Tag Archives: Thickness

Facts About the Arctic in December 2021

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Christmas is coming. Santa’s secret summer swimming pool has frozen over. The time has come for a new monthly Arctic update.

The JAXA/ADS/ViSHOP web site is undergoing maintenance for a week, so let’s start the festive season with a look at high resolution AMSR2 area and extent:

After a brief hiatus in early November both metrics are once again tracking within, but near the upper bound of the last 10 years.

Next let’s take a look at the latest AWI CryoSat-2/SMOS thickness map:

together with the anomaly map from the Finnish Meteorological Institute:

Still thinner than usual in the so called “last ice area” north of Greenland and Ellesmere Island, and thicker than usual on the Siberian side of the Arctic, particularly in the Chukchi Sea.

Finally, for the moment at least, here’s the latest CryoSat-2/SMOS volume graph:

Unlike the previous metrics, this particular one is close to the middle of the pack.

[Edit – December 5th]

The National Snow and Ice Data Center issued their latest monthly Arctic Sea Ice News update earlier than usual this month:

Sea ice extent increased at a faster than average pace through November and by the end of the month, extent was just within the interdecile range. Extent was above average in the Bering Sea, but Hudson Bay remained unusually ice free through the month.

The November 2021 monthly average extent was 9.77 million square kilometers (3.77 million square miles), which ranked tenth lowest in the satellite record. The 2021 extent was 930,000 million square kilometers (359,000 million square miles) below the 1981 to 2010 long-term average. Extent was higher than average in the Bering Sea, but is extremely low in Hudson Bay.

Air temperatures at the 925 millibar level (about 2,500 feet above the surface) were well above average north of the Canadian Archipelago, by as much as 6 degrees Celsius. Conversely, temperatures over southwest Alaska and the eastern sector of the Bering Sea were as much as 6 degrees Celsius below average:

The sea level pressure pattern for November featured widespread low pressure over the Atlantic side of the Arctic and extending into the Barents and Kara Seas, paired with a moderately strong Beaufort Sea High. Strong low pressure over the Gulf of Alaska resulted in a circulation pattern in the eastern Bering Sea that brought cold air from the north. This pattern was favorable for sea ice growth, and can explain the above average ice extent in the region:

[Edit – December 7th]

Since the start of December high resolution AMSR2 extent has been flatlining:

Sea ice area has even declined slightly over the past few days:

Here too is an animation created by Uniquorn on the Arctic Sea Ice Forum using AWI ASMR2 data to reveal ice movement through the Nares Strait during December:

[Edit – December 9th]

The JAXA/ADS/ViSHOP web site is down again, so let’s take another look at high resolution AMSR2 area and extent:

It seems that the “brief hiatus” is over, and extent is now in a “statistical tie” with 2018/19 at 4th lowest for the date amongst recent year.

[Edit – December 13th]

The PIOMAS Arctic sea ice volume data for November 2021 has been released:

Average Arctic sea ice volume in November 2021 was 7,830 km3. This value is the 7th lowest on record for November,  about  1600 km3 above the  record set in 2016.   Monthly  ice volume was 61% below the maximum in 1979 and 45% below the mean value for 1979-2020. Average November 2021 ice volume was about one sigma above the 1979-2020 trend line. October saw relative rapid ice growth  for recent years bringing the mean ice thickness  (above 15 cm thickness) above the recent low values: 

The ice thickness anomaly map for November 2021 relative to 2011-2020 continues to show anomalies divided into positive and a negative halves with areas of positive anomalies increasing since the two prior months. Negative anomalies stretching from North of Greenland and along the Canadian Archipelago across the Eastern Arctic into the Barents Sea. Areas North of Greenland again feature very low ice thickness as in prior years (see our recent paper).  Positive anomalies are notable in the Beaufort and Chukchi seas due to advection of thicker older ice into the areas during the previous winter (See recent paper on this). The Alaskan summer has also been relatively cold contributing to unusually thick ice in this area:

