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Siffy

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Re: The 2015 melting season
« Reply #950 on: May 24, 2015, 01:37:25 PM »
Probably best to compare like for like in terms of date.





Snow cover in the first image is being overestimated by a truly enormous amount.

BornFromTheVoid

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Re: The 2015 melting season
« Reply #951 on: May 24, 2015, 01:53:52 PM »
In case nobody noticed, it says this on the CT page, near the top with the rebuttal to James Taylors Forbes piece.

Note: snow cover data not updating ... we hope to have a new data source by July, 2015.

crandles

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Re: The 2015 melting season
« Reply #952 on: May 24, 2015, 01:55:00 PM »
snow cover looks identical for all dates from 4 Feb 2015 onwards.

I think we should conclude the snow cover is not processed yet.

beaten by better message.

JKDMaineUSA

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Re: The 2015 melting season
« Reply #953 on: May 24, 2015, 03:23:15 PM »
My favorite link for current conditions ..
http://cci-reanalyzer.org/DailySummary/index_ds.php

JKDMaineUSA

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Re: The 2015 melting season
« Reply #954 on: May 24, 2015, 03:29:08 PM »
And not that it has anything to do with the University of Maine either .. ;D

Jim Hunt

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Re: The 2015 melting season
« Reply #955 on: May 24, 2015, 04:01:52 PM »
Doesn't CCI use GFS rather than GEM?  ;)

Whilst we wait to discover what the weather actually does in the real world, here's a picture of some open water at approx 83N, 120W:

http://GreatWhiteCon.info/resources/arctic-sea-ice-images/winter-201415-images/#CAB
Reality is merely an illusion, albeit a very persistent one - Albert Einstein

werther

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Re: The 2015 melting season
« Reply #956 on: May 24, 2015, 10:41:59 PM »
Today, I checked the 23 May MODIS tiles against those I collected in CAD on 29 May last year. This year, weather imposed an impressive swath of meltponding over the American side of the Arctic. In fact, meltponding occurs over all of Chukchi Sea.



It extends more than 400 km N of Barrow (the red circle), into the adjacent parts of the CAB ( the blue lines indicate the limits of Beaufort and Chukchi Seas). To the West, the swath enters the East Siberian Sea N of Ostrov Wrangelj. To the East, it enters the CAA into Coronation Gulf, Prince of Wales Strait and even into McClure Strait. 
Although this meltponding event is, within the limits of my memory, unique for the time of the year, it doesn’t mean the course to a new minimum record is set. Compared to last year, there’s considerably less open water on the Siberian side. Last year, constant Southerly winds created a large polynia all along the Siberian fast ice, which laid the basis for the “Laptev Bite” later that year. This time, cool anomalies prevented the Sib side for an early melt start.



Exception is the Kara Sea, where ice extent rapidly declines and floes are dispersed. In fact, most of the ice in the Southern Kara will soon be isolated from the main pack. Near Baydaratskaya Bay, in the South, there’s widespread meltponding visible.



For 2015 to stay in the race, an important contribution is necessary from Hudson and Baffin Bay, which usually open up during June. The same goes for the Laptev. ECMWF doesn’t indicate speedy Hudson Bay melt circumstances. It only hints at further anomalous warmth on the Bering side, this time aligned over the East Sib Sea.
Nothing seems set yet, so I’ll wait at least till the end of June. I have much more analysis on earlier years around that date.

Nightvid Cole

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Re: The 2015 melting season
« Reply #957 on: May 25, 2015, 01:45:52 AM »
Today, I checked the 23 May MODIS tiles against those I collected in CAD on 29 May last year. This year, weather imposed an impressive swath of meltponding over the American side of the Arctic. In fact, meltponding occurs over all of Chukchi Sea.



It extends more than 400 km N of Barrow (the red circle), into the adjacent parts of the CAB ( the blue lines indicate the limits of Beaufort and Chukchi Seas). To the West, the swath enters the East Siberian Sea N of Ostrov Wrangelj. To the East, it enters the CAA into Coronation Gulf, Prince of Wales Strait and even into McClure Strait. 
Although this meltponding event is, within the limits of my memory, unique for the time of the year, it doesn’t mean the course to a new minimum record is set. Compared to last year, there’s considerably less open water on the Siberian side. Last year, constant Southerly winds created a large polynia all along the Siberian fast ice, which laid the basis for the “Laptev Bite” later that year. This time, cool anomalies prevented the Sib side for an early melt start.



Exception is the Kara Sea, where ice extent rapidly declines and floes are dispersed. In fact, most of the ice in the Southern Kara will soon be isolated from the main pack. Near Baydaratskaya Bay, in the South, there’s widespread meltponding visible.



