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Lord M Vader

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Arctic weather winter 2014/2015
« on: August 21, 2014, 06:32:39 PM »
While we are at most a month ahead of the yearly minima I think this thread will be needed. We are now seeing the second year in a row with a modest melting in the Arctic. In fact, this will also be the first time for "many" years as there haven't been a difference of more than 10 mn km2 from the yearly maxima to the yearly minima. So far, only 8,9 Mn km2 have melted away. This have had the consequences that some people here at the forum are discussing whether the Arctic is being geo engineered secretly. There have also been discussions about how important an early onset of the melt season is to reach low values in September. I think we also need to incorporate the weather during the winters too...

What we have seen during both 2013 and 2014 are very favorable pre-conditions for low melting through summer. The summer of 2013 was, as we have stated, cold in the CAB (according to DMI) with a very late melt onset and an early melting offset. One consequence from this was that the snow pack didn't melt out completely but was later accumulated during the winter which was mainly dominated by cyclones.  This year we have seen very few indications of melt ponds which may be the result of a thicker snow cover which have protected the ice.

In 2009 there was also a cold summer but the winter of 2010 was dominated by high pressures (correct me if I'm wrong!) which should have implicated a low snow cover onto the ice in spring 2010 followed by quite favorable weather conditions for melting. This pattern was repeated both 2011 and 2012 and we ended up with having the lowest SIE as ever have been observed.

The best/worst case scenario IMO for the winter of 2014/2015 are as follow:

Best: high pressures dominating from september-november when refreezing occurs followed by cyclonic activity during the rest of the winter. With a HP early in the season refreezing will be quick and should allow for a thick ice cover.

Worst: cyclonic weather with a small amount of snow during september-november followed by persistent high pressure domes. Snow is, as we know, a good isolator and only a few centimeters of snow make the ice growth much slower than otherwise.

Forecast for the next month: I think we'll see a mix of HP and LP through the next month. AO have been very stable and neutral or weak negative for two months now.

A question for Neven, ChrisReynolds, Friv, Deep Octopus et al is how an eventual El NiƱo will affect the Arctic weather pattern during the winters?

ChrisReynolds

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Re: Arctic weather winter 2014/2015
« Reply #1 on: August 21, 2014, 09:03:41 PM »
LMV,

El Nino - it's popular to say it will have an effect (normally claimed to be large melting - although that may be comments at Neven's blog), I'm not convinced anyone has shown a substantial relationship.

Yes 2010 was high pressure, it led to a large export of MYI from the Central Arctic into Beaufort.



Note the dipole between the Central Arctic high and North Pacific low - that drove fast export of a lot of MYI.

As I've said before, April PIOMAS volume over the last four years has (I assert) levelled.



My long term April volume outlook...   ;)

April 2015 large increase in volume. April 2016 possible carry over of increased volume. But within a few years it will be back to the sort of volumes for April that end the timeseries above. Note that the levelling of the last four winters happened despite very different weather regimes.

Due to the Pacific North American being negative from 2012 onwards, I'd suggest something like 2012/13, or 2013/14 winter for the Arctic.

Nightvid Cole

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Re: Arctic weather winter 2014/2015
« Reply #2 on: August 21, 2014, 11:32:11 PM »
What do you mean? '12-'13 was quite different from '13-'14. The former had a colder than average February over the central Arctic, the latter was warmer than average all winter long with the polar vortex getting dramatically split several times, most notably at the end of January.

ChrisReynolds

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Re: Arctic weather winter 2014/2015
« Reply #3 on: August 22, 2014, 07:23:45 PM »
What do you mean? '12-'13 was quite different from '13-'14. The former had a colder than average February over the central Arctic, the latter was warmer than average all winter long with the polar vortex getting dramatically split several times, most notably at the end of January.

Exactly - who can tell.

I forgot the  ;) sorry.

Lord M Vader

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Re: Arctic weather winter 2014/2015
« Reply #4 on: September 22, 2014, 08:49:34 PM »
So, now when we have reached the minima we can put our attention to the Arctic weather winter 2014/2015.. The last couple of years the SIE per JAXA have been more than 8 Mn km2 at October 31 (except for 2012).

Given the rather high sea ice extension in Barents Sea I won't be too surprised if the SIE may be close to 9 Mn km2 by October 31. Last time that happened was 2008.

Neven

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Re: Arctic weather winter 2014/2015
« Reply #5 on: September 23, 2014, 02:16:59 AM »
Sorry, I forgot about this thread, Lord M, and made this thread here the 2014/2015 freezing season central thread.

I'll copy your comment and post it there.
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