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oren

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Re: The 2018 melting season
« Reply #900 on: May 31, 2018, 05:25:31 AM »
Here's why the Laptev gap stopped refreezing. A chart of Tiksi air temperatures in May, with comparison to climatology, courtesy of http://www.pogodaiklimat.ru/monitor.php?id=21824 (in Russian). The average temp crossed 0oc on the 23rd, and stayed above it since.

Note to bbr1234, high temps cause snow melt, not the other way around (snow melt does not cause high temps). Snow in Tiksi finished melting today, according to Ogimet
Why are you so rude to me? I never said high temps do not cause snow melt. Once snow has fully melted, temps can soar significantly higher. When snow is extant, it modifies airmasses and reduces temperatures (E.G., you are not going to see 85-90F temps with substantial snowcover on the ground). You will see several days of above-freezing temps ranging up to 50-60, it will melt, and then you will see temps shoot up.
First, I apologize. I did not mean the statement to come out as rude, but upon re-reading it does feel rude. Sorry. I will refrain from similar-spirited comments in the future.

I was responding to a previous statement you made:
The origin is therefore not transport, which has been ongoing all winter. Rather, it is the lack of refreeze, which has resulted because of the snowmelt across adjacent Siberian landmass. Now, continental heat is pouring into Laptev (most days), and is the reason refreeze is no longer occurring / open water is now showing.
Which seemed to me to reverse the causal chain. In my view, lack of refreeze came when temps rose above zero, and at that point snow started to melt as well, therefore the snowmelt was not the cause of the lack of refreeze, rather both were the result of a third factor - temperatures.

wallen

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Re: The 2018 melting season
« Reply #901 on: May 31, 2018, 11:07:23 AM »
Haven't seen any reference to the McKenzie river this year. Looks to be just starting to impact on the Beaufort Sea. Will be worth watching this year.

gerontocrat

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Re: The 2018 melting season
« Reply #902 on: May 31, 2018, 11:09:36 AM »

And indeed most of the southern edge of the Laptev opening closely follows the 30m submarine contour with the exception of the section around Kotelny (?) Island. Of course now I am wondering why it follows the shelf contour, and what effect does the Lena river (which looks pretty large) have on the melting.
The Lena River is certainly a big beast, with a huge maximum discharge when the snow melts. June is the big month - but apparently snow-melting is also happening in May now. Presumably large amounts (200gt ?) of fresh water entering the Laptev in just one month must impact how ice loss happens in the Laptev.   See data below and images attached.

And yes, this stuff is a wonderful distraction from less interesting but necessary work

From Wikipedia:-
The Lena (Russian: Ле́на, IPA: [ˈlʲɛnə]; Russian Buryat: Зүлхэ; Evenki: Елюенэ; Sakha: Өлүөнэ) is the easternmost of the three great Siberian rivers that flow into the Arctic Ocean (the other two being the Ob' and the Yenisey). With a mean annual discharge of 588 cubic kilometers per year, it is the 5th largest river globally by discharge and the second largest of the Arctic rivers (after the Yenisey)[2]. It is the largest river whose catchment is entirely within the Russian territorial boundaries. Permafrost underlies most of the catchment, with 77% of the catchment containing continuous permafrost.

Tributaries
 - left   Kirenga, Vilyuy
 - right   Vitim, Olyokma, Aldan Source   
 - location   Baikal Mountains, Irkutsk Oblast, Russia  - elevation   1,640 m (5,381 ft)
Mouth   Lena Delta 
- location   Arctic Ocean, Laptev Sea Basin   2,500,000 km2 (965,255 sq mi)

Discharge   for Laptev Sea[1]
 - average   16,871 m3/s (595,794 cu ft/s)
 - max   241,000 m3/s (8,510,835 cu ft/s)
 - min   366 m3/s (12,925 cu ft/s)


From a 2002 paper
https://stephenschneider.stanford.edu/Publications/PDF_Papers/YangEtAl2002.pdf
The long-term (1935–1999) monthly records of temperature, precipitation, stream
flow, river ice thickness, and active layer depth have been analyzed in this study to
examine Lena River hydrologic regime and recent change. Remarkable hydrologic
changes have been identified in this study. During the cold season (October–April),
significant increases (25–90%) in stream flow and decrease in river ice thickness have
been found due to warming in Siberia. In the snowmelt period (May–June), strong
warming in spring leads to an advance of snowmelt season into late May and results in a
lower daily maximum discharge in June. During summer months (July–September) the
changes in stream flow hydrology are less significant in comparison to those for winter
and spring seasons.
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uniquorn