CryoSat-2 ice thickness shows a similar picture sea ice thickness anomalies but with the maxima slightly displaced which maybe due to temporal sampling of the composite:

The JAXA web site is still down, so here’s another set of high resolution AMSR2 graphs:

[Edit – December 14th]

NOAA have just released their 2021 Arctic Report Card. Here’s the introductory video:

and here is the report itself:

[Edit – December 18th]

Ice hardened LNG tanker Vladimir Vize is about to enter the Vilkitsky Strait on the Northern Sea Route:

Meanwhile Science.org reports that “The Arctic is warming four times faster than the rest of the world“:

“Everybody knows [the Arctic] is a canary when it comes to climate change,” says Peter Jacobs, a climate scientist at NASA’s Goddard Space Flight Center, who presented the work on 13 December at a meeting of the American Geophysical Union. “Yet we’re misreporting it by a factor of two. Which is just bananas.”

Jacob’s co-authors include researchers who oversee several influential global temperature records, and they noted the faster Arctic warming as they prepared to release the global temperature average for 2020. NASA’s internal peer reviewer challenged the higher figure, suggesting the scientific literature didn’t support it. But the researchers have found the four times ratio holds in record sets from both NASA (3.9) and the United Kingdom’s Met Office (4.1), and they hope to soon include the Berkeley Earth record. (Their work also has company: In July, a team at the Finnish Meteorological Institute posted a preprint also arguing for the four times figure.)

The researchers found Arctic warming has been underestimated for a couple of reasons. One is climate scientists’ tendency to chop each hemisphere into thirds and label the area above 60°N as the “Arctic”—an area that would include, for example, most of Scandinavia. But the true definition of the Arctic is defined by Earth’s tilt. And, as has been known for centuries, the Arctic Circle is a line starting at 66.6°N. When researchers lump in the lower latitudes, “you’re diluting the amount of Arctic warming you’re getting,” Jacobs says. “That is not a trivial thing.”

The other difference is the choice of time periods over which the warming rate is calculated. Jacobs and his colleagues focused on the past 30 years, when a linear warming trend emerged for the Arctic. Analyses that look at longer term trends see less divergence between the Arctic and the world.

[Edit – December 23rd]

Here is the latest CryoSat-2/SMOS volume graph, now including some reanalysed data which seems to have come in slightly higher than the earlier “near real time” numbers:

Plus the AWI thickness map:

Further discussion of the divergence between volume and extent continues in the new New Year 2022 thread:

Facts About the Arctic in October 2021

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By way of a change we start this month’s look at all things Arctic with some sea ice statistical analysis. Anthony Watts’ Arctic porky pie production line has been speeding up recently, and I am not the only one who has noticed. As part of his takedown of the latest “skeptical” allegations against the United Kingdom Met Office Tamino has been looking at trends in Arctic sea ice extent over at his “Open Mind” blog:

First and foremost, the yearly minimum is only one day out of the year. We have sea ice extent data throughout the year, and what happens during the rest of the year counts. Instead of using the annual minimum, let’s use the annual average. To avoid losing the most recent data, I’ll compute the yearly average for October through the following September rather than the usual (but arbitrary) January through December. I’ll also omit October 1978 through September 1979 because that year is incomplete. I get this:

The annual averages show much less fluctuation than the annual minima, so we can estimate things like rates of change with greater precision. I find that there is statistical evidence that the rate changed over time. One model of such changes uses three straight-line segments with their changes chosen to best-fit the data, like this:

Continue reading Facts About the Arctic in October 2021 →

ICESat-2 2021 Sea Ice Thickness

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We reported on the first ICESat-2 sea ice thickness data to be released back in May. We are now very pleased to be able to reveal that the data up to April 2021 is now available for download from the NSIDC web site. Here’s a visualisation of April’s data:

For comparison purposes here’s the CryoSat-2/SMOS equivalent:

ICESat-2 looks to have captured the arm of thicker ice extending across the Beaufort Sea suggested by sea ice age data better than CryoSat-2:

However thickness data is totally absent where leads are absent, in land-fast ice for example. It seems that near real time ICESat-2 processing isn’t available as yet, but we await the release of the data for October with barely bated breath!

