This year, satellites saw the extent of Arctic sea ice hit a record low since measurements began in the 1970s. ESA´s SMOS and CryoSat satellites are now taking a deeper look by measuring the volume of the sea-ice cover.
Measurements from ESA´s Soil Moisture and Ocean Salinity (SMOS) mission show that ice has thinned significantly in the seasonal ice zones, with extensive areas less than half a metre thick.
Sea ice has a large influence on the heat exchange between the ocean and the atmosphere. The heat flux can change depending on the sea-ice thickness and the air temperature. Sea ice is also affecting atmospheric circulation at mid-latitudes.
Although not originally designed for looking at ice, the SMOS satellite´s data are being evaluated to monitor Arctic sea ice.
The results reveal that radiation emitted by the ice allows SMOS to penetrate the surface, yielding ice-thickness measurements down to 50 cm - mainly the thinner and younger ice at the edge of the Arctic Ocean.
This allows improved evaluation of the volume of the young ice, which is the basis of old ice in subsequent years. Thick, multi-year ice indicates the health of the Arctic sea-ice cover.
"The amount of thin ice expected during the next freeze-up is about 12 million sq km, covering a larger part of the Arctic Ocean than ever before," said Lars Kaleschke from the University of Hamburg´s Center for Earth System Research and Sustainability.