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Tor Bejnar

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Re: The 2016 melting season
« Reply #2850 on: July 04, 2016, 04:45:19 AM »
Two screen shots are attached.  Both include the area around 90W an 87N. 
First (small image) is from the current concentration map from the ASIG: http://www.iup.uni-bremen.de:8084/amsr2/Arctic_AMSR2_nic.png
Second is from a recent Polar View Sentinel image:  http://www.polarview.aq/images/105_S1jpgfull/S1A_EW_GRDM_1SSH_20160703T190457_16AF_N_1.final.jpg
The concentration map suggest low concentrations in the area, and the Sentinel image shows several significant open-water leads but generally intact ice structure.  I conclude there must be a lot of melt ponds in the area, and that this is not an area of melange (broken up ice floes as seen in other areas of the CAB).  Although melt ponds cause ice loss, high Arctic melt ponds often refreeze in the NH autumn (or drain during the 'summer') and don't lead to a great deal of open sea water/genuine ice area loss.  Of course, time will tell if 2016 is different.
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Tigertown

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Re: The 2016 melting season
« Reply #2851 on: July 04, 2016, 05:00:01 AM »
Using worldview and arctic.io, getting hard to find anywhere the ice is not breaking up in some stage.
Using polar view where clouds are currently blocking view, those areas not looking too great either.
Looks like we are reaching a turning point. Again, I am a little green here, but cannot find an record of anytime the Arctic was full of broken up floes with out one main pack. Not speculating yet as to how much will melt or saying it won't freeze back in the winter.I do however believe, at this point,this will be a year that it all breaks up entirely.

P.S. 92.5k drop in SIE today
« Last Edit: July 04, 2016, 05:30:37 AM by Tigertown »
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Michael Hauber

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Re: The 2016 melting season
« Reply #2852 on: July 04, 2016, 07:26:53 AM »
925hp  temps have finally crossed the 0 degree line, which is somewhat late this year compared to average.

Of course surface melting started well ahead of this mark as temps at ground level are going to be something like 5 C higher (except where constrained by melt), and some parts of the Arctic are going to be significantly warmer than the Arctic average.  Reaching this mark means that the majority of the arctic is significantly warmer than the minimum required for surface melt. 

There definitely seems to be a pattern change coming with more warmth and hints of a dipole.  MODIS images and 925hp temp history suggests a change to a strong high pressure and high temperatures several days ago in 2012.  It will be interesting to see how this year goes in comparison.  Ice thinner than 2012 at end of winter.  2012 had a strong start of surface melt early in June.  Both had low pressure causing cooling and dispersion late June, but this year this period has gone on longer, which looks to have caused more visual dispersion of floes, and presumably less surface melt.  It will be interesting to see whether less surface heating, but more dispersion is worse or better for the ice.  My current vote in the polls is somewhat better for the ice.
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bbr2314

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Re: The 2016 melting season
« Reply #2853 on: July 04, 2016, 07:30:05 AM »
The 00z Canadian takes the upcoming LP and runs with it. Not only does it bottom out in the 970s for over 48 hours (24-66), it remains sub-990 until hr192, after dipping back into the 970s around hr.162. If the EURO follows suit, what had previously looked merely bad may end up being much worse.




Tigertown

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Re: The 2016 melting season
« Reply #2854 on: July 04, 2016, 07:34:34 AM »
Worldview partially updated already for July 4th.
You know the drill; click to enlarge.
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Rob Dekker

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Re: The 2016 melting season
« Reply #2855 on: July 04, 2016, 09:12:25 AM »
No, it doesn't mean anything of the sort. You are in way over your head on infrared false color imagery. Go back and at least read the abstracts of the Perovich papers, #2784.  Go back and read up on what AndreasT has been posting on that forum topic.

When I read the Abstract from Preconditioning of the 2007 sea-ice melt in the eastern Beaufort Sea, Arctic Ocean then it confirms exactly Robs bottom melt thesis:

Quote
During summer 2007, perennial sea ice in the Beaufort Sea, Arctic Ocean, experienced an unprecedented amount of basal melt. It has previously been shown that this basal melt was linked to an increase in open-water fraction, increasing absorption of solar radiation into the ocean.

Also why are infrared images suddenly not suited for studying ocean heat? A few weeks ago we discussed the effect of river discharge into the Arctic and the scientific papers mentioned in this thread used the exact same images to show the heat input of the Mackenzie river. Why is it wrong when I use these images?