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Re: The 2018 melting season
« Reply #903 on: May 31, 2018, 11:25:07 AM »
In my opinion the Laptev gap was a bit bigger same day of year in 2007.
Agreed

imagej brightness contrast 41,255

Aluminium

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Re: The 2018 melting season
« Reply #904 on: May 31, 2018, 12:17:16 PM »
The Lena River is certainly a big beast, with a huge maximum discharge when the snow melts. June is the big month - but apparently snow-melting is also happening in May now. Presumably large amounts (200gt ?) of fresh water entering the Laptev in just one month must impact how ice loss happens in the Laptev.   See data below and images attached.


A nice video about Lena and the nature of Yakutia. The video was shot near the Lena delta at this time of year several years ago. In this video, Lena breaks ice and the ice flow begins.

In 2018, front edge of the ice flow will reach Lena delta in 3-4 days.

F.Tnioli

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Re: The 2018 melting season
« Reply #905 on: May 31, 2018, 01:04:56 PM »
Just found one interesting discovery about Jet Stream. Might be helpful as another little piece of the puzzle, i think.

be cause

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Re: The 2018 melting season
« Reply #906 on: May 31, 2018, 05:55:55 PM »
re the Lena delta .. it looks like flow has begun already .. the sea ice has changed colour over a 10 km area @ mid delta .. first visible 2 days ago but very clear today on worldview .. b.c.
2007 + 5 = 2012 + 4 = 2016 + 3 = 2019 ...

A-Team

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Re: The 2018 melting season
« Reply #907 on: May 31, 2018, 06:11:39 PM »
As FishO noted a while back, there's noteworthy action right now on the Pacific side. The mp4 below shows the Amundsen Gulf breaking up. It shows a WorldView true color at 78 km per 100 pixels with Jaxa and Ascat insets that have considerably lesser resolution.

Tracking the velocity of one large floe coming out of the central Amundsen using the scale provided by WV yielded an average speed of 20 km/day for the last 21 days, rather a wild ride by Arctic Ocean standards.

Nasa shut down WV briefly yesterday to make some software upgrades and today their animation tool is working very well indeed. The frame number limit is 40 but doing one month at a time followed by gif concatenation in ImageJ followed by mp4 compression allows several months to be shown, though clouds can obscure motion.

The first mp4 below squeezes 31 days into 4 seconds which amounts to a 670,000-fold speed-up of ice motion. Given this rate, the ice motion appears quite fluid. It is not feasible to make comparisons to past years however.

The Amundsen has been contributing the ice all season between the Alaskan coast and the CAA Beaufort stringer. A large chunk was pinched off on April 25th by the advancing stringer and now lies to the west of the elbow. The latter's matrix of FYI is melting out, leaving the thicker floes that originated a bit north of Prince Patrick island last October.

Tech note: to make the insets in ImageJ, change canvas size to that of the larger WV taking care to set the inset's position where wanted as there is no undo. Also check 'zero fill' which sets black to transparency. Then in Paste Control, set Transfer Mode to Transparent-zero and paste the inset over the WV host image. Here there was wasted space available in lower M'Clure Strait. At the time https://www.online-convert.com/ is used, set the pixel sizes to final dimensions, say 700x700, even though forum software will force it to 720 pixel width
« Last Edit: June 01, 2018, 01:23:59 AM by A-Team »

Neven

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Re: The 2018 melting season
« Reply #908 on: May 31, 2018, 09:11:45 PM »
I'm going to be off for a couple of days, back on Monday, not sure if I'll have WiFi there.
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FishOutofWater

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Re: The 2018 melting season
« Reply #909 on: May 31, 2018, 11:05:49 PM »
Meanwhile, there are very long cracks in the Nares Strait ice and there has been movement down most of the channel visible on AQUA MODIS Worldview for May 30 and 31. You can't see movement from the Lincoln sea to the polynya, but there is clear movement in the central channel. Because the ice arch formed so late this year the ice holding it together is thin and prone to failure under strong winds.

