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Csnavywx

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Re: The 2017 melting season
« Reply #2650 on: July 08, 2017, 12:23:03 AM »
The EC and EPS have backed away from a longer-lasting TPV pattern and replaced it with strong Pac side ridging with the PV positioned over the CAA and Baffin. Not as damaging as a dipole pattern unless the operational is really on to something and 850 temps actually do get to +15C. The EPS suggests that the operational run is right about ridging placement, but differs on strength. dt/dprog suggests a trend towards strengthening, though.

A long lasting plume of +15-20C 825 and 925 temps with a downslope/chinook wind off the Kamyla range would result in the quick erasure of the majority of the remaining ice in the ESS and Chukchi and a significant spike in SSTs, so it's something to watch over the next week.

Looking at upper level charts for D3-D6, 700mb temps get above +5C en masse and 500 mb temps rise above -10C with the incoming airmass, suggesting a fully subtropical origin and temperature profile. Extremely impressive for the deep arctic, even in summertime.
« Last Edit: July 08, 2017, 12:33:22 AM by Csnavywx »

Tigertown

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Re: The 2017 melting season
« Reply #2651 on: July 08, 2017, 02:27:06 AM »
Touring the CAA.
CLICK IMAGE
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cesium62

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Re: The 2017 melting season
« Reply #2652 on: July 08, 2017, 03:37:14 AM »
A 5.41m km2 September minimum implies an average decline of <50k/day between now and mid-September. We have not seen losses that would support an average of that low a magnitude as yet.

Rob is discussing the September Average, not the September Minimum.  On the Charctic graph, we would be looking at 2017 being slightly above 2013 through most of September.  In 2016, there was a few day period in July when 2016 melting slowed down to the 2013 line.  If 2017 did that, and didn't speed back up afterward, and then 2017 melt slowed in August as it did in 2013...

If Rob's prediction comes true, it seems like the takeaway will be that albedo greatly trumps volume in importance.

The Slater Probabilistic Sea Ice Extent is running well below 5.4m as it approaches the end of August.  (Although I'm probably conflating JAXA numbers with NSIDC numbers...)
« Last Edit: July 08, 2017, 03:56:54 AM by cesium62 »

cesium62

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Re: The 2017 melting season
« Reply #2653 on: July 08, 2017, 03:54:57 AM »
Looking at the areas of that map that are colder in 2017 than 2012, I wondered how much of the nearby ice is "doomed anyway" this year - sure to melt out even if it takes awhile. Beyond the Kara, is there other ice that can be written off at this point? Like the rubble in and above Fram Strait, unless the drift reverses?

From Wipneus regional extent graphs...  In recent years, Kara tends to melt out entirely by 1 Sep.  And we can mostly ignore the small amount of ice present in 2013 and 2014.

I've written off all the ice in the peripheral seas except the CAA and Greenland Sea.

RealityCheck

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Re: The 2017 melting season
« Reply #2654 on: July 08, 2017, 08:58:04 AM »
Hello all.
I have made the leap from reader to member - nice to have 'met' you all via your postings. I have been catching up with the present status on several topics, having discovered ASIF only recently. I am highly impressed by the quality of data, depth of insight and general thoughtfulness of the forum. Many thanks for hours of captivating browsing to date.

My background is more 'interested observer with a technical background' rather than an expert in the relevant specific fields. But I hope I can occasionally add to the discussions anyway.

So here goes. Seems to me that recent posts on this years' melt season point to the implications for the coming freezing season, and here's my tuppence worth. We appear to be headed for one of or the lowest recorded ASI area / extent and volume in September. New ice will be dominated by thin FYI and second year ice. So the odds seem to be growing that higher albedo, weaker jet stream, more open sea in September, and more intense cyclones will combine to disrupt the refreeze - i.e. A stronger 2016-winter type of effect. My own (admittedly rather intuitive) concern: might 2016- 2018 turn out to be a sudden inflection in ASI terms? I.e. Maybe little/no ice in September next year?

Thoughts?
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Neven

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Re: The 2017 melting season
« Reply #2655 on: July 08, 2017, 09:12:19 AM »
Welcome, RealityCheck. This thread is more about what's going on right now in the Arctic, and not a general discussion thread, but to give you my (short) thoughts: The 2016/2017 winter was very mild, with lots of heat and moisture brought into the Arctic by a series of Atlantic storms. This has covered the ice (and probably much of Siberia) with more snow than usual, one of the reasons volume is lowest on record (because snow insulates the ice below, which reduces ice accretion at the bottom). This snow was slow to melt out during May and June, which has predictions based on land snow cover and/or melt ponds (Rob Dekker and David Schröder, for instance) indicating that September sea ice extent will be quite high this year.

Two questions that as far as I am concerned are the themes for this melting season and beyond:

1) Does albedo indeed greatly trump volume in importance, like cesium62 says?
2) Does this constitute a negative feedback that we will see happen more often? ie open, warm water in September -> influence on jet stream -> lots of snow -> high albedo during May and June both of both ice and land -> slowdown in Arctic sea ice loss

If anyone wants to jump in, please keep it short and don't stray off-topic too far. Folks can also go and discuss the answers to these questions on the ASIB, as it's pretty quiet there and the PIOMAS update posts are open threads as far as I'm concerned.
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Rob Dekker

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Re: The 2017 melting season
« Reply #2656 on: July 08, 2017, 09:29:39 AM »
Thanks guys, for your response to the 'optimistic' projection of my statistical model.
Response to your comments below:

Rob
A 5.41m km2 September minimum implies an average decline of <50k/day between now and mid-September. We have not seen losses that would support an average of that low a magnitude as yet.

