Arctic Sea Ice

Animation 9: sea ice concentration

It's oh so cloudy up there in the Arctic due to all those nasty cyclones that it's virtually impossible to make intriguing animations of Passages, glaciers or ice floes the size of European islands. I decided therefore to have another look at sea ice concentration maps and how they have been evolving over the past couple of weeks.

Allow me to kick off with the sea ice concentration map of the University of Bremen because I was quite surprised by what I saw today. A huge part of the ice pack has suddenly turned to yellow, green and even some blue in the area of the Beaufort, Chukchi and East Siberian Seas. Mind you, I expressed my doubt following the last animation I made of the University of Bremen sea ice concentration map, noting that it looked like a blinking flash light. Not entirely fair perhaps as the ice really looks shaky for a while now and weather conditions are making the ice floes diverge and spread out.

Here's the animation where I compare yesterday's date, July 29th, to the same date in previous years. At the end I've added the map of the day before yesterday, just so you can see the change in one day:

Without the multi-coloured area 2010 looks to be ahead of most years, except ice queen 2007.

I've also made an animation of the PIPS sea ice concentration maps from July 15-28. PIPS gets its sea ice concentration data from the SSM/I satellite sensor and I must say the shape agrees pretty well with Uni Bremen:

Sea ice extent update 20: spread it!

I'm regularly writing updates on the current sea ice extent (SIE) as reported by IJIS (a joint effort of the International Arctic Research Center and the Japan Aerospace Exploration Agency) and compare it to the sea ice extents in the period 2006-2009. The IJIS graph is favoured by almost everyone, probably because it looks so nice compared to other graphs (like the one by Arctic ROOS, the University of Bremen and the Danish Meteorological Institute). All the years have a nice colour of their own which makes it easy to eyeball the differences between trends. Most of the betting on minimum SIE is based on the IJIS data. NSIDC has a nice explanation of what sea ice extent is in their FAQ.

July 29th 2010

We are near the end of the month of July and weather conditions have improved somewhat, but still no century breaks in sight. Although the ice looks particularly grey and fragile on satellite images, it is apparent that the losses in extent are partly compensated by a spreading out of the ice in the Beaufort, Chukchi and East Siberian Seas. According to the last SEARCH outlook some of this ice is supposed to be pretty thick, having been transported a long way from home during last winter's extreme negative Arctic Oscillation.

The big question now is: will this sea ice be spread out long enough to keep extent deceptively high until things start refreezing? And that is counting on weather conditions to stay the way have been since the start of July. What happens if weather conditions reverse and stay that way till the end of the season (instead of the to and fro we are witnessing the past weeks), like they did in 2008? Either way, whether ice melts in situ due to air and sea surface temperatures - which will become more difficult by the day - or the ice gets pushed towards the Pole and compacted, extent melt rates will have to seriously start to pick up for 2010 to stay in the race.

Since the last SIE update I was really expecting a century break to be reported, what with high sea level pressure areas developing in the right spots, sea ice area trends decreasing uniformly and large PIPS ice displacement arrows pointing towards Fram Strait. Clearly, the Arctic decided otherwise. And so all we've seen reported by IJIS were decreases that were slightly above the month's average rate, which is of course pretty low itself: 69,531 square km for the 25th, 73,594 square km for the 26th, 68,437 square km for the 27th. And today's reported melt was especially low again with 37,032 square km.

This means that 2009 has taken over 2nd place, although 2010 might clinch it back as 2009 will start to level off soon. 2008 is about to start its final sprint though, with four century breaks next week, just like 2007, which is strolling further and further out of sight.

The current difference between 2010 and the other years is as follows:

• 2006: -208K (70,025)

• 2007: +604K (98,609)

• 2008: -344K (81,069)

• 2009: +30K (92,127)

The average daily melt for the month of July is between brackets. 2010's average daily melt for July is currently 61,808 square km per day.

