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Tor Bejnar

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Re: The 2017 melting season
« Reply #1950 on: June 12, 2017, 03:14:09 PM »
This cloudless image from june 10 shows areas of "grey mush" between the large, and bright white icefloes in the Beaufort. What is that stuff?
My thinking was that the grey mush is thin "glue" ice on its way to early melt, but scrolling through Worldview gives the impression that after it disappears it sometimes makes a comeback. Could it possibly be fog or something?
My guess is waterlogged snow (on thin or very thin ice) - not quite melt pond, but definitely not 'dry' snow or ice.  A subsequent snow fall, given my postulation, could turn it back into a white surface.
Arctic ice is healthy for children and other living things.

Tigertown

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Re: The 2017 melting season
« Reply #1951 on: June 12, 2017, 03:52:48 PM »
No doubt, the positive snow anomaly is having an impact on the melt season. Snow covering ground has the same effect as ice covering water. The increased albedo will result in less warming.

With more open ocean, increased snowfall is a new, persistent feature of a warming Arctic. Not all of the effects will be positive. I worry about the insulating effects of early Fall snow cover on the permafrost but that is for a different thread.
Add to that, the river water seems to be having a lesser effect this year than last. As the water runs through land, it usually warms and takes heat with it, as it dumps into the Arctic. The land being cooler the river water is not heating as much.

Quantum

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Re: The 2017 melting season
« Reply #1952 on: June 12, 2017, 05:16:58 PM »
Neven isn't it soon time for you to do an article on Melting Momentum? Just from looking at the MODIS images it seems that we really don't have that much this year. It seems like 2017 will be a battle of competing elements; the effect of low melt ponding and unusually high snow cover vs fragile and broken ice. I wouldn't be surprised if we end up with either a surprisingly low or high September minimum this year.

meddoc

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Re: The 2017 melting season
« Reply #1953 on: June 12, 2017, 07:03:09 PM »
Neven isn't it soon time for you to do an article on Melting Momentum? Just from looking at the MODIS images it seems that we really don't have that much this year. It seems like 2017 will be a battle of competing elements; the effect of low melt ponding and unusually high snow cover vs fragile and broken ice. I wouldn't be surprised if we end up with either a surprisingly low or high September minimum this year.

My guess is, that Volume is gonna take the hardest Hit. We may end up with an Arctic made up of Slush & Ice Cubes.
Nevertheless, should be catastrophic for the Jetstream.

echoughton

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Re: The 2017 melting season
« Reply #1954 on: June 12, 2017, 07:28:34 PM »
Hi all! Like to cast my vote for the extent minimum at....drum roll...4.75...Always been a hopeless optimist.
Thanks for the assistance, Neven.
Really appreciate the forum.

Tigertown

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Re: The 2017 melting season
« Reply #1955 on: June 12, 2017, 07:29:10 PM »
JAXA SIE is below 2007 for this time of year, and is very close to 2012. For the most part NSIDC has  stayed below of these worst years, on a day to day basis. The last PIOMAS update was the lowest ever per day of year. We have these numbers available for a reason. If we stare at the ice waiting on it to melt before our eyes, it may not appear to be melting much. And it may not have, as we started the year lower and there was less to spare anyhow. The waters are starting to open up now, and Senor Momentum will be here shortly.
Another excerpt from https://www.wunderground.com/cat6/arctic-sea-ice-primed-phenomenal-melt-season
Because volume is running so low right now, even an “average” June-to-September volume loss for the period 2003-2016 (dashed red line) would produce a minimum volume lower than the record value observed in 2012
Again
« Last Edit: June 12, 2017, 07:35:45 PM by Tigertown »

A-Team

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Re: The 2017 melting season
« Reply #1956 on: June 12, 2017, 08:01:53 PM »
Below, highlights from a very readable N-ICE2015 paper relevant to the current melt season, on how to interpret radar imagery (such as Sentinel-1AB) based on ground-truthing by simultaneous ship, helicopter and ground measurements co-located to a satellite track. Here the goal is unattended interpretation of scenes as leads, froze-over leads, pressure ridges, rafted ice, snowed-over features, nilas, open water etc (ie assignment of each image pixel to one of those classes).

The work was bedeviled by frost flowers (below, first frame of 1st gif), internal layers of wetted and refrozen snow, and drifted snow masking features; considerations that raise further questions about ice thickness algorithms that are already mutually inconsistent (2nd frame and 2nd gif).

On these forums, we make two main uses of satellite data. The first is literal, accepting as-is photo-like products, such as a Landsat scene of Nares Strait. We might tile these together, make a time series, or dink with contrast or color palette but don’t often apply a segmentation (classification) algorithm ourselves that allocates each pixel to a bin. Instead we rely on others to provide those products.