2010 comes pretty close : In June it had ice 'area' 8.30 (which is considerably lower than the 2017 June 'area' of 8.51) yet it resulted in 4.93 extent in September.
You are right that it is a pretty unprecedented projection, but then again, the 3.5 million km^2 land snow anomaly that Rutgers posted for June is also unprecedented over the past decade or two.

Sterks said :
Quote
I was expecting the model had yielded a reduced prediction this month, but it is what it is.
That's how I look at it : "it is what it is", and let's not forget it is a model. And all models are wrong, but some are useful. If my model is useful will be decided at the end of September 2017.

Quote
Your model has proven to get the right value and/or tendency of the melting season in most if not all years since you have used it (including rebound years as 2013). Correct me if I am wrong.

It is correct that my current model quite nicely reproduces the 2013 and 2014 'rebound' years in 'hindcast' mode :



However, if we only use data available until 2012 (forecast mode), the optimal formula changes a bit and the rebound of 2013 and 2014 is still reproduced, but not that accurately. Let me run the numbers and show you later.

Quote
I only have a "but" with June snow cover: in many of the satellital images, the snow cover over land has been showing a "grey" appearance during June, in other words, that it is only a partial or a thin cover with many spots (trees, tundra vegetation, valleys void of ice) showing a much lowered albedo, as opposed to the absolutely white covers during much of May.
Very good point.
I would love to get my hands on the land snow 'area' numbers (not just 'extent') and then preferably daily, and even better : gridded. And of course with the full history (20-30 years or so).
I have a feeling that I can come up with an even better correlation between land snow cover and September ice extent if I had that kind of data available.

Unfortunately, Rutgers Snow Lab produces only the monthly land snow 'extent' numbers, and I have not been able to find their source feed.
In Dutch we have a saying : "Je moet roeien met de riemen die je hebt", freely translated to : You need to work with what you have available.

And I'm already impressed with the nice correlation that Rutgers Snow Lab produces for June with the September SIE numbers.

Quote
Furthermore, may I ask what your model would yield should the snow cover be essentially the same as 2016? Just a curious experiment.

Sure. In my formula, every 1 million km^2 of land snow cover in June correlates to about 160 k km^2 of SIE in September. So if the June land snow cover this year would be the same as last year, the prediction would be some 3.5 * 0.16 = 0.56 lower, which means the projection would be 4.85 or so. That is mostly because ice 'area' in June this year was pretty high.

I've also played with reducing the influence of snow cover in the regression formula. That gains a lower number too (but it's hard to get it to go below 4.9) and the standard deviation of the residuals increases. That suggests it's really not a good idea, and I should just stick with the model, and as you said : "it is what it is".
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meddoc

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Re: The 2017 melting season
« Reply #2657 on: July 08, 2017, 10:14:56 AM »
Storms (blue arrows)
Wildfires (red arrows)
&
blueish Ice outside the margin

This doesn't look like dry, cold Polar Region to me...

JayW

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Re: The 2017 melting season
« Reply #2658 on: July 08, 2017, 10:40:28 AM »
Pretty impressive 982mb storm cranking away.  Attachment 1

Attachment 2: July 3-7, 2017  wonder how much rain this is dropping.  It certainly dragged a bunch of Pacific air northward.

Imagery courtesy of the University of Alaska.
http://feeder.gina.alaska.edu/npp-gina-alaska-truecolor-images?search%5Bfeeds%5D%5B5%5D=1&search%5Bsensors%5D%5B3%5D=1

Attachment 3: ECMWF ensemble mean forecast valid for July 14.0z.  This almost looks like a wave 5 pattern to me, and shows multiple omega blocks, the most impressive in the bering strait region.  Run to run consistency has been improving in my humble option.
http://www.tropicaltidbits.com/analysis/models/?model=ecmwf-ens&region=nhem&pkg=z500a&runtime=2017070712&fh=144&xpos=0&ypos=144

Attachment 4: 1000mb vector winds for the past 30 days.  Mean flow has continued to be from Pacific side towards the Atlantic, but not the Fram side, more towards the Kara sea.

In conclusion, I think its gonna be a real tough week for the ESS/Chukchi/Beaufort.

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greatdying2

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Re: The 2017 melting season
« Reply #2659 on: July 08, 2017, 10:56:44 AM »
2) Does this constitute a negative feedback that we will see happen more often? ie open, warm water in September -> influence on jet stream -> lots of snow -> high albedo during May and June both of both ice and land -> slowdown in Arctic sea ice loss

Or, 3) Does it constitute a positive feedback, i.e. lots of snow -> thin ice -> rapid (late) extent loss and other water -> (etc)
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VeliAlbertKallio

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Re: The 2017 melting season
« Reply #2660 on: July 08, 2017, 11:42:26 AM »
There is a bad omen to this. Back in the 1950's Maurice Ewing and William Donn of Columbia University's Lamont Geological Observatory in Palisades, New York proposed that the flips between the Ice Ages and the Interglacials resulted because the Arctic Ocean became ice-free in the summertime. The polar 24-hour sunshine would then warm up the ocean to the point that when the winter darkness sets in, the ocean would precipitate massive snowfalls that could not then melt during the subsequent summers and this kind of mechanism would lead to the onset of a new ice age. The Ewing-Donn Lake-Snow Effect of the Arctic Ocean was modeled after the Great Lakes Region in the North America which sees each fall huge snowfalls from the lakes.

