During the melting season I'm writing (bi-)weekly updates on the current situation with regards to Arctic sea ice (ASI). Central to these updates are the daily Cryosphere Today sea ice area (SIA) and IJIS sea ice extent (SIE) numbers, which I compare to data from the 2005-2014 period (NSIDC has a good explanation of sea ice extent and area in their FAQ). I also look at other things like regional sea ice area, compactness, temperature and weather forecasts, anything of particular interest.
May 19th 2015
Here it is, the first Arctic Sea Ice update for the 2015 melting season, and boy, are we off to a flying start. But more about that later. First a quick overview of what's been happening the last few years.
After the 2007 melting season smashed the 2005 record minimum, it was equalled by the 2011 melting season and subsequently smashed itself by the 2012 melting season. Although the 2013 melting season didn't bode well at all, given the trend and the massive amount of first-year ice, the Arctic sea ice had its traditional post-record rebound after a cold and cloudy melting season.
This (volume) rebound had all but vanished at the start of the 2014 melting season, but again the melting season started out cold and cloudy, after which the sea ice hardly moved during the rest of the melting season. And so there was a similar rebound to the one following the 2013 melting season. However, this time the volume rebound was larger and lingered on through winter.
One would think the ice pack would be strengthened and more resistant to weather conditions at the start of the 2015 melting season. But this also depends on how the volume is distributed across the pack, and as we saw in the 2014/2015 Winter analysis I posted 10 days ago, all of the volume has piled up in the Central Arctic and the Canadian Archipelago, the sea ice's last safe haven. This basically means that as far as the periphery of the Arctic sea ice pack is concerned, there is no big difference with the other post-2007 years. This melting season could turn out to be another rebound, but it might just as well go as low as 2007, 2011 or even 2012. The only thing we know for certain, is that the Arctic won't see below 1 million km2 of sea ice come September, the definition of 'ice-free'.
The outcome is obviously determined by weather conditions, but this month and June are particularly important for what I like to call melting momentum. This momentum is determined by the amount of melt ponds that form on the ice pack during these two months, as they soak up more solar energy that would otherwise be reflected. 2012 had a relatively sunny and warm start of the melting season, after which a stable decrease couldn't be thrown off by weather that was less conducive to melting. And that's how the record was broken, compounded by the Great Arctic Cyclone in August. Conversely, 2013 and 2014 had cold and cloudy starts to the melting season, and this couldn't be made up later on during bouts of sunny weather.
And so melt ponds will be the main theme of this first phase of the melting season. In fact, I'm going to obsess over them in the next two months and report on them outside of the ASI updates. The amount of melting momentum decides whether the melting season has a chance of breaking records.
Off we go.
Sea ice area (SIA)
The people behind the Cryosphere Today website have been experiencing some trouble with their server and so data has been updated up to May 13th only: The 2015 trend line is among the lowest on record. It will be interesting to see if it goes lowest once data is updated, as it is on the SIE chart.
Sea ice extent (SIE)
This is pretty low, and it's probably going to stay that way for the time being.
Regional SIE and SIA
This year I'll be using the regional SIE and SIA graphs on the updated Arctic Sea Ice Graphs website, as provided by commenter and amateur Arctic expert Wipneus. But first, here's a map of the entire Arctic Wipneus has sent me yesterday to show where most of the ice has disappeared in the past two weeks (red = less ice than two weeks ago, blue = more ice than two weeks ago):
Just like last year the sea ice in the Bering and Okhotsk Seas melted out really quickly, which probably has a lot to do with that blob of hot water in the North-Pacific. These regions were also the main reason for the extremely early and record low maximum:
But as we can see on Wipneus' 2-week delta map for the entire Arctic, melt has started in the Kara and Beaufort Sea, and Hudson Bay:
Particularly the melt in the Beaufort Sea is very early, as can be seen on Concentration Maps for May 19th. But these sea ice concentration maps and regional graphs are not even telling the whole story. This LANCE-MODIS satellite image is:
As mentioned in the 2014/2015 Winter analysis there was a cracking event in April, and the ice possibly didn't have enough time for a substantial re-freeze, resulting in this broken mosaic of huge ice floes, interspersed with thin ice, and open water even.
