety of ships and fishing boats,” Dr. Landy added.

“We can also predict whether or not there will be ice at a particular location in September, by measuring the thickness of the ice in May.”

This new method for dealing with the fascination from pools of meltwater also provides an important step forward for the European Space Agency in developing a future altimeter for polar ice and Copernicus ice, Crystal.

By carrying a dual-frequency radar altimeter and microwave radiometer, CRISTAL will measure and monitor the thickness of sea ice and the depth of ice covered. Together, CRISTAL’s measurements will support sea ice extent observations by the Copernican Microwave Imaging Mission (CMMI) marine operations in the polar oceans and contribute to a better understanding of Arctic warming in sea ice volume.

ESA mission scientist at CRISTAL, Dr. Paolo Cipollini, said, “Now that CryoSat has clearly demonstrated that we can perform year-round measurements of sea ice thickness from space, we have confidence that in the not-too-distant future we are able to ensure the continuity of those crucial measurements for many years, This is thanks to two CRISTAL satellites currently under construction.


CRISTAL’s dual-frequency approach combined with the improved operating mode of the radar will make these measurements more accurate.

“Ultimately we need to make sure that we set up an operational land strip to routinely produce data throughout the year for Copernicus services, for the benefit of many users in climate research and business operations.”

Meanwhile, the European Space Agency’s CryoSat team is focusing more on new ways to get the best mission data.

ESA’s CryoSat Mission Director Tommaso Parinello noted, “One of our goals in terms of extending the mission to 2025 is to further improve CryoSat data and also add new data products to the mission’s portfolio.

“We are looking at several new ways, including artificial intelligence, to do this.”