For example, NSIDC sea ice age uses data from 6 satellites + buoys to bin Arctic ice into five age classes (which are highly correlated with ice thickness http://www.mdpi.com/2072-4292/8/6/457/htm). Bin occupancy is then scored and graphed, showing the older ice classes pinching out over time in recent years (3rd image below, underlay). It is very rare on the forums to see a palette scored but common to see bin integrals (eg piomas volume summed over thickness cells).

Every segmentation product has four distinct parts: initial satellite image, product map colored by bin, color key to bin definitions, and bin occupancy graphic. Within university-grade cartographic GIS, if the classification results in N bins, the product map uses exactly N colors which are exactly those of the color key. Outside the map, embedded text or grid lines might be dithered (or offered as a separate layer) but colors within the map (or bin usage graphic) never stray from the palette. If they don't conform, the end user is just guessing at what map colors represent.

Image classification can be done either by defining categories in advance (eg land, open water, slush or ice) using pixel properties of fiducial areas to partition the rest of the image, or by algorithmic ab initio determination of best N bin segmentation with class interpretation left to the investigator. Both methods develop issues over time series and even year-on-year.

Combined observations of Arctic sea ice with near-coincident co-located X-band, C-band, and L-band SAR satellite remote sensing and helicopter-borne measurements
AM Johansson JA King, AP Doulgeris, S Gerland, S Singha, G Spreen and T Busche
doi: 10.1002/2016JC012273 (see doi:10.5194/tc-11-755-2017 for related article on melt-pond sensing)

Here a low-flying helicopter (with camera and altimeter) tows a device that induces and detects eddy currents in (conductive) sea water but not in snow or ice (non-conductive unless briny) as various radar satellites pass overhead in mid-April 2015 north of Svalbard. This yields 40m pixels of snow + ice thickness and snow surface roughness that can be compared to same-afternoon satellites (L-, C- and X-band) passing overhead. Here the radar sees the ice, the altimeter the snow surface, and the magnetic field sensor the salt water surface.

The radar is polarized and channel ratios prove quite informative. In conjunction with surface texture, taken as kurtosis (heavy-tailedness) of the roughness distribution, the ‘extended polarimetric feature space’ segmentation algorithm can produce 13 sea ice bins (those specified by the WMO in 1970), though that was simplified to 4 here that aren’t quite any in that system.

The drifting RV Lance saw one of these -- refrozen leads -- develop asymmetric thickness on the downwind side. A second lead had sheets of young grey-white ice with some rafting and a thin layer of snow and frost flowers with thin ice having elevated roughness corresponding to deformation and edge effect transitioning between thin and thick ice.

They also encountered a snow-free lead with barely solid first-year ice adjacent to nilas/young grey ice, followed by wind-blown nilas and young grey-white ice with frost flowers. Here the GoPro camera on the helicopter and snow pit studies were essential as radar struggles with such subtleties (4th image).

Some scenes have large-scale ridge structures. Variations in ice thickness of up to 5.5 m documented by the helicopter unfortunately had no counterpart in radar backscatter despite non-vertical incidence.

Ridges increase surface roughness and indeed the camera saw evidence of old, consolidated ridges now completely snow-covered. These have a star-shaped signature that forms from snow drifts but those are more easily detected by eye.

The snow had undergone thaw and refreezing by mid-April, presumably from a rain-on-snow event giving an ice layer at the surface, later buried by more recent snowfall. This created a uniform ice layer within the snowpack but above the main ice which then fools the radar return; this ice crust was confirmed within the snowpack in snow-pit studies. If the non-coastal piomas thickness blob is artifactual, this is a conceivable explanation.

In short, the authors see a limited potential for future automatic classification of SAR images to distinguish different ice classes because the ice is complicated enough already and processes that fool the radar could be more common as multi-year ice diminishes (or vanishes) as the Arctic amplification of warming precedes.

All the current segmentation schemes like extent, area, age, and volume will need to be seriously tweaked to keep up with once-rare ice formations and interactive atmospheric processes becoming dominant. It may not be feasible however to maintain time series if new bin classes become necessary.
« Last Edit: June 12, 2017, 08:11:28 PM by A-Team »

bbr2314

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Re: The 2017 melting season
« Reply #1957 on: June 12, 2017, 08:16:10 PM »
12z GFS shows 100F+ readings widespread across Siberia D7-D10...


Comradez

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Re: The 2017 melting season
« Reply #1958 on: June 12, 2017, 08:53:34 PM »
Those Day 7-10 forecasts never seem to pan out.  It seems like the models have been modelling the land snowpack as being much thinner than it actually is.  They have had the snowpack disappearing from Chukchotka since mid-May, to be followed by warm temps a few days later in the Day 7-10 timeframe once the sun starts hitting that bare land...and yet a lot of that snow is still there. 