But also clearly visible are the lack of snow on the Alaskan mainland that is in something of a heatwave, the early clearing of ice in the Amundsen Sea and a bluish hue on the fast ice and a part of the ice pack, which is a sign of - you guessed it - melt ponds. This is a very early start of the melting season in the Beaufort and Chukchi Seas, the places where a lot of the rebound multi-year ice has been transported this past winter to possibly form a barrier that protects the ice behind it:
Let's have a look at what the forecast has in store.
Sea level pressure plays a crucial role in determining the position and percentage of melt ponds on the Arctic sea ice pack, as it gives an idea of where the open skies are and if there is a transport of warmer air from lower latitudes into the Arctic. Open skies due to high SLP mean lots of insolation.
This two-week animation of Danish Meteorological Institute SLP images shows what has been going on with regards to SLP:
Weather systems aren't al that stable and follow each other in rapid succession, but a high pressure area is taking over the Beaufort towards the end of the animation. Like said, this means insolation, ehat being pulled in from the North Pacific and Alaska, and clockwise transport of (the cracked) sea ice towards the Siberian coast.
Here's the weather forecast for the coming 6 days according to the ECMWF model (click for a larger version):
It seems the highs are more or less sticking around over the Beaufort Sea. They're not particularly high (1015-1020 hPa isn't that high), but there will still be plenty of sunlight hitting that part of the ice pack. And so we turn to temperatures.
Surface air temperatures have been low across much of the Arctic sea ice, except for the Beaufort and Kara regions, but very low north of 80°as can be seen on the DMI 80N temperature graph:
Now this is where things get interesting, as the GFS temperature forecast is showing some massive changes. Below is an animation I made using actual temperature forecast maps provided by the excellent Climate Reanalyzer website (I'll be using temperature anomaly maps in future ASI updates, but these actual temperature maps nicely show the distinction between freezing blue and melting green):
This forecast is showing above freezing temperatures spreading over much of the ice pack. If you want to see how anomalous these temps are, you can check out the new Forecasts page on the ASIG. The forecast gets even warmer after that, but of course becomes less reliable the further out you go.
I can't interpret this in any other way than a heavy assault on the multi-year ice in the Beaufort and Chukchi Seas. This combination of above freezing temperatures and insolation should cause considerable melt ponding. At the same time it looks like melt onset is delayed somewhat on the Siberian side of the Arctic.
Of course, high temps across Alaska and NW Canada don't bode well when it comes to wildfires.
Sea surface temperature anomalies on the Atlantic side of the Arctic are already on the up side of things, slightly warmer compared to last year, with some orange showing up in the Beaufort Sea already, but these colours can fluctuate from day to day:
Despite the red blob in the North Pacific there's not much anomalously warm water to be seen near Bering Strait. It's possible that some of it is being transported below the surface waters through the Alaskan Coastal Current, but that's nothing more than speculation:
This melting season started out cold, like 2013 and 2014, but in the past week or so things have been changing, notably in the Beaufort and Chukchi Seas where a lot of multi-year ice has been transported to during winter. This ice is going to get it hard in the next week or so, which will probably mean that sea ice extent and area are going to keep tracking low, if not lowest, on their respective charts. But not only because of this, the ice in the Kara Sea and Hudson Bay is also looking fragile and in for a bout of (relatively) warm, sunny weather.
The big question now is how much melt ponds are going to form, as this is crucial for the melting momentum that can make or break a melting season's record potential. I'll be keeping as close a look on that as possible, as melt ponds are difficult to measure, and come back to it in the next ASI update at the start of June. Or as someone on the Arctic Sea Ice Forum called it Junction June.
Enjoy the Arctic sea ice, it's the only Arctic sea ice you've got.