Arctic Sea Ice

Circumnavigating Greenland

A quite spectacular event took place during the past two weeks, and if it had continued for a while longer, I'm sure it would've been reported widely. It's something I've semi-jokingly alluded to when setting up this blog back in 2010, in my third blog post called Dire Straits, and a partial answer to the question commenter fredt34* asked at the time:

The big hole opening in East Greenland re-activated my interest for this question: will we see Greenland being circumnavigable this year? If not, when?

That was July 23rd 2010, and now a little over 8 years later, we have almost seen it happen: a corridor of open water between Fram Strait and the Lincoln Sea (where Nares Strait starts). Here's an animation of NASA EOSDIS Worldview satellite images showing what has happened during the past two weeks, ending yesterday (click for a slightly larger version):

And here's the animation with only the first and last images, two weeks apart:

Bering goes extreme

The melting season hasn't started in earnest yet, but it seems the Bering Sea hasn't received the memo. For almost the entire winter, sea ice has been reluctant to form there, and now that the Sun has returned, the ice edge has started to retreat to record high latitudes, past the Bering Strait all the way up into the Chukchi Sea. Here's how that looks on Wipneus' regional graph:

To emphasize how truly exceptional this is, here's a comparison with the situation in all other years from the 2006-2018 period (images retrieved from the University Bremen sea ice concentration maps page on the ASIG, click for a larger version):

Now, if this was it, other years would maybe catch up in the next few weeks, but this isn't it. The coupled HYCOM-CICE model from the Naval Research Laboratory forecasts the sea ice to continue to drift northwards, until the end of the month at least:

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 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:

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:

PIOMAS July 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:

As expected after a month of stalling sea ice extent and weather that generally isn't conducive to sea ice loss, 2016 is no longer lowest on record. In fact, 'only' 5890 km3 of volume was lost during June, according to PIOMAS, which is still more than any year before 2010, but less than any year after 2010, except for 2014. 2016 has now dropped into third position, on a par with 2010.

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

As you can see the change in difference with 2012 is massive, which isn't surprising given that 2012 dropped almost 7300 km3 during June. Over on the Arctic Sea Ice Forum I was expecting this year's volume loss to be somewhat higher, but it seems I was wrong. So 2016 is now more than 1000 km3 behind 2012, which is another line of evidence that speaks against new record lows at the end of the melting season. Of course, this doesn't mean everything is hunky dory. Quite the contrary.

Wipneus' version of the PIOMAS volume graph shows how this year's trend line kept veering off its course, while 2012 dropped off a cliff during June:

And look, the trend line on the PIOMAS sea ice volume anomaly graph has dropped well into the 2 standard deviation zone where it hasn't been since 2013. The question is now whether it will drop some more and leave the light grey band like it did in 2010, 2011 and 2012:

Beaufort Gyre guest blog

Not an update of current conditions in the Beaufort Sea, but some science for your reading pleasure.

This is a guest blog by Alek Petty, a postdoc at NASA’s Goddard Space Flight Center and the University of Maryland, specializing in Arctic and Antarctic sea ice variability. Alek has just published a paper in the Journal of Geophysical Research called Sea ice circulation around the Beaufort Gyre: The changing role of wind forcing and the sea ice state, and below he explains in detail what the paper is about (also be sure to check out his website).

Sea ice circulation around the Beaufort Gyre

The Beaufort Sea ice pack has experienced a significant breakup event in recent weeks. This has coincided with some classic Beaufort Gyre ice drift circulations. In this blog, I want to talk a bit more about the sea ice circulation around the Beaufort Gyre, why it’s important, and why it might have changed over the last few decades.

The Arctic is replenished with around ten thousand gigatons of fresh water every year from river run-off into the Arctic basin, Pacific Water inflow (through the Bering Strait), precipitation and – increasingly – sea ice melt.

Figure 1: Mean dynamic topography (MDT) of the Arctic Ocean [from Farrell et al., 2012, GRL]. Grey lines are bathymetry contours [Jakobsson et al., 2012] and the black boxes indicate the Beaufort Gyre study region.