Alas, Milutin Milanković's theory of slow orbital forcing effects re-emerged as the primary contender for the ice ages as the ocean sediment cores did not back up the Ewing-Donne hypothesis. The primary problem with their idea is that if the ocean warms up during the summers, so will the soils. The snow blanket is insular and does not let the heat to escape as easily as it gets thicker. The thermal inertia of wet soils is also quite large although there is no vertical mixing like happens in the ocean. In addition, the decomposition of soils continues deep beneath snow blanket releasing continually more heat as the soils warm in summers. There was no driver-respondent relation between the melting of the ocean and the melting of soils, although these do not run in tandem.

Therefore, it is expected that by the end of summer the heat will once again find its way into the ground to nudge the soil temperatures that little increment up each summer as the Arctic melts. To be sure of this, we should have inserted underground thermometers to different types of permafrost soils, but as it goes with President Trump, the Arctic melting shall be shroud in mystery...  >:(  But all the 1950's debacle about the 'lake-snow versus orbital forcing' isn't at all promising of any thickened snow cover becoming a reliable indicator to be sufficient for a steady negative feedback from the summertime melting of the Arctic Ocean.

2) Does this constitute a negative feedback that we will see happen more often? ie open, warm water in September -> influence on jet stream -> lots of snow -> high albedo during May and June both of both ice and land -> slowdown in Arctic sea ice loss

Or, 3) Does it constitute a positive feedback, i.e. lots of snow -> thin ice -> rapid (late) extent loss and other water -> (etc)
« Last Edit: July 08, 2017, 11:58:06 AM by VeliAlbertKallio »
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Neven

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Re: The 2017 melting season
« Reply #2661 on: July 08, 2017, 12:12:02 PM »
Here's a comparison for July 7th, 2015 vs 2016 vs 2017. Below that I have added July 8th 2013 vs July 13th 2014.

I would say that 2017 is furthest on the Pacific side of the Arctic. On the Atlantic it's not nearly running as warm as 2016, but not that far behind 2015 and warmer than 2013 and 2014. The latter already has red showing in the Laptev Sea/Bite, but my guess is that this year will also be red there by the 13th.
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magnamentis

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Re: The 2017 melting season
« Reply #2662 on: July 08, 2017, 01:05:11 PM »
@VeliAlbertKallio

that's one side of the medal while at those times no mankind was pumping CO2 and other stuff into the atmosphere. as long as we are warming the planet up this will not happen because it WILL be warm enough to subsequently melt all amounts of snow and once temps go furhter up, the amout of snowfall in mid latitudes will be reduced (already is reduced in most places with few exceptions)

that again will speed up spring warming through insolation and have it's impact on upper-mid latitudes like scandinavia etc.

it will be interesting to watch, i'm not so sure whether anyone can predict what's gonna happen with this complicated system, which feedback will overrule another and ultimately prevail.

however i think as long the planet gets warmer and we won't face any special events from volcanos or otherwise extremely cloudy conditions we shall more probably see a total melt out in the long run instead of a new ice age.

i'm just sharing my thought here without sufficient background knowledge to underline my point of view i admit.

magnamentis

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Re: The 2017 melting season
« Reply #2663 on: July 08, 2017, 01:36:46 PM »
@Csnavywx

exactly and that's why i wrote "most often and it can snow...... ;)
« Last Edit: July 08, 2017, 07:00:48 PM by magnamentis »

seaicesailor

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Re: The 2017 melting season
« Reply #2664 on: July 08, 2017, 01:59:42 PM »
The plume of humidity and rain from the Pacific that the storm has digested has left a clear mark of lowered concentration in the latest Uni Bremen maps, from ESS to Beaufort, after the previous day that the concentration seemed to recover. Some cooling follows the storm, then we have the somehow ominous forecasts written above. Def not uneventful.
Laptev sea is very damaged as well from previous days. That bite is almost 80N.
Not to mention the roasting of Barents and Kara
@Neven thank you for the SST maps.

Edit. Just noted from the animation that the "istmus" of ice attached to Alaska has been shrinking extremely fast these last three days. I attach a detail using Uni Hamburg AMSR2 maps this time
« Last Edit: July 08, 2017, 02:30:14 PM by seaicesailor »

Jim Pettit

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Re: The 2017 melting season
« Reply #2665 on: July 08, 2017, 02:36:17 PM »
Rob is discussing the September Average, not the September Minimum.  On the Charctic graph, we would be looking at 2017 being slightly above 2013 through most of September.  In 2016, there was a few day period in July when 2016 melting slowed down to the 2013 line.  If 2017 did that, and didn't speed back up afterward, and then 2017 melt slowed in August as it did in 2013...