For 2015 to stay in the race, an important contribution is necessary from Hudson and Baffin Bay, which usually open up during June. The same goes for the Laptev. ECMWF doesn’t indicate speedy Hudson Bay melt circumstances. It only hints at further anomalous warmth on the Bering side, this time aligned over the East Sib Sea.
Nothing seems set yet, so I’ll wait at least till the end of June. I have much more analysis on earlier years around that date.

We will see melt ponding by the 30th of this month on the Siberian side, based on GFS forecasts.

slow wing

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Re: The 2015 melting season
« Reply #958 on: May 25, 2015, 05:22:28 AM »
@slow wing - I have only played around with the nullschool datasets I do not know the specific correlation to cloudcover or precipitation events.  I don't think that you can extract the level of detail regarding precipitation using it unless it is absolutely obvious (i.e. 25C and 100% humidity is most likely rain!).  For cloud cover if you go to NASA worldview, MODIS can show a rough correlation to cloud cover, I like to work with the 1000 hPa elevation for the arctic and TPW for cloud cover, it correlates, well, ok I guess.

compare

http://earth.nullschool.net/#2015/05/21/1200Z/wind/isobaric/1000hPa/overlay=total_precipitable_water/equirectangular=-69.88,87.24,1193

https://earthdata.nasa.gov/labs/worldview/?p=arctic&l=MODIS_Aqua_CorrectedReflectance_TrueColor%28hidden%29,MODIS_Terra_CorrectedReflectance_TrueColor,Reference_Labels%28hidden%29,Reference_Features%28hidden%29,Coastlines&t=2015-05-22&v=-6553600,-3231744,6553600,3231744

click on earth and select arctic (top right)
then on left click "corrected reflectance 3-6-7
and you can see if they match up very well.  ..
Thanks for the info, Jai, much appreciated!

Jim Hunt

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Re: The 2015 melting season
« Reply #959 on: May 25, 2015, 11:39:05 AM »
An updated version of my Beaufort Sea AMSR2 video:

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

Jim Pettit

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Re: The 2015 melting season
« Reply #960 on: May 25, 2015, 02:20:06 PM »
In case nobody noticed, it says this on the CT page, near the top with the rebuttal to James Taylors Forbes piece.

Note: snow cover data not updating ... we hope to have a new data source by July, 2015.

Yeah, it was 86 yesterday in Fairbanks. Hard to get that with wall-to-wall snow coverage...

Oh, but wait. So one day coming up after a fix is applied, a lot of the snow will disappear from the graphic overnight? Denialist heads will explode. Be prepared for many Watts-ian headlines decrying the "fraud", "deceit", and "manipulation" of the "alarmists". But then again, at least they'll quit showing the out-of-date version over and over and over again as "proof" that the planet's not warming. :)


silkman

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Re: The 2015 melting season
« Reply #961 on: May 25, 2015, 03:13:44 PM »
Fairbanks webcam - anyone for a picnic on the grass?

Jim Hunt

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Re: The 2015 melting season
« Reply #962 on: May 25, 2015, 03:17:21 PM »
Denialist heads will explode. Be prepared for many Watts-ian headlines decrying the "fraud", "deceit", and "manipulation" of the "alarmists".

I don't normally post my "satirical" articles in here, but since you mention Willard here's one I prepared yesterday:

Why It’s So Hard to Convince Pseudo-Skeptics

Be sure to watch the video at the end even if you don't find my experiments with search/replace even vaguely amusing.
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be cause

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Re: The 2015 melting season
« Reply #963 on: May 25, 2015, 03:21:03 PM »
funny that CT snow cover froze the only day with snow here in N Ireland .. I'm sure not still shovelling it . However next door in Scotland snow is accumulating atm. not melting .
2007 + 5 = 2012 + 4 = 2016 + 3 = 2019 ...

JayW

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Re: The 2015 melting season
« Reply #964 on: May 25, 2015, 04:25:46 PM »
Hi Siffy .. based on last years summer forecasts I would not trust the GFS 2m temps forecast for the Arctic . Last year GFS spent the entire summer forecasting @ 10'c more than GEM for the Arctic as a whole . Seems to be the same again... 10 days out GFS has a frost free Arctic , Gem has it averaging @ -8'C . Last year GEM was by far the more accurate and looks likely again in 2015 . Still I don't doubt this is going to be a very interesting melt season :)
be cause - can you point us at some sites producing summary maps based on GEM modelling output?

I'm sifting through a number right now that appear to use it, but if you have something specific, that would be useful.