It isn't, Tealight. I don't understand what A-team meant, so I investigated a bit more :

You showed the WorldView band 31 brightness temperature image of the Beaufort :
https://worldview.earthdata.nasa.gov/?p=arctic&l=VIIRS_SNPP_CorrectedReflectance_TrueColor(hidden),MODIS_Aqua_CorrectedReflectance_TrueColor(hidden),MODIS_Terra_CorrectedReflectance_TrueColor,MODIS_Terra_Brightness_Temp_Band31_Day(palette=rainbow_1,min=270.4,max=285.6,squash),Reference_Labels(hidden),Reference_Features(hidden),Coastlines(hidden)&t=2016-07-01&v=-2595018.9332532175,-207628.2966213263,-1643722.9332532175,375539.7033786737

Now, "band 31" is 11 micro-meter IR.
That is almost IDEAL for measuring temperature around 0 C :



So yes, band 31 shows temperature, and yes, that WorldView channel shows very well that the Beaufort sea is relatively warm, and yes, the images show clearly how the water cools down when these floes drift through the open water in the Beaufort. And thus, yes, it does show there is bottom melt going on. Big time.

So, I'm not sure what A-team was talking about and why he took off against your statements.
« Last Edit: July 04, 2016, 09:37:30 AM by Rob Dekker »
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Rob Dekker

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Re: The 2016 melting season
« Reply #2856 on: July 04, 2016, 10:07:56 AM »
The reason why this (bottom-melt in the Beaufort) is so important is that it is a prime example of Arctic amplification caused by the albedo effect.

Even if we take the lower-bound of 200 W/m^2 net-radiation over open water from the CERES models that Andreas posted (disregarding ANY heat input from lower latitudes), the Beaufort right now (250,000 km^2 open water) is still absorbing some 50 TW, most of which will go to bottom-melt since the sea cannot warm up as long as there is ice floating around. 50 TW is enough heat to bottom-melt 13 Gton of ice each day. Thank you very much.
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jdallen

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Re: The 2016 melting season
« Reply #2857 on: July 04, 2016, 11:15:16 AM »
The reason why this (bottom-melt in the Beaufort) is so important is that it is a prime example of Arctic amplification caused by the albedo effect.
<snippage>
50 TW is enough heat to bottom-melt 13 Gton of ice each day. Thank you very much.
It is, and it would, but most of that uptake isn't in the top 2-5 meters of ocean, but rather much deeper.

A lot of that heat rather than act on the ice promptly, will be around to haunt us next winter.

So, while serious, there are a lot of other factors in play, and I would scale back my expectation of how much direct heat is being applied.
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jdallen

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Re: The 2016 melting season
« Reply #2858 on: July 04, 2016, 11:17:41 AM »
The 00z Canadian takes the upcoming LP and runs with it. Not only does it bottom out in the 970s for over 48 hours (24-66), it remains sub-990 until hr192, after dipping back into the 970s around hr.162. If the EURO follows suit, what had previously looked merely bad may end up being much worse.

That actually does look like a serious dipole, in exactly the wrong direction, in a time frame that suggests the forecast is pretty reliable.
« Last Edit: July 04, 2016, 11:23:46 AM by jdallen »
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jdallen

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Re: The 2016 melting season
« Reply #2859 on: July 04, 2016, 11:22:05 AM »
..........yikes

<snip>

Regarding HYCOM... when I first started following these forums a couple of years ago, I'd get very excited about what the Navy ice forecast implied.  I learned, after having my ears boxed more than once by various more experienced ice watchers, that HYCOM by itself can be a pretty unreliable predictor of conditions.

We will want to see how things play out.
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Laurent

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Re: The 2016 melting season
« Reply #2860 on: July 04, 2016, 11:39:22 AM »
Two screen shots are attached.  Both include the area around 90W an 87N. 
First (small image) is from the current concentration map from the ASIG: http://www.iup.uni-bremen.de:8084/amsr2/Arctic_AMSR2_nic.png
Second is from a recent Polar View Sentinel image:  http://www.polarview.aq/images/105_S1jpgfull/S1A_EW_GRDM_1SSH_20160703T190457_16AF_N_1.final.jpg
The concentration map suggest low concentrations in the area, and the Sentinel image shows several significant open-water leads but generally intact ice structure.  I conclude there must be a lot of melt ponds in the area, and that this is not an area of melange (broken up ice floes as seen in other areas of the CAB).  Although melt ponds cause ice loss, high Arctic melt ponds often refreeze in the NH autumn (or drain during the 'summer') and don't lead to a great deal of open sea water/genuine ice area loss.  Of course, time will tell if 2016 is different.
Yesterday there was more fragmented part than rubble area but seeing how fast things are going we will have to wait a few hours to know what is going on today.
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Laurent

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Re: The 2016 melting season
« Reply #2861 on: July 04, 2016, 11:59:37 AM »
Winds at sea level for the 4th the 5th and the 6th of July.

magnamentis

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Re: The 2016 melting season
« Reply #2862 on: July 04, 2016, 12:32:05 PM »
........most of us try to stick with the known science on melt ponds and the ice preserving effects of June storminess.
there are a few things to consider, sticking with previous data and melt patterns will lead to a huge error the year those pattern change, and old data become irrelevant.

ice preserving effects can change to ice destruction effects if the ice is thin and fractured as well as if the air sucked in from lower latitudes is a 20-30C instead of 10-20C like earlier.

those 2 difference ultimately will make the difference, not even saying it has to be this years but it's possible.
Quote
......we are watching the fine details but what's important is the changes that are taking place over years
..... Many of the details are apparently random.