Watch this space!

Facts About the Arctic in September 2021

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A detailed dissection of the 2021 minimum of various Arctic sea ice extent metrics can be found on a dedicated thread. All other Arctic news in September will be found below.

Let’s start with a map of sea ice age at the beginning of August:

Firstly notice the absence of 3+ year old ice off the coast of north east Greenland. Also visible is a band of 4+ year old ice across the Pacific side of the Arctic Basin, which has slowed melting in the region and explains the following regional sea ice area graphs:


Next here’s the current AMSR2 concentration map:

There is currently a large area of open water in the Wandel Sea to the north of Greenland. There is also an arm of old ice across the Beaufort and Chukchi Seas which is still clearly visible, but also visible is the recent reduction in sea ice concentration in the region. By way of explanation, here’s another look at the thickness of an ice floe currently situated to the north of the Chukchi at 74.84 N, 164.29 W, as measured by an ice mass balance buoy:

As the 2021 melting season draws towards its conclusion the floe is experiencing rapid bottom melt. How much longer will this floe and others like it last? Will it survive to become an “old ice” dot on next year’s ice age maps?

[Edit – September 6th]

As Wipneus puts it on the Arctic Sea Ice Forum, “PIOMAS has updated the gridded thickness data up to the 31st of August”. Here’s the latest modelled thickness map, which shows the thickest remaining ice located north of the Canadian Arctic Archipelago rather than north of Greenland:

The accompanying volume graph shows 2021 in 7th lowest position, at 4.7 thousand km3:

Here too are the current PIOMAS volume trends for each month of the year:

The Swedish icebreaker Oden has recently been exploring the area between northern Greenland and the North Pole as part of the Synoptic Arctic Survey expedition:

Here are the measurements of water temperature it has recorded over the past few days:

Ranging between -0.4 °C and -1.0 °C it doesn’t look as though the 2021 refreeze will be starting in the Wandel Sea just yet.

[Edit – September 10th]

A picture of the sea ice at the North Pole from Ponant’s Le Commandant Charcot on September 6th:

[Edit – September 13th]

Here’s the latest NSIDC sea ice age map:

That shows plenty of old ice still left in the Beaufort Sea. However ice mass balance buoy 52460 now appears to floating free of its ice floe at 75.56 N, 165.99 W:

[Edit – September 14th]

“New ice” has started to appear in previously open water on the Canadian Ice Service charts. See area E south east of Resolute:

[Edit – September 21st]

In answer to Frozen Earth’s metaphorical prayer, Wipneus has just released the mid September PIOMAS gridded thickness numbers on the Arctic Sea Ice Forum. First of all the thickness map:

followed by the volume graph:

and the monthly volume trends:

Volume calculated from the thickness data currently show that 2021’s minimum was reached on September 7th at 4.64 thousand km3, which is the 8th lowest value in the Polar Science Center’s record.

[Edit – September 23rd]

NASA have just announced a new paper about clouds in the Arctic. Highly relevant given their recent overview of the 2021 melting season!

Clouds are one of the biggest wildcards in predictions of how much and how fast the Arctic will continue to warm in the future. Depending on the time of the year and the changing environment in which they form and exist, clouds can both act to warm and cool the surface below them.

For decades, scientists have assumed that losses in Arctic sea ice cover allow for the formation of more clouds near the ocean’s surface. Now, new NASA research shows that by releasing heat and moisture through a large hole in sea ice known as a polynya, the exposed ocean fuels the formation of more clouds that trap heat in the atmosphere and hinder the refreezing of new sea ice.

