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Lord M Vader

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Re: The 2017 melting season
« Reply #2100 on: June 17, 2017, 08:53:05 PM »
Well, the cyclone can be good and bad. It will depend on how much of the precip will come as snow and rain. And the location and extent. And how big will those waves be?  And will the cyclone be able to stir up water from the deep? And how thick is the over the areas that will be affected by the cyclone?

The last two operational  runs from ECMWF have put the cyclone down below 970 hpa. The 00z op run today was crazy having the cyclone down to 960 hpa for two days (!!!) The 12z run had a more "modest" 969 hpa at its lowest.

Cook

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Re: The 2017 melting season
« Reply #2101 on: June 17, 2017, 09:09:08 PM »
I suppose that "the cyclone" will compact the ice and mix up the waters. I suspect that the next 2 weeks or so will see a rather large drop in ice extent, mostly due to compaction. The ice that is there at the moment seems to lack integrity so strong winds will surely push it around.

Tigertown

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Re: The 2017 melting season
« Reply #2102 on: June 17, 2017, 10:46:54 PM »
In the Laptev, it looks there is like more "fast" ice breaking loose. 15th/17th June
CLICK IMAGE for top image and bottom is for a point of reference

Edit: I checked and the ice in this area has been busted up for a while this year and then was lightly compacted back together, perhaps with a little glaze over to boot.

« Last Edit: June 17, 2017, 11:01:17 PM by Tigertown »

oren

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Re: The 2017 melting season
« Reply #2103 on: June 18, 2017, 12:10:31 AM »
It is no wonder people keep citing "normal" extent numbers which  avoid being 1st lowest, and raising question marks. As this year is a prime candidate for breaking the record low, due to its PIOMAS lead and extremely poor winter, it raises expectations. When these expectations don't immediately come true, such doubtful comments are bound to crop up, and rightly so. Despite the PIOMAS lead (which I expect to have shrunk during the first half of June), this year could very well fall short of the record, and every day that a June cliff a-la 2012 isn't happening is a day where the chance of a record low has shrunk somewhat. I still expect a record low (especially for volume) but other opinions are totally valid and must be respected.

Tigertown

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Re: The 2017 melting season
« Reply #2104 on: June 18, 2017, 02:03:25 AM »
It is no wonder people keep citing "normal" extent numbers which  avoid being 1st lowest, and raising question marks. As this year is a prime candidate for breaking the record low, due to its PIOMAS lead and extremely poor winter, it raises expectations. When these expectations don't immediately come true, such doubtful comments are bound to crop up, and rightly so. Despite the PIOMAS lead (which I expect to have shrunk during the first half of June), this year could very well fall short of the record, and every day that a June cliff a-la 2012 isn't happening is a day where the chance of a record low has shrunk somewhat. I still expect a record low (especially for volume) but other opinions are totally valid and must be respected.
It is really just still too early to be dogmatic one way or the other. It is irritating when someone says that it is going to be a terrible or horribly bad melt season based on what has happened thus far, but just as much when someone else says it is such a slow melt season because it is barely dropping as fast as the worst year in history.

JayW

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Re: The 2017 melting season
« Reply #2105 on: June 18, 2017, 02:11:23 AM »

First attachment is a (edit: SUOMI VIIRS) 40 hour loop of the area north of Alaska  It's not the headliner storm, but you can see a cyclone spin up ponder the southern Beaufort Sea, and move east to west.  It also appears to darken the sea ice as it moves across in the "landcover" band.  My humble opinion is that this is wet from rain.

The dark spot is also apparent on the various MODIS bands

Second attachment is a comparison of the blue (7-2-1), purple (2-6-1), red (3-6-7), and "naturalcolor" bands from MODIS

I don't think it's a cloud, but I also cannot definitively rule that out entirely.

All imagery comes courtesy of the University of Alaska at Fairbanks.
http://feeder.gina.alaska.edu
« Last Edit: June 18, 2017, 02:37:43 AM by JayW »
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Darvince

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Re: The 2017 melting season
« Reply #2106 on: June 18, 2017, 03:13:02 AM »
To me it seems to be the beginning of snowmelt, as the dark spot is much less visible now in the final image of the day on MODIS.