IMO it's more reliable to see the bigger picture than to let one detail compete agains another, partly just as
a mention but sounding like "rebukes" or "opposition" depending on mood, personality and language skills.

80% of the time this year we have been close to or below previous lows, almost all records were broken and
it does not really matter whether the ultimate record will be broken as well ( not without special events this year)
i just remember that after each day of the curve flattening some record seekers started to (almost) complain
that the melting is not continuing at record levels, even when it was still lowest, just not lowest rate. at that time i mentioned the relation between current levels and the possible rate declining the lower we are/get. and some of us expected a cliff ahead which without knowing whether it continues, happens right now.

the more details we bring up, the bigger the chance to err in that point and the bigger the loss of the big overview which is the only thing that counts because it describes the direction we're heading at, independent on daily or weekly events and the day form like in sports. this is not a 1-2 hours, daily, weekly and not even a decadal or century game, the process as well as the consequences will last thousands and tens of thousand of years if not more.

magnamentis

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Re: The 2016 melting season
« Reply #2863 on: July 04, 2016, 12:39:07 PM »
..........yikes

one has to read through all your previous post on the matter to understand that comment, a assume you're referring to the "cleavage" LOL

slow wing

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Re: The 2016 melting season
« Reply #2864 on: July 04, 2016, 12:41:07 PM »
...
It is, and it would, but most of that uptake isn't in the top 2-5 meters of ocean, but rather much deeper.
...
Based on what?

Even in clear water at normal incidence most of the energy uptake of the solar spectrum is in the top 2-5 metres.

There is a strong dependence on wavelength.



In the figure, a value of 0.01 cm^-1 means it loses most of its energy within the first metre. (1 - 1/e for clear water at normal incidence, which is 63% from memory.) As shown, this corresponds to about the wavelength boundary between red light and infrared light.

Only for some of the yellow light and for green, blue, violet and UV light can most of the energy flux pass 5 metres, even for clear water at normal incidence. In sum, that still accounts for less than half of the energy in sunlight.

The large infrared component, normally comprising around half the energy at sea level, gets largely absorbed in the top centimetres.

So most of the energy uptake is surely in the top 2-5 metres in Arctic waters, which may also not always be clear and with most of the sunlight arriving at much shallower angles.
« Last Edit: July 04, 2016, 01:13:04 PM by slow wing »

JayW

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Re: The 2016 melting season
« Reply #2865 on: July 04, 2016, 01:07:21 PM »
Two screen shots are attached.  Both include the area around 90W an 87N. 

The concentration map suggest low concentrations in the area, and the Sentinel image shows several significant open-water leads but generally intact ice structure.  I conclude there must be a lot of melt ponds in the area, and that this is not an area of melange (broken up ice floes as seen in other areas of the CAB).  Although melt ponds cause ice loss, high Arctic melt ponds often refreeze in the NH autumn (or drain during the 'summer') and don't lead to a great deal of open sea water/genuine ice area loss.  Of course, time will tell if 2016 is different.

There is a storm in that area you are speaking about.  I'd bet that low concentration was from rain.  Just my opinion though.  :)

Incidentally, the Nares final breakup can also be seen I believe.
just clouds, sorry
Attached is the most recent AVHRR image
http://weather.gc.ca/satellite/satellite_anim_e.html?sat=hrpt&area=dfo&type=nir
« Last Edit: July 04, 2016, 03:53:16 PM by JayW »
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magnamentis

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Re: The 2016 melting season
« Reply #2866 on: July 04, 2016, 01:17:42 PM »

......  I'd bet that low concentration was from rain.  Just my opinion though.  :)

i think you'd loose that bet :-)  ;)

http://cci-reanalyzer.org/wxmaps/#ARC-LEA

JayW

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Re: The 2016 melting season
« Reply #2867 on: July 04, 2016, 01:26:22 PM »

......  I'd bet that low concentration was from rain.  Just my opinion though.  :)

i think you'd loose that bet :-) 

Lol, perhaps, what's your explanation for the concentration drop?

Edit:  Just posted by Wipneus.  ;)
http://forum.arctic-sea-ice.net/index.php/topic,382.msg82269.html#msg82269

Second edit:  I had to include this. The GFS is a terrible model, there, I said it.  It's an embarrassment to put it lightly.  The ECMWF, UKMET, AND CMC all outperform it. 