Pagophilus

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Re: The 2018 melting season
« Reply #910 on: May 31, 2018, 11:13:04 PM »
What a river -- thanks for posting this.  It is huge at maximum discharge -- the rough equivalent of the Amazon!  And it amazing how variable it is ... its flow at maximum is about 650 times greater than its minimum discharge rate -- the Mississippi's differential is a factor of about 25).    And the graph you post shows that the discharge increases about ten fold between May and June.

So an attempt to parse this out for myself -- a huge, ongoing inrush of fresh water is about the arrive in the Laptev Sea.   The lateral freshwater plume in the Laptev is probably going to be enormous by late June, floating perkily on top of salty waters (the Amazon's freshwater plume -- maybe an unfair comparison -- extends hundreds of km into the Atlantic).  So how much warmer are the Lena's waters than those in the Laptev Sea?  Do they warm a lot as they flow through Siberia in late June and July?  And does the Lena and its plume play a significant role in the formation of the Laptev bite?

     

The Lena River is certainly a big beast, with a huge maximum discharge when the snow melts. June is the big month - but apparently snow-melting is also happening in May now. Presumably large amounts (200gt ?) of fresh water entering the Laptev in just one month must impact how ice loss happens in the Laptev. 

From Wikipedia:-
With a mean annual discharge of 588 cubic kilometers per year, it is the 5th largest river globally by discharge and the second largest of the Arctic rivers[/i] (after the Yenisey)[2]. It is the largest river whose catchment is entirely within the Russian territorial boundaries. Permafrost underlies most of the catchment, with 77% of the catchment containing continuous permafrost.

Discharge   [/b]for Laptev Sea[1]
 - average   16,871 m3/s (595,794 cu ft/s)
 - max   241,000 m3/s (8,510,835 cu ft/s)[/b]
 - min   366 m3/s (12,925 cu ft/s)


From a 2002 paper [/b]https://stephenschneider.stanford.edu/Publications/PDF_Papers/YangEtAl2002.pdf
 Remarkable hydrologic
changes have been identified in this study. During the cold season (October–April),
significant increases (25–90%) in stream flow and decrease in river ice thickness have
been found due to warming in Siberia. In the snowmelt period (May–June), strong
warming in spring leads to an advance of snowmelt season into late May and results in a
lower daily maximum discharge in June.
[/quote]
« Last Edit: June 01, 2018, 04:56:58 AM by Pagophilus »

epiphyte

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Re: The 2018 melting season
« Reply #911 on: June 01, 2018, 07:30:48 AM »

Permafrost underlies most of the catchment, with 77% of the catchment containing continuous permafrost.


So what happens to the river when the permafrost starts to melt? Dramatic increase in outflow?
additional fresh water influx accelerating arctic melt through warming, or retarding it due to desalination? Sinkholes appearing from nowhere, filling, and eroding into a string of new lakes? Silt efflux lowering the albedo or increased flooding + winter freezing raising it?

To mix a metaphor,  the further we tumble down the rabbit hole, the more we are moving into uncharted territory. 

uniquorn

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Re: The 2018 melting season
« Reply #912 on: June 01, 2018, 10:38:15 AM »
Thanks for all the information about the Lena. I had a look this morning and the ice in the bay to the east is looking blue after this warm spell.

gerontocrat

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Re: The 2018 melting season
« Reply #913 on: June 01, 2018, 11:37:03 AM »
And don't forget the Yenesei (even bigger than the Lena) flowing into the Kara with the same flow profile as the Lena, the Ob (a bit smaller) with a more spread out flow, and Canada's Mackenzie, N. America's largest source of fresh water for the Arctic.
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be cause

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Re: The 2018 melting season
« Reply #914 on: June 01, 2018, 12:27:57 PM »
and today the outflow from the delta is increasing over a 20 km front .. excellent worldview visibility again as Uniquorn has shown .. the stains are clear.. grey .. mid -delta . The eastern outflow has grown considerably and darkened since yesterday . I am also enjoying watching life flowing back into the veins of the delta again .. until this year my download speeds were so poor that I could rarely even open Worldview never mind enjoy it's daily gifts ! Happy melting season :) b.c.
2007 + 5 = 2012 + 4 = 2016 + 3 = 2019 ...

