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 28th 2014
A few weeks ago it looked as if the Sun was already setting on this year's melting season, but as usual things aren't what they seem in the Arctic, and the opposite has happened. The two previous ASI updates announced that the Sun was coming, and it did, bringing sunshine to compensate for the 2013-esque start of the melting season.
The absolute prerequisite for insolation over (parts of) the Arctic, is high atmospheric pressure. There has been plenty of that in the past weeks, so much so that there has been very little transport, as transport requires wind, caused by low and high pressure systems acting as cog wheels. And so melt rates depend mostly on solar energy, and air and sea surface temperatures.
Apparently this has been enough to let 2014 decline steadily, despite the lack of transport. Not so fast to battle it out with the lower trend lines, but not as slow as the higher trend lines either. The question now is how fast peripheral areas will melt out, as 2014 still has quite a bit of potential there, and if and how the Central Arctic Basin and the multi-year ice in the Beaufort Sea will respond to these high times.
Sea ice area (SIA)
Sea ice area numbers, as calculated at Cryosphere Today, had some very large drops in the past two weeks (4 almost double century breaks), with smaller drops interspersed. The steady drop causes 2014 to stick with years like 2006, 2008 and last year, instead of going the way of big droppers like 2010 and 2012. But, as Wipneus announces on the ASIF, CT will still drop a couple of century breaks before the month is out:
Sea ice extent (SIE)
In contrast to SIA, sea ice extent has been dropping hard on the IJIS graph, with 6 century breaks in the last 10 days.After being behind 500 thousand square kilometres, 2014 is now trailing 2012 by approximately 75K:
The interesting thing is that it was the other way round in 2012, CT SIA dropping very fast (see graph above), with IJIS lagging behind. This most probably has to do with the fact that there were a lot more melt ponds 2 years ago (see graph below).
Here's the link to my IJIS SIE spreadsheet.
Cryosphere Today area per IJIS extent (CAPIE)
When SIE drops relatively fast, and SIA less so, CAPIE naturally goes down slower. Remember, this percentage is calculated by dividing SIA numbers by SIE numbers. Because open water between floes are counted for SIA, but not for SIE, it will always be lower. Added to that, melt ponds fool satellite sensors into thinking there is open water where there is none. Open water in grids gets counted as such for sea ice area, but for sea ice extent there has to be a lot of open water for all of the grid to be counted as open water. This explains why there are two different ways of measuring the amount of sea ice based on sea ice concentration data (read the CAPIE segment in ASI 2014 update 2 for a more thorough explanation).
As we can see on the graph, CAPIE has been dropping relatively slowly. This usually points to a combination of two things: 1) not much melt ponding, 2) ice pack being compacted. Although high pressure has been dominating in the past two weeks, there really isn't much compaction or dispersal to speak of, due to that lack of pressure gradients. And so we can be pretty certain the slow decrease is due to little melt ponding across the ice pack. This is corroborated by satellite images, where there is less of a blue, greyish hue across the pack, compared to previous years.
As I have repeated several times in previous ASI updates (here) and separate blog posts (here), the amount of melt ponds covering the ice pack at the start of the melting season might be crucial for the end result. We'll have to see if subsequent weather conditions and general ice conditions can compensate for melting season 2014's initial lack of melt ponds.
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:
Despite a recent uptick, sea ice area and extent numbers have been dropping hard in the Beaufort Sea. This region is one of the more important, as it's the first station where multi-year ice (MYI) goes after leaving the Central Arctic Basin (CAB). In the past this multi-year ice would make the rounds of the Arctic through the help of the Beaufort Gyre, and return to the CAB to become even thicker MYI. In recent times, however, the Beaufort Sea and Chukchi Sea are where multi-year ice goes to die, causing the drastic decline in older ice.