(Edit:  I found this:
http://weather.gc.ca/data/model_forecast/colour_images/00_054_G1_north@america@zoomout_I_4PAN_CLASSIC@012_000.jpg
You have better?)

Tropical Tidbits is a great resource.  :)

Edit: Meteocentre is another great site, it's the only place I can find free access to the UKMET, albeit limited, and you can compare maps side by side. Very comprehensive.
http://meteocentre.com/models/explorateur.php?mod=gemglb&run=12&stn=PNMPR&hh=156&map=na&stn2=PT&run2=12&mod2=gemglb&hh2=156&comp=1&fixhh=1&lang=en

CMC also know as the GGEM, and the GEPS are the GGEM ensembles.  And it's showing some above freezing temps on the Pacific side (first attachment Hr 48), intensifying day 4 and lasting beyond (second attachment Hr 102) especially so on the Russian side.

http://www.tropicaltidbits.com/analysis/models/?model=gem&region=nhem&pkg=T2m&runtime=2015052500&fh=120&xpos=0&ypos=744

Third attachment is the ECMWF ensemble mean for hour 120, showing the basic agreement on the pattern.
« Last Edit: May 25, 2015, 04:34:10 PM by JayW »
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Greenbelt

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Re: The 2015 melting season
« Reply #965 on: May 25, 2015, 06:58:32 PM »
GFS starting to show large positive temp anomalies on the Siberian side within the six day range.

Timothy Astin

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Re: The 2015 melting season
« Reply #966 on: May 25, 2015, 08:55:59 PM »


The retreat of the snow in western Siberia has intensified in the last few days. So it looks like the Kara is about to see faster melting, and the western Laptev might not be far behind.

The conditions continue to line up for an optimum ice retreat.

slow wing

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Re: The 2015 melting season
« Reply #967 on: May 26, 2015, 01:28:14 PM »
These Nullschool graphics have been a game-changer for helping me to visualise changes in the Arctic  this season compared to previous seasons.

Winds over the past week or so have transported heat from the Alaskan, and nearby Canadian, land mass over much of the Central Arctic basin. This has been so much easier to follow using the following Nullschool display:
http://earth.nullschool.net/#current/wind/surface/level/overlay=temp/orthographic=-35.44,93.43,1444

The affected parts of the Central Arctic are now displaying temperatures around zero degrees Celsius.

I'm wondering, is all the ice below now at close to that temperature, all the way down to the water below at around -2 degrees? (The buoys should tell us that. What do they say?) Has enough latent heat been added that all this region will stay at around zero degrees surface air temperatures for the rest of the melt season, except maybe even heating up a little bit more at the ocean's surface where the ice melts out?


If so then all this region appears ripe for melt pond formation, and then serious melting whenever the sun is shining down around the next couple of months.

So maybe the Central Arctic is primed for a big melt season? And is this earlier than in previous recent years?

So very interesting but a lot of assumptions and speculation on my part.

What do others think? Is this usual? Or is this earlier than usual? And is it setting us up for a potential big, or even record, melt out this season?


 :o


EDIT:
Now looking at the Central Arctic temperature map...
http://ocean.dmi.dk/arctic/meant80n.uk.php
Note that 2012 rose to 0 degrees C earlier than is typical but 2013 & 2014 were both later. Was this a relevant factor in the big 2012 melt and in the suppressed melts of the past 2 years?
(I realise the temperature weighting has been done wrongly for this graph, so it is weighted too heavily around the North Pole rather than being a true average - which would be more probative.)

Will be very interesting to see when this plot hits 0 degrees this year. I'm guessing it will be early again. And this will give a bigger time window of opportunity for melt ponding & fast heat absorbtion.




« Last Edit: May 26, 2015, 01:46:03 PM by slow wing »

Nightvid Cole

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Re: The 2015 melting season
« Reply #968 on: May 26, 2015, 01:41:56 PM »
These Nullschool graphics have been a game-changer for helping me to visualise changes in the Arctic  this season compared to previous seasons.

Winds over the past week or so have transported heat from the Alaskan, and nearby Canadian, land mass over much of the Central Arctic basin. This has been so much easier to follow using the following Nullschool display:
http://earth.nullschool.net/#current/wind/surface/level/overlay=temp/orthographic=-35.44,93.43,1444

The affected parts of the Central Arctic are now displaying temperatures around zero degrees Celsius.

I'm wondering, is all the ice below now at close to that temperature, all the way down to the water below at around -2 degrees? (The buoys should tell us that. What do they say?) Has enough latent heat been added that all this region will stay at around zero degrees surface air temperatures for the rest of the melt season, except maybe even heating up a little bit more at the ocean's surface where the ice melts out?