Greenbelt

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Re: The 2017 melting season
« Reply #2107 on: June 18, 2017, 03:53:40 AM »
GFS seems to be indicating mostly rain from the big long-lasting low pressure area.




Rob Dekker

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Re: The 2017 melting season
« Reply #2108 on: June 18, 2017, 08:06:25 AM »
I find this melting season fascinating.

On the one hand we have a lot of clear skies over the Arctic, which means these 'holes' (ESS, Beaufort, Laptev) are soaking up a lot of the sun's energy, and turning that into melting ice.
And we have a still persistent dipole, which helps in compacting the ice field.
And then we have record low ice volume as per PIOMAS.
All these factors contribute to rapid SIE decline, and we sure have seen a lot of that in these first two weeks of June.

On the other hand, we have an astonishing record land snow anomaly in May :

http://climate.rutgers.edu/snowcover/chart_anom.php?ui_set=1&ui_region=nhland&ui_month=5

which to a great extent (at least all along the Siberian coast) still persists today :



Remember that land snow serves as BOTH a thermometer AND as a feedback.
And consequently we are seeing rather cool temperatures around the Arctic.
And as a result, there is evidence of melt in some places of the Arctic, but mostly the ice pack and surrounding land still is 'whiter' than previous years :
https://lance3.modaps.eosdis.nasa.gov/imagery/subsets/?mosaic=Arctic.2017168.terra.4km

So we still don't know where this is going.....
« Last Edit: June 18, 2017, 08:24:17 AM by Rob Dekker »

Tigertown

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Re: The 2017 melting season
« Reply #2109 on: June 18, 2017, 08:08:04 AM »
NSIDC SIE     x 106 km2

2017,    06,  12,     11.069
2017,    06,  13,     10.959
2017,    06,  14,     10.869
2017,    06,  15,     10.788
2017,    06,  16,     10.677

That's about -98,000 km2 a day for the last 4 days reported.

Rob Dekker

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Re: The 2017 melting season
« Reply #2110 on: June 18, 2017, 08:28:59 AM »
Tigertown,
I know, and it doesn't look good at all.
I still have hope (refer to my argument above), and let's see what the next two weeks give us.
I'm still on the fence.

JayW

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Re: The 2017 melting season
« Reply #2111 on: June 18, 2017, 10:17:52 AM »
Snowcover really only affects the lowest level of the atmosphere (below 925mb) warm air advection is a very powerful force. 

Fresh snow and old crusty snow also have very different effects.  As a snowpack sits and eventually "ripens", it's ability to cool the air above it diminishes.  This past spring I saw temps above 80°F with a snowpack.

I agree that the lingering snow is a symptom of cooler than *normal* temps, but I don't buy that the remaining snowcover can affect temperatures other than very locally, especially when sparse.

Just my opinion, and I'm drawing on my experiences with snow melt where I live.  (I recorded about 3.5 meters of snow at my home this past winter, it's a snowy area)

The snow at the shores of the ESS appears to have been hit hard this last week. This was the biggest patch of snow I saw, so I focused on that.

https://worldview.earthdata.nasa.gov/?p=arctic&l=VIIRS_SNPP_CorrectedReflectance_BandsM11-I2-I1,VIIRS_SNPP_CorrectedReflectance_BandsM3-I3-M11,VIIRS_SNPP_CorrectedReflectance_TrueColor(hidden),MODIS_Aqua_CorrectedReflectance_TrueColor(hidden),MODIS_Terra_CorrectedReflectance_TrueColor,Reference_Labels,Reference_Features(hidden),Coastlines&t=2017-06-18&z=3&v=-1916703.9510083084,508228.11354981665,985071.6241453581,3738044.730323253&r=11.6656
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Neven

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Re: The 2017 melting season
« Reply #2112 on: June 18, 2017, 10:36:16 AM »
Compactness is still very high (indicating a lack of melt ponds and/or dispersion):
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JayW

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Re: The 2017 melting season
« Reply #2113 on: June 18, 2017, 11:05:49 AM »
I was surprised to see the 925mb reanalysis temperatures for the first half of June.  Doesn't really look so cool.

