The 2019 melting season

[aslan]

Sum of forces is definitively not the same. Ice and water does not respond in the same way to winds. And there is also hydrostatic equilibrium, 100 hPa is worth one meter of sea level, but zero point zero meter of ice level. And of course in the end gravity would even out the sea level if the winds stop blowing.

[Freegrass]

Wind @ Surface + Total Precipitable Water

That Laptev storm could do some serious damage to the already weakened ice in that area.

[petm]

Aug 30 - Sep 5

5-day per-pixel minimum v. original Bremen concentration

[Aleph_Null]

Hindcast: 9/2 to 9/6, Forecast: 9/6 to 9/10.
Wind + IWPD @ 850hPa [Instantaneous Wind Power Density: air density ρ, wind velocity v: ½ρv3]

Some improvements, I hope, over my previous effort with Nullschool. A timestamp makes it more legible. Greenland is now oriented at the bottom to accord with Worldview.

[arctic-watcher]

Strange how the latest ECMWF run has the arctic in an almost basin-wide cold temperature anomaly at 850 hPa in 10 days, while GFS has a basin-wide hot temperature anomaly by the same time and beyond.  Maybe it's just really hard to predict when transitioning seasons? 

[grixm]

Strange how the latest ECMWF run has the arctic in an almost basin-wide cold temperature anomaly at 850 hPa in 10 days, while GFS has a basin-wide hot temperature anomaly by the same time and beyond.  Maybe it's just really hard to predict when transitioning seasons?

It's really hard to predict 10 days out regardless of season

[SteveMDFP]

I can't really visualize this. If gravity could move the ice down the slope, it would simply even out the water bulge as well.

I actually started writing that down as a joke, but then started wondering if there could be some truth to this. But mainly, I was joking, because the wind would of course have a much bigger impact on the ice than gravity.

Briefly, both the water and ice respond to coriolis effects in their motion.  Ice moves roughly 30 degrees to the right when pushed by wind in the arctic.  Water acts similarly.  Thus, cyclohic winds cause dispersion and water upwelling (e.g., tidal surges in hurricanes).  High pressure systems cause compaction and surface water downwelling.  High pressure systems are broader, with more modest winds, so the effects are less obvious, but still at play.
Apologies for the off-topic addition.  Back to melting season....

[philopek]

The weakest ice under full (90° Angle) attack

Windspeeds around 50km/h at a bit of a distance to the "Eye"

Some compaction will be the least impacting extent numbers, some melt still ongoing could
keep area drops in line with extent losses, despite higher concentration.

That's a low pressure system so it causes dispersion -- the opposite of compaction.

On your figure, I suggest you redraw your arrows at 45 degrees to the right of the actual wind directions displayed -- which is the direction the ice goes (Coriolis) -- and then you will see the dispersion.

I hear you, thanks for kind elaboration and a good lesson, totally forgot about it

[pearscot]

Strange how the latest ECMWF run has the arctic in an almost basin-wide cold temperature anomaly at 850 hPa in 10 days, while GFS has a basin-wide hot temperature anomaly by the same time and beyond.  Maybe it's just really hard to predict when transitioning seasons?

As others have said, looking 10 days in advance is way too variable to be reliable. For the most part, in this day in age 5 days tends to be about the furthest out with some degree of accuracy.

[Phil.]

Strange how the latest ECMWF run has the arctic in an almost basin-wide cold temperature anomaly at 850 hPa in 10 days, while GFS has a basin-wide hot temperature anomaly by the same time and beyond.  Maybe it's just really hard to predict when transitioning seasons?

As others have said, looking 10 days in advance is way too variable to be reliable. For the most part, in this day in age 5 days tends to be about the furthest out with some degree of accuracy.

Also Dorian is expected to pass over Iceland in a few days which will doubtless throw a curveball.

[MyACIsDying]

NASA put a nice animation of arctic ice loss online

Two take-aways for me: The Fram export starting up is nothing less than expected and the persistent arm in the ESS is a tail of MYI that made a full clockwise circle on the edge of the Beaufort Gyre, snapped off in the summer.

[gandul]

NASA put a nice animation of arctic ice loss online

Thank you for bringing it here.
The outcome of 2016 was as bad or worse than 2007/12 in terms of thick old ice loss, with its GAC, garlic press, weak Winter and high ice export. 2017 dodged that bullet.
This year’s September distribution setup for second year ice, and what is left of MYI, is not as bad as those years, but bet fall/winter probably will turn out bad for the pack.