  Folks can investigate model skill here
http://www.emc.ncep.noaa.gov/gmb/STATS_vsdb/
« Last Edit: July 04, 2016, 01:40:09 PM by JayW »
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seaicesailor

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Re: The 2016 melting season
« Reply #2868 on: July 04, 2016, 01:50:08 PM »
...
It is, and it would, but most of that uptake isn't in the top 2-5 meters of ocean, but rather much deeper.
...
Based on what?

Even in clear water at normal incidence most of the energy uptake of the solar spectrum is in the top 2-5 metres.

There is a strong dependence on wavelength.

In the figure, a value of 0.01 cm^-1 means it loses most of its energy within the first metre. (1 - 1/e for clear water at normal incidence, which is 63% from memory.) As shown, this corresponds to about the wavelength boundary between red light and infrared light.

Only for some of the yellow light and for green, blue, violet and UV light can most of the energy flux pass 5 metres, even for clear water at normal incidence. In sum, that still accounts for less than half of the energy in sunlight.

The large infrared component, normally comprising around half the energy at sea level, gets largely absorbed in the top centimetres.

So most of the energy uptake is surely in the top 2-5 metres in Arctic waters, which may also not always be clear and with most of the sunlight arriving at much shallower angles.

I don't think it really matters right now in the Beaufort sea given the stirring it is being subject to. This plays both ways: if all the solar energy is absorbed in the first 5 meters, vertical mixing will tend to redistribute it for the whole mixed layer (first 30 meters) and make temperature uniform. The same applies if it is absorbed over a much deeper column.

I don't think much of the solar radiation reaches 30+ meters beneath the surface (to start with, divers need lights at this depth to see around; for non-visible frequencies your plot shows the reaching radiation intensity must be negligible as well).

I am trying to locate an itp bouy at Beaufort with recent data to see the temperature and salinity profile. For the time being I attach temperature measured by this buoy (below) that stopped sending data in August 2015. It shows indeed that the temperature increases, and becomes almost uniform in a couple of weeks, from surface to bottom of mixed layer, where salinity stable stratification kills vertical mixing.

Now the question is: how much of this heat is transferred to the bottom of the ice, given that there is an abrupt change of temperature from over freezing to -1.8 C ? In this case the ice is a perfect sink of heat at constant temperature. The calculation can be done... will try this evening. Neglect complications such as fresher water right below the ice...

And, how much of it goes under the 30 m deep halocline? I would say negligible given that the gradient of temperature is much smoother and the vertical mixing is inhibited none given that temperature in fact increases with depth below the halocline.

Finally, given the rate of heat transfer from water to ice, how much heat that was required to elevate the temperature of the mixed layer uniformly is transferred to the ice during the present melting season? Is this going to affect future freezing/melting seasons?

Note: Strange format given to these plots. Temperature is in C, depth is in meters, and the time scale origin is Jan 1 2014, so the end of the plot corresponds to August 2015
« Last Edit: July 04, 2016, 02:01:08 PM by seaicesailor »

Laurent

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Re: The 2016 melting season
« Reply #2869 on: July 04, 2016, 03:04:24 PM »
I don't know if weather forecast is much better but there is clearly a huge difference where cci-reanalyser shows very few rain this one is saying a lot will pour on this weak ice.
http://www.weather-forecast.com/maps/Arctic?symbols=none&type=prec

Tor Bejnar

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Re: The 2016 melting season
« Reply #2870 on: July 04, 2016, 04:00:23 PM »
Two screen shots are attached.  Both include the area around 90W an 87N. 

The concentration map suggest low concentrations in the area, and the Sentinel image shows several significant open-water leads but generally intact ice structure.  I conclude there must be a lot of melt ponds in the area, and that this is not an area of melange (broken up ice floes as seen in other areas of the CAB).  Although melt ponds cause ice loss, high Arctic melt ponds often refreeze in the NH autumn (or drain during the 'summer') and don't lead to a great deal of open sea water/genuine ice area loss.  Of course, time will tell if 2016 is different.
There is a storm in that area you are speaking about.  I'd bet that low concentration was from rain.  Just my opinion though.  :)
...
I almost included in my earlier post that clouds might affect the data that concentration algorithms use. (I vaguely recall discussions about clouds affecting data in various ways, but am basically conjecturing with this "might".)  Rain, of course, could create "melt ponds" or otherwise affect data.  (I'm not going to claim any particular cause of the apparent hole, though.)

