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 2005-2013 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.
June 15th 2014
Nothing in the Arctic is a dead certainty, but I feel it has already become clear that this year won't be as extreme as 2012 or 2013, even though there are still some similarities with the latter.
The most important of these similarities are relatively low temperatures, and slow sea ice area and extent decreases. Even though the Sun came out and shone on various parts of the Arctic, massive melt was muted. Perhaps this had to do with the lack of pressure gradients that make for winds and export the ice to lower latitudes, combined with a forecast for warmer temperatures that failed to materialize. There could be other reasons as well (snow on ice, fog), but these are difficult to quantify.
Either way, by this time 2012 had already started a never before seen drop on area and extent graphs that would make itself felt towards the end of the melting season. But 2014 is still chugging along, waiting for more Sun. And higher temps.
Sea ice area (SIA)
As predicted in the last ASI update, the dominance of high pressure over a large part of the Arctic, caused the trend line to plummet briefly at the start of the month, caused by a melt pond surge in Hudson and Baffin Bay mainly. But as temps stayed low, and there was no transport to speak of, things slowed down again, with the 2014 trend line now just above the main pack. Also note 2012's amazing run:
Sea ice extent (SIE)
As extent is less sensitive to melt pond formation, there was neither a drop nor a slowdown, just a steady decrease. Nevertheless, look at how 2014 crosses a crashing 2012 trend line:
Here's the link to my IJIS SIE spreadsheet.
Cryosphere Today area per IJIS extent (CAPIE)
With SIA dropping slightly faster than SIE, CAPIE is also bound to go down. 2014 is right in the middle of the pack here. 2012 was already low around this time and dropping fiercely, a sign that heavy melt ponding was going on over the Arctic (check the previous update for an explanation of CAPIE):
Here's the link to my updated CAPIE spreadsheet.
Regional SIE and SIA
Regional graph of the week, taken from the Regional Graphs page on the ASIG:
Two weeks ago it was the neighbouring East Siberian Sea, this week we look at the Laptev Sea, the other region where the huge polynya is asserting itself. Although the speed with which it is opening has slowed down, it's size is still largest in the recent record (see the MASIE graph). It's these two regions, with the adjacent Chukchi Sea, where ice has been disappearing the fastest,and the fast ice is starting to disintegrate as well, as can be seen on this image produced by Wipneus on the ASIF:
But the easy ice in peripheral regions like Hudson, Baffin and Barentsz/Kara is still holding on. The map below, custom-made by Wipneus for this update, shows the changes over the past two weeks in Hudson and Baffin bay. The map is made using University of Hamburg AMSR2 data. Red = ice two weeks ago, open water now; blue the other way around:
A big change, but smaller than in previous years. However, sooner or later his ice will go, and no longer keep SIE and SIA numbers pumped up.
Sea Level Pressure (SLP)
The two-week animation of Danish Meteorological Institute SLP images shows us recent events:
The forecast high came about, brightening up large parts of the Arctic for a couple of days by shifting to and fro. Pressures went down again, with a cyclone showing up briefly in the central Arctic, but the (not so high) highs never yielded the American side of the Arctic.
I've taken the ECMWF forecast maps, and cropped them a bit to make them clearer. First I wanted to turn them into an animation, but there's too much info and detail for that, so I've decided to stick with the 6-day panel. Mind you, forecasts beyond 4 days out can change a lot in the meantime. Still, if they've been pointing in a certain direction for consecutive days, there's a good chance of the forecast coming about.
Let's have a look:
It looks like the highs are in the process of reasserting their domination on the American side of the Arctic and beyond. Again, they're not mirrored by a strong cyclone on the Siberian side, so no Dipole and probably not a lot of transport. Whether this time insolation will cause that June cliff in SIA numbers (see Dosbat post from last year), will also depend on temperatures.
I know it only shows a small part of the Arctic, mostly based on modeled data, but it's remarkable and seemingly unprecedented how low temperatures have been in the past couple of weeks on the DMI 80N temp graph:
And though the trend line is now finally climbing steeply towards 0 °C, things are still anomalously cold or neutral across the Arctic:
Forecasted warmer temperatures have failed to materialize a couple of times now in the past few weeks, but it seems things just must start warming up now. The people running the ClimateReanalyzer website (produced by the Climate Change Institute at the University of Maine) have now added special forecast maps for the Arctic, which are highly recommended and thus have been added to the ASIG (scroll down towards the middle, right hand side). I'm still fiddling around a bit with it, but here's an animation of the GFS weather model forecast for the next 8 days:
This combination of higher temps and dominating high pressure areas should cause a lot of melt ponding, almost Arctic-wide. If so, we can expect sea ice area numbers (and CAPIE) to start dropping big time.
Here's a comment on the ASIF showing June 15th 2012 and June 21st 2013.
I'm going to repeat myself, but just like last year cold temperatures have put a damper on melting. The big difference is that this year there hasn't been a persistent cyclone dominating the Arctic, and so SIE and SIA decrease have been relatively average so far. This bad start (bad for melting) will make a new record extremely difficult to attain, although 2007 weather conditions could make it happen, as the ice is thinner now than it was back then.
For the coming week 2007-like weather conditions have been forecasted, bringing more Sun and higher temps to the Arctic, although - again - there won't be a strong Dipole to compact and push ice through Fram Strait. We will have to see whether the ice pack reacts strongly through melt ponding this time. If combined with peripheral areas catching up to previous years, 2014 could easily drop towards the lower trend lines.
What happens after that, is up in the air and down in the sea, of course.