uniquorn

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Re: The 2018 melting season
« Reply #915 on: June 01, 2018, 12:56:30 PM »
Mackenzie bay, may29-31.
Worldview Terra/modis corrected reflectance(bands 7-2-1) false colour used here to accentuate melt. Fast moving floes highlighted by A-team visible in the bay

Technical note:  terra/modis corrected reflectance(bands7-2-1)
This combination is most useful for distinguishing burn scars from naturally low vegetation or bare soil and enhancing floods. This combination can also be used to distinguish snow and ice from clouds. Snow and ice are very reflective in the visible part of the spectrum (Band 1), and absorbent in Bands 2 (near infrared) and 7 (short-wave infrared, or SWIR). Thick ice and snow appear vivid sky blue, while small ice crystals in high-level clouds will also appear blueish, and water clouds will appear white.

Water
Liquid water on the ground appears very dark since it absorbs in the red and the SWIR. Sediments in water appear dark blue. Ice and snow appear as bright turquoise. Clouds comprised of small water droplets scatter light equally in both the visible and the SWIR and will appear white. These clouds are usually lower to the ground and warmer. High and cold clouds are comprised of ice crystals and will appear turquoise.

https://tinyurl.com/y7c42h8h

numerobis

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Re: The 2018 melting season
« Reply #916 on: June 01, 2018, 02:49:33 PM »
There was no rudeness.

I’ve not been on snow at 85 F, but I have at 80 F (27 C). Some warm front popped up from somewhere and drove a huge amount of heat quite far north of Montreal. Snow isn’t that powerful that it can soak up imported heat quickly. What it can do is prevent heat from building up locally via its albedo effect.

bbr2314

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Re: The 2018 melting season
« Reply #917 on: June 01, 2018, 07:18:34 PM »
There was no rudeness.

I’ve not been on snow at 85 F, but I have at 80 F (27 C). Some warm front popped up from somewhere and drove a huge amount of heat quite far north of Montreal. Snow isn’t that powerful that it can soak up imported heat quickly. What it can do is prevent heat from building up locally via its albedo effect.
He admitted it was rude. It is a moot point since he apologized. Why bring it up again with a meaningless anecdote? The equivalent of a senator flinging a snowball in Congress to disprove AGW.

In any case, the CMC wants to setup continental heat cannons depositing directly into the High Arctic by the end of its run. Important to note the CMC is much more conservative than the GFS when it comes to heat due to its superior modeling re: snowfall (both falling, and extant).

I would think that the anomalous snow extent in low latitudes actually supports the notion that we will see very deep negative 500MB anomalies across 50-60Nish areas adjacent to remaining snow/ice, which will act to fling vast quantities of heat from the mid-latitudes north into the Arctic via "blocking". June should prove a nasty month for volume, if not area and extent as well.


JayW

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Re: The 2018 melting season
« Reply #918 on: June 02, 2018, 11:21:29 AM »
106 hour loop of Chukchi and Beaufort.  Some larger pieces in the Beaufort can be seen breaking up.  Open water in the Chukchi is slowly expanding.  It makes me wonder about the time of wind stress on the currents in the Chukchi, due to its late freeze up the last couple years combined with early breakup.


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bbr2314

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Re: The 2018 melting season
« Reply #919 on: June 02, 2018, 09:58:17 PM »
Not to be rude but DMI is clearly on crack. The thickness comparison with HYCOM (which has seemingly improved its algorithm/data) is beyond absurd. DMI shows 2-3M ice NE of Svalbard when satellite confirms HYCOM is clearly correct. DMI also shows no Laptev bite whatsoever.




Ktb

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Re: The 2018 melting season
« Reply #920 on: June 02, 2018, 10:44:59 PM »
The slater projection is functional once again. Predicting extent of 7.62 million kn^2 on July 22, 2018. Thanks to b.c. For prompting me to update from the meaningless thread.

I'd love to believe my nagging to University of Colorado had some impact
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Frivolousz21

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Re: The 2018 melting season
« Reply #921 on: June 02, 2018, 11:13:17 PM »
Warm air is finally pouring into the Pacific side of the Arctic basin.