My basic point was to show that "obvious" conclusions drawn from one type of map (or data set - in this case, "Oh, see the 40% low ice concentration!  The CAB is melting out!!! [Nobody actually said or implied this particular thing about this apparent high-Arctic hole, though.]) need to be tempered with (or supported by) information drawn from other types of maps (or data sets).  I suppose I could have written this paragraph last night!
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Re: The 2016 melting season
« Reply #2871 on: July 04, 2016, 07:30:01 PM »
The forecasts for today from 4-5 days ago seem to be verifying: strong low pressure drifting back toward Siberia and high pressure building in the Canadian Arctic and Greenland.

This week, the main op model runs indicate a continuation of that trend, with surface low spinning down near the Siberian coast and lots of sun and warmth on the American side.



seaicesailor

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Re: The 2016 melting season
« Reply #2872 on: July 04, 2016, 08:35:42 PM »
Well, that looks like the mother of all dipoles

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Re: The 2016 melting season
« Reply #2873 on: July 04, 2016, 09:41:35 PM »
Perhaps, but the mother's mother of all dipoles has at least 1035 hPa over the Beaufort.  ;)
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bbr2314

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Re: The 2016 melting season
« Reply #2874 on: July 04, 2016, 09:45:46 PM »
Perhaps, but the mother's mother of all dipoles has at least 1035 hPa over the Beaufort.  ;)
Only thing worse than HP and 850s of +8-12C for 10 days is relatively low pressure with the same readings.... tick tock for big block!

jdallen

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Re: The 2016 melting season
« Reply #2875 on: July 04, 2016, 09:53:04 PM »
...
It is, and it would, but most of that uptake isn't in the top 2-5 meters of ocean, but rather much deeper.
...
Based on what?

Even in clear water at normal incidence most of the energy uptake of the solar spectrum is in the top 2-5 metres.

There is a strong dependence on wavelength. <snippage>

Thank you, and happy to have my misperception corrected by science. :D
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jdallen

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Re: The 2016 melting season
« Reply #2876 on: July 04, 2016, 10:06:11 PM »
A follow on to that, looking at our "Big Block" in the Beaufort (BBB?).

It appears the closer formation of floes has dispersed somewhat, and pretty much all the thinner FYI and slush around them has melted out.

Looking to the right of the image further to the north of the Beaufort and the edge of the CAB, the process is repeating itself.  There is a large field of reasonably compact smaller floes, which appear to show considerable melt ponding.  It's similar to what we see frequently in the Bering and Chukchi earlier in the season prior to their disintegration in earnest.

The fact there are so many smaller floes here may be a factor - below 150M diameter, lateral melt starts to become a significant factor in how fast they disintegrate.  The high granularity suggest to me a modest proportion of the ice in the area I'm looking at may be approaching that.

Further thought regarding floe size and the storms; with the ice broken up and the high winds, it follows that we may be seeing much more wave action, fairly deep in the pack.  That could be one factor in producing the broken up bowl of ice cubes we're looking at.
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Michael Hauber

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Re: The 2016 melting season
« Reply #2877 on: July 04, 2016, 10:57:42 PM »
Perhaps, but the mother's mother of all dipoles has at least 1035 hPa over the Beaufort.  ;)

And lined up with high pressure in the east Pacific and low in the west to draw tropical Pacific air directly to the north pole.  I think I saw seeing this once.
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Gray-Wolf

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Re: The 2016 melting season
« Reply #2878 on: July 04, 2016, 11:57:06 PM »
Off topic , but then ,not.

This year , to me , and for the past number of years in fact, has been our last, best chance, to build ice capable of weathering the next 'perfect melt storm synoptic' (P.M.S.S.).

We were informed , back in 07' ,that such events occur every ten to twenty years with the two prior to 07' showing the ten year spacing.

Is the ice in better condition than 07'?

Will the past repeat and the ten year spacing between the two events, prior to 07', be observed?

How do folk think the recent pack volume/thickness would cope with the P.M.S.S. the next time around?
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Michael Hauber

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Re: The 2016 melting season
« Reply #2879 on: July 05, 2016, 12:19:41 AM »
I've always thought that another perfect melt storm synoptic would push us quite close to ice free.

But the other question is how close was 2012 to the PMSS?  Big heat in early June to start surface melting with a bang.  Decent sized low in late June to spread the ice, more big heat in July to pump lots of heat into the water between all the ice.  Massive storm in August to stir the weakened ice and heated water together.

Looking back at 2007 there were two spikes of cooler weather, and these do correspond to brief low pressure systems, but relatively weak.  What is the ideal mix of heating (high pressure) and dispersion (low pressure).  2007 was very much heating dominated.  2012 was heating dominant, but had significant dispersion.  2013 was dispersion dominated, and that turned out to be good for ice retention.
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seaicesailor

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Re: The 2016 melting season
« Reply #2880 on: July 05, 2016, 01:09:42 AM »

Let's give these physics (of heat preservation) a try :
We know that any open water around the summer solstice absorbs something like 280 W/m^2 for average weather. That sunlight gets absorbed by the ocean, with most of it absorbed in the 'mixing layer' which is the upper 20 meters of ocean. Simple calculation, using 4200 J/kg/C, shows that a water column of 20 meters will warm by some 0.3 C per day if heated with 280 W/m^2.

