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) I'm reluctant to say this since I cannot prove it, but I REALLY am starting to wonder if we're witnessing a somewhat paradigm shift in the Atlantic currents to cause the breakup above Greenland/Lincoln Sea. I realize it's been quite warm in that entire region, but I do not think surface melt alone is enough to facilitate so much action and change.
A lot changes in a week. A week ago a record year looked very possible but now the slowdown and dispersion have made a top 3 place seem likely. Even the thin ice takes a while to melt and as nights get darker peak melting has passed now.
Still a lot of things happened in the Arctic in 2020 that never happened before so 2030 free of sea ice in Summer is very possible.
Every year the Arctic makes us think it is all going to melt out only to surprise us in another way. Slowdown is well under way now but there will be further big drops bringing final Jaxa extent to just under 4m like 2019 but let's wait and see.
On the other hand, strong storms can substantially break up the ice, potentially leaving it more vulnerable to higher temperatures and faster melting later in the season. And they can churn up the ocean, as well, allowing warmer waters to rise to the surface.
It’s all part of the vicious cycle of Arctic climate change. Within just a few decades, scientists predict the Arctic could be seeing totally ice-free summers.
2019 vs. 2020I was intrigued by how, on your gif, the 2019 ice looked in a worse condition is some respects, particularly in looking more scattered and therefore more vulnerable, blumenkraft.
2019 vs. 2020I was intrigued by how, on your gif, blumenkraft, the 2019 ice looked in a worse condition in some respects, particularly in looking more scattered and therefore more vulnerable.
But whatever the outcome might be, the gravest damage is already partly avoided: The open waters would not serve as giant collectors of solar energy, as strong insolation is already coming to an end in August.I think you are wrong - the storm now is probably the worst that could happen, and if more storms arrive in the next weeks the situation will be even worse.
Sorry to ruin the party again but Hycom is thickness is not comparable between these years, the model has been changed several times since then, and 2012 has not been back-calculated.
BTW, DMI thickness is also not considered very reliable, again I would appreciate decreasing the frequency of posting it to the main thread.
Ah ok thanks for the info found a 2015 Hycom seems more compatible now they have fixed it, still a sucky year 2020. I Prefer data from small democratic socialist countries like Denmark and Finland, large democratic countries data is manipulated in a lot of cases it seems.
Sorry if this is ubiquitous and I just missed the boat, but is there one or a handful of consensus best thickness models/data and image sets to pay attention to in the summer? Hycom seems pretty decent intra-year unless I'm wrong there, but I was wondering if there is anything comparable or better out there to watch as well.
NASA’s ICESat-2 Measures Arctic Ocean’s Sea Ice Thickness, Snow Cover
Arctic sea ice helps keep Earth cool, as its bright surface reflects the Sun’s energy back into space. Each year scientists use multiple satellites and data sets to track how much of the Arctic Ocean is covered in sea ice, but its thickness is harder to gauge. Initial results from NASA’s new Ice Cloud and land Elevation Satellite-2 (ICESat-2) suggest that the sea ice has thinned by as much as 20% since the end of the first ICESat mission (2003-2009), contrary to existing studies that find sea ice thickness has remained relatively constant in the last decade.
ICESat-2 has a laser altimeter, which uses pulses of light to precisely measure height down to about an inch. Each second, the instrument sends out 10,000 pulses of light that bounce off the surface of Earth and return to the satellite and records the length of time it takes to make that round trip. The light reflects off the first substance it hits, whether that’s open water, bare sea ice or snow that has accumulated on top of the ice, so scientists use a combination of ICESat-2 measurements and other data to calculate sea ice thickness.
By comparing ICESat-2 data with measurements from another satellite, researchers have also created the first satellite-based maps of the amount of snow that has accumulated on top of Arctic sea ice, tracking this insulating material.
“The Arctic sea ice pack has changed dramatically since monitoring from satellites began more than four decades ago,” said Nathan Kurtz, ICESat-2 deputy project scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “The extraordinary accuracy and year-round measurement capability of ICESat-2 provides an exciting new tool to allow us to better understand the mechanisms leading to these changes, and what this means for the future.”
Arctic sea ice thickness dropped drastically in the first decade of the 21st Century, as measured by the first ICESat mission from 2003 to 2009 and other methods. The European Space Agency’s CryoSat-2, launched in 2010, has measured a relatively consistent thickness in Arctic sea ice since then. With the launch of ICESat-2 in 2018, researchers looked to this new way of measuring sea ice thickness to advance the study of this data record.
“We can’t get thickness just from ICESat-2 itself, but we can use other data to derive the measurement,” said Alek Petty, a sea ice scientist at NASA Goddard. For example, the researchers subtract out the height of snow on top of the sea ice by using computer models that estimate snowfall. “The first results were very encouraging.”
In their study, published recently in the Journal of Geophysical Research: Oceans, Petty and his colleagues generated maps of Arctic sea ice thickness from October 2018 to April 2019 and saw the ice thickening through the winter as expected.