I find this year's land snowmelt quite baffling, really.  I wonder how one could disentangle the relative strengths of increased initial snow depth vs. decreased heat transfer to snow as causal factors.  Unfortunately, I don't think surface temperatures help us here, at least not straightforwardly, because those temps will tend to be influenced by the initial existing snowpack as much as the lack of heat being absorbed by/transported to the snowpack region. 

Also, it would be great to have a map of lost or gained albedo potential that encompasses both water and land areas in the arctic.  As far as I'm aware, such a product does not exist yet....

Lord M Vader

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Re: The 2017 melting season
« Reply #1959 on: June 12, 2017, 09:13:41 PM »
At Ostrov Golomjannyj (whereever that island is located, or at least east of Ostrov Vize) the snow cover have INCREASED with 4 cm the last two days to an impressive 64 cm.

And yes, the runs are worse at 7-10 days. But, a subjective opinion is that each run from ECMWF is getting worse.. More dipolish set up and high pressure over Beaufort...

TerryM

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Re: The 2017 melting season
« Reply #1960 on: June 12, 2017, 10:02:44 PM »
Warmer in Siberia than in Death Valley just doesn't sound reasonable.

IMeretricious

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Re: The 2017 melting season
« Reply #1961 on: June 12, 2017, 10:18:40 PM »
Warmer in Siberia than in Death Valley just doesn't sound reasonable.

Keep in mind that Death Valley can still get cold at night, and this forecast is for mid-afternoon in Siberia and close to midnight in Death Valley.

edit: I was curious, so I checked the forecast for Furnace Creek (Death Valley). Woah:
« Last Edit: June 12, 2017, 10:30:14 PM by IMeretricious »

gerontocrat

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Re: The 2017 melting season
« Reply #1962 on: June 12, 2017, 10:20:11 PM »
In a time of unprecedented rapid climate change,  is it not a natural consequence that longer-term forecasts become less reliable ?  Hence I am ignoring anything beyond 5 days when looking at the current melting season

Neven

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Re: The 2017 melting season
« Reply #1963 on: June 12, 2017, 10:24:41 PM »
Neven isn't it soon time for you to do an article on Melting Momentum? Just from looking at the MODIS images it seems that we really don't have that much this year.

I've been in contact with David Schröder and he has confirmed (or rather his model) that this year (again) there is lesser melt pond formation than in years with record low minimums. Below is a comparison of 2012, 2013, 2016 and this year:



As you can see, there are even less melt ponds than last year. In fact, it looks very similar to 2013. David Schröder wrote to me in an e-mail:

We predict the September Arctic sea ice extent 2017 to be slightly larger than last year: 5.0 +/- 0.5 mill. km2. In spite of the lowest Arctic ice volume in April, the May melt pond fraction in May is the second lowest of the last 10 years in our simulation with the sea ice model CICE. Anomaly figures with respect to 2006 to 2015 are shown for May 2017, 2016, 2012 (highest pond fraction) and 2013 (lowest pond fraction). Stronger melting and pond formation only occurred north of Canada and some parts of the Beaufort Sea. Otherwise the pond fraction is very similar to May 2013. Below average air temperatures (with respect to 2008 to 2015) and increased snow depth seem to have had a stronger impact in reducing pond formation than the thinner ice in increasing pond formation.

Persisting snow on the ice is the best explanation for the fact that we haven't seen much melt ponding (ice turning blue on satellite images), despite ideal weather conditions during the past two weeks. Of course, as we have seen last year, preconditioning isn't absolutely decisive when it comes to the final outcome of the melting season, but this data seems to put a damper on prospects of breaking the 2012 minimum records. For now.

Addendum: What's nice about this, is that it confirms our suspicions back in February when we discussed what could be the reason there was such a divergence between PIOMAS and CryoSat. The number one suspect was snow cover, due to the relentless series of storms coming in from the Atlantic.

As I wrote at the time:

This is pretty big, IMO, as it tells us something about snow depth on the sea ice which may have consequences for the state in which the ice pack enters the melting season.

Maybe we're getting the answer. The last time there was such a divergence between PIOMAS and CryoSat was during the 2012/2013 winter. Remember, 2013 was cold and cyclonic, causing an unexpected rebound after 2012's spectacle. I don't think this year will be the same, if only for the fact that volume is at a record low because of a record mild winter, but 2017 could be 2016's rebound.

I think I'll be looking a lot at SSTs in weeks to come. And the weather, of course.
« Last Edit: June 12, 2017, 10:42:10 PM by Neven »
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Csnavywx

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Re: The 2017 melting season
« Reply #1964 on: June 12, 2017, 10:25:09 PM »
Looking at Worldview vs the last 5 years reveals less ponding than even 2013 at this point, but a lot more open water in the ESS/Chukchi and Beaufort (except last year -- which was similar in the Beaufort).