In other words, it will take about 10 days for open water to warm up 3 C.

The Beaufort has been open since April, which is at least 60 days now.
Since it has not warmed up more than 3 degrees C, we can safely conclude that that only 10/60 = 16 % of the absorbed insolation went to warming up the water.
The remainder (more than 80%) of absorbed heat thus went to (bottom) melting the ice that drifts around in the Beaufort.

Been doing my own reasoning; then after rereading this post I can't see major flaw in Rob estimates.
I assumed 30 m of mixed layer and the lower 200 W/m2. You get 1 degC per week of temperature increase. Given the agitation in Beaufort, laterally (and consequently vertically), it is reasonable that the open waters rised from -2 degC to above zero in two or three weeks, from surface to -30 m, no matter how deep whatever color is absorbed. If we assume that in the following weeks (since early June rather than May) these 200 W/m2 have been going to melting of a comparable extension of ice than that of open water, then the absurdly simplified formula gives 5 cm/day of bottom melt (150 cm per month).
I think this number is high but others may know better. What I can expect then is a more moderate 100 cm per month that gives 300 cm of bottom melt per season (but certainly not 50 cm per month!)

Is that reasonable?
« Last Edit: July 05, 2016, 01:25:35 AM by seaicesailor »

Paladiea

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Re: The 2016 melting season
« Reply #2881 on: July 05, 2016, 03:12:12 AM »
150cm/month seems reasonable to me...
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Tigertown

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Re: The 2016 melting season
« Reply #2882 on: July 05, 2016, 05:31:13 AM »
Better than a century drop today. Down to 8,598,133 km2 SIE per JAXA.
Hugging the line with 2012 now.(Actually 2016 is about 70k ahead of same date in 2012 on this chart)

« Last Edit: July 05, 2016, 05:36:19 AM by Tigertown »
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georged

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Re: The 2016 melting season
« Reply #2883 on: July 05, 2016, 06:32:19 AM »

Let's give these physics (of heat preservation) a try :
We know that any open water around the summer solstice absorbs something like 280 W/m^2 for average weather. That sunlight gets absorbed by the ocean, with most of it absorbed in the 'mixing layer' which is the upper 20 meters of ocean. Simple calculation, using 4200 J/kg/C, shows that a water column of 20 meters will warm by some 0.3 C per day if heated with 280 W/m^2.

In other words, it will take about 10 days for open water to warm up 3 C.

The Beaufort has been open since April, which is at least 60 days now.
Since it has not warmed up more than 3 degrees C, we can safely conclude that that only 10/60 = 16 % of the absorbed insolation went to warming up the water.
The remainder (more than 80%) of absorbed heat thus went to (bottom) melting the ice that drifts around in the Beaufort.

Been doing my own reasoning; then after rereading this post I can't see major flaw in Rob estimates.
I assumed 30 m of mixed layer and the lower 200 W/m2. You get 1 degC per week of temperature increase. Given the agitation in Beaufort, laterally (and consequently vertically), it is reasonable that the open waters rised from -2 degC to above zero in two or three weeks, from surface to -30 m, no matter how deep whatever color is absorbed. If we assume that in the following weeks (since early June rather than May) these 200 W/m2 have been going to melting of a comparable extension of ice than that of open water, then the absurdly simplified formula gives 5 cm/day of bottom melt (150 cm per month).
I think this number is high but others may know better. What I can expect then is a more moderate 100 cm per month that gives 300 cm of bottom melt per season (but certainly not 50 cm per month!)

Is that reasonable?

Question (to you or anyone else who cares to answer it): How much heat do rivers dump into the Arctic?

Water is of course a very effective heat sink, and rivers that flow through Arctic land areas are essentially taking heat from warmer land areas and putting that in the ocean. Land temperatures in Siberia and Canada are in the 20s and even 30s right now, and the Laptev and East Siberian shelves are comparatively shallow.

Apologies if this has been discussed elsewhere. I found a little on turbidity and effect on albedo, which is important, but this is a separate question.

Tigertown

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Re: The 2016 melting season
« Reply #2884 on: July 05, 2016, 06:46:27 AM »
Does anybody have any idea how to get a measure of all the river water reaching the Arctic? I read somewhere that a total of 72 rivers dump into it overall. Some of these are coming from areas of land that have lost the albedo of snow cover a little sooner this year. We have seen the effects near some of the main deltas. However, it would be interesting to get the bigger picture of this year compared to past years; or is a negligent amount?