And here's the IJIS sea ice extent graph:

Compare this to the IJIS sea ice area graph:

Remember, when analysing satellite images a grid cell representing a surface area of 25kmx25km is added to total extent when at least 15% of the grid cell contains ice (and is then counted as 100% ice). With area the actual ice percentages of all grid cells are added up.

From the graph it is obvious that the spreading out of the ice is not having an effect on the steady decrease in area since the start of July. This is also reflected in the Cryosphere Today sea ice area graph that dropped from an anomaly of almost 2 million square km (compared to the 1979-2008 mean) to 1.150 million square km, but has crept back to 1.418 million square km:

Most of this is due to melt on the Siberian side of the Arctic, but the trend of the Arctic Basin sea ice area has also been dropping for a few days in a row now:

SEARCH September sea ice outlook: July report

The second SEARCH sea ice outlook has just been released:

The July Outlook for arctic sea ice extent in September 2010 shows some notable adjustments from the June Outlook, with both downward and upward revisions from last month.

Downward revisions reflect in part rapid ice loss observed during June together with the presence of the Arctic Dipole Anomaly (DA), which promotes clear skies, warm air temperatures, and winds that push ice away from coastal areas and encourages melt. Upward revisions reflect the slowdown of ice loss during the first two weeks of July and a change in atmospheric conditions to cooler, cloudier weather.

The July 2010 Sea Ice Outlook Report is based on a synthesis of 17 individual pan-Arctic estimates using a wide range of methods: statistical, numerical models, comparison with observations and rates of ice loss, composites of several approaches. Two contributors to the outlook represent "public" contributions.

Including all contributors, the individual Outlook values for September 2010 range from 1.0 to 5.6 million square kilometers, with a mean of 4.6 +/- 1.10 million square kilometers. Excluding the outlier of 1.0 million square kilometers by one of the public contributors gives a range of 4.0 to 5.7 million square kilometers, with a mean of 4.8 +/- 0.62 million square kilometers. This is below the 2009 minimum of 5.4 million square kilometers and just slightly above the 2008 minimum of 4.7 million square kilometers. Only three of the Outlook contributions give a value equal to or above the long-term linear trend line (5.6 and 5.7 million square kilometers, respectively). All of the estimates remain significantly below the 1979-2007 average of 6.7 million square kilometers, and six estimates indicate a new record minimum.

Passing the Passages

As the melting season enters its final phase our attention increasingly turns towards the opening up of the sailing and shipping routes that connect Europe and the East coast of the US to Asian harbours and markets. Potentially connect, I should say, because the Northwest Passage (on the Canadian and US side of the Arctic) and the Northern Sea Route (on the Russian side of the Arctic) do not open up every year and mostly only for a short time in August and September. Click the links for animations I have made of critical areas in both Passages. I update these images as often as conditions allow it.

The history of the Passages is too large a subject to broach and not the purpose of this post, but one thing is for sure: with the decreasing trend in sea ice area and extent in the past decade the Passages have not only been opening up more frequently, but earlier as well. In 2007 the northern/direct route of the Northwest Passage was open. In 2008 both Passages were open for the first time in recorded history.In 2009 both Passages were open again, even though the Northwest Passage was pretty clogged up with ice.

This year there's a good chance both Passages will be open. In the Northwest Passage the ice bridges broke up a few weeks ago. With all the ice shoved to one side a few days back it looked open enough already to be navigable by a sturdy ship. On the Siberian side of the Arctic the only question is whether and when the ice behind Vilkitsky Strait - which is already free of landfast ice - will disperse or get pushed towards the coast and effectively block the Northern Sea Route. The ice in the East Siberian Sea looks so grey and rotten that it will most probably not survive, even if it stays in place and doesn't get pushed aside by currents and wind.