We can expect the big albedo drop over essentially the entire Pacific side up to 80N within a couple days.


After day 5 the models keep flip flopping all over


The latest GFS shows a major dipole.  The euro shows the opposite.

But the euro is also a huge torch over the ESS and Laptev with nasty warmth bulleting into the Arctic on a powerful long wind fetch. 
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Juan C. García

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Re: The 2018 melting season
« Reply #922 on: June 03, 2018, 05:35:26 AM »
It is interesting that according to the DMI 80°N temperature, now it is colder than normal there.
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.

meddoc

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Re: The 2018 melting season
« Reply #923 on: June 03, 2018, 08:15:33 AM »
The slater projection is functional once again. Predicting extent of 7.62 million kn^2 on July 22, 2018. Thanks to b.c. For prompting me to update from the meaningless thread.

I'd love to believe my nagging to University of Colorado had some impact

I'd say that is a helluvan optimistic Projection by the Look of Things now.

jdallen

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Re: The 2018 melting season
« Reply #924 on: June 03, 2018, 08:59:09 AM »
It is interesting that according to the DMI 80°N temperature, now it is colder than normal there.
That graph makes utterly no sense, when the weather models are all showing *current* positive anomalies.
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DavidR

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Re: The 2018 melting season
« Reply #925 on: June 03, 2018, 09:13:03 AM »
It is interesting that according to the DMI 80°N temperature, now it is colder than normal there.
That graph makes utterly no sense, when the weather models are all showing *current* positive anomalies.
It looks pretty right to me.  Climate Reanalyzer is currently showing a -0.1 anomaly across the Arctic and most of the negative area is in the plus 80N region.  By Tuesday the anomaly climbs to plus 2 and stays near that for the rest of the week. There's some very hot weather in Northern Russia and the CAB by then.
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gerontocrat

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Re: The 2018 melting season
« Reply #926 on: June 03, 2018, 10:16:01 AM »
It is interesting that according to the DMI 80°N temperature, now it is colder than normal there.
That graph makes utterly no sense, when the weather models are all showing *current* positive anomalies.
Oh yes it does. That bit of the Arctic is showing negative anomalies, and the area above 80 degrees north is but a small fraction of the area of the Arctic (as defined by the Arctic circle). See below for some actual data.
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S.Pansa

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Re: The 2018 melting season
« Reply #927 on: June 03, 2018, 10:30:39 AM »
Add to that the fact that the DMI-80N-temps are heavily biased to a small area around the North Pole. See for instance Rob Dekkers explanation on Nevens blog:

Quote
... because the data is not area-weighted.

For example, in the DMI temperature graph (on a 0.5 deg grid) attaches 40x the significance to the temperature within 0.5 deg of the NP as compared to the significance of a similar area at the 80 deg North lateral. And since area/distance around the NP is a quadratic function, the DMI graph is for 50% determined by the temperature between 87.5-90N, which is only 25% of the area North of 80deg.

In short: The DMI 80N temps do miss most of the Arctic action ... or is overly dramatic

gerontocrat

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Re: The 2018 melting season
« Reply #928 on: June 03, 2018, 11:09:39 AM »
Add to that the fact that the DMI-80N-temps are heavily biased to a small area around the North Pole.
Quote
... because the data is not area-weighted.

For example, in the DMI temperature graph (on a 0.5 deg grid) attaches 40x the significance to the temperature within 0.5 deg of the NP as compared to the significance of a similar area at the 80 deg North lateral. And since area/distance around the NP is a quadratic function, the DMI graph is for 50% determined by the temperature between 87.5-90N, which is only 25% of the area North of 80deg.

In short: The DMI 80N temps do miss most of the Arctic action ... or is overly dramatic
Quote
the DMI graph is for 50% determined by the temperature between 87.5-90N, which is only 25% of the area North of 80 deg.

Nope - much less

                                                                 Million Km2       Percent of 80+
Surface area above 80+ North in  million km2       3.875    
Surface area above 87.5+ North in  million km2    0.243              6.3%




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cesium62

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Re: The 2018 melting season
« Reply #929 on: June 03, 2018, 11:32:16 AM »
The slater projection is functional once again. Predicting extent of 7.62 million kn^2 on July 22, 2018. Thanks to b.c. For prompting me to update from the meaningless thread.

