June 21st 2013
Happy June Solstice!
With the fading of the persistent cyclone (PAC-2013) that held the Arctic in its grip for several weeks, the slow start of the melting is now definitely behind us. The cold has almost dissipated and massive heat waves in Alaska and Siberia spell trouble for the ice that is still clinging to respective coasts. The melting is shifting gears as we speak.
But 2013 is still trailing most of the other years, and especially 2012 that put on quite a show last year around this time. Whether 2013 can make up the deficit in weeks to come, depends as always on the weather, but also on the postponed effects PAC-2013 might have had on the ice pack, especially in its centre. There are large zones that look particularly weak, full of small ice floes, but it's not entirely sure what will happen, and more importantly, when it will happen.
Sea ice area (SIA)
The 2013 trend line (based on Cryosphere Today sea ice area data) was about to reach a cluster of years following a series of five century breaks in a row, but an uptick reported today threw a spanner in the works.
Here's the graph based on the latest data:
2013 trails 2012 by a massive 826 thousand km2, but is not trailing that much when it comes to the daily average decrease. Last year saw an enormous 111K daily drop in June, and 2013 is currently on 108K. When it comes to century breaks 2013 is performing decently with 21 century breaks for the season so far, which is already more than 2005 and 2006 had at the end of June.
Here's the link to my updated CT SIA spreadsheet.
IJIS didn't report any sea ice extent data for a couple of days, which happens every once in a while, but everything's fine now. The 2013 trend line is still above all the others on this graph:
Just like last year we see a lag between extent and area data, where area seems to decrease much faster than extent. This usually has to do with melt ponding, to which SIA is more sensitive than SIE, but another factor this year could be the 'holes' in the interior of the ice pack - due to PAC-2013 - that definitely don't get registered for SIE. Sea ice area and sea ice extent graphs start to look more alike during the second half of the melting season.
Here's the link to my updated IJIS SIE spreadsheet.
Regional SIE and SIA
Regional graph of the week, taken from the Regional Graphs page:
This week we turn our attention to the Laptev Sea where most of the recent decline has taken place. As we can see on the historical graph showing data from the satellite era there were some big anomalies in 2011 and 2012 that occurred at the end of the melting season. This, of course, had to do with massive heat getting built up in the water, preventing the Laptev Sea from freezing over quickly.
A prerequisite for that large amount of heat is an early opening up of the Laptev Sea, like the one we are seeing at this very moment, even faster than last year. There's a good chance we'll also see the so-called Laptev Bite, a northward opening up of the ice pack towards the central Arctic. What's causing the Laptev Bite isn't entirely clear yet. Some people speculate it might have to do with the way the ocean floor is shaped, causing warmer waters from below to penetrate the halocline and get at the bottom of the ice.
Sea Level Pressure (SLP)
Let's have a look at what the animation of Danish Meteorological Institute SLP images for the last two weeks shows us:
PAC-2013 falls apart, immediately followed by other cyclones, but before that happens, the cyclone combines with high-pressure areas on the other side of the Arctic, over the Canadian Archipelago and Alaska, to create a small Dipole. This intrusion of high-pressure areas is what is causing the increased speed with which sea ice area declines by bathing the coasts of Alaska and Siberia in sunshine, causing the fast ice to turn blue, a sign of widespread melt ponding.
If that set-up keeps up, this blue ice will disintegrate and retreat from the coast, and so it makes sense to see what the 6-day weather forecast by the ECMWF model looks like:
It looks like the high-pressure areas are here to stay for a while longer, and so the ice in the Beaufort Sea can finally start to retreat from the Alaskan coast, much later than almost all recent years around this date. At the same time a high-pressure area over the Kara Sea will deal summarily with the ice there. And as a bonus, there's a third zone of high pressure near Hudson Bay and Baffin Bay where there's a lot of fragile ice waiting to be transformed into its liquid form.
With PAC-2013 now out of the way, it's time for the cold air temps in the Central Arctic Basin to finally exit. The heat waves in Alaska and Siberia can clearly be made out as well, but no anomalously warm temperatures over the Arctic Ocean as of yet:The DMI 80N temp graph is finally showing an extra uptick towards the 0 °C threshold, but it is taking an exceptionally long time and the modelled air temperature at the top of the Earth is still way below average:
Compared to two weeks ago, the DMI sea surface temperature anomaly map shows more orange and less dark red, except for the Bering Strait, where things are much warmer at the surface than they were in the last two years:
Lately I've noticed that the ice floes that have passed through Fram Strait are much more dispersed than usual, as can be seen on the latest satellite image (if you look past the haze):
Perhaps warm waters there are melting the floes much faster than usual and if transport through Fram Strait is slow, we could be seeing an ice-free Greenland Sea off the east coast of Greenland. I could be wrong, but I don't think this has happened often. Like a lizard shedding its tail.
Things are no less interesting on the west coast of Greenland, where Disko Bay is filled to the brim with warm water (image obviously courtesy of DMI):
Disko Bay is the place where icebergs start their journey, after leaving Jakobshavn Isbræ, one of the largest and fastest flowing Greenland glaciers (it drains 6.5% of the Greenland ice sheet and produces around 10% of all Greenland icebergs), also known for the largest glacier break-up ever caught on tape, as shown in the Chasing Ice documentary.
We'll see whether the anomalously high SSTs will have an effect on that region.
Like I said in the first two ASI updates, it was a matter of time before conditions would align and the Arctic would go POP, like a new garden where after a few years everything suddenly falls into place, plants start to grow abundantly and the ecosystem comes into being. This moment seems to have come.
I'm expecting a very fast decline in area numbers - also known as The Cliff - especially after the slowest start in years. There's a lot of ice on the edges of the ice pack that had already melted out by this time last year, but at the same time there are more 'holes' in the interior of the ice pack that could increasingly play a role in July and August.
Whether the records will be broken for the second year straight (something that hasn't happened often in the Arctic, if ever), is still very much in the air, although personally, I believe that things looked a bit worse last year around this time. It's interesting to see the difference between a good and a bad start to the melting season. I think 2013 will start to catch up with 2007 and 2011 now, 2012 might be too big a hurdle, but I'm not ruling anything out. Nothing in the Arctic is a dead certainty.
We'll see where the 2013 melting season stands after the smoke clears in two to three weeks.
I'll be gone from home for a week, but will keep an eye on things. It might take longer for comments to get released from the spam bucket. Sorry in advance.