FishOutofWater

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Re: The 2017 melting season
« Reply #1965 on: June 12, 2017, 11:00:10 PM »
I think we can disregard the lack of melt ponds in the Chukchi sea. It's open water now, more open water than ever for this date. All that snow in Siberia has bought us some time this year but on the other hand, heavily snow covered ice doesn't thicken as  much in the winter. We're dealing with thinner ice with fewer melt ponds.

The albedo effect is important so the discussion of an "ice free" Arctic is not about this year, but I wouldn't rule out a record low yet because the ice is so thin. The July cliff in Slater's model may be real.

There is now less snow than normal on the American side of the arctic and the ice from Greenland to the CAA to the shores of Alaska is thin and shattered. It's in the worst shape I've ever seen it for this time of year. So thank your lucky stars for the snow in Siberia.

The Arctic weather has not been cold and stormy like June 2013 but it has been cold on the Siberian side of the Arctic ocean. It was warmer in the CAA and the Beaufort sea this May and June than in 2013.

seaicesailor

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Re: The 2017 melting season
« Reply #1966 on: June 12, 2017, 11:22:08 PM »
Nice post Neven (now that I can't tell you in the blog :-) and FOOW, your arguments are really strong and well explained.
Just I am curious how fast the open water is developing, with the persistent circulation toward the Atlantic since March or April! There seems to be a lot of compaction too ---which can help our thin ice to pack together on the short run, but that can be disastrous come August ---.  Also, let's not say there is no June momentum; ice is darkening subtly as we speak Arctic wide; let us say it lacks a lot of punch, the air being pulled from Asia... we'll see what happens in the second mid and in July.
Fascinating how season after season things do not repeat at all.

Neven

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Re: The 2017 melting season
« Reply #1967 on: June 12, 2017, 11:27:34 PM »
Nice post Neven (now that I can't tell you in the blog :-)

You can tell me on the blog too, because I decided to turn that comment into a blog post;)

As I write at the end of the blog post, this is too important not to mention.

But I agree with George/FOOW that this doesn't mean we can rule out a new record. 2016 also ended lower than I had expected after a significant lack of preconditioning.
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Csnavywx

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Re: The 2017 melting season
« Reply #1968 on: June 12, 2017, 11:39:08 PM »
I think we can disregard the lack of melt ponds in the Chukchi sea. It's open water now, more open water than ever for this date. All that snow in Siberia has bought us some time this year but on the other hand, heavily snow covered ice doesn't thicken as  much in the winter. We're dealing with thinner ice with fewer melt ponds.

The albedo effect is important so the discussion of an "ice free" Arctic is not about this year, but I wouldn't rule out a record low yet because the ice is so thin. The July cliff in Slater's model may be real.

There is now less snow than normal on the American side of the arctic and the ice from Greenland to the CAA to the shores of Alaska is thin and shattered. It's in the worst shape I've ever seen it for this time of year. So thank your lucky stars for the snow in Siberia.

The Arctic weather has not been cold and stormy like June 2013 but it has been cold on the Siberian side of the Arctic ocean. It was warmer in the CAA and the Beaufort sea this May and June than in 2013.

I'm curious to see how warm SSTs get in the Chukchi this year. The warmth there last year was one of the factors in its very late refreeze (and subsequent early opening this year). That'll be a clue as to how warm it can get when the peripheral seas begin to act the same -- and how much heat release there will be in the fall.

Neven

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Re: The 2017 melting season
« Reply #1969 on: June 12, 2017, 11:58:47 PM »
Compactness has been going up too lately, which is another sign of a lack of melt ponding for the time of year:
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Phil.

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Re: The 2017 melting season
« Reply #1970 on: June 13, 2017, 01:26:09 AM »


As you can see, there are even less melt ponds than last year. In fact, it looks very similar to 2013. David Schröder wrote to me in an e-mail:


Looking at the Archipelago on MODIS today it looks very blue, is that not melt ponds?

https://lance3.modaps.eosdis.nasa.gov/cgi-bin/imagery/single.cgi?image=crefl1_143.A2017163181500-2017163182000.2km.jpg

StopTheApocalypse

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Re: The 2017 melting season
« Reply #1971 on: June 13, 2017, 01:58:56 AM »


As you can see, there are even less melt ponds than last year. In fact, it looks very similar to 2013. David Schröder wrote to me in an e-mail:


Looking at the Archipelago on MODIS today it looks very blue, is that not melt ponds?

https://lance3.modaps.eosdis.nasa.gov/cgi-bin/imagery/single.cgi?image=crefl1_143.A2017163181500-2017163182000.2km.jpg

Neven's post was based on May's data, so any melt ponding in June wouldn't be taken into account yet. Weirdly though, predictions don't become much more accurate when taking into account melt ponding in June vs only May, if I remember right.

magnamentis

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Re: The 2017 melting season
« Reply #1972 on: June 13, 2017, 02:04:57 AM »
Warmer in Siberia than in Death Valley just doesn't sound reasonable.

not sure hence just mentioning, sibiria is very very hot in summer, 40+ C is the norm and very very cold in winter -40C is the norm. to think sibiria to be a synonym for being cold is a widely spread error while i somehow think you know that and meant something else, as i said, just to be sure that this is not an issue, sorry to bother in case it was clear.