I'll also add the surface. (Second attachment)
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oren

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Re: The 2017 melting season
« Reply #2114 on: June 18, 2017, 11:08:22 AM »
In related news, the snow in Tiksi (Laptev shore) has finally given up and melted, the latest in at least 15 years.
Out of sheer boredom while waiting for cliffs and the hopeful mid-month PIOMAS update, I decided to graphically quantify this snowy lateness. Horizontal axis is date from present backwards.
BTW, took ages to produce. If anyone has a link to historical station data that can be downloaded, it would be very welcome.

« Last Edit: June 18, 2017, 11:29:48 AM by oren »

seaicesailor

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Re: The 2017 melting season
« Reply #2115 on: June 18, 2017, 01:08:27 PM »
In related news, the snow in Tiksi (Laptev shore) has finally given up and melted, the latest in at least 15 years.
Out of sheer boredom while waiting for cliffs and the hopeful mid-month PIOMAS update, I decided to graphically quantify this snowy lateness. Horizontal axis is date from present backwards.
BTW, took ages to produce. If anyone has a link to historical station data that can be downloaded, it would be very welcome.
Great plot Oren.
I think it is reasonable to expect as well a significant excess snow cover over the ice, due to the anomalous winter, spanning from the Barents and then along Eurasia, but that we cannot prove.Perhaps explainimg delay on melt ponds

meddoc

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Re: The 2017 melting season
« Reply #2116 on: June 18, 2017, 07:10:54 PM »
I was surprised to see the 925mb reanalysis temperatures for the first half of June.  Doesn't really look so cool.

I'll also add the surface. (Second attachment)

The Polar Vortex is being taken care of with that.
Now, only the Ice left to finish off the Show.

Tigertown

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Re: The 2017 melting season
« Reply #2117 on: June 18, 2017, 08:01:18 PM »
seaicesailor,
Perhaps explainimg delay on melt ponds
Or, as someone pointed out a few days ago, the snow is disguising the melt ponds.

Robert Greer

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Re: The 2017 melting season
« Reply #2118 on: June 18, 2017, 08:35:37 PM »
seaicesailor,
Perhaps explainimg delay on melt ponds
Or, as someone pointed out a few days ago, the snow is disguising the melt ponds.

How do you expect melt ponds to form if there is no insolation getting to the ice?

RoxTheGeologist

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Re: The 2017 melting season
« Reply #2119 on: June 18, 2017, 09:43:31 PM »

The skies have been relatively clear for the last few weeks over the Canadian side of the Arctic, which is why forum members have been theorizing about the lack melt ponds despite the amount of insolation.

slow wing

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Re: The 2017 melting season
« Reply #2120 on: June 18, 2017, 09:46:37 PM »
The current and forecast weather provides more evidence that the Arctic has become more windy over the past couple of years (could pick December 2015 storm as starting point), even during the melt season.

  Currently a large cyclone of 985 hPa sits in the Arctic basin, fairly central and towards the Atlantic side. That is already unusual for June and perhaps almost unprecedented in the satellite record. (Does anyone remember similar or lower in June?)

  All of ECMWF, GFS, CMC, NAVGEM and JMA expect it to stay there and even intensify down into the high or mid 970s in around six days from now.

  I presume that such persistent and strong low pressure over the Arctic Basin is new territory over the satellite record for June.

  It is unclear to me that this helps to preserve the ice for this melt season, as some above appear to be suggesting. To the contrary, it generates a lot of wind to carry heat and moisture in from the land and to fracture and push the ice around.

  I view it as concerning both for this melt season and also as a sign of changes in the Arctic climate occurring within timescales of only a few years.

   Shown below is the furthest forecast displayed by Nullschool, about 5 days from now. It uses GFS forecasting and the predicted MSLP at the cyclone's core, currently at 985 hPa, has dropped by then to 980 hPa.