I'd love to believe my nagging to University of Colorado had some impact

I'd say that is a helluvan optimistic Projection by the Look of Things now.

From Charctic, the extent on the 22nd (203rd day of the year) for the past 7 years has been in a fairly tight band from 7.2 to 7.9 mk2.  2016 extent was lower than 2018 at this time of year, but hit 7.65 on the 22nd.  So the Slater projection seems plausible based on Charctic trend lines.  On the other hand, the Kara typically loses 3/4ths of its ice by late July, and the Slater projection kind of shows it full of ice then.  And the Hudson typically loses 5/6ths of its ice by the time the Slater projection suggests it losing around half of its ice... 

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Re: The 2018 melting season
« Reply #930 on: June 03, 2018, 11:44:58 AM »
Speaking about Lena River Delta, then quite high temperatures (+25.3 °C) forecasted for Wednesday.

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Re: The 2018 melting season
« Reply #931 on: June 03, 2018, 11:52:12 AM »
What am i missing ? The first 2 pics are from yesterday. The 3th is for 22 July. There shoud be a 4,5 million square km gap.

Steven

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Re: The 2018 melting season
« Reply #932 on: June 03, 2018, 12:19:01 PM »
Quote
because the data is not area-weighted... the DMI graph is for 50% determined by the temperature between 87.5-90N, which is only 25% of the area North of 80deg.

He probably meant 85-90N:

the DMI graph is for 50% determined by the temperature between 85-90N, which is only 25% of the area North of 80deg.

JayW

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Re: The 2018 melting season
« Reply #933 on: June 03, 2018, 12:23:01 PM »
What am i missing ? The first 2 pics are from yesterday. The 3th is for 22 July. There shoud be a 4,5 million square km gap.

It's a purely statistical "forecast".  Areas that have a positive extent anomaly currently will be "assumed" by the model to persist. 

Perhaps the late Dr. Slater's post explains it.  I couldn't quote the original post. Linked here https://forum.arctic-sea-ice.net/index.php/topic,778.msg28212.html#msg28212

Quote
Persistence (light blue line) in the time series plot is an anomaly persistence. At the issue date (d), compute the difference of the observation from the long term mean for that day of year; this is the anomaly. At the forecast date (d+lead_time), find the long term mean and add the previously computed anomaly i.e. you have persisted the anomaly.
The "Forecast" is the method based on regression and integrating the probability of ice survival etc.
Persistence is on the plot in response to a comment that the Forecast provides no added value compared to persistence, but this can't be judged from just one year. My brief bits of work suggest it is non-trivial to beat persistence at sub-seasonal timescales.

The plots on the page should update every day - it's only a 50-day forecast (though I have run longer cases).  I haven't got around to adding conf. intervals ...
"To defy the laws of tradition, is a crusade only of the brave" - Les Claypool

Alexander555

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Re: The 2018 melting season
« Reply #934 on: June 03, 2018, 12:43:32 PM »
It's a 3,5 million square km gap. But the 3th pic looks a lot like the first one. The surface that is covered is the same, and still they are talking about 7,7 million km2 and almost 11 million km2. Some magic.

uniquorn

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Re: The 2018 melting season
« Reply #935 on: June 03, 2018, 12:54:20 PM »
The  kolyma river that runs into the ESS already had some warmer weather recently. Worldview may29 and jun3.

terra/modis true color images adjusted using imagej brightness/contrast 41,256

Koop in VA

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Re: The 2018 melting season
« Reply #936 on: June 03, 2018, 01:11:10 PM »
It's a 3,5 million square km gap. But the 3th pic looks a lot like the first one. The surface that is covered is the same, and still they are talking about 7,7 million km2 and almost 11 million km2. Some magic.

I agree with you and therefore share your confusion.  Let's just focus on one area, the Hudson.  Based on recent historical extent numbers, by July 22 we would expect approximately 80% of the extent to melt out.  On the Slater projection there is very little detectable extent reduction.  So I'm not sure how that is an accurate representation of what the extent will be in 7 weeks.

uniquorn

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Re: The 2018 melting season
« Reply #937 on: June 03, 2018, 01:33:37 PM »
The slater projection is functional once again. Predicting extent of 7.62 million kn^2 on July 22, 2018. Thanks to b.c. For prompting me to update from the meaningless thread.