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Re: The 2017 melting season
« Reply #1973 on: June 13, 2017, 02:06:55 AM »
Neven isn't it soon time for you to do an article on Melting Momentum? Just from looking at the MODIS images it seems that we really don't have that much this year.
I've been in contact with David Schröder and he has confirmed (or rather his model) that this year (again) there is lesser melt pond formation than in years with record low minimums.

<snippage>

I think I'll be looking a lot at SSTs in weeks to come. And the weather, of course.
I'm comparing those coastal anomalies with what we've got in Worldview.  It looks very much like a significant percentage - I estimate over 50% - of the really dark anomalies are actually a result of ice being replaced with open water.  Consider the Kara for example, snap shot of today's ice state shown below.

A further difference to consider *again* is what passes currently for extent.  While large areas of the interior CAB are showing slight downward anomalies for melt pond fraction, we similarly do not have the wide areas of undisturbed extent that existed in 2012 and earlier.  I think we need a better picture of albedo over all, rather than just melt ponds, as there is an awful lot of extent that consists of pans and slash that barely has the structural integrity to walk on, much less hold melt ponds.
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Tigertown

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Re: The 2017 melting season
« Reply #1974 on: June 13, 2017, 02:40:46 AM »
I wonder how much of the sea ice anywhere in the Arctic has enough freeboard to allow for melt-ponding. Obviously, everything is whiter this year, but it may just be because there is not much more than snow above the water. If someone has some pics from here and there, they can easily shoot down that supposition.

P.S. A little tangent to this discussion; check this out.
www.bbc.com/news/av/world-europe-38562814/parts-of-greece-have-been-blanketed-in-snow

« Last Edit: June 13, 2017, 02:56:38 AM by Tigertown »

jdallen

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Re: The 2017 melting season
« Reply #1975 on: June 13, 2017, 04:25:04 AM »
I wonder how much of the sea ice anywhere in the Arctic has enough freeboard to allow for melt-ponding. Obviously, everything is whiter this year, but it may just be because there is not much more than snow above the water. If someone has some pics from here and there, they can easily shoot down that supposition.

P.S. A little tangent to this discussion; check this out.
www.bbc.com/news/av/world-europe-38562814/parts-of-greece-have-been-blanketed-in-snow



Could be paradoxically, lower freeboard, more snow and smaller blocks of ice might ablate the warmer winter. Damn the complexity...
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Re: The 2017 melting season
« Reply #1976 on: June 13, 2017, 04:28:18 AM »
I wonder how much of the sea ice anywhere in the Arctic has enough freeboard to allow for melt-ponding. Obviously, everything is whiter this year, but it may just be because there is not much more than snow above the water. If someone has some pics from here and there, they can easily shoot down that supposition.

P.S. A little tangent to this discussion; check this out.
www.bbc.com/news/av/world-europe-38562814/parts-of-greece-have-been-blanketed-in-snow




Photos a few days ago of ice in Fram Strait pushed below the waterline by thick snow don't fill me with confidence. Melt ponds aren't so important if the sea can wash over, especially with fragmentation and dispersal. And all that snow would have retarded thickening when the weather got cold at the end of winter.

SSTs will drive momentum. Anomalous warmth is appearing almost everywhere with the exception of southern Baffin Bay and the cold pool south of it in the Atlantic which . There are some pretty outrageous temperature gradients to fire up the cyclone cannon later on -
« Last Edit: June 13, 2017, 04:49:08 AM by subgeometer »

Tigertown

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Re: The 2017 melting season
« Reply #1977 on: June 13, 2017, 05:36:04 AM »
You might want to zoom in on this. June 11th vs 12th. Other than a little reverse flow in the Baffin, everything seems to really open up over a days time. This could just be the beginning of this seasons momentum. BTW, sometimes, quite ironically, momentum is called "the snowball effect."
CLICK IMAGE and zoom
Look at the hole that opens up on the 50o N Longitude line (Bottom still-frame)
« Last Edit: June 13, 2017, 05:46:15 AM by Tigertown »

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Re: The 2017 melting season
« Reply #1978 on: June 13, 2017, 06:37:12 AM »
Tigertown, the Worldview image doesn't confirm a hole there, looking around (165W, 77N) - maybe a bit of grey showing surface melting.

Nullschool confirms that was a hotspot yesterday, at above +1 degree Celsius, near the centre of a high pressure system.