Hmmm. This list shows what the September monthly average extent would be were 2017's remaining melt trajectory to exactly follow the trajectory of each of the years in the list:

2016: 4.541M km2
2015: 3.959M km2
2014: 5.063M km2
2013: 4.958M km2
2012: 3.767M km2
2011: 4.595M km2
2010: 4.866M km2
2009: 4.598M km2
2008: 3.918M km2
2007: 4.205M km2
2006: 5.424M km2
2005: 4.820M km2
2004: 4.489M km2
2003: 4.818M km2
2002: 4.345M km2

As you can see, only a repeat of 2006's tepid August/September melt would result in Rob's 5.41M, and that just barely. True, repeats of either 2013 or 2014 would result in a September monthly average of around 5M--but even that's statistically a long way from 5.41.

Of course, and as always: we'll see...

Neven

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Re: The 2017 melting season
« Reply #2666 on: July 08, 2017, 03:21:38 PM »
@Neven thank you for the SST maps.

I'll have more next week.

Here's an animation of the ice south of Novaya Zemlya. Given the forecast it should be gone 10-12 days from now.
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Quantum

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Re: The 2017 melting season
« Reply #2667 on: July 08, 2017, 03:56:43 PM »
What do people think about the possibility of a Baffin Bay survival this year? Even post 2007 there have been a few years where ice has survived in peripheral seas. I believe even last year a small amount of ice survived in the Hudson bay. Baffin bay ice survival used to be fairly routine in the 80s.

Retron

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Re: The 2017 melting season
« Reply #2668 on: July 08, 2017, 04:15:33 PM »
Edit. Just noted from the animation that the "istmus" of ice attached to Alaska has been shrinking extremely fast these last three days. I attach a detail using Uni Hamburg AMSR2 maps this time
Utqiagvik (Barrow) has been reporting some very moist, very mild air of late - all blown in by southerly or SW'ly winds. A dewpoint of 8-11C will zap ice at an alarming rate, so it's no surprise to see that "isthmus" shrinking so quickly.

http://w1.weather.gov/obhistory/PABR.html


Archimid

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Re: The 2017 melting season
« Reply #2669 on: July 08, 2017, 04:21:59 PM »
This melting season looks to me like a recovery year. Compared to 2016 there seems to be a lot less energy accumulated in the atmosphere and the Atlantic ocean side. The Pacific Ocean side looks worse than last year inside the basin, but the Pacific Ocean looks a little cooler. According to nullschool, the atmosphere above the ice seems also colder than last year by a significant margin. 

Yet the arctic is at near record low levels. I think that is due to the mild winter and subsequent thinner, younger ice. I think that to reach record low levels in extent double and triple century drops must happen in the next 3 weeks. That's unlikely but the thin ice is a big uncertainty.  I think that if the big drops happen or not, this melting season will finish early, grow strongly for a little then back to the new normal timid growth.
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oren

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Re: The 2017 melting season
« Reply #2670 on: July 08, 2017, 04:36:02 PM »
2012 reached its record from a similar extent, with no triple and just one double century. It's certainly within the realm of possibility, considering the relatively thin ice. A big question is whether the strong Atlantic side (Barents, Kara, CAB next to Svalbard/FJL), and/or Laptev and Baffin, will manage to retain some ice. 2012 had basically zero ice everywhere but CAB, CAA, and Greenland Sea. This year shows all signs of zero September ice in Beaufort and ESS, not a trivial achievement. But more is required for a shot at the record, and of course the CAB itself will still determine the final outcome.
My forecast: 2017 will manage to keep close to 2012 until the end of July, based on the current situation and typical peripheral trajectories from here onward. After that it's the hard-to-melt ice and up to weather and chance.
« Last Edit: July 08, 2017, 04:47:44 PM by oren »

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Re: The 2017 melting season
« Reply #2671 on: July 08, 2017, 04:47:33 PM »
subgeometer,
Quote
Large areas of the basin are going to see rain over the next 6 days, further conditioning it for destruction, and rendering the outlook from May meltponds irrelevant, in my opinion anyway
I am thinking likewise. The meltponds have made up for lost time.

I am leaning the other way.  iirc Schröder's model heavily weighs the albedo effect of melt ponding, which is why the May-June values have such a good predictive track record.
     I do think his prediction of 5.1 million Sept. mean ice extent is on the high side, but owing more to thickness distribution than the current (post-solstice) rain over ice.  Much of the Atlantic-side relatively thick ice will eventually melt, while the FYI and other thin ice toward the Pacific continues to weaken.

FishOutofWater

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Re: The 2017 melting season
« Reply #2672 on: July 08, 2017, 05:06:00 PM »
There has been an anomalous wind field from the subtropical Pacific all the way to the pole right through the Bering sea for the past 30 days. CS Navy WX made excellent observations we should all note. Rob Dekker's model is likely to have trouble this year because of the strong heat and water vapor advection from the Pacific towards the pole. In all the years scientists have been watching the Arctic, excepting possibly 2007, Pacific heat has not been as important to conditions in the Arctic.

The map of the Arctic shown in the comment above for the past 30 days is an anomaly map, not the actual mean vector wind map.