If so then all this region appears ripe for melt pond formation, and then serious melting whenever the sun is shining down around the next couple of months.

So maybe the Central Arctic is primed for a big melt season? And is this earlier than in previous recent years?

So very interesting but a lot of assumptions and speculation on my part.

What do others think? Is this usual? Or is this earlier than usual? And is it setting us up for a potential big, or even record, melt out this season?


 :o

It looks right now like the surface melting schedule this year is about on par with 2012 and one month ahead of both 2013 and 2014.

In 2012, the surface melting was slowed quite dramatically by a double snowstorm over the central Arctic from approximately June 15 - June 22.

By contrast, in both 2007 and 2011, the melt pond fraction derived from MODIS was over 30% in the Pacific sector of the arctic by June 26th, up to over 85 degrees North, because of warmer weather in mid-June.

If we have a June with weather conditions like 2007, and maybe also if like 2011, this melt season will be a blowout and smash 2012.

OTOH, if we get a snowy pattern in mid-June as we did in 2012, then we'll end up like 2012 again.

There is zero chance of a (relatively) high extent, area, and volume like 2013 or 2014 being repeated this year - the surface melt has simply started too soon for that to even be possible.

seaicesailor

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Re: The 2015 melting season
« Reply #969 on: May 26, 2015, 03:38:47 PM »

...

There is zero chance of a (relatively) high extent, area, and volume like 2013 or 2014 being repeated this year - the surface melt has simply started too soon for that to even be possible.


I agree with your comment, except for the fact that there's a lot more volume of ice to be melt, a lot more latent heat required. I suppose that might slow down things later on, unless exceptional weather makes melt ponds grow and spread, and so.

plinius

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Re: The 2015 melting season
« Reply #970 on: May 26, 2015, 04:16:53 PM »
I cannot see any reliable indication that the sea ice volume is larger this year than it was 2014. While PIOMAS may have the volume estimate higher, the fall estimate from Crysat was actually quite lower, if I remember this right.

@Nightvid: I would not put too much value into the DMI graph: It is heavily biased towards the pole, and it also does not cover the more important imbalance this year between early melt regions and a cold central arctic (which however does not experience significant ice growth).

BornFromTheVoid

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Re: The 2015 melting season
« Reply #971 on: May 26, 2015, 04:26:02 PM »
Daily NSIDC extent has dipped below 12 million km2 for the earliest date on record (May 25th), beating the previous record of May 30th in 2006.


DavidR

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Re: The 2015 melting season
« Reply #972 on: May 26, 2015, 05:02:32 PM »

...

There is zero chance of a (relatively) high extent, area, and volume like 2013 or 2014 being repeated this year - the surface melt has simply started too soon for that to even be possible.


I agree with your comment, except for the fact that there's a lot more volume of ice to be melt, a lot more latent heat required. I suppose that might slow down things later on, unless exceptional weather makes melt ponds grow and spread, and so.
2015 appears to  have started the June melt about 10 days early. NSIDC extent is now almost 300K km^2 below the previous record low. This compares with a range of values of less than 500K km^2 over the past 9 years.  It  would be surprising if this figure was significantly  smaller by  June 1st.  This would put 2015 600K km^2 ahead of 2012, which should be enough headway to prevent 2011 or 2012 catching up by the end of June.

I am watching a metric based on the estimated thickness of ice lost so far and in this area 2015 is well ahead of 2012  and every other recent year except 2010.  If May turns out to have been relatively warm across as I  expect it will a record low this year is a distinct possibility.
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Nick_Naylor

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Re: The 2015 melting season
« Reply #973 on: May 26, 2015, 05:24:18 PM »
These Nullschool graphics have been a game-changer for helping me to visualise changes in the Arctic  this season compared to previous seasons.

Have you played with the MeteoEarth App for portable devices? I'm not sure exactly what the data source is, but the projections seem to be very reasonable, and the interface & presentation are excellent, especially on iPad. You can see global projections for surface temperature and precipitation, clouds at 3 altitudes, and wind at any altitude.

You might want to validate what you see here with an 'industrial-strength' data source, but you can check a lot of things in 30 seconds with this app.


Nightvid Cole

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Re: The 2015 melting season
« Reply #974 on: May 26, 2015, 05:29:59 PM »
I cannot see any reliable indication that the sea ice volume is larger this year than it was 2014. While PIOMAS may have the volume estimate higher, the fall estimate from Crysat was actually quite lower, if I remember this right.

