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Gray-Wolf

Arctic Sea Ice Discussion 2017 - The Melt Season

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I've recently been reading the write up on the persistent Arctic cyclone of August 2016 .....

http://onlinelibrary.wiley.com/doi/10.1002/asl.757/full

Quote

Abstract

An extremely strong Arctic cyclone (AC) developed in August 2016. The AC exhibited a minimum sea level pressure (SLP) of 967.2 hPa and covered the entire Pacific sector of the Arctic Ocean on 16 August. At this time, the AC was comparable to the strong AC observed in August 2012, in terms of horizontal extent, position, and intensity as measured by SLP. Two processes contributed to the explosive development of the AC: growth due to baroclinic instability, similar to extratropical cyclones, during the early phase of the development stage, and later nonlinear development via the merging of upper warm cores. The AC was maintained for more than 1 month through multiple mergings with cyclones both generated in the Arctic and migrating northward from lower latitudes, as a result of the high cyclone activity in summer 2016.

Are we going to see a reprise for 2017?

 

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I think any move toward a higher energy basin will shift us away from the type of basin that encourages recovery of the ice cover and instead releases the energy from the ocean itself eventually moving from a season ocean to an ice free one even witrhout the input of 'warming' to drive things along ( though we will keep warming!).

Since 07' I have voiced concerns over the loss of the Halocline, the layer that marked out the Arctic Ocean from all other world oceans. Ice loss opens up the basin to swells and wave action ( no longer damped out by ice cover) mixing out the 'layers' below. this can bring up warmer Atlantic/Pacific waters and lead to rapid bottom melt of floes. Thin floes can be broken up by swells as wave crests stress the ice. Such swell activity will result in floes breaking down to more 'stable sizes' for that wave height/length/interval? Smaller floes expose more surface area to their mass ratio's than do larger floes and so absorb heat faster and so melt quicker.

We are 'evolving' a pack that will not survive an average Arctic summer.

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3 hours ago, Snipper said:

Not sure if this is appropriate to be here. Shift as necessary. 

'Unusual' Greenland wildfires linked to peat http://www.bbc.co.uk/news/science-environment-40877099

We saw a little of it last year but this is huge by comparison!

I have concerns about the 'hibernating carbon cycle' buried beneath our ice sheets but i hadn't considered this 'fast track' in the returning of this carbon back into the current Carbon Cycle!

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Temperatures dropped below freezing above 80 N. Earlier than usual, but worth remembering it would need to drop to -4 or below for sea ice to start regrowing, so losses will still continue, but if the trend continues, perhaps the losses will finish a week or so earlier than usual.

The extent is hanging in there fairly well. Curious to see if we will have a repeat of last year in terms of sluggish regrowth season.

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Looking at the ice extent it looks like the melt has slowed down considerably in the last few days.

https://ads.nipr.ac.jp/vishop/#/extent

The models show high pressure to develop in the Arctic in a few days time which may speed up the melt somewhat. Hopefully it is too late in the season for any big loses.

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2 hours ago, Seasonality said:

Was this from the Greenland fires?

And North America I would imagine.

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Seems we may have been having an early end to the melt season. Considering the low point it started off at it's done pretty well. 

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9 hours ago, Seasonality said:

Was this from the Greenland fires?

that will be from the forest fires in British Columbia that have been raging pretty much all summer

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On 8/23/2017 at 08:57, karyo said:

Looking at the ice extent it looks like the melt has slowed down considerably in the last few days.

https://ads.nipr.ac.jp/vishop/#/extent

The models show high pressure to develop in the Arctic in a few days time which may speed up the melt somewhat. Hopefully it is too late in the season for any big loses.

From my understanding high pressure at this time of year is not all that bad of a thing and can actually be a more positive for sea ice as clear skies at night can help to let heat from the ocean to escape into the atmosphere(rather than being trapped by cloud) and the sun not being strong enough to really heat the SST's and melt the ice. High pressure which brings strong southerly winds and heat from the continents are by far the worst case scenario but to me this high does not really does that and for the most part there is coldish air trapped underneath especially towards Beaufort.

Be interesting what the final orientation of the high will be as the models are flipping a bit between whether the high ends up near Beaufort which will create a dipole or end up nearer Laptev and creating a reverse dipole - today's runs has suggested the latter which will be interesting as that could slow down extent again but potentially creating quite strong southerly winds towards the Atlantic edge which has retreated a bit lately despite the cold air temps.

Either way, it seems the Arctic has dodged the bullet this year but I still dread to think what another 07/11 type of summer would bring with the ice the way it is.

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On 8/29/2017 at 09:44, summer blizzard said:

Have we officially ended yet?

Nope, JAXA extent dropped again yesterday reaching a new low for the year, while it wouldn't take a great deal to see the NSIDC extent start dropping again too.

Compaction of the pack alone can cause big changes this time of year, so it's unlikely we'll see anything official called before mid month, even if there was a sustained increase in extent over the next 2 weeks.

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I tent to always distrust extent grows when the temperature is above -4 and historically, looking at the last 10 years, it would be against the trend for it to drop below that temperature so early on, although it is pretty close now.

What you will likely start seeing is the curve flatlining and some dips or rises depending on how the pack is situated. Another clue is that you will start to see different indexes decreasing and increasing for the same period. But the temperatures jumping up and some weather patterns with it(Happened a lot in recent years), its still possible for significant decreases over the next two weeks, even if it isn't the form horse now. 

 

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On 9/10/2017 at 12:31, summer blizzard said:

Have we yet reached minimum (provisionally).

Not quite yet. NSIDC extent is at a new low as of yesterday, and the latest ADS (IJIS) extent is only 1k off its minimum for the year.

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On 10/09/2017 at 12:31, summer blizzard said:

Have we yet reached minimum (provisionally).

Going to be soon now. 

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3 hours ago, jvenge said:

Might be true, but seems a little premature to me. We're currently just 60k above the 13th and there's currently a large storm over the Arctic which could shake things up over the coming days.
ECH1-24.GIF?20-12

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40 minutes ago, BornFromTheVoid said:

Might be true, but seems a little premature to me. We're currently just 60k above the 13th and there's currently a large storm over the Arctic which could shake things up over the coming days.
ECH1-24.GIF?20-12

Depends what the storm brings. A storm itself won't shake things up now, but in recent years temperatures have had a tendency to jump way above average in Autumn and Winter. It would need to be an almighty jump to melt some ice now, but we did see some huge jumps last year, so never say never I guess.

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