September 2nd 2013
We have almost reached the end of the 2013 melting season, perhaps even earlier than in the last couple of years. After months of predominantly cyclonic weather - that has pushed the ice pack apart, but at the same time preserved a lot of the first-year ice - there are large patches with low sea ice concentrations within the ice pack (also see this recent blog post). Here's an animation of images provided by Wipneus, based on Uni Hamburg data, showing what has happened from August 28th to 31st:
There's some compaction going on, but the open water within the ice pack is easier to freeze and ice floes get re-connected to each other. This will slow down whatever melt, compaction and transport there is left, or even supersede it and thus effectively end the melting season.
Of course, it all depends on the exact weather conditions (more on that later this week), and we have to keep in mind that a significant part of the ice pack is very fragile. In fact, a third of the ice pack that was almost cut off from the main ice pack north of Greenland and the Canadian Archipelago, would have probably melted out if weather conditions hadn't been the exact opposite from previous melting seasons. More on that later as well.
Let's first have that overview of the current situation.
Because Cryosphere Today SIA data wasn't forthcoming yesterday, I decided to wait one day with this update to have the full month displayed on the graph:
I didn't think it was possible, but area-wise 2013 is now even above 2009. Apparently this can happen when the weather isn't conducive to ice decrease (melt, compaction and transport) for almost the entire melting season, even if you start out with a record amount of first-year ice. Fascinating stuff. After the lowest average daily decrease since 2006 for the month of August, 2013 is almost 1.3 million km2 behind last year!
The SIA minimum usually occurs somewhere in the first two weeks of September, but given the way things have proceeded this melting season, I wouldn't be surprised if it happened a couple of days ago. Either way, it won't be going much lower than this.
Here's the link to my updated CT SIA spreadsheet.The SIA anomaly is still below the -1 million km2 mark. We've gotten used to records getting broken in the past couple of years, but it's good to remember that the Arctic is still quite far away from the 1979-2008 average:
Sea ice extent (SIE)
The IJIS SIE numbers are slightly less dramatic than CT SIA, with 2013 on a par with 2009 and 2010:
The 2013 trend line went below the 2005 minimum today and already was below the 2006 minimum. It will probably go under the 2009 minimum in a couple of days, and with a similar end sprint to the one we saw in 2010 it could even end up below 5 million square kilometres. But that's still 1.5 million above last year's stunner.
Here's the link to my updated IJIS SIE spreadsheet.
Cryosphere Today area per IJIS extent (CAPIE)
CAPIE also keeps showing us that this year has been cold enough to completely minimize the role melt ponds have in this metric:
Although I still think that clouds also influenced the high CAPIE numbers throughout the melting season, it's clear that the massive divergence we saw this year has been fully compensated by the cold. The lowest CAPIE percentage of 65.87% was reached on July 23rd, almost two weeks earlier and 10% higher than last year.
Regional SIE and SIA
Regional graph of the week, taken from the Regional Graphs page:
With some late compaction action on the Siberian side of the Arctic (see animation at the top of the post), SIA in the Laptev Sea has made a final dip. This basically has caused the Northern Sea Route to finally open up, but ships would have to go around the islands of Severnaya Zemlya if they really want to see as little ice as possible, as there's still some left in Vilkitskiy Strait. So that streak is still running (since 2007), but the main route of the Northwest Passage has remained closed for the first time since 2008.
We can see the changes in the past two weeks on this map that Wipneus has custom-made for this ASI update (based on Uni Hamburg data, see here).
Red = ice two weeks ago, open water now; blue the other way around:
The edge of the ice pack has retreated even more on the Atlantic side of the Arctic, almost reaching 85° N. With temps dropping low, freezing the water in the 'holes' I discussed last week, we're not going to see a completely ice-free North Pole (that is connected to the Atlantic Ocean even). But this year came even closer than 2010.
Sea Level Pressure (SLP)
This animation of Danish Meteorological Institute SLP maps from the past 15 days shows us just how weak weather conditions have been for melt, compaction and transport:
So let's have a look at what the 6-day weather forecast from the ECMWF model has in store, as it might give us a clue about when we're going hit that minimum (click for a larger version):
Now there's an interesting forecast. It seems a large - though not intense - high is taking over the central Arctic and then moves over the Beaufort. In previous years this meant that the minimum would take a while longer to be reached. Although this year nothing quite went the way I expected, I think that we won't be seeing an IJIS extent minimum in the next week. I'm not sure about CT SIA though.
Air temperatures have gone up quite a bit over the Arctic Ocean, when compared to two weeks ago:
This is also reflected on the DMI 80N temp graph:
The quick turnaround makes me suspect that perhaps some of the water in the Arctic Ocean is already releasing heat so that it can start to freeze up, but it could just be warm air being blown in from somewhere.
We're nearing the end of a melting season that would've fit in snugly between 2008 and 2009. Weather conditions have been completely opposite to what I've seen since the inception of this blog in 2010, highlighted by the three cyclones we witnessed from May onwards. But let's save that analysis for when the minimum is reached and we can weigh the difference between expectations and reality.
Later this week I will try to post about a new feature I haven't finished yet on the ASIG that helps somewhat in determining the timing of the minimum. It's just one of several things that slipped through my fingers this year, and so I apologize for not having been able to cover this melting season as closely as I did the previous three melting seasons. I have great excuses, of course, like the fact that I'm in the process of building a house (slowly reaching its climax in the next 2-3 weeks), and the melting season being less of a spectacle with slow melting and an extremely cloudy Arctic. But still, there's always plenty of stuff to talk about when it comes to that fascinating place that is the Arctic. Next year will probably be better.
I don't know about you, but I'm looking forward to the next PIOMAS update!