So the hole in that U. Bremen reconstruction of AMSR2 might well be modified for their 13 June map. It's still above freezing around there so the melt pond hole might possibly even get bigger and/or track the centre of the high pressure system heading northwards.
« Last Edit: June 13, 2017, 06:47:02 AM by slow wing »

Juan C. García

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Re: The 2017 melting season
« Reply #1979 on: June 13, 2017, 06:48:23 AM »
Well, I can't wait to see what will happen in these two places. I also have a doubt that the hole will stay, but it looks real on Bremen June 11th and 12th. 
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.

Juan C. García

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Re: The 2017 melting season
« Reply #1980 on: June 13, 2017, 06:55:35 AM »
A century drop on IJIS  :o

A drop of -119,941.00 km2
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.

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Re: The 2017 melting season
« Reply #1981 on: June 13, 2017, 07:21:23 AM »
This seems simple enough to me; more late spring snow + less melt ponding = retarded ice melt. Past observations supports this pretty clearly. Of course, the situation can change rapidly and a different preconditioning with record low spring volume may impact the outcome, but beware of attempts (conscious or unconscious) to over-complicate or downplay the impact of more snow and higher albedo to support a narrative of imminent collapse. It is far from guaranteed that there will be new record lows this year, if the volume trajectory follows that of 2014 the September volume will be 5th lowest between 2013 and 2010, and there are early signs of a 2014 syndrome developing - lots of snow and a awkwardly situated HP which (presumably) removes insulation without really contributing any heat influx. I think this season will be very instructive in determining the impact of weather vs climate on annual sea ice loss, since short term variables seems to be favoring less melt, whereas long term variables seems to be favoring rapid melt.

In that regard I would also ask people to please stop posting 5-10 day weather forecasts, especially the GFS non-ensemble forecasts which has repeatedly proven to have ZERO value beyond 5-7 days. This is just speculative nonsense, or even worse cherry picking of model runs which support a desired outcome/narrative.

epiphyte

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Re: The 2017 melting season
« Reply #1982 on: June 13, 2017, 08:17:04 AM »
I don't think the melt pond info is necessarily prognostic, especially where there is new snow over new ice, as is the case over most of the area currently exhibiting anomalously low melt-pond fraction.

Earlier today I posted on one of the extent prediction threads about this year's ice in Laptev, ESS, and the CAB north of both. Much of it is started off as open water off the coast in March this year or later, and was snowed on when it was only a few CM thick. It has not been subjected to the normal ridge-promoting onshore-offshore oscillation, but rather has been marching north, under an insulating blanket of snow, in mostly barely-freezing weather, to fill the void left by the MYI exiting the Fram, for the past three months.

Today was literally the first day this year that any of this ice has seen above freezing temps, and it already appears to be wilting fast. Tomorrow and the next day, it's going to get rained upon. I honestly will be quite surprised if any of that anomalously-low melt pond ice is still there at the end of July.

Lord M Vader

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Re: The 2017 melting season
« Reply #1983 on: June 13, 2017, 08:58:38 AM »
Wrt the melt pond discussion and all that snow onto the ice there is one thing that seems to have been forotten.

1) with a thick snow cover onto the ice, there is a decent weight onyto the ice. Water from beneath is coming up to the layer closest to the ice. This is something you don't see on the satellite images.

2) All that thick snow is a double egged sword. or the next couple of days, a series of cyclones are making its entrance to the Siberian side. And guess what they are bringing to the ice? RAIN! If you want to melt the snow it's just as efficient with rain and wind as with a 24/7 sun shining.

3) If you add a dipole to that you should get severe problems later in the melting season!

---> My analysis is that the weather during the rest of June and especially during July will be extremely important to the final outcome this melting season.

Finally, it's not important if we are going down to 3,2 Mn km2 or 4,0 Mn km2 this year. More important is the area that is opening up earlier and earlier for every year allowing tremendeous amounts of heat to be stored in the ocean. The area that is melting away during the last few weeks is quickly refreezing as well as the sun by then is so weak that no significant amounts of heat will go down into the ocean.

EDIT: D10 at ECMWF 00z run is making a 976 hpa big cyclone. Shouldn't pan out but you never know... The ingredients are there for a decent cyclone.

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Re: The 2017 melting season
« Reply #1984 on: June 13, 2017, 12:03:15 PM »
Looking at the Archipelago on MODIS today it looks very blue, is that not melt ponds?


There have been melt ponds in the southern CAA for quite a while now:

http://GreatWhiteCon.info/2017/06/facts-about-the-arctic-in-june-2017/

Elsewhere it's a different story however. The first signs of surface melt on the fast ice in the Laptev Sea are only just starting to appear:
Reality is merely an illusion, albeit a very persistent one - Albert Einstein

slow wing

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Re: The 2017 melting season
« Reply #1985 on: June 13, 2017, 01:51:51 PM »
More widespread melt ponds might be expected to appear once much of the Arctic Basin has surface air temperatures rising above freezing.

Nullschool shows this happening around 5 days out - admittedly at the limit of any sort of predictive power for GFS forecasting.