@Nightvid: I would not put too much value into the DMI graph: It is heavily biased towards the pole, and it also does not cover the more important imbalance this year between early melt regions and a cold central arctic (which however does not experience significant ice growth).

DMI is actually not one of the factors I looked at. The main things I watch are the snow albedo on MODIS and the snow depth forecast on Climate Reanalyzer.

A bit later in the season when the melt ponds get more established, they will be easily discernible on both uni-bremen and CT concentration maps, but until then, I am truly astonished by the prediction by GFS to lose 15-30 cm of snow depth in large portions of the central Arctic between now and June 2nd!

We don't have near-real-time data on the actual distribution (in the statistical sense) of local snow depths in the Arctic, so it is tricky to infer melt pond formation from snow depth loss alone. Even if we assume that we know the depth of an under-snow liquid water layer, without knowing the snow surface height distribution, we strictly do not know exactly what the pond coverage will be.

Fortunately, we don't really need to know that, because melting snow already starts losing albedo even before exposed ponds form, thus accelerating its own loss. The onset of snow melting has been shown to be related to the total absorption of solar radiation over the entirety of the melt season by the authors of "Changes in Arctic melt season and implications
for sea ice loss" ...here: http://onlinelibrary.wiley.com/doi/10.1002/2013GL058951/pdf
« Last Edit: May 26, 2015, 05:41:33 PM by Nightvid Cole »

oren

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Re: The 2015 melting season
« Reply #975 on: May 26, 2015, 05:37:02 PM »

...

There is zero chance of a (relatively) high extent, area, and volume like 2013 or 2014 being repeated this year - the surface melt has simply started too soon for that to even be possible.


I agree with your comment, except for the fact that there's a lot more volume of ice to be melt, a lot more latent heat required. I suppose that might slow down things later on, unless exceptional weather makes melt ponds grow and spread, and so.
2015 appears to  have started the June melt about 10 days early. NSIDC extent is now almost 300K km^2 below the previous record low. This compares with a range of values of less than 500K km^2 over the past 9 years.  It  would be surprising if this figure was significantly  smaller by  June 1st.  This would put 2015 600K km^2 ahead of 2012, which should be enough headway to prevent 2011 or 2012 catching up by the end of June.

I am watching a metric based on the estimated thickness of ice lost so far and in this area 2015 is well ahead of 2012  and every other recent year except 2010.  If May turns out to have been relatively warm across as I  expect it will a record low this year is a distinct possibility.

At about June 1st 2012 extent took a nosedive that brought it to the 2011 level. My big question mark looking at the extent graph is whether 2015 will have a similar early breakdown and take a strong lead, or will follow the average curve and thus merge with 2012 and 2011 during June.

wanderer

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Re: The 2015 melting season
« Reply #976 on: May 26, 2015, 05:45:17 PM »
Looking at https://earthdata.nasa.gov/labs/worldview/ 
and comparing 2012 to 2015 on Cryosphere Today
http://igloo.atmos.uiuc.edu/cgi-bin/test/print.sh?fm=05&fd=24&fy=2015&sm=05&sd=24&sy=2012
(with the PIOMAS estimates in mind)
at least the CAB 2012 still looks "slushier" to me. But as long as the weather forecasts stays that bad for sea ice, I think I will be more convinced soon that 2015 is a big melt year!


Nick_Naylor

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Re: The 2015 melting season
« Reply #977 on: May 26, 2015, 06:37:06 PM »
. . . "Changes in Arctic melt season and implications
for sea ice loss" ...here: http://onlinelibrary.wiley.com/doi/10.1002/2013GL058951/pdf

Your original post has a fatal terminating period hidden in the URL, fixed above.

seaicesailor

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Re: The 2015 melting season
« Reply #978 on: May 26, 2015, 08:15:27 PM »
In three or four days warm air will be flowing into the Arctic from Canada, Alaska, Bering, Siberia and Northen Europe.
So from everywhere except Greenland.


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Re: The 2015 melting season
« Reply #979 on: May 27, 2015, 01:18:39 AM »

2015 appears to  have started the June melt about 10 days early. NSIDC extent is now almost 300K km^2 below the previous record low. This compares with a range of values of less than 500K km^2 over the past 9 years.  It  would be surprising if this figure was significantly  smaller by  June 1st.  This would put 2015 600K km^2 ahead of 2012, which should be enough headway to prevent 2011 or 2012 catching up by the end of June.

I am watching a metric based on the estimated thickness of ice lost so far and in this area 2015 is well ahead of 2012  and every other recent year except 2010.  If May turns out to have been relatively warm across as I  expect it will a record low this year is a distinct possibility.