The opening up of the Passages opens up possibilities. Accomplishing something like the passing of the Passages have always been considered heroic feats, as they are indeed. Many sailors have thus been attracted by the lure of open Passages with the legendary names of Alfred Wegener, Roald Amundsen and the St. Roch in the back of their minds. Especially the fabled Northwest Passage has seen many ships and yachts make it through safely in the past three years. The Northern Sea Route even saw a commercial ship make it through. This year will see more attempts to sail the Passages, but there is one attempt I'd like to put the spotlight on.

After many months of planning and preparation Norwegians Børge Ousland and Thorleif Thorleifsson have started a voyage that they hope takes them through both Passages during the same season. As can be read in the presentation of their expedition: Børge Ousland has more than 20 years’ experience with record-breaking Arctic and Antarctic expeditions. He was the first person to complete a solo expedition to the North Pole without re-supplying, and the first to cross the Antarctic continent alone. He is still the only person to have accomplished both feats. In 2007 he completed the expedition In the Footsteps of Nansen, a gruelling 5000-kilometre voyage from the North Pole to Oslo, via Franz Josef Land.

Thorleif Thorleifsson is a former Naval Officer – a submariner. In the last three decades he has sailed extensively in the North Atlantic, North Sea and Barents Sea. In August 2007 he sailed his yacht to Franz Josef Land to pick up Børge and his expedition partner Thomas Ulrich. Thorleifsson will be the skipper for the upcoming expedition. For the Northeastern Passage, which is to be traversed first, the third crewmember will be Russian Stanislav Kostyashkin. Frenchman Vincent Colliard will be part of the crew for the Northwestern Passage.

Here's an image of the route they are planning to follow:

Sea ice extent update 19: promising, but premature

I'm regularly writing updates on the current sea ice extent (SIE) as reported by IJIS (a joint effort of the International Arctic Research Center and the Japan Aerospace Exploration Agency) and compare it to the sea ice extents in the period 2006-2009. The IJIS graph is favoured by almost everyone, probably because it looks so nice compared to other graphs (like the one by Arctic ROOS, the University of Bremen and the Danish Meteorological Institute). All the years have a nice colour of their own which makes it easy to eyeball the differences between trends. Most of the betting on minimum SIE is based on the IJIS data. NSIDC has a nice explanation of what sea ice extent is in their FAQ.

July 25th 2010

2010 has still not decided to stay on the canvas and let the referee declare a knock-out. After the abrupt ending of a small century break series a few days ago, things seem to be picking up yet again. But the Beaufort Gyre still hasn't reversed to a clockwise motion and pressure areas still haven't firmly installed themselves for the Arctic Dipole Anomaly to be either strongly positive or negative. Except for low pressure areas continuing to dominate the Arctic - reflected by a positive Arctic Oscillation - things are overall still quite erratic.

The big drop after the first two century breaks of the month was followed by a slightly higher 54,532 square km reported for the 22nd. The 23rd saw the second upward revision of the season and ended at a respectable 84,375 square km. Today it was a bit better still, though this morning's reported century break didn't survive the revision: 93,906 square km.

2010 is still holding onto that second spot. If it manages to produce a few good melting days it will have succeeded in fending off 2009's attack, after which it is 2008's turn with its series of century breaks in the first week of August.

The current difference between 2010 and the other years is as follows:

• 2006: -217K (70,025)

• 2007: +523K (98,609)

• 2008: -391K (81,069)

• 2009: -49K (92,127)

The average daily melt for the month of July is between brackets. 2010's average daily melt for July is currently 61,751 square km per day.

And here's the IJIS graph:

The erratic behaviour is still apparent in the Cryosphere Today Sea Ice Area graph. It has been going up and down again in the past few days, oscillating around the 1.3 million square km anomaly mark. It currently stands at 1.292 million square km, with the large drops in the East Siberian Sea and Laptev Sea having halted for the moment. The Arctic Basin is still hovering on the same level it has for the past few weeks.