The forecast for 0600 UTC on 18 June shows a fair amount of wind over the Arctic Basin and with nearly all of it above freezing.

Quantum

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Re: The 2017 melting season
« Reply #1986 on: June 13, 2017, 04:51:35 PM »
Good view yesterday of Alaska looking into the beaufort. Still some snow cover on the extreme northern coast. Assuming it melts out this week that will still be a good week or two later than many recent years. Lakes and ponds on the land are likely to stay frozen for several days yet which can only be a good thing as it modifies air masses moving over them.


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Re: The 2017 melting season
« Reply #1987 on: June 13, 2017, 04:54:56 PM »
Hullo Rubikscube.
You are not happy about longer-term weather forecasts. Pity the UK public. The  Murdoch And other yellow press tabloids are predicting 3 months of scorching weather. Source ? A plonker called James Madden  who runs a man-and-dog outfit called Exacta Weather. Why do the yellow press throw money at him ? Because he is a denier claiming the little ice age is upon us - Maunder minimum, solar activity etc.

Off-topic ? Yes. but one must expect a load of denier crap if there is no record low this year. Last gasp of Murcoch and his best mates the Kochs ?

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Re: The 2017 melting season
« Reply #1988 on: June 13, 2017, 04:57:36 PM »
I don't think the melt pond info is necessarily prognostic, especially where there is new snow over new ice, as is the case over most of the area currently exhibiting anomalously low melt-pond fraction.

Earlier today I posted on one of the extent prediction threads about this year's ice in Laptev, ESS, and the CAB north of both. Much of it is started off as open water off the coast in March this year or later, and was snowed on when it was only a few CM thick. It has not been subjected to the normal ridge-promoting onshore-offshore oscillation, but rather has been marching north, under an insulating blanket of snow, in mostly barely-freezing weather, to fill the void left by the MYI exiting the Fram, for the past three months.

Today was literally the first day this year that any of this ice has seen above freezing temps, and it already appears to be wilting fast. Tomorrow and the next day, it's going to get rained upon. I honestly will be quite surprised if any of that anomalously-low melt pond ice is still there at the end of July.

thanks a lot for blowing that horn, the days of melt-ponding being a main indicator are coming to an end IMO because the melt-water will drain through fissures and leads in significant amount.

for extensive melt-ponding like in the old, pre 2015 days, we would need a stable and homogeneous ice cover consisting of floes of a certain size. many expamples show (barneo for example) that it's not easy to find such places nowadays, not even above 80N, not even taling the typical early melt-pond birth places in lower latitudes. fragmentation, mobility and wave action are taking their toll in that aspect and there is more to come, crash ice would be a term that is crossing my mind more and more often when looking at images.
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JimboOmega

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Re: The 2017 melting season
« Reply #1989 on: June 13, 2017, 05:55:07 PM »
Well, I can't wait to see what will happen in these two places. I also have a doubt that the hole will stay, but it looks real on Bremen June 11th and 12th.

The one the "right" of your image is real as per worldview - the ice there is broken into lots of bits and is melting and dispersing and so on.

The one on the left is another glitch, since I don't see any evidence of it on worldview and there's no reason for it to be there.

I do wonder what leads to these deep in the pack "hot spots", especially since the last one - the North Pole one - lasted a couple days too. But absent any other evidence for it existing I have to think it's a Uni Bremen error.  I'd imagine certain atmospheric conditions could cause deep cracks to form into the ice, splitting the pack up, but... not just a big hole in one spot like that.  Perhaps it has to do with satellite tracks and getting marginal sampling of an area.

In other news, here in California, the Tahoe ski resorts picked up more snow over the weekend. This is rare, happening only every 5-10 years. 

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Re: The 2017 melting season
« Reply #1990 on: June 13, 2017, 06:06:08 PM »
I don't think the melt pond info is necessarily prognostic, especially where there is new snow over new ice, as is the case over most of the area currently exhibiting anomalously low melt-pond fraction.

Earlier today I posted on one of the extent prediction threads about this year's ice in Laptev, ESS, and the CAB north of both. Much of it is started off as open water off the coast in March this year or later, and was snowed on when it was only a few CM thick. It has not been subjected to the normal ridge-promoting onshore-offshore oscillation, but rather has been marching north, under an insulating blanket of snow, in mostly barely-freezing weather, to fill the void left by the MYI exiting the Fram, for the past three months.

Today was literally the first day this year that any of this ice has seen above freezing temps, and it already appears to be wilting fast. Tomorrow and the next day, it's going to get rained upon. I honestly will be quite surprised if any of that anomalously-low melt pond ice is still there at the end of July.

thanks a lot for blowing that horn, the days of melt-ponding being a main indicator are coming to an end IMO because the melt-water will drain through fissures and leads in significant amount.


I don't think this is at all certain for 2 reasons.