At about June 1st 2012 extent took a nosedive that brought it to the 2011 level. My big question mark looking at the extent graph is whether 2015 will have a similar early breakdown and take a strong lead, or will follow the average curve and thus merge with 2012 and 2011 during June.

2012  had an extent drop of just over 3M Km^2 in June, whereas the average over the past  9 years has been just over 2.5M Km^2.  All of the past five years have seen extent drops greater than 2.55M Km^2.  If 2015 drops the equivalent of the smallest June decline in the past 5 years and starts out 600K km^2 ahead it will still be 150 K Km^2 ahead at the end of June.   

With May temperatures across the Arctic being a major driver of June decline, we should have a good idea once the May  temperatures are available how likely it is that 2015 will still be in record territory at the end of June.

The May  temperature anomaly for the years with a low decline  2011 and 2013 was 0.676 and 0.402 respectively. For 2010 and 2012 the years with big declines the May anomaly  was 2.335 and 1.096 respectively.  If we see a May anomaly around 1.0 we can expect 2015 to be well below 2012 at the end of June.  However 2012 had the highest temperature anomalies for June and July were the highest on record, so it has plenty of scope to  go lower than 2015 in later months.
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Re: The 2015 melting season
« Reply #980 on: May 27, 2015, 08:56:09 AM »
Between 2006-14 on May 31st/June 1st no year has anything even close to the mega death ridge forming now.

Major headstart.

Mega death ridge




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Gray-Wolf

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Re: The 2015 melting season
« Reply #981 on: May 27, 2015, 11:03:06 AM »
I think the continued 'cold plunges' that set the WAA in motion may be key now?

With only the surface of the Arctic producing cool temps and not any 'saved' deep cold from winter ( the last of that being beyond 80N according to DMI) it takes a lot less energy to see temps rise above freeze.

The pattern shows that only the ice on Greenland driving cold anoms?

Though very early in the season I'd also wondered about the impacts of a warming world on the 'perfect melt storm synoptic' ? We were told, back in 07', that the perfect melt storm synoptic came around every 10 to 20 years but that the two before 07' had ten year spacing's.

 Could it be that the 'period' of the 'perfect melt storm' has reduced further and we are seeing the return of 'the perfect melt storm' after only 8 years?
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Frivolousz21

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Re: The 2015 melting season
« Reply #982 on: May 27, 2015, 01:35:58 PM »
Csnavy posted some enso based analogs on American wx and they showed large ridging.
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Greenbelt

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Re: The 2015 melting season
« Reply #983 on: May 27, 2015, 07:10:25 PM »
GFS seems to concur with a very large and stationary (and persistent) surface high

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Re: The 2015 melting season
« Reply #984 on: May 27, 2015, 07:37:03 PM »
not sure where to post this, but a little puzzle:
http://seaice.alaska.edu/gi/observatories/barrow_radar

Looking at the Barrow ice radar of the past 12 hours, you see a thin ridge line of ice flowing nearly parallel to the coast. It is definitely not a sea ice edge, since there is different motion in the reflections behind. What are the mechanics behind this? A local surface convergence? But why?

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Re: The 2015 melting season
« Reply #985 on: May 27, 2015, 08:02:14 PM »
not sure where to post this, but a little puzzle:
http://seaice.alaska.edu/gi/observatories/barrow_radar

Looking at the Barrow ice radar of the past 12 hours, you see a thin ridge line of ice flowing nearly parallel to the coast. It is definitely not a sea ice edge, since there is different motion in the reflections behind. What are the mechanics behind this? A local surface convergence? But why?

Isnt that just the (free) sea ice drifting parallel to the fast sea ice?


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Re: The 2015 melting season
« Reply #986 on: May 27, 2015, 08:05:13 PM »
Yes, but if you look closely the very edge of the free pack ice seems to be moving faster than the body of the pack ice, which seems odd.  But maybe the body of the pack is simply less free to move because it's more tightly packed than the floes at the edge ?

seaicesailor

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Re: The 2015 melting season
« Reply #987 on: May 27, 2015, 08:18:19 PM »
I see now. Looks like a current near the coast, and faster than the drifting sea ice, like a jet. Other than that  :o
 

Tor Bejnar

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Re: The 2015 melting season
« Reply #988 on: May 27, 2015, 08:29:41 PM »
Looking at some old links in the Arctic Maps thread, I visited polarportal.dk from a 2013 post by 'anonymous'.  I'm intrigued by this sea ice temperature map (image below is reduced in size) that appears to show lots of the Arctic on the Bering Strait side [the" high longitude" side?] with temperatures hovering around plus 1 degree.  This is a little different from the map available on  ASIG showing DMI's 2-meter temperatures.  The two maps show the same base map and scale.