Here is the mean vector wind map for June 6 to July 6 which shows the actual flow from the subtropical Pacific into the Bering strait and across to the pole. This flow is anomalous. These winds will force a much higher than normal amount of warm summer water through the Bering strait into the Arctic ocean. The winds themselves, are carrying extraordinary amounts of heat water vapor towards the pole.

This year is very strange. I have no idea how much ice will be left in September.  I don't think the old rules are going to apply to this bizarre weather. The CIMSS loops of water vapor flux into the Arctic form the Pacific are shocking. The web site http://tropic.ssec.wisc.edu/ is down now but check out the morphed water vapor imagery when it comes back up. It's crazy that subtropical water vapor is flowing deep into the Arctic.

ps The jet stream is not "broken". The high snow NH amounts kept the jet stream strong into late spring. However, that stronger than normal jet stream is transporting more vapor and heat than normal towards the north pole.

FishOutofWater

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Re: The 2017 melting season
« Reply #2673 on: July 08, 2017, 05:27:40 PM »
The anomalous vector winds for the past 30 days from the subtropical Pacific towards the pole has amplified SST anomalies in the north Pacific, the Bering sea and the Chukchi sea. This ocean heat will help melt out the ice in the east Siberian sea, the Chukchi sea and the Beaufort sea.

 

Retron

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Re: The 2017 melting season
« Reply #2674 on: July 08, 2017, 05:48:34 PM »
Looks like some pretty big action going on off the coast of Siberia - this is a comparison of the 7th and 8th July, via Worldview.


A-Team

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Re: The 2017 melting season
« Reply #2675 on: July 08, 2017, 07:54:25 PM »
Quote
Greenland Sea
Folks, don't add in this ice, subtract it. A banana peel isn't fruit.

You are monitoring export loss here, not the Arctic Ocean melt season. Not once during the satellite era 1979-2017 has ice ever entered the Fram but returned to the Arctic Ocean. It's 100% doomed export plus east-side Greenland calving irrelevant to this forum. Melt dates, extent, area, and volume of this ice are not a proxy for anything we monitor here, they're a red herring.

Heavy snow pack on Arctic Ocean ice this year?

Please, can we drop the endless repetition of this until someone can cite physical basin-wide observational data that supports it and provide monthly maps of snow depth and snow condition that are something beyond an unvalidated algorithm?

Up-forum we still puzzle over rain vs snow just barely off Alaskan coastal villages. There is meagre weather station data from around the rim, pretty reanalysis graphics that are upended by a single in situ shipboard radiosonde, and a Rutgers land product whose snow does not address the dominant moisture advection issue affecting the Arctic Ocean in recent years.

I'm not seeing much directly applicable to snow depth or snow condition beyond casual and abortive Borneo notes, failed buoys in the wrong locations, a short plane transect off Alert (unpublished) meant to calibrate an uncalibrated ice satellite, two year old N-ICE2015 papers on snow core complexity, and the blog from the Polarstern which is only today entering the deep Arctic. It's a big winter ice pack and nobody is out there.

Look at where July 15th of 2017 stands relative to July 15th of previous years -- and where those years ended up two months later.

Then melt out all the ice in the upper right corner that is <1.5m thick (darkish green, purple, pink, white) plus the bathymetric Barents ice over the next two months, plus garlic press the CAA. By October 1st, we'll be effectively down to open water and dispersed residual sub-meter ice.
« Last Edit: July 09, 2017, 12:41:28 AM by A-Team »

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Re: The 2017 melting season
« Reply #2676 on: July 08, 2017, 08:35:17 PM »
This melting season looks to me like a recovery year. Compared to 2016 there seems to be a lot less energy accumulated in the atmosphere and the Atlantic ocean side. The Pacific Ocean side looks worse than last year inside the basin, but the Pacific Ocean looks a little cooler. According to nullschool, the atmosphere above the ice seems also colder than last year by a significant margin. 

Yet the arctic is at near record low levels. I think that is due to the mild winter and subsequent thinner, younger ice. I think that to reach record low levels in extent double and triple century drops must happen in the next 3 weeks. That's unlikely but the thin ice is a big uncertainty.  I think that if the big drops happen or not, this melting season will finish early, grow strongly for a little then back to the new normal timid growth.

I am reading all of the varied opinions about the current melt and the projected end result and can only say that, just like the previous freeze season, this is a strange melt season. The Arctic has gotten very weird in the past few years (the new normal?). I don't really know where we will end up regarding extent, unlikely a new record though.

If the melt slows considerably, resulting in a rebound from last year, I am still doubtful that the melt season will end early nor do I think we will see a vigorous early freeze. Vigorous freezing is a thing of the past, I fear. The fall will be relatively warm, humid and overcast, not conducive to rapid freezing.

Neven

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Re: The 2017 melting season
« Reply #2677 on: July 08, 2017, 09:13:49 PM »
Heavy snow pack on Arctic Ocean ice this year?

Please, can we drop the endless repetition of this until someone can cite physical basin-wide observational data that supports it and provide monthly maps of snow depth and snow condition that are something beyond an unvalidated algorithm?
I was hoping for some observational data as well, when we started discussing the growing discrepancy between PIOMAS and CryoSat-2 data, back in February, and speculated that it was because of snow on the ice. The same had happened in 2013.

