Arctic Sea Ice

PIOMAS November 2019

Another month has passed and so here is the updated Arctic sea ice volume graph as calculated by the Pan-Arctic Ice Ocean Modeling and Assimilation System (PIOMAS) at the Polar Science Center:

During October there was a slowdown in ice growth, which is also reflected in the PIOMAS numbers. 2019 was the third year since 2007 to record a volume increase under 2000 km3. Given that 2016 increased even more slowly, it has overtaken 2019, which is now third lowest on record. But as can be seen on the graph above, the difference with 2012 (99 km3) and 2016 (31 km3) is negligible.

Here's how the differences with previous years have evolved from last month:

If you carefully observe the 2019 trend line on Wipneus' version of the PIOMAS graph, you'll see that it would have been lowest, had it not shot up during the last week of October (more on that below):

June 2019, one hell of a month

Before the latest PIOMAS data are published, somewhere next week, I wanted to present an overview of all the things that have been happening in the Arctic these past couple of weeks, and what they may mean for the outcome of the 2019 melting season. You've guessed it, I'm going to be talking about melting momentum (for those not familiar with the concept, here's the archive). 

But I want to start off with something else. Almost every melting season is marked by some spectacular event nowadays. From the Great Arctic Cyclone of 2012, the huge cracking event of February 2013, the possibility to sail beyond 85N in September 2014, to the almost circumnavigation of Greenland in August last year. This year, another event has really stood out so far.

Every melting season, the entire North American coast clears of ice at some point, making it possible to sail from Bering Strait to M'Clure Strait (western exit/entrance of the Northwest Passage central route). Back in 2016, there was a chance of this happening record early, but it didn't pan out. This year it did, four weeks earlier than any other year in the Concentration Maps section of the ASIG. The event was reported by Rick Thoman (ACCAP) and Lars Kaleschke (University of Hamburg), both providing some great graphs and animations (see here).

Here's an animation of Uni Bremen Sea Ice Concentration maps showing how it all came about (we even had a great poll on the ASIF to speculate about the date when there would be open water all the way):

But just one event does not a record melting season make. What does make a record melting season, is melting momentum. Here follows a barrage of maps and graphs, with short commentary, to give you an idea of how the 2019 melting season stacks up so far (click on the images for larger versions).

As we approach the final stretch...

For years we've talked about one of the most fascinating phenomena of Arctic sea ice loss as it progresses from year to year: The moment when the ice disappears regardless of the weather. We've seen some of that, back in July 2012, when extent and area numbers kept going down steadily, even though weather conditions weren't conducive to melt and should have caused a marked slowdown on the graphs (like they did in the preceding years). Some time later I concluded that this had to do with what I now call melting momentum.

The idea is that if during May and July the ice gets hit by lot of sunshine, lots of melt ponds form and they soak up a lot of heat. This doesn't immediately cause the ice to melt, but starts to make itself felt towards the later stage of the melting season. The built-up momentum keeps the melting going. For this reason I've been focusing on things like compactness, that tells us something about the amount of water within the ice pack, whether open water or melt ponds (satellite sensors can't see the difference).

But does this still hold true? Will there be a moment when the ice disappears regardless of melting momentum as well? We saw in 2016 that there wasn't much melting momentum built up during May and June, but despite the cloudiness, a record warm winter and persistent high air temperatures were enough to make the ice vulnerable enough for a big cyclone and massive dipole to have 2016 come in second on almost all graphs (see this overview). Yes, melting momentum is important, but there are other things at play as well, of course.

NSIDC Compactness (are divided by extent) as of July 29th

Now, this year has been extremely interesting so far. For the third time in a row, the winter preceding the melting season was relatively mild, the maximum was low (second lowest on record), and the trend line on many a graph went low from the get-go. Not as low as 2016, but low. However, as in previous years, clouds moved in and things slowed down to a crawl, taking the trend line as high up as 11th lowest on record on the JAXA sea ice extent chart last week. But then this happened in the last couple of days, suggesting spectacular melting on the Pacific side of the Arctic:

So, what's going on?