In the comment section of the last SIE update there has been some discussion of the Swiss cheese quality of several parts of the central ice pack's interior that have become increasingly visible on the MODIS satellite images. These areas seem to become a bit smaller now with the tentative shifts in atmospheric circulation and winds blowing more towards the Pole causing the ice to be pushed together and against Greenland and the Canadian Archipelago:

Updated NWP animation

It's been almost a month since I posted the first Northwest Passage animation. Because of the lack of detail I had decided to put some more effort into it and updated it with a second animation that zoomed on a large part of the direct route of the Passage, using the 250m scale satellite images from MODIS.

Now that the sky over the Canadian Archipelago has finally cleared up a bit I figured it was time to zoom out again - no more cracks in ice bridges in the direct route to put under the blogoscope - so we can see what is happening in all the straits and channels and sounds and bays and gulfs:

I've still not rotated the image, as I guess most people who check out MODIS images are used to it looking like this (and I'm too lazy to make the effort), but here's the animation:

Sea ice extent update 18: under pressure

I'm regularly writing updates on the current sea ice extent (SIE) as reported by IJIS (a joint effort of the International Arctic Research Center and the Japan Aerospace Exploration Agency) and compare it to the sea ice extents in the period 2006-2009. The IJIS graph is favoured by almost everyone, probably because it looks so nice compared to other graphs (like the one by Arctic ROOS, the University of Bremen and the Danish Meteorological Institute). All the years have a nice colour of their own which makes it easy to eyeball the differences between trends. Most of the betting on minimum SIE is based on the IJIS data. NSIDC has a nice explanation of what sea ice extent is in their FAQ.

July 22nd 2010

We have a few interesting days behind us. As noted in the previous update pressure areas in the Arctic were shifting a bit towards a set-up, also known as the positive Arctic Dipole Anomaly, that is causing extent and area to drop. This positive anomaly was largely responsible for the record-breaking melt rates in May and June, but things shifted radically by the end of June and since then we have seen a considerable slowdown. For more information, read NSIDC's mid-month special update explaining how the rate of ice loss slowed in the first half of July, primarily because of this change in atmospheric circulation.

The importance of this reversal has been confirmed in the past few days. No sooner did cyclones (low pressure areas) and anti-cyclones (high pressure areas) start shifting or we witnessed two century breaks in a row: 108,906 and 109,219 square km respectively. These were the first century breaks of the month and the first time in 3 weeks that 2010 had the highest reported daily melt in the last 5 years. It was that bad.

But alas, there will not be a definite reversal for the moment. Pressure areas have shifted again and the Arctic is dominated by low pressure areas which enhance cloudiness and reduce temperatures (and animations, sniff). This is reflected in today's reported melt of just 43,906 square km.

The two century breaks helped 2010 hold on to second position, but it looks like 2009 will take over the coming days with its small series of century breaks. 2006 will soon be out of the competition and with 2009 melt starting to level off next week, 2010 might regain that second position and prepare itself for 2008's final sprint. 2007 is gone with the wind.

The current difference between 2010 and the other years is as follows:

• 2006: -132K (70,025)

• 2007: +445K (98,609)

• 2008: -464K (81,069)

• 2009: -237K (92,127)

The average daily melt for the month of July is between brackets. 2010's average daily melt for July is currently 59,487 square km per day. 

And here's the IJIS graph:

The drop-back of extent melt numbers was presaged yesterday by another uptick on the Cryosphere Today Sea Ice Area graph. It went up from a steady -1.395 million square km to -1.156 million square km compared to the 1979-2008 mean, accompanied by big upswings in the Arctic Basin and the East Siberian Sea. Today it went down again to -1.248 (make up your mind, will ya!):

Unfortunately the daily mean ice drift forecast from the Russian Arctic and Antarctic Research Institute (AARI) hasn't been updated yet - in fact, the site has been down for a few days -, but I've made a small animation of PIPS daily ice displacement forecasts to show how things were reversing again for a while, but re-reversed in the past few days. On today's forecast for the 23rd we have arrows pointing everywhere:

Scientists receive first CryoSat-2 data

Every good gift and every perfect gift is from above, says the King James bible. That is certainly true when it comes to satellites measuring ice thickness and sending data back to Earth. Ice thickness constitutes one of the most important Arctic puzzle pieces, so this data will in large part answer the questions surrounding the state of the Arctic (and Antarctic) land and sea ice.

