ASI 2013 update 7: cold and cloudy

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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 2005-2012 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.

The animation on the right consists of NSIDC
sea ice concentration maps, one for each ASI update.

Check out the Arctic Sea Ice Graphs website (ASIG)
for daily updated graphs, maps, live webcam images and
the Arctic Sea Ice Forum (ASIF) for detailed discussions.

August 18th 2013

In the past two weeks sea ice decrease has been chugging along happily, with that huge area of low concentration ice still staring us in the face. All melting season long I've been expecting massive losses after the cyclones did their churning act on the large patches of first year ice, but they have failed to materialize. The loss is there, but it isn't massive.

Apparently the cold and cloudy conditions the cyclones brought in from May onwards, have been enough to compensate for the churning of the ice pack, that was never really preconditioned by a sunny start to the melting season. And so 2013 has remained part of the group of slow years and didn't come any closer to the group of record years.

This melting season has been a great and humbling teacher so far, but there's still a couple of weeks left.

Sea ice area (SIA)

I've been waiting all day for the Cryosphere Today SIA data to be updated, but as none are forthcoming, I post the graph with data up to August 15th:

After the crazy uptick that was described in the previous update the trend line has resumed dropping again, battling it out with 2009 and 2010 right now. It's still over 1 million km2 behind 2012, and around 850K and 700K behind 2007 and 2011 respectively. If this year follows the 2010 pattern (and 2010 was a year with a very patchy ice pack as well) it might still get somewhat close and perhaps overtake 2008.

Here's the link to my updated CT SIA spreadsheet.

The SIA anomaly has dipped below the -1 million km2 mark again:
Sea ice extent (SIE)

IJIS hasn't reported any data either today, so here's their SIE graph up until August 16th:

With a century break reported for the 16th (might be revised, once data gets reported again) the trend line is making a small swoop towards the big melt years, but is still massively behind here as well. Nevertheless, if it can keep up this tempo, it might creep a little closer to 2007 and 2011 towards the end of the month.

Here's the link to my updated IJIS SIE spreadsheet.

Cryosphere Today area per IJIS extent (CAPIE)

CAPIE percentage is still way above that of last year. We've discussed it a bit more on the forum, but most agree that this is due to melt ponds getting frozen over in this year's cold temperatures, which were much less pronounced last year:

If the difference were just 2-5% I would agree that melt ponds explain the difference (remember, there has been a lot of divergence going on this year, making the ice pack less compact), but 10% is a bit too much in my view. Perhaps increased cloudiness is making it harder for sensors to pick up all those small holes in the pack's interior, or maybe they don't get counted either way because resolution isn't high enough. However, the exact cause of the discrepancy between 2012 and 2013 - probably a bit of everything - is hardly relevant.

For a thorough explanation of what CAPIE is, read the CAPIE subsection in this ASI update. Here's the link to my updated CAPIE spreadsheet.

Regional SIE and SIA

Regional graph of the week, taken from the Regional Graphs page:

The channels and leads between the islands of the Canadian Archipelago have been slow to melt out this year as well, but the melt has picked up in the last two weeks, as can be seen on this map that Wipneus has custom-made for this ASI update (based on Uni Hamburg data, see here), showing the differences that have taken place since the previous ASI update. Red = ice two weeks ago, open water now; blue the other way around:

The southern route of the Northwest Passage has now opened up, but it still remains to be seen if the main passage will open up. With a blot of persistent ice blocking the Northern Sea Route over at the Severnaya Zemlya Islands, we could be looking at the first melting season with neither of the two passages opening up in a long time.

Sea Level Pressure (SLP)

The two-week animation of Danish Meteorological Institute SLP images tells us a bit about the weather in the Arctic in the past fortnight:

We see how the third storm gets into play, rages for a day or three and then quickly disappears again. The dipole anomaly set-up, with a high over the Beaufort Sea, also didn't last long and so no accelerated sea ice loss was observed on the Pacific side of the Arctic. In fact, towards the end of the animation, the dipole is replaced by a reverse dipole, with a high-pressure area over the Siberian side of the Arctic, mirrored by a low-pressure area over the American side.

How this is going to develop, can be seen on the the 6-day weather forecast from the ECMWF model (click for a larger version):

The reverse dipole remains in place for the week to come. Traditionally, this would mean a very slow rate of ice loss, but perhaps that sunny conditions on the Siberian side of the Arctic and compacting winds can still take a bite out of that low-concentration patch that extends well out towards the East Siberian Sea. If this comes about, the rate of decrease could remain stable.

Temperatures

Compared to the map from two weeks ago, the cold over the Arctic Ocean has spread out and intensified over the Arctic Ocean:

Air temps north of 80° are extremely low for this time of year, according to the DMI 80N temp graph:

There are definitely no more melt ponds in the central basin, and leads between floes are probably also starting to freeze over. What this means for the hole in the ice pack, close to the North Pole, that has been asserting itself more prominently in the past week, remains to be seen.

Sea surface temperatures on the DMI SST anomaly map also seem to have gone down a bit, compared to two weeks ago, with a patch of cold water developing near the Bering Strait:

Here's the map from August 25th 2012. There's a marked difference in the Beaufort Sea on one side, and the Kara Sea on the other.

Conclusion

Mid-melting season it became clear that beating 2012 was going to be a tough proposition (100% impossible now), but it looks like 2007/2011 and even 2010 might be out of reach. Given the hundreds of thousands of square kilometres that need to be made up to come close to the Top 3, combined with the weather forecast, I don't think much is going to change, but never say never in the Arctic. There's still quite a bit of melting potential out there, though not much melting potency.

To be honest, I'm still a bit surprised at that. With the record amount of first year ice at the start of the melting season, and lower maximum volume, and a spectacular cracking event causing the Beaufort Sea to fill up with additional thin ice in leads, I thought that there's was a good chance that for the first time we would be seeing back-to-back melting records.

But it all turns out differently, and so instead of new records we see the traditional regression to the mean. This is a careful first conclusion, but I'll have more on that, of course, when the melting season officially ends, 2-4 weeks from now.