Given what has happened so far - you know, the NH land snow cover and the fact that the ice pack stayed white for so long - I would say that more snow has indeed fallen on the ice this winter, and that this has caused the substantial discrepancy between sea ice volume model and observations.

Unfortunately, there is no way to quantify it. Which is very frustrating. But I believe that this is the story of this melting season.

I don't know how it will play out. At some point the ice will so thin that other influences play a minor role in whether it disappears or not. It simply disappears. I don't know if this point will be reached this year.
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Re: The 2017 melting season
« Reply #2678 on: July 08, 2017, 09:23:14 PM »
Heavy snow pack on Arctic Ocean ice this year?

Please, can we drop the endless repetition of this until someone can cite physical basin-wide observational data that supports it and provide monthly maps of snow depth and snow condition that are something beyond an unvalidated algorithm?
I was hoping for some observational data as well, when we started discussing the growing discrepancy between PIOMAS and CryoSat-2 data, back in February, and speculated that it was because of snow on the ice. The same had happened in 2013.

Given what has happened so far - you know, the NH land snow cover and the fact that the ice pack stayed white for so long - I would say that more snow has indeed fallen on the ice this winter, and that this has caused the substantial discrepancy between sea ice volume model and observations.

Unfortunately, there is no way to quantify it. Which is very frustrating. But I believe that this is the story of this melting season.

I don't know how it will play out. At some point the ice will so thin that other influences play a minor role in whether it disappears or not. It simply disappears. I don't know if this point will be reached this year.

We found deep snow cover observed from our field cruise northwest of Svalbard in May. When I have some time, I'll write a bit more. Sea ice thickness ranged from 1-1.7 m on our measured flows with snow cover > 0.5 m in several snow pits.
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Tor Bejnar

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Re: The 2017 melting season
« Reply #2679 on: July 08, 2017, 09:37:19 PM »
... Folks, ...
Your rant pretty much speaks my mind.

I appreciate folks going 'out on a limb' (makes things interesting), but posts read 'best' when there is some sort of acknowledgement they're projecting and not thinking they are standing on a firm foundation with The Truth by their side (and not repeating themselves every day). [I hope I didn't write this yesterday!  :D  Note to Neven: there's A-Team's rant, my response, so the next person gets to condemn us with a superior air, then you delete all three: right?]
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Re: The 2017 melting season
« Reply #2680 on: July 08, 2017, 09:37:56 PM »
We should not forget the cyclone cannon that persisted throughout the winter, a progression of moisture laden storms formed in the North Atlantic and moving up through the Barents and into the CAB. These had to have resulted in high snowfall amounts on the Atlantic side of the CAB.

Jim Williams

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Re: The 2017 melting season
« Reply #2681 on: July 08, 2017, 09:42:50 PM »
We're watching the Warm Arctic Cold Continents (or Maritime Arctic) play out here.  The only questions are how warm and how cold.  I'm betting the land isn't all that cold.

greatdying2

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Re: The 2017 melting season
« Reply #2682 on: July 08, 2017, 10:03:47 PM »
@VeliAlbertKallio

... at those times no mankind was pumping CO2 and other stuff into the atmosphere... we shall more probably see a total melt out in the long run instead of a new ice age.
Is there really much doubt about the next hundreds and thousands of years?
https://climate.nasa.gov/system/resources/detail_files/24_co2-graph-021116-768px.jpg

(Apologies for taking another step down this OT trail.)
The Permian–Triassic extinction event, a.k.a. the Great Dying, occurred about 250 million years ago and is the most severe known extinction event. Up to 96% of all marine species and 70% of terrestrial vertebrate species became extinct; it is also the only known mass extinction of insects.

Jim Williams

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Re: The 2017 melting season
« Reply #2683 on: July 08, 2017, 10:22:40 PM »
Is there really much doubt about the next hundreds and thousands of years?
https://climate.nasa.gov/system/resources/detail_files/24_co2-graph-021116-768px.jpg

(Apologies for taking another step down this OT trail.)

The only real doubts are about the extent and duration of this thawing season.

See!  Back on Topic!

greatdying2

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Re: The 2017 melting season
« Reply #2684 on: July 08, 2017, 10:27:57 PM »
I am leaning the other way.  iirc Schröder's model heavily weighs the albedo effect of melt ponding, which is why the May-June values have such a good predictive track record.
It would be very interesting to see an estimate of the extra energy input due to early melt ponds (albedo) vs. reduced the energy of melting (enthalpy of fusion) needed to melt thinner ice; i.e., what thickness of ice is melted by a given abundance*time of early melt ponds. Alas, I am too ignorant to do a reasonable job at such a calculation. Just keep in mind that there are 2 sides to this equation, and that heuristics or models that have worked well in the past may rely on assumptions (e.g. roughly constant year-to-year thickness) that no longer hold.
The Permian–Triassic extinction event, a.k.a. the Great Dying, occurred about 250 million years ago and is the most severe known extinction event. Up to 96% of all marine species and 70% of terrestrial vertebrate species became extinct; it is also the only known mass extinction of insects.