Lowest maximum on record (again)

After a drop of almost 262 thousand km2 in just three days, it looks highly likely that the maximum for sea ice extent was reached two weeks ago, according to the data provided by JAXA, the Japan Aerospace Exploration Agency (via ADS-NiPR ; it used to be provided by IJIS).

It's a new lowest maximum record, and the third time in a row that extent stayed below the 14 million km2 mark. The previous lowest max on record was reached in 2015 (13.942 million km2), almost beaten last year (13.959 million km2), but this year SIE went lower still and peaked at 13.878 million km2.

This graph by commenter Deeenngee, posted on the Arctic Sea Ice Forum, visualizes maximums from the past and the trajectory to this year's max:

It looks highly likely that the max has been reached for NSIDC daily SIE as well (graph provided by Jim Hunt from the Great White Con blog), a third record low in a row if my eyes don't deceive me:

The drops are mostly driven by sea ice reductions in the Bering and Okhotsk Seas, but will soon be joined by drops on the Atlantic side of the Arctic as well, as the ice is pretty thin there, according to the Uni Bremen SMOS thin sea ice map.

Given the wind forecast, I also expect further sea ice retreat from the southern shores of Novaya Zemlya (similar to what happened in 2011 and 2012):

ASI 2016 update 7: minimum time

During the melting season I'm writing (bi-)weekly updates on the current situation with regards to Arctic sea ice (ASI). Because of issues with data based on the SSMIS sensor aboard DMSP satellites, I mainly focus on higher-resolution AMSR2 data from the Japan Aerospace Exploration Agency (JAXA), as reported on the Arctic Data archive System website. I also look at other things like regional sea ice area, compactness, temperature and weather forecasts, anything of particular interest.

The animation on the right consists of NSIDC
sea ice concentration maps, one for each ASI update.

Check out the Arctic Sea Ice Graphs website (ASIG)
for daily updated graphs, maps, live webcam images, and
the Arctic Sea Ice Forum (ASIF) for detailed discussions.

September 10th 2016

It's that time of year when the melting season is drawing to a close and the Arctic sea ice pack is reaching its lowest size of the year, also known as the minimum.

This melting season was a strange one. After the mildest winter on record, a spectacular opening up of the Beaufort and Chukchi Seas made trend lines on graphs go extremely low even before the melting season had properly started. But then clouds moved in during the period when the Sun is at its peak, and solar radiation causes melt ponds to form on the ice pack, building up so-called melting momentum.

June and July were really cloudy, as cloudy as in rebound years 2013 and 2014, but this time around atmospheric conditions weren't accompanied by low temperatures on the ground and in the water. The warm winter, early opening up of the ice pack and the rapid melting of land snow cover, caused another kind of momentum, one of heat, that kept the melting going throughout.

And then in August, a massive storm that kept on re-intensifying (or maybe they were two separate storms), followed by a Dipole with a massive pressure gradient, battered the ice pack. Again, as in 2012, we've witnessed the detachment of one large piece of ice from the main pack. And now the 2016 melting season has reached 2nd place on almost all extent and area graphs out there.

You read it right, a melting season that saw mostly cloudy conditions during the sunniest period of the year (June-July-August) has beaten the 2007 melting season which went astonishingly low after weeks of ceaseless sunshine and a massive Beaufort Gyre, continuously compacting the ice pack, well into September.

But it looks rather unlikely that the 2016 melting season will end that late. The past few weeks have promoted massive ice dispersal, with large zones of low concentration near the Pole, and so there's a lot of compaction potential. But for compaction to happen, winds need to blow towards Greenland and the Canadian Arctic Archipelago, or else freezing temperatures start to dominate and all that open water within the ice pack and on its fringes starts to fill up with ice. The reverse is the case.

We can see that happen on this animation of Uni Bremen sea ice concentration maps of the past week:

The remnants of the now fully detached Wrangel Arm are still melting, compensating the ice growth elsewhere, but I'm pretty sure the minimum has been reached.