Neven

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Re: The 2017 melting season
« Reply #2121 on: June 18, 2017, 10:13:41 PM »
The current and forecast weather provides more evidence that the Arctic has become more windy over the past couple of years (could pick December 2015 storm as starting point), even during the melt season.

  Currently a large cyclone of 985 hPa sits in the Arctic basin, fairly central and towards the Atlantic side. That is already unusual for June and perhaps almost unprecedented in the satellite record. (Does anyone remember similar or lower in June?)


Yes, back in 2013. I wrote a couple of blog posts at the time about the PAC and persistent Arctic cyclones in general, but Robertscribbler has a blog post dated June 4th 2013 where he mentions the storm reached 980 hPa.
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Tealight

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Re: The 2017 melting season
« Reply #2122 on: June 19, 2017, 01:22:19 AM »
I believe melt ponds will become less important in the Arctic. The increased mobility of sea ice and lower thickness allows sea ice to just break away from the coast and leave big open ocean areas behind. If the wind is right then waves increase the energy transfer from the warm water to the cold ice. Thankfully the compaction ratio is influenced by melt ponds and ice dispersion. This way we can look at one variable over a long period of time for changing melt mechanisms.

In the Antarctic we can already see that sea ice melts just fine in stormy conditions and on Worldview its hard to spot any melt ponds at all. But sheltered areas like the Weddell Sea still struggle to melt significantly.

Tigertown

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Re: The 2017 melting season
« Reply #2123 on: June 19, 2017, 05:54:23 AM »
JAXA SIE is now in a virtual tie with 2012 at 9.98 x 106 km2.
Hudson Bay is getting baked. As for the rest of these bright colors, will have to watch for a day or two.I expect the shoreline to open up soon between the ESS and the Laptev.CLICK IMAGE & Zoom

Tor Bejnar

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Re: The 2017 melting season
« Reply #2124 on: June 19, 2017, 06:10:12 AM »
JAXA SIE is now in a virtual tie with 2012 at 9.98 x 106 km2.
With opposites sides of the greater Arctic (Hudson Bay and East Siberian & Chukchi & Bering Seas) 'ahead of' (more ocean water exposed than) 2012, other areas can 'lag', leaving us watchers in suspense!
Arctic ice is healthy for children and other living things.

Juan C. García

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Re: The 2017 melting season
« Reply #2125 on: June 19, 2017, 07:03:46 AM »
I expect the shoreline to open up soon between the ESS and the Laptev.

I agree. Seems that the cyclone will melt or at least push the ice away of these regions. On the other hand, I expect some sea ice melt on Hudson, Greenland Sea, Barents and Kara. On the last three, they should be receiving ice, but there should be also some melt on the ice that is there.
« Last Edit: June 19, 2017, 07:12:01 AM by Juan C. García »
Which is the best answer to Sep-2012 ASI lost (compared to 1979-2000)?
50% [NSIDC Extent] or
73% [PIOMAS Volume]

Volume is harder to measure than extent, but 3-dimensional space is real, 2D's hide ~50% thickness gone.
-> IPCC/NSIDC trends [based on extent] underestimate the real speed of ASI lost.

epiphyte

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Re: The 2017 melting season
« Reply #2126 on: June 19, 2017, 07:05:20 AM »
I'm repeating myself, but are those who are judging the season on melt-ponds looking at what is actually happening to the ice in the areas of unusually low May melt-pond fraction? It certainly seems to me that a big chunk of it has already gone from "apparently healthy" to "not there anymore", without ever a melt-pond to be seen.

E.g. although mostly under cloud, it's possible to glimpse through the gaps that open water in Laptev has been advancing steadily for the past week and is on-track to go north of 80 degrees earlier than ever before.

Meanwhile, both forecasts show a blowtorch in ESS and hard rain set to fall on Beaufort over the next few days.

This is not a slow season. If you think that it is, then the only thing I can suggest is - just look harder.




bairgon

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Re: The 2017 melting season
« Reply #2127 on: June 19, 2017, 07:47:31 AM »
I guess, based on HYCOM ice thckness animation, that the MacKenzie delta has given way for a large melt pulse. As the ice is disappearing fast phase in the MacKenzie Bay and around it in the Beaufort.
You better look at the worldview images https://go.nasa.gov/2ri0zKP
There is ice movement away from the coast, surface melt on landfast ice, an ice free McKenzie river and some recently formed ice melting away in the Beaufort. Not all opening water equates to ongoing melt. Open water absorbs sunlight and will melt ice because it is warming up now, but that takes a while to come together.