The findings come from a study over a section of northern Baffin Bay between Greenland and Canada known as the North Water Polynya. The research is among the first to probe the interactions between the polynya and clouds with active sensors on satellites, which allowed scientists to analyze clouds vertically at lower and higher levels in the atmosphere.

The approach allowed scientists to more accurately spot how cloud formation changed near the ocean’s surface over the polynya and the surrounding sea ice.

Watch this space!

Facts About the Arctic in August 2021

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Let’s first of all take a look at JAXA’s flavour of Arctic sea ice extent:

After reaching lowest extent for the date in early July, the weather in the Arctic Basin was stormy, cloudy and cool compared to other recent years until the last few days of the month:

Here’s the same period in 2020 for comparison purposes:

Consequently the rate of extent loss in the second half of July was significantly less than last year.

Next let’s take a look at AMSR2 concentration:

Continue reading Facts About the Arctic in August 2021 →

Facts About the Arctic in June 2021

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Let’s begin the month with a “true colour” image from the Terra satellite of the Laptev Sea and thereabouts:

The blueish tinge indicates the appearance of melt ponds almost everywhere over the land-fast ice currently covering the majority of the Laptev Sea.

Let’s also take a look at the high resolution AMSR2 metrics for the end of May 2021:

Thanks to the recent “brief hiatus” in areal decline, Arctic wide compaction is no longer in record territory:

Finally, for the moment at least, here is the Danish Meteorological Institute’s high Arctic temperature data in the form of a graph of freezing degree days:

For some reason the data file still doesn’t include data to the end of May, but things won’t change much by then. Over the winter as a whole only 2016/17 was significantly warmer.

Let the 2021 Arctic sea ice summer melting season officially begin!

[Edit – June 4th]

Perhaps unsurprisingly the GFS forecast from four days ago hasn’t quite worked out as predicted. The Arctic as a whole is certainly on the warm side, with a +2 C anomaly at this moment:

However the 966 hPa MSLP cyclone predicted for Monday is now forecast to be a mere 978 hPa:

With 3 days to go there is a reasonable chance of it verifying in the “New Arctic” of 2021. As you can see from the map above a large area of the Central Arctic has now lost its snow cover. This is confirmed by the Rutgers Snow Lab northern hemisphere data for May:

A new Sentinel 3 melt pond fraction product from the University of Bremen confirms that on the fast ice in the Laptev & East Siberian Seas snow cover has departed and melt ponds have arrived:

In other news Wipneus has released the latest PIOMAS gridded thickness and volume data on the Arctic Sea Ice Forum:

For some strange reason 2021 volume at the end of May is almost identical to 2012 and 2020! Plus of course there’s the modelled volume export from the Central Arctic via the Fram Strait:

[Edit – June 6th]

This “false colour” image reveals that there’s virtually no snow cover left on land, and this “false colour” image reveals that the land-fast ice in the East Siberian Sea is now awash with melt ponds:

[Edit – June 8th]

The forecast low pressure area appears to have bottomed out near the Severnaya Zemlya islands with a 978 hPa MSLP:

High resolution AMSR2 Arctic sea ice area is now 2nd lowest for the date after 2016:

Laptev sea ice area is still lowest for the data, and looks as though it will retain that position for a while:

[Edit – June 9th]

The effect of the recent heat and wind on the remaining sea ice in the Laptev Sea is now all too apparent:

It’s also evident in the DMI >80N temperature graph, which has now reached sea ice “melting point” ahead of the climatology:

Note that the blue line is actually above the “freezing point” of salty Arctic sea water.

