Arctic Sea Ice

2016 Arctic cyclone, update 1

As announced in ASI 2016 update 5 a very large cyclone is raging in the Arctic, as we speak. According to Environment Canada the storm's current central pressure is 970 hPa, but it was 968 hPa 12 hours ago, which is probably the lowest it will go. I've combined the weather map with yesterday's Uni Bremen sea ice concentration map, for geographical orientation and the storm's position in relation to the ice pack:

 

There hasn't been a marked effect on the ice as of yet. On the Forum Wipneus reports a large drop of 170K in the Cryosphere Today sea ice area numbers he calculates. This is the third largest August daily drop in the last decade, but Wipneus explains it is partly due to flash melting in the Canadian Arctic Archipelago. A large drop in NSIDC SIE numbers of 122K is entirely due to the CAA, but it would be even larger if it weren't for ice in the Laptev Sea 'unflashing' into the view of the SSMIS satellite sensor aboard the DSMP F18 satellite.

I expect some more flashing tomorrow in the regions that are directly affected by the storm. Not only is there a lot of ice jutting out towards the East Siberian and Chukchi Seas, there is also a 'bite' developing towards the pole. It can clearly be seen on this animation of Uni Bremen SIC maps. Also note the movement in the last two frames, due to the storm. This movement will become more marked in the next 2-3 days:

ASI 2016 update 5: big cyclone

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 13th 2016

In the previous update I wrote with regards to the 2016 trend line on the JAXA sea ice extent graph:

If it now somehow manages to end the month between 2011 and 2015, there's still room for August weather to keep the race exciting.

The 2016 trend line managed to end July right between 2011 and 2015, it is still in 3rd position as we speak, and now August weather is going to keep the race exciting. Another big cyclone is on its way and will hit the ice pack the day after tomorrow (no pun intended). This storm will not be as intense as the Great Arctic Cyclone of 2012, but it will be almost as big, and linger for a few days. I think it's the second biggest storm I have seen since starting this blog, back in 2010.

It's difficult to tell whether this storm will have as much of an effect as GAC-2012 had. The ice pack was much weaker back then due to plenty of periods that were conducive to melting, in other words melting momentum. There hasn't been much melting momentum to speak of this year, as there has been little preconditioning of the ice pack during May and June, and cloudy conditions kept dominating the Arctic up till last week.

There has been a second kind of momentum, though, caused by the preceding mild winter and the spectacular retreat at the very start of the melting season. Snow cover melted out really fast and sea surface temperatures have been as high as they've ever been. A handful of cyclones so far have helped disperse the ice pack, with quite a large zone of ice, jutting out from the Central Arctic towards the East Siberian Sea, about to bear the brunt of the big storm (source: Uni Bremen):

When the Great Arctic Cyclone hit in 2012 all of the weak ice in this zone detached from the main pack and was annihilated. We'll have to wait and see if something similar can happen this time around.

Sea ice extent (SIE)

As said, the 2016 trend line on the JAXA SIE graph keeps moving downwards steadily:

PIOMAS August 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:

With a slightly above average drop during July 2016 is maintaining its position relative to other years. Although the monthly decrease was smaller than most years of the past decade, the difference with 2012 went down from 1136 to 924 km3. The difference with 2014 went up by a large margin, from 1218 to 1977 km3, but the difference with 2015 was almost halved, from 1852 to 1020 km3. This was to be expected, of course, as melting conditions during July 2015 were perfect (see last year's PIOMAS update).

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

2016 is currently 4th lowest, after 2010, 2011 and 2012.

Wipneus' version of the PIOMAS volume graph clearly shows this year's steady drop, closely following the 2010 and 2011 trails:

ASI 2016 update 2: closing the gap

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.

June 11th 2016

This update could have easily borne the same title as update 1: Both sides. Two weeks ago the ice pack was shrinking on both sides of the Arctic, causing sea ice extent to drop to unprecedented daily lows. In the meantime, weather patterns have switched and the ice pack is now expanding on both sides!

Of course, a dispersing ice pack will cause extent loss to slow down, or even stall completely for a while. Especially if extent was extremely low to begin with. And so that enormous gap between this year and 2012 is getting smaller every day, fast. 2012 had perfect weather for melting during the first two weeks of June, and there was a large amount of thin ice that kept extent artificially high.

More importantly, these weather conditions set the tone for the rest of the 2012 melting season, as a large amount of melt ponds preconditioned the ice for big melts during July and August. This is where 2016 is falling behind now, even though it has been and still is lowest in many respects (extent, volume, snow cover).