I'd love to believe my nagging to University of Colorado had some impact
Maybe they posted that image without checking that it updated. Can you send another message?

gerontocrat

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Re: The 2018 melting season
« Reply #938 on: June 03, 2018, 02:19:38 PM »
It's a 3,5 million square km gap. But the 3th pic looks a lot like the first one. The surface that is covered is the same, and still they are talking about 7,7 million km2 and almost 11 million km2. Some magic.

I agree with you and therefore share your confusion.  Let's just focus on one area, the Hudson.  Based on recent historical extent numbers, by July 22 we would expect approximately 80% of the extent to melt out.  On the Slater projection there is very little detectable extent reduction.  So I'm not sure how that is an accurate representation of what the extent will be in 7 weeks.

I am also convinced that the pretty picture is NOT the forecast extent / thickness.

It is the sort of thing that happens when an old package is dug out of the cupboard (as I know to my discomfort).
"Para a Causa do Povo a Luta Continua!"
"And that's all I'm going to say about that". Forrest Gump
"Damn, I wanted to see what happened next" (Epitaph)

gerontocrat

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Re: The 2018 melting season
« Reply #939 on: June 03, 2018, 03:18:00 PM »
I like pretty pictures - here are two.
Concentration maps from NSIDC and University of Bremen.

My old eyes actually find the NSIDC one easier to look at. Central Arctic is looking a bit shaky?

One needs to click on them to see them properly, and then click on them again to see them in full size
"Para a Causa do Povo a Luta Continua!"
"And that's all I'm going to say about that". Forrest Gump
"Damn, I wanted to see what happened next" (Epitaph)

Telihod

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Re: The 2018 melting season
« Reply #940 on: June 03, 2018, 07:05:12 PM »
Speaking about Lena River Delta, then quite high temperatures (+25.3 °C) forecasted for Wednesday.
The temperature anomaly forecast for thursday looks insane. 15-20 C above normal in some parts of Siberia.

bbr2314

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Re: The 2018 melting season
« Reply #941 on: June 03, 2018, 07:21:44 PM »
If the GFS is anywhere close to correct there will be widespread 80-90F+ temperatures beginning over Siberia starting today/tomorrow. By D4-5-6 the 90s are becoming widespread. And the heat is dumping into the Arctic, with 50F readings and rain occurring over the Siberian-adjacent seas and CAB...!





The conservative Canadian shows something similar (but less dramatic).






Richard Rathbone

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Re: The 2018 melting season
« Reply #942 on: June 03, 2018, 07:32:27 PM »
What am i missing ? The first 2 pics are from yesterday. The 3th is for 22 July. There shoud be a 4,5 million square km gap.

They are pictures of different things. One is concentration, the other is probability of extent. Crudely approximating the Slater model says it takes about 50 days to melt out once ice concentration is reliably below 100%. Consequently ice concentration now looks very similar to the model's extent probability in 50 days time during the melt season.

bbr2314

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Re: The 2018 melting season
« Reply #943 on: June 03, 2018, 07:35:12 PM »
What am i missing ? The first 2 pics are from yesterday. The 3th is for 22 July. There shoud be a 4,5 million square km gap.

They are pictures of different things. One is concentration, the other is probability of extent. Crudely approximating the Slater model says it takes about 50 days to melt out once ice concentration is reliably below 100%. Consequently ice concentration now looks very similar to the model's extent probability in 50 days time during the melt season.

It looks like the model is having problems with the Atlantic front as it shows two "fronts" to the ice. I believe this is because the current situation N of Svalbard is unprecedented / therefore it predicts ice where it already isn't even 50 days ahead (you can see this on the map). I would assume it will have the same issues with the Pacific front, where it shows no losses through the end of July...

Pagophilus

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Re: The 2018 melting season
« Reply #944 on: June 03, 2018, 09:28:26 PM »
Thanks, Telihod, bbr.  That mad hot section of Siberia on your forecast post is pretty much the catchment of the Lena River.   Here is some more on the Lena River – yes, I got a bit obsessed, but what with the forecast for the catchment area being what it is, and the maximum period of discharge of the Lena launching right now, the following might be of direct interest. 

