New paper and of course it’s worse than we thought.
New estimates of snow depth, from a combination of lidar and radar, improve sea ice thickness estimates, according to a new study in the AGU journal Geophysical Research Letters. The study found that Arctic sea ice has lost 16% of its thickness over the past three years.
Image supplier: NASA / Kathryn Hansen
According to the press release:
– Multi-year sea ice in the Arctic at the end of the season is about 1.5 feet thinner in 2021 than in 2019
– Sea ice in the Arctic Ocean has lost a third of its volume in the past 18 years
New Arctic snow depths suggest previous estimates of sea ice thickness may have been overestimated
and
WASHINGTON — Over the past two decades, the Arctic has lost about a third of its winter sea ice, largely due to a decline in the amount of sea ice that lasts for several years, known as multiyear ice, according to a study. new. Study also suggests that sea ice may be thinner than previously estimated.
Seasonal sea ice, which melts completely in the summer instead of accumulating over many years, is displacing thicker, multi-year ice, and leading to a trend toward thinning sea ice, according to new research.
And coming straight out of Rick’s Cabaret, I tell you it was shocking.
“We didn’t really expect this decline, as the ice sheet has been much thinner in just three short years,” said Sahra Kacimi, a polar scientist at the California Institute of Technology’s Jet Propulsion Laboratory. “.
First published: March 10, 2022 | https://doi.org/10.1029/2021GL097448
abstract
Using the ICESat-2 and CryoSat-2 refrigerators, we examine the monthly variation of Arctic sea ice depth, thickness, and volume between October 2018 and May. April 2021. Over three years, satellite-based estimates have noted a decrease in average April snow depth (∼2.50 cm) and ice thickness (∼0.28 m) equivalent to ice loss ∼12.5%. The results show more thinning of multi-year ice with end-season thickness in 2021 lower than ∼16.1% (0.50 m), with negligible changes compared to first-year ice. During this period, sea ice thickness estimates using snow depths from the climate resulted in thicker ice (up to ∼0.22 m) with smaller multi-year ice thickness reductions (∼0.38 m) ). A satellite record spanning 18 years, since the launch of ICESat, shows a distance of ∼6,000 km3 or one-third of winter Arctic ice mass is driven by multi-year loss of ice cover during a multi-stage transition to a predominantly seasonal ice cover.
Pure language summary
Ice thickness and mass are important variables for assessing the evolution and response of polar sea ice to a warming climate. Obtaining sea ice thickness from altimeter skis (i.e. vertical elevation of ice and snow floating above local sea level) requires knowledge of snow loads. Until recently, snow depth was determined with climatology based on historical field records. Using the difference of the cardboard compared to ICESat-2 and CryoSat-2, we can now calculate the snow depth. In this paper, we examine the difference between climate and satellite-acquired snow depths as well as ice thicknesses obtained from two altimeter missions. Their changes over the three winters from 2018 to 2021 were noted. The estimates of the mass of the derived ice are placed in the context of a satellite record spanning 18 years.
1. Introduction
As of December 2021, ICESat-2 has completed its 3-year main mission (Markus et al., 2017) and is currently being expanded. For the ice-covered Arctic Ocean, the lid on the ICESat-2 observatory is responsible for providing the elevation of sea ice and local sea surface to calculate the eastern part — the vertical height of the floating ice above local sea level. The total freefall obtained (snow plus ice) facilitates the estimation of the thickness of the Arctic and Southern Ocean ice sheets. Non-stop operations (with only a few interruptions) have provided the full seasonal coverage of the polar oceans. Here, we examine estimates of Arctic snow and ice depth and thickness between October 2018 and April 2021.
Time-varying snow depth on sea ice, for calculating snow loads, is a limiting factor in the accuracy of sea ice thickness estimates. Prior to the launch of ICESat-2, the potential for combining the ICESat-2 (IS-2) and CryoSat-2 (CS-2) refrigerators to provide an estimate of snow depth was explored by Kwok and Markus (2017). The measurement concept is based on the difference between frozen plates with IS-2 (measurement of the height of the air snow surface above the local sea surface) and CS-2 (measurement of the height of the surface snow above the surface). local sea). For an arctic growing season (October 2018 to April 2019), Kwok et al. (Year 2020) provided a first test of snow depth recovery using IS-2 and CS-2 slotted plates. The results show that the snow depth compares well with atmospheric estimates and spatial models of the reconstructed snowfields. In addition, free-plank variability, derived snow depths, and ice thickness estimates were evaluated in Antarctica (Kacimi & Kwok, Year 2020).
In this paper, we examine year-over-year variation in snow depth, thickness and volume of frozen board-derived ice during the first three winters of IS-2 operations (from May October 2018 to April 2021). The article is organized as follows. The next section describes the data used in this analysis. Section 3 briefly describe the two different estimates of snow depth used here – one from the IS-2 and CS-2 skis and the other from the modified Warren climate (Kwok & Cunningham, 2015; Warren et al., 1999) – followed by an analysis of spatial variability and their seasonal evolution. In section 4, we describe the sea ice thickness and volume calculated from IS-2 and CS-2, and the observed year-to-year variation. Section 5 summary of the estimated ice volume profile since the launch of ICESat in 2003. The final section concludes the paper.
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