[kassy]

It is distressing watching it at that speed just going and going.

I remember some of those shapes. 

[pauldry600]

Amazed that its survived all these Summers

One year it will just go thump.

[sailor]

Although the cold low over the Atlantic side moves to Russia, and warmer air takes place initially, with some moderate winds, yet high pressure soon dominating will bring clear skies, that is, rapid heat loss...

Given the SSTs one would expect a rapid refreeze of the disperse regions second half of September, and a slow continuation in mid October,  sort of 2016. But who knows.

Very interesting season. Indeed, as said before even probably the warmest May-June-July on record failed to deliver even a second lowest. The CAB is very resilient if heat does not reach it very soon enough, and it starts consistent melting at higher latitudes. This year's sun in May over the core of the CAB was a learning moment. It was mostly reflected probably  by the still existing high-Albedo snow layer. Not a single melt pond was apparent.

And a GAC matters, if only, to accelerate the melt out of huge areas of slush and marginal ice.

[gandul]

Although the cold low over the Atlantic side moves to Russia, and warmer air takes place initially, with some moderate winds, yet high pressure soon dominating will bring clear skies, that is, rapid heat loss...

Given the SSTs one would expect a rapid refreeze of the disperse regions second half of September, and a slow continuation in mid October,  sort of 2016. But who knows.

Very interesting season. Indeed, as said before even probably the warmest May-June-July on record failed to deliver even a second lowest. The CAB is very resilient if heat does not reach it very soon enough, and it starts consistent melting at higher latitudes. This year's sun in May over the core of the CAB was a learning moment. It was mostly reflected probably  by the still existing high-Albedo snow layer. Not a single melt pond was apparent.

And a GAC matters, if only, to accelerate the melt out of huge areas of slush and marginal ice.

You miss something. I'd say, respectfully, you miss a lot. I explained on another thread that, even with all this heat, events must come precise in time as a Swiss watch.

And for this reason I am no longer surprised of the disappointing melt.

A different kind of climate mode is necessary to melt the CAB. 2016 was not 'warm' in the sense of killer ridges, rather was a non-stop succession of storms and, see what ice was left in 2017. The lowest volume in history by a large margin.
No clockwork, just high NH temperatures and storm after storm. Also in Winter

[sark]

September CanSIPS results are out

It is getting away from the quadrupole

Yes, you can say Quadrupole.  It's in Mitchell 2013 -- I recall the late July block over Europe and Greenland to be a slow moving what you describe as Dipole.  The rest of these AO weakening events have been more dynamic and quadrupole.  Look at Jan 4-6, 2014 and of course, the last 5 months.

the pattern is changing away from two distinct polar cells into something more diffuse and more mixed with blocking pressure.  good or bad who knows

I do expect the US corn belt will be under similar rain pressure during planting season in 2020.

[Aluminium]

September 2-6.

2018.

[Freegrass]

Wind + Temp @ 1000hPa and Wind @ Surface

[Freegrass]

And for this reason I am no longer surprised of the disappointing melt.

Disappointing melt???
Are you seriously disappointed that the world isn't coming to an end sooner? What a disgusting thing to say...

[sark]

It's not the model that I take seriously

it's the physics that causes it to do this

[oren]

September 2-6.

2018.

Dispersion is a bitch... but the Beaufort/CAB border looks like the open water gaps froze and that the pack solidified. Area numbers show a >150k (!) rise in the CAB. Start of the actual freezing season? Looking at Worldview, this certainly did not happen, so I am betting these are cloud artefacts that should disappear if/when the clouds move away.
BTW, I am deeply disturbed by the slush that counts for extent these days. I am surprised that it survives for so long thanks to the lucky weather, but it is still a far cry from "the ice is saved".
CLICK to animate.

[Pavel]

the slush that counts for extent these day

Well said. But I would say the Arctic has managed to dodge a cannonball in summer (August). It could be worse now.  I'm concerned about the SST and the possibility the ice won't recover this winter and next melt season will start with record low volume.

[Lord M Vader]

Time to restart the thread about refreezing season now Neven?🙂

[Neven]

Time to restart the thread about refreezing season now Neven?🙂

Nope, after the minimum.

[SimonF92]

It's not the model that I take seriously

it's the physics that causes it to do this

Ill believe that forecast when i see it

[sailor]

September 2-6.
2018.