I found a fine and relevant paper on-line (Baozhong Liu & Daqing Yang, 2011).    The study, published in 2011, mainly cites 1950-1990 information, but it is probably safe to assume trends have continued or accelerated.  Three takeaways:  Discharge in June has been (i) increasing over time (ii) the flood discharge is beginning earlier in the year and (iii) the average temperature of the water is increasing.  A triple-whammy for Arctic ice. 

June waters are the highest volume by far and averaged just under 3 C for the study period (see the excellent graphs from the paper below).  The actual heat flow of the Lena rises somewhat in June, but the waters are so cool then, that heat flow is actually at its greatest in July and August, when the river is much warmer (ca 13 C and upwards ). 

An increase of heat flow of ca. 40% was observed for June over the 1950-1990 study period, with much lower heat flow increases in July and August.   The Lena is estimated to provide 5-10% of the yearly heat flow into the Laptev Sea.   Roughly extrapolating the trends from the study, then the Lena could be pouring up to about 80% or perhaps considerably more heat into the Laptev during June than it was in 1950, and it is doing so earlier.

A few additional thoughts, some on the comforting side.   The size of the Lena delta is not discussed as a factor in the article.  Data were measured before the river arrives at the delta and then splits into innumerable small channels.  The Lena delta is really big … about 100 km long and 400 km wide.  So it strikes me that it may well take much of the water a while to meander and slowly flood through the delta itself, making its arrival in the Laptev maybe a few days after the discharge station dates, actually arriving on June 5, say, rather than on June 1.  I don’t know if any correction for this factor is made in most studies. 

Also, the river cools as it flows north, so the temperatures at the discharge stations may be higher than the temperatures of that 400 km wide flood that actually enters the Laptev.  Evaporative losses in particular may cool such a huge sheet of water flowing through the delta.

 The paper can be accessed at https://iahs.info/uploads/dms/16848.16-71-76-346-29_Baozhong_Liu-H02Corr.pdf     I have also thrown in a false color mostly IR Satellite photo of the Lena delta from Wikipedia, in part because it is so beautiful. 


If the GFS is anywhere close to correct there will be widespread 80-90F+ temperatures beginning over Siberia starting today/tomorrow. By D4-5-6 the 90s are becoming widespread. And the heat is dumping into the Arctic, with 50F readings and rain occurring over the Siberian-adjacent seas and CAB...!
« Last Edit: June 03, 2018, 10:03:05 PM by Pagophilus »

Pagophilus

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Re: The 2018 melting season
« Reply #945 on: June 03, 2018, 11:26:50 PM »
Aluminium, I really appreciated this beautiful, evocative video ... it allowed me to layer some reality on all the data.  Thanks!


A nice video about Lena and the nature of Yakutia. The video was shot near the Lena delta at this time of year several years ago. In this video, Lena breaks ice and the ice flow begins.

In 2018, front edge of the ice flow will reach Lena delta in 3-4 days.

Nikita

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Re: The 2018 melting season
« Reply #946 on: June 03, 2018, 11:59:27 PM »
...

numerobis

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Re: The 2018 melting season
« Reply #947 on: June 04, 2018, 12:17:24 AM »
That's one of the Svalbard hot spots (you can see the other). They're always there; there seems to be some debate about whether they're real.

https://forum.arctic-sea-ice.net/index.php?topic=2194.0

uniquorn

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Re: The 2018 melting season
« Reply #948 on: June 04, 2018, 12:24:43 AM »
The Lena Delta looks very warm but I think the Kara Sea will be feeling the heat more than the Laptev on Wednesday if the forecasts are correct. (edit:saturday might be a different story..)
Despite cooler weather ice in the east Kara/Barents is already very mobile.

windy.com ecmwf and gfs temperature forecasts for wed jun6
« Last Edit: June 04, 2018, 12:42:59 AM by uniquorn »

bbr2314

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Re: The 2018 melting season
« Reply #949 on: June 04, 2018, 06:26:03 AM »
First GAC of the season? The ATL front is about to get... quite a wallop. GFS upped ante and heat at 00z.