2012 is punching hard in this round. Will it be enough to knock 2016 out?

An exceptional exception

Winter is supposed to be a time when things quiet down in the Arctic, animals hibernate in complete darkness, and all that can be seen from satellites is this great, icy mass getting bigger and bigger. That's how it goes most of the time, despite the spectacular summer sea ice losses of the past decades. But of course, there are exceptions, and this winter is one of those. In fact, it's an exceptional exception.

I want to highlight a couple of things to give you an idea of what's going on in the Arctic right now. As some of you may already know, this year's trend line is the lowest on record in practically every graph (see here). So far, it has played a major role in the breaking of Global sea ice area and extent minimum records, and it looks highly possible that last year's Arctic sea ice maximum record gets broken too. Mind you, that record was already spectacularly early and low, which is why I referred to it as Mad Max at the time.

It's a bit too early to be calling the max, which I vowed never to do again anyway, but here's the current situation on the Cryosphere Today sea ice area and JAXA sea ice extent graph (as provided by ADS-NIPR):

2015 peaked on this date in the CT SIA data set, but this year is currently 700K lower (last week's preliminary peak was almost 600K lower). The 2015 maximum occurred on February 15th in the JAXA SIE data set, but this year's preliminary peak is almost 274K lower. That's no small change, if things stay this way.

When area/extent is exceptionally low, it's usually a sign of something going on one side of the Arctic, while things are relatively quiet on the other side. This year, however, there's stuff going on on both sides of the Arctic. I'll start with the Pacific side of the Arctic, where regional extent is again very low in the Bering Sea, though high in the Sea of Okhotsk (these graphs are produced by Wipneus and can be found on the Regional Graphs page):

2015 minimum overview, part 1

A week has passed by since the melting season ended and the minimum on all sea ice extent and area graphs has been reached. During this week I've been collecting images that show various aspects of this year's melting story, which will be accompanied by short explanations/interpretations.

Such an overview must inevitably start with an image showing the shape of the ice pack, and the University of Bremen has put up a great sea ice concentration map that also shows the ice pack outlines at the end of record melting seasons 2007 and 2012, as well as the 1981-2010 average:

2012 (cyan) clearly had less ice, but there are a couple of spots where this year had less ice than in 2007 (red). The September graph for ADS-NIPR/JAXA sea ice extent shows how close 2015 came to the lower years, slipping right below 2011 and ending in 3rd position:

The same can't be said of the Cryosphere Today sea ice area graph. 2015 ended relatively low there too, but at the top of the bundle of trend lines, in 6th position:

Minimum and MYI

The lowest point has been reached on all sea ice area and extent graphs, and so the melting season has ended. I'll have more on the details later this week, but here's a quick preview of one of the most important features of this melting season, and that's the decimation of multi-year ice (MYI) on the Pacific side of the Arctic.

Here's a nice video that shows how the melting season developed and ended, based on AMSR2 data. It's made by Felicia Brise of the University of Hamburg, and I've taken the liberty to upload it to YouTube:

There's a stunning contrast between the destruction on the Pacific side of the Arctic, and the relative stable and compact situation on the Atlantic side of the Arctic, even though the ice there was thinnest at the start of the melting season. In fact, this region of first-year ice was so large that it even covered the North Pole, perhaps for the first time on record. I even speculated in my 2014/2015 Winter analysis that under the right conditions the North Pole could become ice-free this year.

But the opposite happened, the first-year ice on the Atlantic side was spared (there was also remarkably little transport of ice through Fram Strait) and it was the multi-year ice on the Pacific side that took barrage after barrage of warm, sunny weather. Now that the ice age distribution maps (developed by J. Maslanik and C. Fowler, and currently produced by M. Tschudi of CCAR) have been updated, we can see how things have proceeded since my last blog post on the subject three weeks ago:

As expected, all of the 5+-year old ice on the Pacific side of the Arctic has disappeared in truly spectacular fashion. As there wasn't that much 4-year old ice to begin with, there will be less of the oldest class of ice next year. On the other hand a lot of the 3-year old ice (green) will become 1 year older, and as said, first-year ice (dark blue) got off lightly.