The predominantly clockwise winds over the northern Beaufort Sea draw in a significant fraction of this freshwater – through a process called Ekman pumping – resulting in a characteristic doming of the ocean surface (a ‘spin-up’ of the ocean as it is often called).

The combined forces of gravity and Coriolis drive a clockwise ocean current that circulates this relatively fresh surface water – along with its overlying sea ice cover – around the center of the dome (also clockwise). The end result is one of the most prominent features of the Arctic Ocean: the Beaufort Gyre (see Figure 1).

The sea ice sandwiched between the atmosphere and ocean responds to the combined effects of wind and ocean drag and thus modulates how effectively the winds can ‘spin up’ the ocean. The interaction between winds, ocean currents and sea ice are intrinsically linked, making it an extremely challenging system to study. We’ll get back to this point later.

Beaufort final update

This isn't a final update as such, because I will certainly be mentioning events in the Beaufort Sea in upcoming ASI updates. But it is the last in a series of blog posts I have written (one, two and three) about this unprecedented event that started over 6 weeks ago and has led to a heavily cracked ice pack and a huge amount of open water on the American side of the Arctic.

The event has received some attention on other blogs and in the mainstream media. Just yesterday this image was posted on NASA's Visible Earth website, comparing this year to 2015 and 2014 (mind you, the Beaufort Sea opened up early last year as well):

The image is accompanied by a text, quoting Walt Meier:

“It really is quite remarkable,” noted Walter Meier, an ice specialist at NASA’s Goddard Space Flight Center. “There is always fracturing of the ice, but it seems to have become more prevalent and more widespread in recent years. This region used to be mostly multi-year ice, which is quite a bit thicker. Now, most of the Beaufort is seasonal, first-year ice. The thinner ice is weaker and more easily broken up by the winds.”

There are some links to other articles at the end of the Visible Earth article.

As I mentioned two weeks ago it looked as if that persistent high-pressure area was shifting away from the Beaufort, which would probably put "an (temporary) end to the massive cracking and ice movement". The animation below shows there has been some movement, but not as much as in prior weeks. Cloudiness makes it difficult to perceive, but if you focus on one of the two larger ice floes in the red circles, you can get an idea of the scale of movement/change:

Beaufort under relentless (high) pressure

When I wrote the Beaufort under early pressure blog post last month, I didn't quite expect this unprecedented pressure (timing and magnitude) to keep up for so long. High pressure areas tend to be short-lived in the Arctic, but this one was still going strong when the Beaufort quick update was published. Now, almost three weeks later, things still haven't completely calmed down, and this animation of satellite images showing weekly changes from March 30th to May 4th provides an astonishing sight:

Astonishing, mindblowing, frightening even. May is the month when melt ponds start to form on the ice, pools of water that lower the albedo and cause the ice to melt faster, leading to open water that absorbs solar radiation and warms up. The open water is already there in the Beaufort Sea. Look at all that open water!

No other year comes even close to it, as can be seen on the ASIG comparison of sea ice concentration maps, or on this sea ice extent graph (based on AMSR2 data, provided by Wipneus):

Jim Hunt provides this close-up view on the resources page of his Great White Con website (also be sure to read his latest blog post on early wave activity in all this open water):

Beaufort quick update

It's been a week since I announced that the ice in the Beaufort Sea was going to come under early pressure. Here's a quick update on what has happened so far, how the forecast played out, and what the short-term conditions for this part of the Arctic will be.

As expected, the Beaufort Gyre kicked into action, big time, with winds causing large cracks in the ice pack, moving it westwards and away from the Alaskan and Canadian coasts. The massive polynyas that are left behind, get partially covered with a thin veneer of ice.

Here's an animation showing the difference between LANCE-MODIS satellite images on the first of the month and two weeks later:

Quite impressive, isn't it? As if someone threw a giant brick into it.

Here's an animation showing all days between April 1st and 14th (the file is somewhat large, apologies if it loads slowly):