A satellite from the European Space Agency that will do just that, Cryosat-2, lifted off successfully this April from the Baikonur Cosmodrome in Kazakhstan.

Two days ago this news was released on the ESA website (h/t Artful Dodger):

A better understanding of how Earth's ice fields are changing has come another step closer as the first data from ESA's ice mission are released to selected scientists around the world for fine-tuning.
 
This release, which comes just three months after CryoSat-2 was launched, is the first milestone in the scientific exploitation of the mission's data. These data are essential for determining tiny variations in the thickness of ice floating in the polar oceans and in the large ice sheets that blanket Antarctica and Greenland. Around 150 scientists from about 40 research institutes now have access to the data. As part of the calibration and validation procedure, it is their job to help ensure these measurements meet the mission's exacting standards before the data are released to the wider scientific community later this year.  

Continue reading here.

 

For more information on satellites gathering data on land and sea ice, I highly recommend reading this article from Yale e360.

Animation 8: Kangerdlugssuaq Glacier

Hold on, let me check if I spelled that right. K-A-N-G-E-R-D-L-U-G-S-S-U-A-Q. Okay, all clear.

I received a comment from Werther in the blog post on Jakobshavn Isbræ pointing me towards another Greenland glacier called Kangerdlugssuaq. On the MODIS satellite images he noticed a strange blue swath showing up behind the glacier terminus. Happy as I was to have heard of a new Greenland glacier (and there are so many more), I decided to make a short animation before offering more information on this glacier.

The animation starts with an image of the situation last year, with a round marker to show where the terminus is located. The next images are from the last three days. What can be seen is that there has been a small terminus retreat compared to 2009 and on the last image we see the large blue swath.

 

After having looked attentively at the animation I conclude that the blue swath must be some sort of artefact, if only for the fact that it is physically impossible for a melt pond or glacial lake of that size to form within 24 hours. Besides, it occurs right at the edge where two satellite images have been stitched together and you can see some of the dark patches right through it. Unless it rained very heavily for 20 hours, I think it's either a glitch or the shadow of a cloud.

So, this probably doesn't mean much, but it gives us the opportunity to learn some more about the Kangerdlugssuaq Glacier. Here's a picture of Greenland I found on ScienceDaily that shows the location of the glacier:

Graphs of the Week

The comment section is becoming a veritable goldmine. Soon I will not have to think up new subjects for blog posts. The title of this blog post, for instance, was proposed by fredt34. I only had to adjust it a bit, as I'm going to show several graphs, not just one.

In the latest SIE update L. Hamilton (Larry, not Lewis, a professor of sociology) came up with a cycle plot that brings out the downward trends in each month of the year, in the period 1979-2010:

 

According to L. Hamilton the idea for this graph came up while discussing it at a conference with his colleague Nicholas Cox. The latter has written a paper on the subject at large: Cox, N.J. (2006) "Graphs for all seasons," Stata Journal 6(3):397-419. The graph more or less looks as if summer ice melting is structurally a month ahead of schedule.

Meanwhile Anu came up with a graph from Uni Bremen that I don't remember seeing yet. It shows the monthly change of sea ice extent:

I think it was Gas Glo who in the comment section of another blog post linked to a similar graph he made of extent melt rates. Anyway, the recent slowdown is plain to see.

Anu also put up links to the Uni Bremen AMSR-E archive to ice concentration maps in previous years. I've used them for a small animation: