ESA Cryosat’s SIRAL radar does accurate real time Ice thickness measurements

The thickness of floes in our planet’s far north is routinely monitored by a European spacecraft called Cryosat. In 2013, the spacecraft encountered the thinnest winter ice it has ever seen. This year, on the contrary, Cryosat found that the Arctic ice was around 25 cm thicker on average (an increase by 17%).

The Cryosat team, however, has cautioned that the long-standing trend is still downwards. It released its Arctic winter assessment at this year’s European Geosciences Union General Assembly, an event held in Vienna, Austria.

Rachel Tilling, an expert representing the UK-based organization Nerc Center of Polar Observation and Modelling, said that the volume of sea ice is the number we should actually watch as it presents a better idea about the amount of ice left.


Keeping track of the volume of floes is also important for recognizing the factors responsible for changing the Arctic climate. Identifying those factors will help researchers in developing a more accurate model demonstrating the future of sea ice.

On February 25, 2015 the extent of winter ice reached the maximum level for this year; the exact recorded number is 14.54 sq. km. It is the lowest winter maximum to be ever recorded by satellite.

Here, however, it must be remembered that the numbers have been recorded based on a 2D view of the Arctic region; in addition, the only factor considered during the measurement was that winds at times may pile up the floes and at times might spread them out.

The thickness measurement process is different. Cryosat performs that job by measuring the height of ice above the water level of the ocean. The combination of both numbers i.e. extent and thickness allows researchers to measure the changes in the volume of sea ice.

When carrying out measurements in February, 2015, Cryosat found that the average thickness of the floes is a little over 1.7 meter. This makes the volume of winter Arctic ice 24,000 cubic kilometer.

The number was much less in the winter of 2013. Back then, the thickness of winter ice was just 1.5 meter and its volume was lower than 21,000 cubic kilometer.

Cryosat was launched five years back; it has evolved over the years and now it can deliver results more quickly and accurately than ever. This year, the Cryosat team is celebrating its 5th birthday by introducing a new service capable of delivering near-real-time results.