The Mackenzie delta melt has been impressive since then. See animation from 1st June below.

gerontocrat

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Re: The 2017 melting season
« Reply #2128 on: June 19, 2017, 02:09:55 PM »
Weather-forecast.com  forecasts strong southerly winds from the N. Pacific through the Bering Strait into the CAB developing over the next few days (in addition to the cyclones close to the pole). Will the cyclones also shove a lot of ice in the general direction of the Fram ?

F.Tnioli

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Re: The 2017 melting season
« Reply #2129 on: June 19, 2017, 02:26:55 PM »
Compactness is still very high (indicating a lack of melt ponds and/or dispersion):
I (much) blame extra snow cover. Can't see melt ponds if they are forming under some snow, right? See recent (few pages ago) post in this topic describing how it happens, made by someone who walked his feet through such "water under the snow" conditions. Sorry about my awful memory for names...

P.S. Interestingly, 2011, which demonstrates basically the same rate of compactness decrease per this graph for the last couple weeks (very little decrease), - is 2nd-lowest for the whole season's compactness minimum. Also, 2016, which is not far "below" 2017 for the date, ends up being 1st lowest of years present on this graph.

I suspect there is indeed some correlation; slower / later periphery melt = more "badly damaged" ice surviving the minimum in parts of periphery, and such ice should decrease season's minimum compactness alot. Feasible?

Obviously that correlation would cease to be in a season which manages to melt periphery well despite somewhat later start, and we know such seasons will come at very least, or perhaps this season will end up being of the kind already, even.

Tigertown

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Re: The 2017 melting season
« Reply #2130 on: June 19, 2017, 05:06:06 PM »
I've seen a lot of snow melt, some deep and some shallow.  I recall thin snow (sometimes on lake ice) develop something like melt ponds.  I also recall walking in the spring through foot-deep snow and coming to 'bogs' where the surface was grey and 'melt pondy' or even a temporary pond, and places where the surface was pristine white but my feet got soaked by the hidden water below.

I want to guess there is a lot of this hidden water below the surface sort of melt pond in the Arctic right now.  The white surface is certainly causing a great deal of reflectance, but real damage is happening below, none-the-less.
F. Tnioli, here is the comment. I got snapped at earlier for referring back to it myself, but it makes sense to me. A percentage of energy gets past the snow surface, and some ponding could have formed between snows.

seaicesailor

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Re: The 2017 melting season
« Reply #2131 on: June 19, 2017, 06:08:02 PM »
I've seen a lot of snow melt, some deep and some shallow.  I recall thin snow (sometimes on lake ice) develop something like melt ponds.  I also recall walking in the spring through foot-deep snow and coming to 'bogs' where the surface was grey and 'melt pondy' or even a temporary pond, and places where the surface was pristine white but my feet got soaked by the hidden water below.

I want to guess there is a lot of this hidden water below the surface sort of melt pond in the Arctic right now.  The white surface is certainly causing a great deal of reflectance, but real damage is happening below, none-the-less.
F. Tnioli, here is the comment. I got snapped at earlier for referring back to it myself, but it makes sense to me. A percentage of energy gets past the snow surface, and some ponding could have formed between snows.
But that happens over soil frequently. However to find lhat pool of water sandwiched between snow and -1.8C or so of ice, which is under freezing temp for hypothetically melting snow or fresh-water, and without the direct source of heat ( siince insulated both at the top and bottom). I don't see it...

Shared Humanity

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Re: The 2017 melting season
« Reply #2132 on: June 19, 2017, 09:02:50 PM »
Compactness is still very high (indicating a lack of melt ponds and/or dispersion):
I (much) blame extra snow cover. Can't see melt ponds if they are forming under some snow, right? See recent (few pages ago) post in this topic describing how it happens, made by someone who walked his feet through such "water under the snow" conditions. Sorry about my awful memory for names...