Nevertheless, it seems that part of the rebound in MYI that happened since 2012 has been wiped out (something I speculated about almost two months ago in this guest blog for the Guardian Environment page). We'll know how much exactly when the NSIDC puts up their monthly analysis two weeks from now. Of course, ice age doesn't necessarily tell us how thick the ice is - this isn't our (grand)fathers' Arctic anymore - but it gives us an idea of long-term changes in the Arctic.

Another indicator is sea ice volume, both modelled and observed. To know whether 2015 will dip below rebound years 2013 and 2014, we'll also have to wait a week or two for the PIOMAS model to be updated. Either way, yet another fascinating melting season is now behind us. Thanks for watching.

Arm's race (and a storm)

As I write this, a storm is battering the ice pack on the Pacific side of the Arctic. It's not as huge as the Great Arctic Cyclone of 2012, but it's pretty decent as far as cyclones go, and it's doing its thing in that part of the Arctic where the ice pack looks weakest, but was strongest at the start of the melting season.The timing of this event is perfect for discussing one of the most important aspects of this melting season.

The image on the top right shows the ice age distribution at the start of the melting season, red being the oldest multi-year ice at that time. Due to a very intense high pressure area over the Beaufort Sea at the end of the freezing season, heavy winds drove the ice pack apart there (a so-called cracking event), causing this multi-year ice to become interspersed with very thin ice. That's the dark blue spots between all the red.

During the very first phase of the melting season the Beaufort Sea region witnessed a heat wave causing a lot of this thin ice to melt out. Because the ice pack wasn't pushed back together again, many of the multi-year ice floes were surrounded by warming waters, and ever larger holes within the ice pack on the Pacific side of the Arctic started to form. The animation below shows what happened between week 27 and week 32, or June 29th to August 9th:

Just towards the end of the animation the holes are showing up. Unfortunately these maps aren't updated until the minimum has hit, but we can still get an idea of what happened after August 9th by checking out the sea ice concentration maps provided by the University of Bremen. The following animation shows how the holes separate a so-called 'arm' of multi-year ice from the rest of the ice pack:

New map on the block

Further down is a short update on the effects the SAC-2013 (Small Arctic Cyclone of 2013) has had so far, but first I want to draw some attention to a great new product that has recently come online, a sea ice concentration map with the highest resolution so far. When I started this blog the NSIDC used a 25 km grid, meaning that every pixel on their SIC map represented an area of 25 x 25 km, or 625 square kilometres, on the ground. IJIS had a 12.5 km grid and the University of Bremen even had and still has a 6.25 km grid.

Last year the GCOM-W1 (Shizuku) satellite was launched, with the AMSR2 microwave sensor aboard, and soon after that the Japanese space agency JAXA started to put out data. Alexander Beitsch from the University of Hamburg's KlimaCampus optimized the processing of this data, improving grid resolution to a stunning 3.125 km. This was part of his PhD in the framework of the IRO2 project that is being funded through the German Federal Ministry of Economics and Technology (BMWi). Sehr gut und danke schön!

There was just one problem with the sea ice concentration map that was produced, and that was that it was huge. 17 MB for just one image makes it difficult for us amateurs to play around with it. Luckily, the Arctic Sea Ice blog has some very smart bunnies on its member list, and it was Wipneus (well-known for his work on PIOMAS data) who managed to reduce the file size by ten times. For the time being he is putting those images on a separate Google Site. Thank you, Wipneus!

Bilateral freezing

It happened a while back, but it's one of those interesting details that make what's happening in the Arctic so unique. In August we saw something that hasn't been recorded before (not on that scale, that is): the detachment of large parts of the ice pack. In October the opposite happened.

In the East Siberian and Laptev Seas freezing started on the coasts before the ice pack had expanded far enough to reach them first. For a couple of days, the freezing on both sides caused a large pool of open water surrounded by ice on all sides:

In a way the detachment had something to do with this event, as a lot of ice floes that had been part of the little ice pack were still bobbing around (just not enough to show up on the Uni Bremen sea ice concentration maps), making freezing easier near the coast. But of course, the main reason for this to happen is the fact that the edge of the ice pack was so far North. I think bilateral freezing on this scale is a first.

So the East Siberian and Laptev Seas froze over relatively quickly, the Beaufort Sea was behind on schedule (causing a nice new record anomaly dip), but is now filling up nicely, Baffin Bay and the Kara/Barentsz Sea are late, late, late (as can be seen on the regional graphs page of the ASI Graphs website). I will soon start to compare those regions, but in the meantime I have extended the concentration maps on the aforementioned ASI Graphs website with November, so you can compare to previous years yourself.