I don't know about real-time data, but here's what I've written about it on the ASIB:

A warm river runs through it

Warm rivers and Arctic sea ice loss

I brought up similar thought and Neven provided a couple article links on his blog.
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seaicesailor

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Re: The 2016 melting season
« Reply #2885 on: July 05, 2016, 09:40:09 AM »
150cm/month seems reasonable to me...
And more re-reading, Rob's own estimate is 8 cm/day 240 per month. Which may be the case for the more isolated (though huge) floes as the Big Block.

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Re: The 2016 melting season
« Reply #2886 on: July 05, 2016, 10:46:20 AM »
I've always thought that another perfect melt storm synoptic would push us quite close to ice free.

But the other question is how close was 2012 to the PMSS?  Big heat in early June to start surface melting with a bang.  Decent sized low in late June to spread the ice, more big heat in July to pump lots of heat into the water between all the ice.  Massive storm in August to stir the weakened ice and heated water together.

Looking back at 2007 there were two spikes of cooler weather, and these do correspond to brief low pressure systems, but relatively weak.  What is the ideal mix of heating (high pressure) and dispersion (low pressure).  2007 was very much heating dominated.  2012 was heating dominant, but had significant dispersion.  2013 was dispersion dominated, and that turned out to be good for ice retention.

I've also been thinking a lot about how that first ice-free season would look like. 2007 wasn't just heating dominated, but also very compaction dominated. Such weather conditions will always lead to a thicker core, one would think, which means it would take a lot more heating and radiation to melt that out.

Like Michael says, and I've said before, it's a combo of heating and dispersal, alternating as it were at just the right times. I suppose 2012 gave us a glimpse of that, but the melting season would probably have to start out with lower volume for such a scenario to be possible. And it would have to mimic this year's transition phase and early start.

It's confusing because open skies (bad for ice) are associated with compaction (good for ice pack as a whole). If you'd have open skies and dispersal...  ;)
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Re: The 2016 melting season
« Reply #2887 on: July 05, 2016, 11:13:39 AM »
The forecast suggests that anomalous heat will persist over the CAA and spread to Beaufort and the thickest ice in the CAB north of the CAA:





Meanwhile, the weak-looking ice in Laptev and the ESS, which we would expect to melt out reasonably soon, will be somewhat protected. This could limit extent losses in the short term, but is probably not good for volume or the longer term situation.

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Re: The 2016 melting season
« Reply #2888 on: July 05, 2016, 12:29:36 PM »
Does anybody have any idea how to get a measure of all the river water reaching the Arctic? I read somewhere that a total of 72 rivers dump into it overall. Some of these are coming from areas of land that have lost the albedo of snow cover a little sooner this year. We have seen the effects near some of the main deltas. However, it would be interesting to get the bigger picture of this year compared to past years; or is a negligent amount?

I don't know about real-time data, but here's what I've written about it on the ASIB:

A warm river runs through it

Warm rivers and Arctic sea ice loss

I brought up similar thought and Neven provided a couple article links on his blog.

Those are genuinely interesting, thanks.

Michael Hauber

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Re: The 2016 melting season
« Reply #2889 on: July 05, 2016, 12:32:38 PM »
The thicker ice along the Russian coast after winter seems to be coming into play with the Laptev melt starting really slow this year.  Wipneus homebrew figures suggest slowest melting out of all years since 2012.  My eyeball on ADS images suggests that since 2007 only 2008 has started slower.

I also see that PIOMAS has updated and the ice seems to be thicker than 2012 pretty much everywhere except beaufort.
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Re: The 2016 melting season
« Reply #2890 on: July 05, 2016, 12:58:36 PM »

Like Michael says, and I've said before, it's a combo of heating and dispersal, alternating as it were at just the right times.

not that long back you made a post with that "morse" code or whatsoever, i think that was it and which exact combination it will be we can't predict while the warmer the yearly average temps get the less the exact pattern will matter. further i think that the less ice is there the more the air and water reaching the reminder will be able to attack that remaining ice. air melts the ice while the ice cools the air and the water, which is probably why we're not there yet. at the end it's not only about heat distribution but about surplus heat that taking into account a given remaining ice volume ( km3 ) can be calculated how many terawatts it will take to melt a given amount of ice.

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Re: The 2016 melting season
« Reply #2891 on: July 05, 2016, 01:16:07 PM »
Will the past repeat and the ten year spacing between the two events, prior to 07', be observed?

Hence why I keep talking about 2006 and it's similarities to this year.

10 year cycle is next year for P.M.S.S.

My personal belief is that 2011/12 was an outlier which was also driven by shortening cycles due to the state of the ice.