[Edit – June 13th]

Fairly clear skies over the Laptev Sea and the western East Siberian Sea, revealing wall to wall melt ponds and the land-fast ice starting to break up near the coast as well as on the edge of the now open ocean:

Plus yesterday’s view of the Beaufort Sea, revealing fast ice breaking up in the western entrance to the McClure Strait:

[Edit – June 18th]

A clearish view of the Laptev Sea today, revealing assorted cracks in a variety of locations:

[Edit – June 20th]

The latest mid-month PIOMAS thickness/volume numbers have been released:

[Edit – June 23rd]

The skies over the Vilkitsky Strait have been cloudy for a few days. However a fairly clear view yesterday reveals that breakup is well under way in what is usually one the last areas along the Northern Sea Route to become navigable:

[Edit – June 26th]

The land-fast ice in the East Siberian Sea has started to disintegrate en masse:

Data from ice mass balance buoy 441910, currently located at 76.1 N, 151.1 W in the Beaufort Sea, reveals the onset of both surface and bottom melt:

Watch this space!

ICESat-2 Gridded Sea Ice Thickness

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It’s been a long wait since NASA launched the ICESat-2 satellite in September 2018:

However some good news has arrived at long last! ICESat-2 level 4 monthly gridded Arctic sea ice thickness data is now available for download via the NSIDC:

https://nsidc.org/data/IS2SITMOGR4

Now for the bad news. Currently it’s only available from 1 November 2018 to 30 April 2020 . There also seems to be an absence of data in summer, just like CryoSat-2.

Here is my first visualisation of the most recent data, for April 2020:

Here is the equivalent from AWI’s CryoSat-2/SMOS gridded thickness product for comparison purposes:

The 2021 Maximum Arctic Sea Ice Volume

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If the 2021 maximum Arctic sea ice extent is more your thing then please see the previous article:

“The 2021 Maximum Arctic Sea Ice Extent“

Maximum volume is still several weeks away, but let’s first of all take a look at the PIOMAS modelled volume numbers for February. They are not yet available via the University of Washington’s Polar Science Center web site, but Wipneus has once again crunched the gridded thickness numbers which are already available. Here is what they reveal:

As you can see, it will be a big surprise if the 2021 volume maximum occurs in March rather than April, and 2021 is currently 3rd lowest for the date, behind 2017 and 2018. For completeness here too is the PIOMAS thickness map for the end of February:

This does contain some surprises, such as an area of thick ice along the shore of the East Siberian Sea, but no such thing along the north coast of Greenland, the traditional bastion of “the thickest ice in the Arctic Ocean”.

The “measured” Arctic sea ice volume calculated from CryoSat-2 and SMOS thickness data has also updated to February 28th:

Note that the “near real time” figures graphed in blue will almost certainly be revised upwards when the “reanalysed” data is released in a couple of weeks. Equally certainly they will be “lowest for the date” in the 11 year record.

Here also is the CS2/SMOS thickness map for February 28th for comparison purposes:

Continue reading The 2021 Maximum Arctic Sea Ice Volume →

Facts About the Arctic in November 2020

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Arctic sea ice volume is of course far more important in the grand scheme of things. However sea extent is easier to measure, and the JAXA AMSR2 flavour thereof has now nudged into second place for the date above 2016:

[Edit – November 4th]

The PIOMAS gridded thickness numbers have been released, to reveal this end of October thickness map:

and these calculated volume graphs:

These show Arctic sea ice volume to be lowest for the date, even if extent has slipped into 2nd place.

For comparison purposes here too is the latest AWI CryoSat-2/SMOS merged thickness map:

Continue reading Facts About the Arctic in November 2020 →

Facts About the Arctic in September 2020

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A detailed dissection of the 2020 minimum of various Arctic sea ice extent metrics can be found on a dedicated thread. All other Arctic news in September will be found below. As is usually the case, let’s set the ball rolling by taking a look at Wipneus’s visualisations of the August PIOMAS gridded thickness data:

together with the computed volume:

and anomaly graphs:

PIOMAS volume at the end of August was still firmly in 3rd place behind 2012 and 2019.

Continue reading Facts About the Arctic in September 2020 →