As suggested by a comparison of the initial results of NASA’s ICEsat-2 satellite with the first ICEsat mission, which operated between 2003 and 2009, the thickness of the sea ice in the Arctic has decreased by as much as 20% in the last decade and has not has been held constant as thought by the ESA Cryosat-2 mission data .
More accurate measurement
In their study, recently published in the Journal of Geophysical Research : Oceans, Alek A. Petty , first author of the study and a scientist at NASA’s Goddard Center, and his colleagues generated maps of the thickness of Arctic sea ice from October 2018 to April. of 2019 and saw the ice thicken over the winter as expected.
CryoSat-2 carries a radar to measure height, unlike the ICESat-2 lidar, and the radar mainly passes through the snow to measure the top of the ice, hence the differences in measurements .
ICESat-2 has a laser altimeter, which uses pulses of light to accurately measure elevation down to approximately one inch. Every second, the instrument sends out 10,000 pulses of light that bounce off the Earth’s surface and return to the satellite, recording the time it takes to make that round trip. As Petty explains:
I think we are going to learn a lot from having these two approaches to measuring ice thickness. They could be giving us an upper and lower limit on the thickness of the sea ice, and the correct answer is probably somewhere in the middle. There are reasons why ICESat-2 estimates could be low, and reasons CryoSat-2 could be high, and we need to do more work to understand and align these measurements with each other.