P.S. Interestingly, 2011, which demonstrates basically the same rate of compactness decrease per this graph for the last couple weeks (very little decrease), - is 2nd-lowest for the whole season's compactness minimum. Also, 2016, which is not far "below" 2017 for the date, ends up being 1st lowest of years present on this graph.

I suspect there is indeed some correlation; slower / later periphery melt = more "badly damaged" ice surviving the minimum in parts of periphery, and such ice should decrease season's minimum compactness alot. Feasible?

Obviously that correlation would cease to be in a season which manages to melt periphery well despite somewhat later start, and we know such seasons will come at very least, or perhaps this season will end up being of the kind already, even.

Don't entirely understand your argument but dispersion at minimum has been trending upward for decades.

Lord M Vader

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Re: The 2017 melting season
« Reply #2133 on: June 19, 2017, 09:23:15 PM »
ECMWF 12z op:  967 hpa bomb cyclone at +144h

GFS 12z op run: 967 hpa bomb cyclone at +126h

The fact that both models put the cyclone down to sub 970 hpa is really ominous. Five days ahead is quite  The most critical question is how much of the precipitation will fall as rain? IMO,with a thinner ice pack more and more dominated by floes, rain and strong winds will have a stronger impact on the ice rather than high pressure and sunshine. Melt ponds are important if the ice is "stable" but when the integrity is being lost I think other factors will be more important.

How much damage will we see from this cyclone?

Lastly, Ostrov Golomyannyj reported an impressive 66 cm/26 in today. Last year by the same time it was 48 cm/19 in there, 45 cm/18 in in 2014, 49 cm/19 in cm in 2013 and finally 1 cm in 2012...
This station is located at Severnaya Zemlya. The highest observed temperature that has been observed there is +14oC in June.

JimboOmega

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Re: The 2017 melting season
« Reply #2134 on: June 19, 2017, 10:18:07 PM »
Rather than look at distant forecasts...

I noticed that right now, according to cci-reanalyzer, there's rain falling over a lot of the arctic, including near the pole. Is this a fantasy or known model issue?

Comradez

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Re: The 2017 melting season
« Reply #2135 on: June 19, 2017, 11:39:24 PM »
Here are my impressions of the latest worldview imagery and how 2017 compares with 2012-2016 around this time:

Summer solstice 2017 Sea Ice Outlook
https://youtu.be/sBOvUaaX754

Crocodile23

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Re: The 2017 melting season
« Reply #2136 on: June 20, 2017, 12:19:15 AM »
Rather than look at distant forecasts...

I noticed that right now, according to cci-reanalyzer, there's rain falling over a lot of the arctic, including near the pole. Is this a fantasy or known model issue?

No it's completely a stupidity of the page(cgi-reanalyzer).
The temperature profile(same run of GFS as your map) is all below 0 °C(blue line).




I've chosen this point(with red arrow) but it's the same for others.

Neven

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Re: The 2017 melting season
« Reply #2137 on: June 20, 2017, 12:29:20 AM »
Here are my impressions of the latest worldview imagery and how 2017 compares with 2012-2016 around this time:

Summer solstice 2017 Sea Ice Outlook
https://youtu.be/sBOvUaaX754
Thanks, Comradez. Very informative.
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slow wing

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Re: The 2017 melting season
« Reply #2138 on: June 20, 2017, 01:38:31 AM »
ECMWF 12z op:  967 hpa bomb cyclone at +144h

GFS 12z op run: 967 hpa bomb cyclone at +126h

The fact that both models put the cyclone down to sub 970 hpa is really ominous. ...

You've only looked at those two models though. I checked with two other models on Tropicaltidbits.com and they don't show the same level of 'weather bomb'.


Viewing CMC instead, the 12z 19 June run only drops to 977 hPa (is at 150h).

At 126h - when GFS has its 'bomb' - CMC has gone in the other direction with that system, to 992 hPa.


Viewing NAVGEM 12z 19 June run, the lowest that drops to is 976 hPa, at 136h.


