US, WASHINGTON (ORDO NEWS) — Global warming is leading to critical changes in the face of the Earth. Subpolar regions are most affected: the amount of ice is decreasing at an unprecedented rate. Thus, a study published in the journal Geophysical Research: Oceans shows that the thickness of ice in the Arctic has decreased by 20% since 2008.
Scientists draw such conclusions based on data from the ICESat-2 satellite launched by NASA. This device continued the mission of its predecessor, ICESat, which monitored the thickness of the Arctic ice from 2003 to 2009, as well as the current satellite CryoSat-2, created by the European Space Agency.
ICESat data showed that in the early years of the 21st century, the thickness of the ice around the North Pole sharply decreased. CryoSat-2, on the contrary, encouraged scientists: the information obtained from this device testified to a relatively constant thickness of the ice cover. However, the data from the new satellite alarmed the researchers in earnest .
A team of specialists from the NASA Cryosphere Research Laboratory and the Jet Propulsion Laboratory analyzed the data collected by ICESat-2 from the fall of 2018 to the spring of 2019 and compared the figures with the data from the ICESat satellite for the same period of 2007-2008. Such a comparison showed that the thickness of the Arctic ice cover in February-March 2019 was 20% less than eleven years earlier, which completely contradicts the data transmitted by CryoSat-2.
This difference may be due to differences in equipment on the two satellites. A lidar is installed on ICESat-2, and a radar on CryoSat-2: measurements of the latter can be distorted by sea water, which fills the ice. In addition, ICESat-2 is a relatively young device, its computer information processing algorithms require improvement, which can subsequently lead to a reassessment of previously obtained data.
“I think we will learn a lot by using these two [different] approaches to measurements <…>. They can give us upper and lower bounds for the thickness of sea ice, and the correct answer is likely to be somewhere in the middle, says lead author of the study, Alex Petty. “There are reasons why ICESat-2 data can be underestimated, and CryoSat-2 can be overestimated, and we need to do a lot of work to <…> bring these measurements into line with each other.”
Comparison of data from two satellites also allowed researchers to begin work on creating satellite maps of Arctic snow cover. “This is the first opportunity to get depth of snow across the entire ice sheet of the Arctic Ocean,” says study co-author Ron Kwok.
Calculations showed that snow begins to accumulate in October; the most intense snowfalls are observed in December-January, and the maximum snow cover is in April: from 17 centimeters on new ice to 27 centimeters on old ice on average.
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