FishOutofWater

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Re: The 2017 melting season
« Reply #2685 on: July 08, 2017, 10:35:33 PM »
A Greenland vortex pattern is setting up. This pattern pulls heat into the Arctic from the Atlantic and Pacific oceans while dumping cold air into the seas south of Greenland. The persistence of this pattern is one of the causes of the persistent oceanic cold pool in the ocean southeast  of Greenland. The northwest flow of air down the Labrador sea speeds the flow of cold fresh water out of the Arctic and the CAA. It also speeds up the flow of Atlantic water into the European Arctic seas.

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Re: The 2017 melting season
« Reply #2686 on: July 09, 2017, 12:18:00 AM »
I know we're not supposed to overhype the highly uncertain forecasts on this thread, but...

After the current low pressure fills in and exits into the Canadian islands, and after  the next likely big feature, the high bridging across from East Siberian Sea to the Beaufort, the operational models have been signaling another big high spanning most of the Russian side of the Arctic, with lots of low pressure west of Greenland, as Fishoutofwater notes above.

It seems like a very sunny time coming up all along the melting fronts of the central Arctic.



Andre

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Re: The 2017 melting season
« Reply #2687 on: July 09, 2017, 01:19:29 AM »
Slater's model forecast for August 27 is down to 4.68 million sq km. Seems to be predicting quite a drop during the second half of August.

Considering that the model probably hasnt received any inputs since his passing and just continues on auto-pilot, it has been pretty good at keeping up during the melt season so far.

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Re: The 2017 melting season
« Reply #2688 on: July 09, 2017, 01:24:14 AM »
That low over Baffin sparked some indecent winds today in Iqaluit, 55 km/h at the airport (gusts to 70). Despite the strong winds aiming straight up Frobisher Bay from the Baffin Sea, there's only a couple small forlorn chunks of ice that floated in.

The storm will shake around the ice in Baffin sea, and dump some moisture (but not much -- it's still a desert up here). I've no idea the net effect on the ice though: insolation is powerful, and the clouds block it.

Regardless, as A-team points out, Baffin Sea ice is doomed ice floating.

Csnavywx

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Re: The 2017 melting season
« Reply #2689 on: July 09, 2017, 02:16:19 AM »
At first glance, that D3-D6 pattern may not look that damaging, but more careful inspection reveals otherwise. Very strong WAA (warm air advection) on the NW flank of that developing omega block will push purely subtropical air into the developing cyclone over the central basin. Freezing levels push all the way to 13kft and 925/850 temps will push 15C. The wind and wind fetch is the real killer here, as it mechanically mixes away the near-surface inversion and blasts that quadrant with extremely warm and moist air.

The EPS and OP Euro forecast another gale to push directly into the CAB at D6 on the heels of the first. Though not quite as warm as the first, it's still very warm by high Arctic standards (700mb temps pushing 0C). We'll have to see if that second punch verifies, but if it does, we're talking about huge area drops over the next 10 days or so.

The omega block also has the secondary effect of drawing the TPV away from the CAB over time, forcing it into a southerly position. The longer range ensembles all agree in forming a sort of tripole pattern by mid-month, with the TPV locked away near the Hudson or Baffin areas between a powerhouse subtropical ridge over the CONUS and a cutoff high near the pole or Eurasian side. While this will slow export losses, it could expose the previously shielded Atlantic front to severe pressure while maintaining melt conditions on the Pacific front.

Potentially interesting times ahead.

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Re: The 2017 melting season
« Reply #2690 on: July 09, 2017, 06:29:05 AM »
NSIDC SIE
106 km2

2017,    07,  01,      9.244               
2017,    07,  02,      9.154
2017,    07,  03,      9.087
2017,    07,  04,      8.963
2017,    07,  05,      8.910
2017,    07,  06,      8.845
2017,    07,  07,      8.722       = Day 188 on which SIE in 2012 was  8.897 x 106 km2
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Tigertown

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Re: The 2017 melting season
« Reply #2691 on: July 09, 2017, 07:44:39 AM »
JAXA volume and thickness.
Are we under 6k km3? Probably not.
Are there so many melt ponds, they are confusing the output? Probably so.
Is this significant? Probably so.
« Last Edit: July 09, 2017, 08:10:19 AM by Tigertown »
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Re: The 2017 melting season
« Reply #2692 on: July 09, 2017, 08:18:41 AM »
00z GFS  is warm   

Clearing  and Southerly torching incoming on the Pacific side
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oren

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Re: The 2017 melting season
« Reply #2693 on: July 09, 2017, 08:59:40 AM »
So I was reading cdnavywx's forecast and thinking to myself what Friv would have said about it.
Well, hullo Friv...  :) 8)

S.Pansa

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Re: The 2017 melting season
« Reply #2694 on: July 09, 2017, 09:11:46 AM »
And here the comparison with 2012. In general terms it seems to agree with the volume differences of PIOMAS.
And last but not least: The Current TOPAZ4-guess for the volume decline for the first half of July
.
There is no general agreement between these images and the link you provided.  4-year old sea ice in 2012 is 5X the average thickness currently found north of Greenland.  I do not see only -500 km^3 delta between 2012 and now.  The Arctic Ocean is ~14 million km^2.

It looks closer to -2,000 km^3  I do not know if 2012 is now understated or if (likely) 2017 is overstated.
I was talking in really general terms here, in the sense of: On the Pacific side the ice was much thicker in 2012 and thinner on the Atlantic side. But you are right that on a closer look TOPAZ4 shows quite a different picture compared to PIOMAS and Cryosat. But how different?