Overall, however, calculations using ICESat-2 found that the ice was thinner during that time period than what researchers have found using CryoSat-2 data. Petty’s group also found that small but significant 20% decline in sea ice thickness by comparing February/March 2019 ICESat-2 measurements with those calculated using ICESat in February/March 2008 – a decline that the CryoSat-2 researchers don’t see in their data.
These are two very different approaches to measuring sea ice, Petty said, each with its own limitations and benefits. CryoSat-2 carries a radar to measure height, as opposed to ICESat-2’s lidar, and radar mostly passes through snow to measure the top of the ice. Radar measurements like the ones from CryoSat-2 could be thrown off by seawater flooding the ice, he noted. In addition, ICESat-2 is still a young mission and the computer algorithms are still being refined, he said, which could ultimately change the thickness findings.
“I think we’re going to learn a lot from having these two approaches to measuring ice thickness. They might be giving us an upper and lower bound on the sea ice thickness, and the right answer is probably somewhere in between,” Petty said. “There are reasons why ICESat-2 estimates could be low, and reasons why CryoSat-2 could be high, and we need to do more work to understand and bring these measurements in line with each other.”
With ICESat-2 and CryoSat-2 using two different methods to measure ice thickness – one measuring the top of the snow, the other the boundary between the bottom of the snow layer and the top of the ice layer – but researchers realized they could combine the two to calculate the snow depth.
“This is the first time ever that we can get snow depth across the entire Arctic Ocean’s sea ice cover,” said Ron Kwok, a sea ice scientist at NASA’s Jet Propulsion Laboratory in Southern California and author of another study in JGR Oceans. “The Arctic region is a desert – but what snow we do get is very important in terms of the climate and insulating sea ice.”
The study found that snow starts building up slowly in October, when newly formed ice has an average of about 2 inches (5 centimeters) of snow on it and multiyear ice has an average of 5.5 inches (14 cm) of snow. Snowfall picks up later in the winter in December and January and reaches its maximum depth in April, when the relatively new ice has an average of 6.7 inches (17 cm) and the older ice has an average of 10.6 inches (27 cm) of snow.
When the snow melts in the spring, it can pool up on the sea ice – those melt ponds absorb heat from the Sun and can warm up the ice faster, just one of the impacts of snow on ice.
For more information on ICESat-2, visit www.nasa.gov/icesat-2 or icesat-2.gsfc.nasa.gov
I have just looked at the data again, odd things popped up in the pre 2000 era data (including 2000) for certain but nothing like it in the last 20 years so see it how you will, it is a pattern break to me.
Apparently Friv you and I are the only ones shocked by this which surprises me!Perhaps the rest of us have seen Freegrass's post which shows that this is not at all an uncommon occurrence.
IF 2020 remaining melt to minimum (and sea ice gain in late September) is at the average of the last 10 years, the September NSIDC Extent average would be 3.68 million km2. Just, but only just, above 2012.Guilty as charged for conflating Sept avg with Sept min. Still, those SIPN estimates look high. but the truth will soon be known!It would be interesting if an ASIF consenus for <3.5M km2 (with not a small chance of <3) (if there is any such consenus) is more accurate than almost all these offical expert estimates which cluster near or above 4M km2. At this point I'd put my money on ASIF.There are different metrics. September mean extent above 4M is quite possible. At least more likely than below 3M. This year has great potential to surprise but also some obstacles.
Binntho, good afternoon,
I was considering an answer, but you expressed it quite punctuated. Over the years, I often felt struck by the similarity in form of bathymetry and remaining ice at the end of the melt season. But I never struck upon an explanation that convincingly tied the two.
The sink of saline waters N of the Svalbard-Frantsa Yosefa continental shelf, sure. But the year over year quite constant ice pack front over there is partly based on the formerly well structured 'safe haven' of 1,8 Mkm2 N of Greenland. Wind moved ice usually formed a dense belt, not free to move further N.
Now that the whole pack is more mobile than ever, it 'll be interesting to see what the 5-8 Bft southerly winds are capable of (ECMWF +96-+240h).
Thankfully these crazy predictions of 2.5million are now gone. Looks like a stall will mean we finish in the pack. Though probably whether we come 2nd or 3rd will be the only question. Think 2019 and 2020 will be very close at the end despite everything. Hopefully August will be a boring month for the ice.
... I think I will read posts in future and not write.
July 22-26.
2019.
[ADS NIPR VISHOP (JAXA)] Arctic Sea Ice Extent.
July 26th, 2020:
5,962,825 km2, a drop of -31,737 km2.
2020 is the lowest on record.
Source: https://ads.nipr.ac.jp/vishop/#/extent
Maybe today news is only this image and what it represents...
Cyclone damage forecast for ice.
https://psl.noaa.gov/forecasts/seaice/
Here is my current prediction for the sea ice min.
I'd love to see everyone's thoughts.
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