Interesting, really, that the P.M.S.S 10 year cycles tend to match a particular point in the 10/11 year solar cycle...

If you look at it that way, 2011/12 were on the up side of the cycle and 2006/7 were on the downside of a cycle almost twice the size...  Which would mean, to me, that the ice state is so bad, post 2007, that it no longer needs the heat of a whole solar cycle to create the P.M.S.S.

Just an observation of the logistics rather than a sound science based deduction.
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Re: The 2016 melting season
« Reply #2892 on: July 05, 2016, 04:23:05 PM »
'Just an observation of the logistics rather than a sound science based deduction'

there is no physical basis for a ten year cycle - there's a slightly better argument for a four or five year cycle based on lack of snow insulation after a big melt season (at least there's some peer reviewed evidence), but weather trumps almost everything, so you can't even really say 'we're due a big one', anymore than you can say that a coin toss is due to land on tails bcz it just landed on heads five times in a row. it's just naked numerology

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Re: The 2016 melting season
« Reply #2893 on: July 05, 2016, 05:52:58 PM »
150cm/month seems reasonable to me...
And more re-reading, Rob's own estimate is 8 cm/day 240 per month. Which may be the case for the more isolated (though huge) floes as the Big Block.
8CM/day is a *lot*, and pretty much demands water between 0-1C or better to achieve.  150CM is much more reasonable considering albedo, various sinks and the energy budget.  It's still 5CM a day, which is *still* a lot, and quite enough to eliminate easily half the remaining ice in the pack.

I doubt BB has been losing that much a day.  I think at those rates it would have lost its structural integrity a while ago.
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Re: The 2016 melting season
« Reply #2894 on: July 05, 2016, 06:44:56 PM »
The fresh PIOMAS numbers confirms again the extremely strong and perfectly logical correlation between arctic 925 pHa temps and actual ice melt, and once more go against the nonsense, wishfull saying that "extent doesn't matter", which seems to pop up whenever extent loss stalls.

Weather patterns are about to change though, Beaufort and CAA are currently under heavy attack from powerfull heat, which should spread across all western hemisphere arctic within 72 hours. This kind of -ve NAO assosiated dipole has arguably been the most melt favoutable setup of them all in the past, featuring strong heat influx and ice compaction. The resilience of "big block" and other MYI Beaufort floes will be tested for real.

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Re: The 2016 melting season
« Reply #2895 on: July 05, 2016, 06:48:28 PM »
'Just an observation of the logistics rather than a sound science based deduction'

there is no physical basis for a ten year cycle - there's a slightly better argument for a four or five year cycle

Actually the last time I mentioned this the concensus was that there was evidence of a 10 year cycle but absolutely NO evidence of a 5 year cycle...  ;D ;D

I'm sure once we've analysed the loss of the ice enough, we'll have all  the evevidence we could ever want about how the ice vanished.

But it will stlil be gone...
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seaicesailor

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Re: The 2016 melting season
« Reply #2896 on: July 05, 2016, 06:52:28 PM »
150cm/month seems reasonable to me...
And more re-reading, Rob's own estimate is 8 cm/day 240 per month. Which may be the case for the more isolated (though huge) floes as the Big Block.
8CM/day is a *lot*, and pretty much demands water between 0-1C or better to achieve.  150CM is much more reasonable considering albedo, various sinks and the energy budget.  It's still 5CM a day, which is *still* a lot, and quite enough to eliminate easily half the remaining ice in the pack.

I doubt BB has been losing that much a day.  I think at those rates it would have lost its structural integrity a while ago.
Check out PIOMAS thread. The rate estimated by PIOMAS in Beaufort is pretty much 5 cm/day for effective thickness (which means more than 5 cm/day for real average bottom melt given the sparsity of ice). Will be easier when looking at the monthly change per region.

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Re: The 2016 melting season
« Reply #2897 on: July 05, 2016, 07:09:10 PM »
The fresh PIOMAS numbers confirms again the extremely strong and perfectly logical correlation between arctic 925 pHa temps and actual ice melt, and once more go against the nonsense, wishfull saying that "extent doesn't matter", which seems to pop up whenever extent loss stalls.

Sorry for asking, but is this meant in jest/ i.e. as a satire, or seriously?

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Re: The 2016 melting season
« Reply #2898 on: July 05, 2016, 07:33:22 PM »





What are the odds this year of the Northern Sea Route vessels navigating directly via the Pole and thru the Fram Strait?

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Re: The 2016 melting season
« Reply #2899 on: July 05, 2016, 07:59:19 PM »
What are the odds this year of the Northern Sea Route vessels navigating directly via the Pole and thru the Fram Strait?
Vanishingly low.  I'd put it at under 1% unless it's an icebreaker.
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