The models sometimes generate very low pressure predictions out beyond 5 days that don't come to pass. So in my view this one is still too uncertain to be concerned about just yet.

bbr2314

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Re: The 2017 melting season
« Reply #2139 on: June 20, 2017, 04:55:05 AM »
If UBremen wasn't a 150K+ area drop into the 19th I'd be surprised. With the impending first GAC of the season I anticipate an end-of-June cliff unlike any we have seen in recent years, and I would bet that the gap with 2012 widens once more in terms of volume (and I also suspect 2017 surges into first place on area). The Atlantic/Russian sectors are going to be absolutely hammered.

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Re: The 2017 melting season
« Reply #2140 on: June 20, 2017, 05:21:50 AM »
Partial quote of post from June 7th by Neven,
(my rule of thumb with Uni Bremen SIC maps is that pink/yellow/green colours need to persist at least for three days to be a sign of something like open water or melt ponding)
And that makes sense to me. Here is the 16th-19th
CLICK IMAGE Zoom if you like.

slow wing

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Re: The 2017 melting season
« Reply #2141 on: June 20, 2017, 05:48:03 AM »
Neven, thanks for Reply #2121 and its links, informing that in 2013 the Arctic Basin also had a strong and persistent low pressure system in June.

That's mildly comforting given that 2013 was a recovery year from the carnage of 2012.

There are differences from this year though that may make comparisons unsafe.

Firstly, the 2013 system was earlier in the melt season, beginning towards the end of May.

The CAB ice pack has already opened up more than was the case in 2013 and is starting to melt out more, particularly on the Russian side.


  In both years, the melt will be retarded by increased cloud cover.


  I'm wondering if this year there may be a stronger competing effect from ice movement induced by the storm winds generated.

  The ice is thin and may be more likely to move around than was the case in 2013.

  Also, the winds North of Greenland will be from West to East, so pushing the ice in the direction of the Atlantic and the Fram Strait 'ice sink'. This year's thick ice is already biased over towards that side and so we may lose thicker ice.

  Also, that displaced ice will likely produce leads and other gaps in its wake. Right at the Summer solstice now, those areas of open water will then heat up and seed melt in the adjacent ice.


  Quantitatively? If those winds persist for 1-2 weeks then the thicker ice will likely move a couple of hundred kilometres towards the Atlantic. (To set the scale, the Fram Strait is 450 km wide, so perhaps half of that.)

  If the ice front is of order 1000 km long then the total displacement towards the Atlantic might be of order 200 km x 1000 km ~ 200,000 km^2.

   Given that the Fram Strait and Atlantic are 'death zones' in recent years, that 200,000 km^2 might be considered extra ice lost.

   Correspondingly, the leads opened up in the pack behind might also have a total area of 200,000 km^2. That would be significant in seeding melt in the adjacent ice.


  This is all speculative and back-of-the-envelope, but it will be interesting to see how much the thicker ice is pushed East to the Atlantic and also to see if any visible leads are opened up.

  Then there will be Ekman pumping as well, which might melt some more ice.

  Having said that, the cloud cover afforded from the 24 hour a day sunlight is a big loss of melting potential to compensate for.


  So, in summary, this storm might be steering us towards a weaker melt season, like in 2013, but there are compensating effects so it might not.















subgeometer

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Re: The 2017 melting season
« Reply #2142 on: June 20, 2017, 05:53:56 AM »
In the ESS and Laptev seas meltponds have been appearing on the fast ice but not on adjacent mobile floes. The meltponds appear to be rapidly draining, sometimes they only appear to last a day or 2. So a bay in the eastern ESS where meltponds appeared on June 5 is now in a state of disintegration(first image). The region to its west was showing intensely blue meltponds a few days later, which also soon disappeared leaving a grey discoloured ice(?) within a few days, and is now beginning to crack up.

Now the Laptev seas has bright blue on the fast ice, but mobile ice beside it remains whitish(second image). Why, I don't know, but there is definitely something interfering with the appearance of meltponds.