I now found the time to do what I wanted to do a long time. Count the pixels and calculate - based on that and the model resolution fo 12,5 km^2 - a volume estimate.  I am not sure if I have done things right (I used pics with zero enlargement, colour palette set to 4m) - well actually I am quite confident I messed up somewhere. :P
Nevertheless, here are the results for TOPAZ4 (based on the pics below):

TP4-Volume 090712: 13.593 km³
TP4-Volume 090717: 8.411 km³

So TOPAZ4 thinks that 2012-volume currently trails 2017 by ~5.200 km³!! Without further ado I think this is completely unreasonable (compared to PIOMAS and earlier measurements from Cryosat). I hoped that TOPAZ4 - opposed to the Navy version of HYCOM - offers a better way to compare thickness data from different years. Imo, it apparently doesn't. Hence I'll stop posting them.

The annual data on the other hand do not look completely useless:
TP4-Volume 300617: 10.000km³ (PIOMAS 12.164km³)
TP4-Volume 090717: 8.411 km³
current TP4-volume estimate for 150717: 7.376km³

So TOPAZ4 estimates a volume loss of about 26% for the first half of July. For Piomas that would mean a mid-July volume of around 9.000 km³ - still on track with 2012. Of course this is numerology at its worst.

But to get this post back on topic. For the last three days with all its inflow of warm and moist air into the Pacific side TOPAZ4 estimates a volume loss of around 550 km³. So while the extent decline has somewhat slowed down, the volume loss seems to have kept a steady pace (would equate to a 15-day-volume-loss of around 2.750 km³).
Of course, all these numbers should be taken with a huge grain of salt, because they are based on my own calculation. Hence the confidence interval is ~0%.



Frivolousz21

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Re: The 2017 melting season
« Reply #2695 on: July 09, 2017, 09:22:13 AM »
So I was reading cdnavywx's forecast and thinking to myself what Friv would have said about it.
Well, hullo Friv...  :) 8)


It's definitely not a perfect torch pattern but it's nasty in places.

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a Desert Eagle that I call Big Pun
a two shot that I call Tupac
and a dirty pistol that love to crew hop
my TEC 9 Imma call T-Pain
my 3-8 snub Imma call Lil Wayne
machine gun named Missy so loud
it go e-e-e-e-ow e-e-e-e-e-e-blaow

Neven

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Re: The 2017 melting season
« Reply #2696 on: July 09, 2017, 10:30:29 AM »
The omega block also has the secondary effect of drawing the TPV away from the CAB over time, forcing it into a southerly position. The longer range ensembles all agree in forming a sort of tripole pattern by mid-month, with the TPV locked away near the Hudson or Baffin areas between a powerhouse subtropical ridge over the CONUS and a cutoff high near the pole or Eurasian side. While this will slow export losses, it could expose the previously shielded Atlantic front to severe pressure while maintaining melt conditions on the Pacific front.

Potentially interesting times ahead.
I had to look up TPV, and it means Tropopause Polar Vortex (added to the glossary).

And yes, lots of high pressure ahead according to the ECMWF forecast.

Traditionally, what would make for record lows, is high pressure over the Beaufort Sea, because it would make for sunny skies over the ice on the Pacific-American side of the Arctic, while compacting the rest of the ice, and transporting some of it towards Fram Strait. This is also known as the Arctic Dipole Anomaly. 2007 was the prime example of such a set-up.

But I think that this compaction also sets a limit to how low the minimum can go. I don't think a new record low minimum or an ice-free Arctic will occur because of a dominant Dipole, but rather because of high pressure over the right regions at the right time, interspersed with intense cyclones.

This weather that is forecast now, would be such a moment of high pressure over the right regions (as PIOMAS tells us that sea ice is thinner everywhere, except for the region from Laptev to the Greenland Sea). We've also had a period of high pressure over the Beaufort/Chukchi region, and already a couple of short-lived, but intense cyclones. And remember, how last year ended with a Mega-Dipole, preceded by a storm that came close to equalling the Great Arctic Cyclone of 2012.

But all of that has to start with low volume, and then some serious preconditioning like we saw in 2010 and 2012. And that's what missing this year, not just because of the weather, but also because of increased snow fall during winter. Another factor that is equally difficult to assess, is ocean heat flux, of course.

Those are the ingredients. Some are there this year, others aren't, and the weather is a wild card.

But anyway, here's the ECMWF forecast as offered by Tropical Tidbits. Of course, the 1032 hPa over the Chukchi stands out, but the high pressure over the Laptev and Kara Seas could be more important:
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anotheramethyst

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Re: The 2017 melting season
« Reply #2697 on: July 09, 2017, 10:42:16 AM »
YAY friv is back!!! My favorite forecaster!!

DoomInTheUK

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Re: The 2017 melting season
« Reply #2698 on: July 09, 2017, 10:42:56 AM »
Yep - now things start to really get interesting!

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Re: The 2017 melting season
« Reply #2699 on: July 09, 2017, 11:29:20 AM »
I will be shocked if this subtropical air surge doesn't bring century drops from Chukchi/ESS/Beaufort.

Click to animate for all gifs.