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Michael Hauber

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Re: The 2015 melting season
« Reply #989 on: May 27, 2015, 11:21:23 PM »
I suspect part of the reason why el nino years have not been good for melt in the past is the position of the high pressure system in the North Pacific.  In an El Nino year it tends to weaken and push more towards the west.  This means less warm air transported into the far North Pacific.  In contrast during a cooler ENSO set up it is more likely that the North Pacific will have high pressure in the east, and low in the west pumping warm air into the far north Pacific.  Then if we get anything like a dipole the air being sucked into the Arctic from the North Pacific is very warm and you can get an almost direct path from the tropical Pacific deep into the arctic.  In contrast in 2009 I remember dipole like weather at times, but the impact was restricted by the North Pacific not lining up.  And currently we have a Beaufort high positioned to suck air out of the North Pacific, but the air there at the moment is not all that warm.  Although there is a lot of hot air available from the west American ridge.

The current forecast is moving the high much more into the Arctic, which is going to push cold air and ice back into the Beaufort (or at least the east part of it)  The melt focus will shift towards the chukchi and ESS.  If this produces any significant open water in ESS it will be the first time that this has happened before July. 

June is typically dominated by melt on the Atlantic side, particularly Hudson, Baffin and Kara.  Conditions in Hudson and Baffin are quite mild at the moment, although Kara has been getting some decent heat and southerly wind.  These three regions are still all melting at a decent rate to keep us at or near record depending on which measure.  I think one thing that has been missing on the Pacific side which has restricted the melt (besides being so early) is a lack of wind.  sAs the high builds into the Arctic this will change to some extent with moderate winds around this high.
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Re: The 2015 melting season
« Reply #990 on: May 28, 2015, 12:06:35 AM »
not sure where to post this, but a little puzzle:
http://seaice.alaska.edu/gi/observatories/barrow_radar

Looking at the Barrow ice radar of the past 12 hours, you see a thin ridge line of ice flowing nearly parallel to the coast. It is definitely not a sea ice edge, since there is different motion in the reflections behind. What are the mechanics behind this? A local surface convergence? But why?
My 2c  pacific water is being drawn into the arctic, it's surface water from much further south and has the energetic imprint [think of it as lots of gyroscopes] of say 65deg north naturally it turns right [at point Barrow] and moves much faster than the winds or tides would otherwise suggest  possible. It looks to me that this influx has been more or continuous for 3 weeks and meets less and less resistance the more it's established.

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Re: The 2015 melting season
« Reply #991 on: May 28, 2015, 12:27:02 AM »
not sure where to post this, but a little puzzle:
http://seaice.alaska.edu/gi/observatories/barrow_radar

Looking at the Barrow ice radar of the past 12 hours, you see a thin ridge line of ice flowing nearly parallel to the coast. It is definitely not a sea ice edge, since there is different motion in the reflections behind. What are the mechanics behind this? A local surface convergence? But why?
My 2c  pacific water is being drawn into the arctic, it's surface water from much further south and has the energetic imprint [think of it as lots of gyroscopes] of say 65deg north naturally it turns right [at point Barrow] and moves much faster than the winds or tides would otherwise suggest  possible. It looks to me that this influx has been more or continuoeeeks and meets less and less resistance the more it's established.

I read earlier that bottom melt in Barrow fast ice had started too soon, maybe even before surface melt. So that may be it


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Re: The 2015 melting season
« Reply #992 on: May 28, 2015, 02:09:06 PM »
The ADS/vishop site now has a "Sea Ice Forecast" overlay feature. The images don't copy well to show here... go play with it on their page.

https://ads.nipr.ac.jp/vishop/vishop-monitor.html?N

It seems they are predicting wide open NW and NE passages, and a bit less than the 2013/2014 "rebounds" in extent, but still more than 2012 (just eyeballing, they don't have data for 2012).


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Re: The 2015 melting season
« Reply #993 on: May 28, 2015, 04:19:49 PM »
I have noticed that the ADS thickness/melt area tool shows considerably larger areas of melt for the ascending orbit as compared to the descending orbit for each date.  This pattern is apparent for every day as far as I can tell.  Possibly to do with time of day?

(1st image descending, second image ascending).