I will have a blog post with more images characterizing this melting season up later this week.

PIOMAS September 2016

Another month has passed and so here is the updated Arctic sea ice volume graph as calculated by the Pan-Arctic Ice Ocean Modeling and Assimilation System (PIOMAS) at the Polar Science Center:

Weather conditions in the past month - the (Great?) Arctic Cyclone followed by the Mega-Dipole to be precise - have left a mark on volume decrease. During August 2016 more sea ice volume was lost than during any other August in the past decade, with the exception of 2008, even more than during August 2012 (2909 km3 vs 2744 km3). Just like on the area and extent graphs, 2016 is almost in second position here too, as the difference with 2011 shrunk from 621 km3 to 84 km3.

Here's how the differences with previous years have evolved from last month:

Last month I wrote:

There is a lot of melting potential in the East Siberian Sea region, extending into the Central Arctic, that could make this year end up close to the 2011 minimum, which is second lowest after the 2012 record lowest minimum.

We now know that melting has been massive in this region, as can be seen on this Uni Bremen SIC maps animation, showing the spectacular changes from August 2nd to September 2nd, the main reason for the significant volume drop:

Wipneus' version of the PIOMAS volume graph also clearly shows that this year's trend line dropped a bit faster, breezed past 2010 and is now almost at a par with 2011:

2016 Mega-Dipole

As reported in the last ASI update, the forecast Dipole has now set up. Yesterday's last analysis chart provided by Environment Canada, at 18Z, showed the high pressure moving in via the Bering Strait at 1037 hPa, while a rapidly weakening storm that had moved in from Siberia (lowest central pressure was 967 hPa, two days ago) was still at 974 hPa on the other side of the Arctic. This then evolved to a massive 1041 hPa on one side of the Dipole, and 977 hPa on the other:

That's a humongous pressure gradient of 63-64 hPa! You don't see that often around this time in the Arctic, a not so nice story for the grandkids. Right now, the high is still at 1041 hPa, but the low has weakened further to 980 hPa. That's still a pressure gradient of 61 hPa.

It means very strong winds are blowing over the ice pack, from Siberia to Canada, compacting the ice pack and further pushing open water towards the pole, as can be seen on this animation of Uni Bremen sea ice concentration maps:

If one looks carefully at the ice in the so-called Wrangel Arm, you can clearly see the ice flash in and out of existence. There comes a point where the ice no longer flashes back, but in the meantime it makes for wild swings on the CT sea ice area graph, as calculated by Wipneus:

ASI 2016 update 6: hell and high pressure

During the melting season I'm writing (bi-)weekly updates on the current situation with regards to Arctic sea ice (ASI). Because of issues with data based on the SSMIS sensor aboard DMSP satellites, I mainly focus on higher-resolution AMSR2 data from the Japan Aerospace Exploration Agency (JAXA), as reported on the Arctic Data archive System website. I also look at other things like regional sea ice area, compactness, temperature and weather forecasts, anything of particular interest.

The animation on the right consists of NSIDC
sea ice concentration maps, one for each ASI update.

Check out the Arctic Sea Ice Graphs website (ASIG)
for daily updated graphs, maps, live webcam images, and
the Arctic Sea Ice Forum (ASIF) for detailed discussions.

August 26th 2016

A spectacular start to the melting season is being matched by a spectacular ending. And that's probably putting it mildly.

In the past 10 days we've witnessed a storm that comes close to equalling the Great Arctic Cyclone of 2012 (see the three updates I've written: 1, 2 and 3) and even though cyclonic activity has now lessened, it is still there. Worse still, it is going to be joined by massive high pressure on the American side of the Arctic.

That means - you've guessed it - that the final stage of the melting season will be dominated by a so-called Dipole set-up, where the pressure gradient between the high over the Beaufort Sea and the low over the Siberian Seas is going to have a major impact on the final shape of the ice pack. Just when you thought you had seen it all, the Arctic throws another curve ball.