Dispersion is a bitch... but the Beaufort/CAB border looks like the open water gaps froze and that the pack solidified. Area numbers show a >150k (!) rise in the CAB. Start of the actual freezing season? Looking at Worldview, this certainly did not happen, so I am betting these are cloud artefacts that should disappear if/when the clouds move away.

The storm on the Atlantic side is inflating the pack and at the same time bringing a lot of cold and plausibly “sealing” the new openings with snow or even refreeze. It is very cold with constant temperatures under -5C. I think that the area increase comes from that side, and is real.
Clear skies starting to dominate the CAA and the ‘western’ CAB may seem to maintain even over zero temperatures, but in the long nights heat loss will gradually cool down the air and the open water within the polynya. The cooling is apparent from forecasts too.
Next week there’s a final bout of wind as the storm migrates to Siberia. Beyond that (Sep 12)  there’s no more melting season if it hasn’t finished already.

[VeganPeaceForAll]

September 2-6.
2018.

Dispersion is a bitch... but the Beaufort/CAB border looks like the open water gaps froze and that the pack solidified. Area numbers show a >150k (!) rise in the CAB. Start of the actual freezing season? Looking at Worldview, this certainly did not happen, so I am betting these are cloud artefacts that should disappear if/when the clouds move away.

The storm on the Atlantic side is inflating the pack and at the same time bringing a lot of cold and plausibly “sealing” the new openings with snow or even refreeze. It is very cold with constant temperatures under -5C. I think that the area increase comes from that side, and is real.
Clear skies starting to dominate the CAA and the ‘western’ CAB may seem to maintain even over zero temperatures, but in the long nights heat loss will gradually cool down the air and the open water within the polynya. The cooling is apparent from forecasts too.
Next week there’s a final bout of wind as the storm migrates to Siberia. Beyond that (Sep 12)  there’s no more melting season if it hasn’t finished already.

Numbers not backing up your theory. The central Arctic area is decreasing and beautfort area increasing. See the other data thread.
There is still a very strong bottom melt momentum at the Pacific side and the side adjacent to ESS, Laptrev, see petm's pictures.
Most of the cold area is between 4-6.4 degrees Celsius, which is around 2.2-4.6 degrees below the Arctic sea ice freezing point.

[sailor]

The storm on the Atlantic side is inflating the pack and at the same time bringing a lot of cold and plausibly “sealing” the new openings with snow or even refreeze. It is very cold with constant temperatures under -5C. I think that the area increase comes from that side, and is real.
Clear skies starting to dominate the CAA and the ‘western’ CAB may seem to maintain even over zero temperatures, but in the long nights heat loss will gradually cool down the air and the open water within the polynya. The cooling is apparent from forecasts too.
Next week there’s a final bout of wind as the storm migrates to Siberia. Beyond that (Sep 12)  there’s no more melting season if it hasn’t finished already.

Numbers not backing up your theory. The central Arctic area is decreasing and beautfort area increasing. See the other data thread.
There is still a very strong bottom melt momentum at the Pacific side and the side adjacent to ESS, Laptrev, see petm's pictures.
Most of the cold area is between 4-6.4 degrees Celsius, which is around 2.2-4.6 degrees below the Arctic sea ice freezing point.

- Bottom melt will keep going on until November in some places. Not really to the point I was making.
- I never talked about Beaufort ice, which right now is a residual appendix of very broken ice.
- A cold storm like the current one has not promoted melt, and if anything, at this time of the year, ii is promoting re-freezing.
- I didn’t find the numbers about central Arctic that you mention, but don’t bother, continuing this discussion I think is pointless, the freezing season will have started before we agree.

[binntho]

Perhaps a new poll - Which Will Happen First: BOE or FFA?

(FFA: Full Forum Agreement)

[gandul]

Perhaps a new poll - Which Will Happen First: BOE or FFA?

(FFA: Full Forum Agreement)

I’d love to see the first, hate to see the second.

[Eco-Author]

After spending four months at well above records, global ice has fallen to last year's levels definitely reflecting the recent slow down and up-tick in the north.  Speculation... are we to assume the 'original' global ice max would have been prior to man???  The CAB, not near to the coast is well able to survive recent extremes and it will take a definite step change (rain/export/blowtorchestothenth).  I don't think it matters much as we will not survive the weather as it is let alone the possibilities if it gets any worse...?!