As for cci-reanalyser rain forecasts, we are now in the season of above freezing temperatures in the arctic, DMI is showing above freezing avg temps above 80N, so if precipitation is coming down, surely it falls as rain except in those areas where it is freezing

Neven

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Re: The 2017 melting season
« Reply #2143 on: June 20, 2017, 06:35:45 AM »
Neven, thanks for Reply #2121 and its links, informing that in 2013 the Arctic Basin also had a strong and persistent low pressure system in June.

That's mildly comforting given that 2013 was a recovery year from the carnage of 2012.

There are differences from this year though that may make comparisons unsafe.
Absolutely, the biggest difference probably being surface air temperatures. 2013 was very anomalously cold. This year isn't a scorcher, but it's not exactly cool either.
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Rob Dekker

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Re: The 2017 melting season
« Reply #2144 on: June 20, 2017, 07:01:09 AM »
Snowcover really only affects the lowest level of the atmosphere (below 925mb) warm air advection is a very powerful force. 

Fresh snow and old crusty snow also have very different effects.  As a snowpack sits and eventually "ripens", it's ability to cool the air above it diminishes.  This past spring I saw temps above 80°F with a snowpack.

I agree that the lingering snow is a symptom of cooler than *normal* temps, but I don't buy that the remaining snowcover can affect temperatures other than very locally, especially when sparse.


Thanks for your response, Jay.
I think the main issue with land snow cover (apart from it serving as a 'thermometer') is its albedo feedback.
When we are having a multi-million km^2 land snow anomaly, as we did in May, we are talking about thousands of TerraWatt in reflected power, simply because of the snow being white, as opposed to the snow-free soil that is dark. That kind of power seriously reduces the amount of heat that gets absorbed by the Arctic lands, and thus affects the temperature around the Arctic.

Statistically speaking we find that effect in a correlation between land snow cover and Arctic sea ice extent left over in September. I reported about that correlation first here :
http://neven1.typepad.com/blog/2013/07/problematic-predictions-2.html
and have been reporting about it ever since, with the notion that the correlation is strongest in the  June data, when the sun is highest in the Arctic sky.

Ice Shieldz

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Re: The 2017 melting season
« Reply #2145 on: June 20, 2017, 08:22:20 AM »
With persistent & large low pressure systems dominating, it's interesting to compare the counter-clockwise direction of export out the Fram – versus the more typical clockwise direction. I'm wondering how this will effect volume, since north of Greenland and CAA the ice floes are generally thicker and they seem to be more readily moved toward to the Fram by counter-clockwise export.





Notice in the next animation on the 19th the acceleration of export at more than twice the speed of previous days. This seems to be a combination of the counter-clockwise winds reaching further south and a large swath of off-screen wind-driven ice from the northwest pushing against the ice.

« Last Edit: June 20, 2017, 08:28:19 AM by Ice Shieldz »

oren

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Re: The 2017 melting season
« Reply #2146 on: June 20, 2017, 09:09:18 AM »
Great post IceShieldz, thanks.
With all this export, PIOMAS could indeed take a hit later.

meddoc

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Re: The 2017 melting season
« Reply #2147 on: June 20, 2017, 10:10:56 AM »
The Kara, Laptev side is getting a huge Bite the next Week, according to Hycom.

BenB

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Re: The 2017 melting season
« Reply #2148 on: June 20, 2017, 11:14:21 AM »
Melt ponding is getting going in the southern Laptev by the Lena and Khatanga deltas:



Also in the southern ESS:



Sterks

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Re: The 2017 melting season
« Reply #2149 on: June 20, 2017, 04:07:01 PM »
The Wetterzentrale web contains maps of ECMWF temperature for 850 mPa geopotential height, not only deviations from the climatology but the temperature itself. Below the map forecast in five days, which clearly shows a fairly cold and big core (-5 ° C or less toward the Asian side). Thus, we can expect a widespread Arctic cooling past the current storm and this other short-lived monster. Mechanical damage to the ice? Certainly, but it will not be like in August because there is not so much water expansion.
But I was surprised to see in the map a band of warm air pulled by a warm front of the storm from the Pacific. The American side will not cool much if at all, at least in five days.