Edit: Actually, there is a discussion of exactly this point over on Wipneus' Home Brew AMSR2 thread.
« Last Edit: May 28, 2015, 04:30:56 PM by sedziobs »

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Re: The 2015 melting season
« Reply #994 on: May 29, 2015, 03:53:10 PM »
Nick Stokes has created his own version of DMI's 80+ N temperature plot using NCEP/NCAR reanalysis.  He also added a tool that allows you to adjust the plot to include any lat/long range above 60 degrees.

http://moyhu.blogspot.com/2015/05/daily-arctic-temperatures.html

Here is my approximation of the Beaufort and Chukchi seas:

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Re: The 2015 melting season
« Reply #995 on: May 29, 2015, 05:09:43 PM »
Nick Stokes has created his own version of DMI's 80+ N temperature plot using NCEP/NCAR reanalysis.  He also added a tool that allows you to adjust the plot to include any lat/long range above 60 degrees.

http://moyhu.blogspot.com/2015/05/daily-arctic-temperatures.html

Here is my approximation of the Beaufort and Chukchi seas:

Nice job, though being able to choose a past year to plot would also be nice.

Nightvid Cole

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Re: The 2015 melting season
« Reply #996 on: May 29, 2015, 05:17:45 PM »
I suspect part of the reason why el nino years have not been good for melt in the past is the position of the high pressure system in the North Pacific.  In an El Nino year it tends to weaken and push more towards the west.  This means less warm air transported into the far North Pacific.  In contrast during a cooler ENSO set up it is more likely that the North Pacific will have high pressure in the east, and low in the west pumping warm air into the far north Pacific.  Then if we get anything like a dipole the air being sucked into the Arctic from the North Pacific is very warm and you can get an almost direct path from the tropical Pacific deep into the arctic.  In contrast in 2009 I remember dipole like weather at times, but the impact was restricted by the North Pacific not lining up.  And currently we have a Beaufort high positioned to suck air out of the North Pacific, but the air there at the moment is not all that warm.  Although there is a lot of hot air available from the west American ridge.

It does not need to be that warm to cause a lot of melting in the Arctic if it is humid enough - latent heat can do the job just as well as sensible heat.

A plume of really humid Pacific air with dew points > 1 deg. C or precipitable water > 15 mm essentially any time in the month of June will cause surface melting to really go nuts, and it will be  early enough in the season for it to result in a sharply reduced September extent.

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Re: The 2015 melting season
« Reply #997 on: May 29, 2015, 05:57:22 PM »
I suspect part of the reason why el nino years have not been good for melt in the past is the position of the high pressure system in the North Pacific.  In an El Nino year it tends to weaken and push more towards the west.  This means less warm air transported into the far North Pacific.  <snippage for brevity>

It does not need to be that warm to cause a lot of melting in the Arctic if it is humid enough - latent heat can do the job just as well as sensible heat....

To amplify Nightvid's point, we can look at differences in preciptable water.  May has had significantly higher - year over year - higher imports of moisture from lower latitudes as compared to previous averaged daily values; qualitatively higher by double or more in fact, as illustrated below in the attached images.

In 2013 and 2014 we saw a lot in the way of moisture via low clouds and fog - but as a result of heat transport via evaporation out of leads and open water.  That's not happening this season, as the moisture is arriving from elsewhere.

It represents a huge store of heat accumulated outside of the arctic, being added to the seasonal import of heat.  (I should check earlier figures from this winter - I expect well see imported moisture has had a big role to play in the low winter maximum(s) we've seen recently).

(Edit:  Interestingly, a quick check of some March and February dates shows moisture in 2014 tended to be higher than this year.  Fascinating, as 2015 tended to be much warmer.)

« Last Edit: May 29, 2015, 06:04:01 PM by jdallen »
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Greenbelt

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Re: The 2015 melting season
« Reply #998 on: May 29, 2015, 08:23:11 PM »
Watching the weather, it looks like the GFS is still predicting the formation of a persistent, stationary surface high on the Pacific side, which would lead to sunny skies over a lot of ice, and bring moisture and warmth to the Siberian side while cooling off the Yukon and NWT. Prediction has been pretty stable on this, and ECMWF has similar features.



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Re: The 2015 melting season
« Reply #999 on: May 29, 2015, 09:58:10 PM »
Nick Stokes has created his own version of DMI's 80+ N temperature plot using NCEP/NCAR reanalysis.  He also added a tool that allows you to adjust the plot to include any lat/long range above 60 degrees.

http://moyhu.blogspot.com/2015/05/daily-arctic-temperatures.html

Here is my approximation of the Beaufort and Chukchi seas:

Nice job, though being able to choose a past year to plot would also be nice.

You can timeseries past months of NCEP/NCAR here:
http://www.esrl.noaa.gov/psd/cgi-bin/data/timeseries/timeseries1.pl