1) Meltwater doesn't drain through fissures or pores in the ice, as a recent study has shown, because the seawater and the ice will be a lower temperature (~1.8C) so any meltwater flowing down freezes quickly and forms a seal to prevent any more draining through the ice.

2) for meltponds to drain off the sides of the floes in a quantity significant enough to make a difference, I would think that the size of the melt ponds would have to be relatively close to the size of the floes. Yes, the ice is all broken up and looks a mess right now, but the broken pieces we're looking at are still sizeable, often 100km across. Meltponds seem to be in the order of magnitude of meters, not kilometers, so yes, while there are more edges to drain ponds, it's an order of magnitude problem, so there aren't enough edges to drain enough meltponds to say that meltponds don't count anymore.

My thought experiment would be to take a smallish floe that's 10km x 10km square, so 100 sq km. A ~25% meltponded piece of ice would have say 1 melt pond for every 100 sq m (10m x 10m)(assuming the photos we see of ice and meltponds are representative), and if evenly distributed, the floe would have ~1,000,000 meltponds. To count the ones draining at the edges would be 10,000 m / 10m = 1000 on each edge, so 4000 in total.

Which means the broken up ice cap in this case would have allowed 0.4% of the meltponds to drain. I'd think that the floes would have to get under 1 sq. km for this to have an effect, and on a satellite image that would probably look like slush, I'd guess.

WHile I'm guessing the increasing open water and increasing leads within the pack will cause the  upcoming bottom melt will have a big affect on how much of the ice survives this year, I think that the lateness of the meltponding isn't insignificant and may well help a lot of it survive by keeping the albedo higher for longer, thus decreasing the solar energy absorbed.

We still have to see what the weather holds though, as the melt ponds could still increase a lot within the next few weeks, with still a lot of insolation available in July.




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Re: The 2017 melting season
« Reply #1991 on: June 13, 2017, 06:16:40 PM »
1) Meltwater doesn't drain through fissures or pores in the ice, as a recent study has shown, because the seawater and the ice will be a lower temperature (~1.8C) so any meltwater flowing down freezes quickly and forms a seal to prevent any more draining through the ice.

 How many times did it form a seal as opposed to not forming one in the experiment, or did it simply do it one time in one experiment under one set of circumstances?
I am not buying that.

RoxTheGeologist

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Re: The 2017 melting season
« Reply #1992 on: June 13, 2017, 06:39:26 PM »

I believe in the experiment the fissures sealed after the third melt, the first two times the melt water drained away, more slowly the second time.


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Re: The 2017 melting season
« Reply #1993 on: June 13, 2017, 06:54:33 PM »

I believe in the experiment the fissures sealed after the third melt, the first two times the melt water drained away, more slowly the second time.

Thanks. That makes sense and is believable. However, if whatever caused the cracks and fissures  from the beginning causes new ones, then the process resets. If it had been waves vs thin ice, the waves will probably win in long run, as they seem to be reaching deeper into the Arctic now.

jplotinus

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Re: The 2017 melting season
« Reply #1994 on: June 13, 2017, 07:07:23 PM »
Good view yesterday of Alaska looking into the beaufort. Still some snow cover on the extreme northern coast. Assuming it melts out this week that will still be a good week or two later than many recent years. Lakes and ponds on the land are likely to stay frozen for several days yet which can only be a good thing as it modifies air masses moving over them.

That large crack in the fast ice is located close to Utqiagvik and might become visible in the webcam there as open water if  the crack widens or if additional fissures open up.

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Re: The 2017 melting season
« Reply #1995 on: June 13, 2017, 07:15:40 PM »
There's been another update of Mark Tschudi's Arctic sea ice age maps. Video's don't seem to be embeddable here any more, so here's a link:

https://youtu.be/6vBmBCBUuN8

plus a couple of stills:

Reality is merely an illusion, albeit a very persistent one - Albert Einstein

RoxTheGeologist

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Re: The 2017 melting season
« Reply #1996 on: June 13, 2017, 08:38:22 PM »
Tigertown, the Worldview image doesn't confirm a hole there, looking around (165W, 77N) - maybe a bit of grey showing surface melting.

Nullschool confirms that was a hotspot yesterday, at above +1 degree Celsius, near the centre of a high pressure system.


This whole region has darkened the last 2-3 days. With near zero air temperatures and a clear sky over the next 3 days of peak insolation this is an area to watch.

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Re: The 2017 melting season
« Reply #1998 on: June 13, 2017, 09:46:01 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.
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Lord M Vader

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Re: The 2017 melting season
« Reply #1999 on: June 13, 2017, 10:29:11 PM »
Moderate cyclone to impact the Siberian side in about 5 days. ECMWF ensemble has a 985 hpa cyclone at D4 and D5. Quite impressive! The main question is whether the precipitation will fall as snow or rain. That might have a detrimental effect on the rest of the melting season.