[Eco-Author]

the ice spreading out more is likely a sign of its weakness over past years.  the eratic/collapse-like behavior of berring sea is definitely a sign of a step change, get another two or three seas acting like this and it likely would be over; down 500k right-at/shortly after the year's max!  Regardless of min. the arctic seems broken and falling far faster than just increasing average melts would suggest.

[Freegrass]

Wind @ 250hPa

Look at how that resident low gets pushed out of the arctic by that high that's taking its place.

[Freegrass]

I finally figured it out now. Nullschool gets an update every 6 hours instead of every 3 hours. So I'll try to give an update every 12 hours. Is that enough?

[sailor]

If the current ECMWF forecast (about to become obsolete but I’ll pull a sharpie here) was reliable for September 17, I might consider the possibility that extent would drop to minimum by then, but I don’t think it will happen. Still it makes a nice picture.

[Freegrass]

Can this be considered clear proof that low pressure systems puch the ice outwards?
https://go.nasa.gov/2UGRLuU

[uniquorn]

the slush that counts for extent these days

If the mercator model is correct slush dispersion doesn't significantly affect SST yet. Depending on the weather, extent may follow 2018's slush path (brown) to meet 2012 (yellow).
amsr2-uhh overlaid at 60% transparency onto mercator SST, aug1-sep6
wipneus regional extent, CAB, sep6
piomas percentage of maximum by year, CAB, 2011-2019
edit:forgot scale

[oren]

Another UH AMSR2 animation, zoomed in, this one shows nicely the "solidification" of the CAB sector facing the Beaufort. I believe that is where a lot of the growth in UH area has been, and as said above I expect this area to "un-solidify" once the clouds pass.
CLICK to animate.

[Niall Dollard]

Can this be considered clear proof that low pressure systems puch the ice outwards?
https://go.nasa.gov/2UGRLuU

I doubt if there is any more debate on this Freegrass. When last we mentioned this, it went on too long and Neven snipped it.

I commented on the way wind is pulled towards the centre of low pressures (due to surface friction). But that is only for wind and the coriolis effect is predominant for ice floes/drift. Ice will drift to the right (of the isobar) in the northern hemisphere, outwards from the low centre. I was mixing up ice drift with wind and stand corrected on this.

[sark]

It's not the model that I take seriously

it's the physics that causes it to do this

Ill believe that forecast when i see it

You don't think November can be +7C in the entire Arctic?  sheesh, tough crowd

[aperson]

You don't think November can be +7C in the entire Arctic?  sheesh, tough crowd

Heh, that CFS chart to me looks like a standard, modern November. Looks like a lack of Bering Sea ice, a relentless -EPO run, and sustained warm air advection toward the pole in the Pacific.

[Freegrass]

Can this be considered clear proof that low pressure systems puch the ice outwards?
https://go.nasa.gov/2UGRLuU

I doubt if there is any more debate on this Freegrass. When last we mentioned this, it went on too long and Neven snipped it.

I commented on the way wind is pulled towards the centre of low pressures (due to surface friction). But that is only for wind and the coriolis effect is predominant for ice floes/drift. Ice will drift to the right (of the isobar) in the northern hemisphere, outwards from the low centre. I was mixing up ice drift with wind and stand corrected on this.

I didn't want to continue the debate Niall. I agree that the debate is settled now. I just thought this was a beautiful visual on the theory. You'll see it when you zoom in and out a little. It's a perfect storm, visually...

[slow wing]

7 September is a date displayed in Neven's fine year-to-year comparison of sea ice extent & concentration - here.

2019 is shown at bottom right, along with 7 previous years that Neven has chosen as some of the worst for minimum extent. (Further years are displayed further down on the webpage - not seen in the figure below.)

As expected, 2019 looks like it belongs with the previous worst years.

[Freegrass]

Wind + Temp @ Surface

[SimonF92]

Sark if that November model forecast is actualised then I will be genuinely apologetic but until then I remain healthily sceptical. Those kind of anomalies in the ESS and Laptev in November just dont make sense. There will be bumps absolutely but a sustained >+13C?

[Pavel]

Wind + Temp @ Surface

The bottom melting continues almost everywhere and the slush in the Pacific side still be melting for some weeks.

[blumenkraft]

Freegrass, i made a GIF for you. Click it.

[Freegrass]

That's awesome blumenkraft. You can clearly see the fractures opening up in a counterclockwise circle. Pretty impressive. Thanks for that!

[blumenkraft]

Welcome.