This past winter a lot of the multi-year ice that was conserved during last year's cold and cloudy melting season, has moved into the Beaufort Sea. As I've said in the conclusion of the 2013/2014 Winter Analysis:
The bastion of older ice has been re-inforced, although part of it has moved out into a zone where it could be either vulnerable or hang on long enough to prevent any records.
Right now it looks vulnerable, due to a somewhat prolonged period of clear skies and higher air temperatures. The vulnerability is clearly visible on the LANCE-MODIS satellite image, combined with Wipneus' self-made sea ice concentration map for the region (click for a larger version):
As for the rest of the Arctic: there's little ice in the Greenland Sea, because of the mentioned lack of transport, the Kara Sea has a lot of pent-up ice to release, and the Canadian Archipelago has started to melt, with fast ice turning blue on satellite images.
Wipneus sent me this treat, a map of the entire Arctic showing the changes in the past two weeks:
The Laptev/ESS hole is getting larger and larger...
Sea Level Pressure (SLP)
Here's the two-week animation of Danish Meteorological Institute SLP images:
It's clear how the Sun came when a large high pressure area formed over the Beaufort Sea and stayed there for a while. After that, pressure has been relatively high all over the Arctic, but due to the size of the weak high pressure over the central Arctic, there's a lack of pressure gradients and thus wind to push out ice through Fram Strait.
Here is the ECMWF forecast for the next 6 days (click for a larger version):
High times are here to stay. Still, it could have been a lot worse for the ice. Pressures are not that high (1020 hPa max), widespread, and thus there will still be very little transport to lower latitudes, be it through Fram Strait or elsewhere.
Surface air temperatures (SAT) have finally gone up, with the Arctic now mostly around average, but relatively cool conditions on the Siberian coast:
This is also visible on the DMI 80N temp graph with the trend line almost touching the average:
I have made yet another animation of Arctic forecast maps produced by the ClimateReanalyzer website (from the Climate Change Institute at the University of Maine), this time showing temperature anomalies, with the added bonus of clearly visible arrows showing which way and how hard the winds blow, for the coming 6 days (two images each day, 0000 and 1200 UTC) :
The Beaufort and Kara Seas are in for some warm air, added to insolation, if this forecast comes about.
2012 also showed more heat in Baffin Bay, but this year the Bering Strait is relatively warm, as is the hole in the Laptev/East Siberian Sea, which will only heat up more in weeks to come.
More and more the comparison with 2013 is falling apart, despite similar starts. In fact, last year's recovery of multi-year ice (not a real recovery, only compared to record crashing 2012) is in real danger of getting wiped out, keeping the Arctic death spiral poised for more steps towards ice-free conditions.
Nevertheless, a couple of factors are keeping me from seeing 2014 as a true title contender. It's a bit like taking a chicken out of the oven, to find out it was still frozen when you put it in: hot on the outside, cold on the inside. Melt at the peripheries is seriously underway now, and there's even some extra melt potential left that hasn't come to expression yet on the graphs. But the Central Arctic Basin is looking strong compared to previous years, we don't see as many holes as in 2010 or 2013, or as many melt ponds as in 2007 or 2012.
In the past it would surely be too late to make up for that, but the Arctic has changed so much that no one can tell with certainty what happens next. Either way, a true onslaught will require periods of even higher pressure for more insolation and higher SSTs on the Atlantic side, with low pressure elsewhere to get those winds blowing warm air to and fro, tearing the ice apart.
The reverse is also true: If this doesn't come about, things could stall again big time.
The next PIOMAS update might tell us more about the ice pack's ability to withstand whatever conditions the weather throws at it. In the meantime, we watch and fail to be bored.
PS Talk about not being bored. Commenter John Christensen reports:
That's pretty extreme!Even more extreme than it already was. We now have extremes going on at both poles.
As you probably won't hear much about the possible reasons behind this unprecedented growth of thin sea ice in the Antarctic (in the satellite record) elsewhere, I refer you to this thread on the ASIF where amateur Antarctic expert AbruptSLR posts multiple links to all the scientific investigation into this phenomenon.