Although temperatures are now going down and the sun is too low to provide enough energy to melt the ice from the top, massive winds will keep moving the ice around and promote bottom melt. But more importantly, these atmospheric conditions are going to heavily compact the highly dispersed ice pack, and cause some extra transport of ice towards the North Atlantic that is running hotter than ever. It's like putting a plate of biscuits in front of the Cookie Monster (om nom nom).

Here's an animation of Uni Bremen sea ice concentration maps from the past week to show you the current state of Arctic sea ice:

Two questions pop up immediately: How much of the Wrangel Arm is going to survive this final onslaught? And how far will that wedge of open water, or 'bite' as we've called it during previous melting seasons, be pushed towards the pole? Further than the 86N we saw in 2014?

The rest of the update will be about what's in store and what this will probably mean for the minimum.

2016 Arctic cyclone, update 3

Two days have passed since the previous update, and in those two days the storm re-intensified, bottomed out at 971 hPa (slightly higher than the first lowest central pressure of 968 hPa), as can be seen on the image on the left, provided by Environment Canada. It quickly weakened after that, but lo and behold, the image on the right shows it has re-intensified again and is currently at 971 hPa as well!

Just like that, as if it's nothing. Which brings us to the first of three questions (there were two in the previous updates, but now there's a third one at the end of this blog post):

1. Is this a Great Arctic Cyclone?

I'm still not entirely sure how this storm will rank, compared to previous storms. Remember the quote from Simmonds and Rudeva paper I mentioned in update 1:

The plot shows that AS12 was at the tail of the distribution and, at 966.38 hPa, was the lowest in our record, beating the previous deepest (966.94 hPa) (for a storm at 06UTC 7 August 1995) by 0.56 hPa. The next lowest central pressure, 969.23 hPa, was associated with a cyclone at 06UTC 22 August 1991, followed by the fourth lowest storm central pressure in the earlier part of that month 00UTC 7 August 1991 (970.47 hPa).

But it's definitely a very powerful storm, and even if it doesn't boast the lowest central pressure, all these re-intensifications will probably have it score high in other requirements for GAC nomenclature. And that reminds me of something I wrote back in 2012, following a quote that is highly relevant today:

“This past week’s storm was exceptional, and the occurrence of Arctic storms of extreme intensity is a topic deserving closer investigation,” noted Walsh. “With reduced ice cover and warmer sea surfaces, the occurrence of more intense storms is certainly a plausible scenario. The limitation at present is the small sample size of exceptional events, but that may change in the future.”

That last bit is the reason I'm hesitant calling this the Great Arctic Cyclone of 2012, or Arcticane, or some such. What if we see a similar cyclone in 2013 or 2014? We'll run out of names.

Mind you, I don't want to downplay the importance and magnitude of this storm, it's by far the biggest thing I have seen in the Arctic since I started the blog, but to me this whole event isn't about the storm itself, but about a possible new regime - a new aspect of the new abnormal - with big summer storms in the middle of the Arctic.

I called it the new abnormal at the time, but if this becomes 'normal' (compare coverage of this storm to 2012, for instance), then what cachet does the name 'Great Arctic Cyclone' still have?

2016 Arctic cyclone, update 2

So, the storm has been raging for a while now. The latest Environment Canada weather map shows it's at 984 hPa.

According to this tweet by PhD climatologist Brian Brettschneider a IABP buoy from the University of Washington measured a lowest central pressure of 966.5 hPa, which is somewhat lower than the 968 hPa reported by Environment Canada (see previous update):

This animation of Uni Bremen sea ice concentration maps for the past 4 days shows how the ice has started to follow the winds. Also notice how far open water is reaching into the ice pack now, almost getting past 85N:

The impact on the extent and area graphs isn't as outspoken as in 2012, because there was a lot of weak, preconditioned ice back then that was poised to go poof. But make no mistake, the current exceptional weather is keeping 2016 in the race for that top 3 position when the minimum is reached next month.

Cryosphere Today sea ice area as calculated by the inimitable Wipneus has 2016 in second place now: