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Glen Koehler

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Re: The 2019 melting season
« Reply #1550 on: June 07, 2019, 04:42:40 AM »
Thanks pccp82. 
My bad.  The image I had in mind was August 6, 2012.

I guess at that point we were discussing the Great Arctic Cyclone of 2012, and I confused that with the great GIS melt day of July 11, 2012.


Looking at that same view for dates on either side of either event, or July-Aug dates in other years, gives some perspective for how out of bounds both events were.   For example the July 21, 2018 image seems to be typical for recent dates in July-August:     

Trying to save face, I went looking for the average 2meter max temp. forecast for Greenland over the next 3, 5 and 10 days https://climatereanalyzer.org/wx/fcst_outlook/, but those are now not showing anywhere near the extent of GIS surface melt shown in the 2012 images.  Update-as of June 9, GFS forecast on Climate Reanalyer shows majority of GIS above freezing on June 13, not too far behind extensive and record breaking surface melt events on July 11 and August 6, 2012.

    While the updated hourly forecasts have no shortage of positive 2M temp anomalies for Greenland over the next 10 days, the max temp hourly forecast also indicates that the area of GIS surface melt next week won't be anywhere close to the July 11 and August 6, 2012 images.  So either I just blew it with respect to Greenland surface melt coming next week, or the 10-day outlook changed.    ***My mistake in previous post was misunderstanding that the 10-day Greenland surface temp reading was not the average for a 10-day period, but the average of hourly values for the 10th day, i.e. a single day reading not a 10-day average.  As noted above, updated forecast shows that June 13 (which was the 10th day noted in original post) is forecast to have an extent of surface melt similar to record-setting events in 2012.

    That said, the current hourly forecasts still shows the high precipitable water, the persistent crazy high temp. anomalies stretching across long arc of northern Siberia, and for much of the forecast period, also on the North American side.  The forecast shows snow cover depth north of Greenland essentially gone by June 10 2019 (scale is cm).



vs. June 10 in 2018. 


It took until June 22, 2018 for snow depth image to match the June 10, 2019 forecast.  While that does not seem like a cataclysmic difference to my untrained eye, a 12 day earlier loss of snow cover with the sun at near maximum height, combined with many blue sky hours also in the forecast, does seem notable in terms of insolation.   

Enough covering my tracks.  What I definitely did get right and did not exaggerate was an Arctic weather expert ringing the alarm bell about the forecast as it appeared at that time, and the Arctic sea ice situation overall.  Vote climate.
 
« Last Edit: June 10, 2019, 12:54:37 AM by Glen Koehler »

wallen

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Re: The 2019 melting season
« Reply #1551 on: June 07, 2019, 05:23:12 AM »
 A simple viewing of Worldview, show many, many cracks across the basin. Amid these cracks are a great number of holes in the ice (Mini polynas ??) What is the possible impact these may have as the season progresses and no, a lot of them are still there day after day.
« Last Edit: June 07, 2019, 07:39:15 AM by wallen »

Aluminium

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Re: The 2019 melting season
« Reply #1552 on: June 07, 2019, 08:00:03 AM »
June 2-6.

Sea ice area in the Beaufort. There is huge albedo warming potential and clear sky now.

wdmn

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Re: The 2019 melting season
« Reply #1553 on: June 07, 2019, 08:30:49 AM »
Ice in the northern part of Baffin Bay is all slushy and a significant gap has opened between the North East coast of Baffin Island fast ice and the pack ice (not sure how long ago that happened).

Also looks to be melt ponds on some of the inlets (fjords?) along the coast.

jdallen

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Re: The 2019 melting season
« Reply #1554 on: June 07, 2019, 09:45:03 AM »


The North East of the Foxe Basin and Baffin island seem to be in the worst state in the last decade
Here is a the link if you want to step through the previous years: https://go.nasa.gov/2IoGtp8

It's not good, but I had a similar reaction and spent some time a week or two ago shuffling back and forth through the last 8 years of images, and it seemed to me what is happening in Foxe Basin didn't really stand out at the time as being that exceptional.

I'll have another look.  It might be things have progressed more rapidly than in the past.
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Yuha

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Re: The 2019 melting season
« Reply #1555 on: June 07, 2019, 10:02:32 AM »
Here is a tentative ranking of subjective whiteness from whitest to bluest/greenest for June 5th from 2000 to 2019, based on https://go.nasa.gov/2WWvSva these Worldview settings.

1st (lightest): 2004
2nd: 2000
3rd: 2003
4th: 2009
5th: 2006
6th: 2018
7th: 2002
8th: 2008
9th: 2014
10th: 2013
11th: 2001
12th: 2017
13th: 2010
14th: 2005
15th: 2015
16th: 2011
17th: 2019
18th: 2007
19th: 2016
20th (darkest): 2012

And 2012 was just getting started on June 5th and continued to darken over the next days.
I made a gif about it a couple of years ago:


jdallen

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Re: The 2019 melting season
« Reply #1556 on: June 07, 2019, 10:07:50 AM »
I was offering some thoughts about the Beaufort a week or so ago.

It has evolved much as I expected.  Dramatic disintegration, and rapid melt at the margins as the SST's rise into the low single digits - good for stripping 3-4CM/day off of any ice unfortunate enough to be exposed to it.

Images are a week apart.
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b_lumenkraft

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Re: The 2019 melting season
« Reply #1557 on: June 07, 2019, 10:28:32 AM »
Random floe in the Beaufort Sea. You can clearly see how it cracks along the pinkish ice which i suspect to be a frozen melt pond.

oren

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Re: The 2019 melting season
« Reply #1558 on: June 07, 2019, 12:49:10 PM »
In the Beaufort, it's not just insolation and the SSTs, but the movement as well. Bottom melt increases when the ice is dragged through warm water, with no chance of cooling/freshening the local surface water in which the floe is floating.

b_lumenkraft

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Re: The 2019 melting season
« Reply #1559 on: June 07, 2019, 01:18:13 PM »
In the M8 band, you can see a strong darkening of the fast ice in the area around the Lena Delta.

Those who follow the Rammb Slider Thread know, we suspect this to be melting or wet snow or ice.

johnm33

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Re: The 2019 melting season
« Reply #1560 on: June 07, 2019, 02:36:50 PM »
3 days near Amundsen Gulf

https://go.nasa.gov/2WUyc5F

GoSouthYoungins

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Re: The 2019 melting season
« Reply #1561 on: June 07, 2019, 03:16:06 PM »
The system moving north through the Lena River Basin looks set up to really do a number on Laptev Sea ice. The coastal temps should be in the mid 20s and the winds should be perfect for expanding the Laptev bite.

big time oops

FishOutofWater

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Re: The 2019 melting season
« Reply #1562 on: June 07, 2019, 03:17:47 PM »
I might have expected the ice free landward side of the Beaufort to melt out as it has under the east winds in coastal waters but I am surprised by the melting in place towards the center of the gyre that has left large floes separated by open water. There has clearly been substantial bottom melting going on. What's unclear to me is were the ocean heat came from. Was it early melt ponding and clear skies of did some heat come up from below, or both? The loss of ice towards the center of the gyre has been pretty shocking to me. It melted out much faster than I expected.

b_lumenkraft

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Re: The 2019 melting season
« Reply #1563 on: June 07, 2019, 03:19:02 PM »
More Lena Delta.

This time from Sentinel

(Click to play)

FishOutofWater

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Re: The 2019 melting season
« Reply #1564 on: June 07, 2019, 03:24:04 PM »
The low pressure areas on the Siberian margins will cause large volume losses of the fast ice, but don't expect to see large drops in sea ice extent because lows cause ice dispersion. The warm winds off the continent will take a toll, but that toll will not be immediately evident in the JAXA and NSIDC data.

It will likely not be readily apparent how much damage is being done on the Siberian side for a few weeks.

Glenn Tamblyn

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Re: The 2019 melting season
« Reply #1565 on: June 07, 2019, 04:12:50 PM »
<sarc><offf-topic> "even smaller then Trump's tiny little extremities (I'm talking about his hands, jeesh, get your mind out of the gutter!)"

Where do you think his hands are?

</off-topic></sarc>

Sterks

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Re: The 2019 melting season
« Reply #1566 on: June 07, 2019, 04:22:15 PM »
Summary: despite record strong high pressure dominance in the Arctic and abundance of blue skies from late April to first week of June (that’s like 50 days) , record SATs as well, surface melting shows a delay of at least 1 week wrt 2012 or even 2016.
So something is missing from the “lots of insolation” formula to really get the surface melting season going.



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Re: The 2019 melting season
« Reply #1567 on: June 07, 2019, 04:45:23 PM »
Based on what?  Not being argumentative, but wondering your metric for "surface melt".   

There's lots of melting happening.  Dispersion is keeping extent from looking terrible, but still about to pass 2016, and area and volume are ready to tank.

b_lumenkraft

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Re: The 2019 melting season
« Reply #1568 on: June 07, 2019, 05:00:22 PM »

ajouis

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Re: The 2019 melting season
« Reply #1569 on: June 07, 2019, 05:02:31 PM »
What do you all think about the pacification trend that seems to be steadily growing and in this melting season seems to take the role of the atlantification at that point in other years?

Neven

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Re: The 2019 melting season
« Reply #1570 on: June 07, 2019, 05:23:41 PM »
Summary: despite record strong high pressure dominance in the Arctic and abundance of blue skies from late April to first week of June (that’s like 50 days) , record SATs as well, surface melting shows a delay of at least 1 week wrt 2012 or even 2016.
So something is missing from the “lots of insolation” formula to really get the surface melting season going.

Indeed, and as said before, I think it may have to do with melt onset (which starts earlier under cloudy, moist conditions). Here's that paper I referred to, called Melt onset over Arctic sea ice controlled by atmospheric moisture transport: 2016 Mortin et al. I still haven't looked at it properly, to see whether 2010 and 2012 were extra early.

But here's what it's about:

Quote
The timing of melt onset affects the surface energy uptake throughout the melt season. Yet the processes triggering melt and causing its large interannual variability are not well understood. Here we show that melt onset over Arctic sea ice is initiated by positive anomalies of water vapor, clouds, and air temperatures that increase the downwelling longwave radiation (LWD) to the surface. The earlier melt onset occurs; the stronger are these anomalies. Downwelling shortwave radiation (SWD) is smaller than usual at melt onset, indicating that melt is not triggered by SWD. When melt occurs early, an anomalously opaque atmosphere with positive LWD anomalies preconditions the surface for weeks preceding melt. In contrast, when melt begins late, clearer than usual conditions are evident prior to melt. Hence, atmospheric processes are imperative for melt onset. It is also found that spring LWD increased during recent decades, consistent with trends toward an earlier melt onset.

Here's a recent paper on how radar satellite images can be used to monitor melt onset, 2019 Howell et al. From the conclusion:

Quote
Given that the timing of melt onset influences the end of summer sea ice extent in the Arctic (Perovich et al., 2007) and that positive trends in downwelling longwave radiation are linked to positive melt onset trends across the Arctic (Mortin et al., 2016), continuing to provide melt onset estimates is important for understanding the response of sea ice to a warming Arctic.

(...)

In this study, we have shown excellent potential for the use of multi-sensor backscatter from SAR to provide high quality melt onset information over Arctic sea ice which would be of significant value to data assimilation systems. In anticipation of the availability of data from even more SAR satellites with the launch of the RADARSAT Constellation Mission, the multi-sensor γCo approach presented here may offer the most robust approach to estimate the timing of melt onset over sea ice across the Arctic.

Sorry, for the slightly off-topic, but given that May was so sunny and there was thus less atmospheric moisture transport, this could possibly explain why 2019 is lagging when it comes to melt ponding. Because the ice wasn't pre-preconditioned as much as in other years.
« Last Edit: June 07, 2019, 05:37:05 PM by Neven »
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Jontenoy

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Re: The 2019 melting season
« Reply #1571 on: June 07, 2019, 05:51:09 PM »
Interesting article in the Guardian regarding the Carbon Pump caused by zooplankton . Also, ice loss is averaging 10,000 tonnes / second over the past few years.... most of it through the Fram.

"Since the start of the satellite era in 1979, the summer Arctic has lost 40% of its extent and up to 70% of its volume, says Wagner. Other scientists calculate the rate of decline at 10,000 tonnes a second. Much of the multiyear ice is now gone. Most of what is left is the younger, thinner layer from the previous winter, which is easier for the sun to melt and the wind to push around. Wagner expects ice-free summers in 20 to 40 years, which would allow ships to cruise all the way to the north pole"
See https://www.theguardian.com/environment/2019/jun/07/oceans-demise-the-end-of-the-arctic-as-we-know-it

Sterks

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Re: The 2019 melting season
« Reply #1572 on: June 07, 2019, 07:56:25 PM »
Summary: despite record strong high pressure dominance in the Arctic and abundance of blue skies from late April to first week of June (that’s like 50 days) , record SATs as well, surface melting shows a delay of at least 1 week wrt 2012 or even 2016.
So something is missing from the “lots of insolation” formula to really get the surface melting season going.

Indeed, and as said before, I think it may have to do with melt onset (which starts earlier under cloudy, moist conditions). Here's that paper I referred to, called Melt onset over Arctic sea ice controlled by atmospheric moisture transport:

(...)


Sorry, for the slightly off-topic, but given that May was so sunny and there was thus less atmospheric moisture transport, this could possibly explain why 2019 is lagging when it comes to melt ponding. Because the ice wasn't pre-preconditioned as much as in other years.

That’s great research, thanks. it seems that the “perfect” melting season requires several events happening in sequence at perfect timing.
That train seems to be gone by now, but there are plenty of things for a bad season already. Also, when it comes to surface melt the delay is one week or so, not one month (yet).

Sterks

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Re: The 2019 melting season
« Reply #1573 on: June 07, 2019, 08:04:38 PM »
Based on what?  Not being argumentative, but wondering your metric for "surface melt".   

There's lots of melting happening.  Dispersion is keeping extent from looking terrible, but still about to pass 2016, and area and volume are ready to tank.
Just look at Worldview, 
https://go.nasa.gov/2WU5fGY
by this date in 2012 the pack was blueish in CAA, Beaufort sea and the entire Eurasian coast from Bering to Kara sea. Play with the dial of the years to see the difference

magnamentis

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Re: The 2019 melting season
« Reply #1574 on: June 07, 2019, 08:25:48 PM »
<snip, no politics here, thank you; N.>
« Last Edit: June 07, 2019, 11:08:58 PM by Neven »

meddoc

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Re: The 2019 melting season
« Reply #1575 on: June 07, 2019, 08:35:14 PM »
<snip, no politics here, thank you; N.>
« Last Edit: June 07, 2019, 11:09:08 PM by Neven »

magnamentis

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Re: The 2019 melting season
« Reply #1576 on: June 07, 2019, 08:44:04 PM »
<snip, no politics here, thank you; N.>
« Last Edit: June 07, 2019, 11:09:23 PM by Neven »

Jacobus

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Re: The 2019 melting season
« Reply #1577 on: June 07, 2019, 08:48:43 PM »
<snip; N.> Let's stay on topic, please. Or at least have a salient point.
« Last Edit: June 07, 2019, 11:09:53 PM by Neven »

Capt Kiwi

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Re: The 2019 melting season
« Reply #1578 on: June 07, 2019, 09:34:53 PM »
Hope this is relevant/appropriate! I found it very interesting as it illustrates the practical outcome of much of the technical observations discussed here.

https://www.smithsonianmag.com/science-nature/record-breaking-heat-alaska-wreaks-havoc-communities-and-ecosystems-180972317/?fbclid=IwAR0z3e52IlmDd_dKrXOj4X6nx6m0RUh9txe0C-NW0szkjRdmDLVt-1QdEDc#OcPZ1CFsbxUM01c8.99

Thank you all so much btw, I read this thread every day and find it absolutely riveting. Much appreciation!  :)

Michael Hauber

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Re: The 2019 melting season
« Reply #1579 on: June 07, 2019, 09:54:22 PM »
I think one of the things slowing down surface melt is that the high pressure is shallow and not reflected in the uppers.  So plenty of sunshine, but no warming from forced air decent from an upper ridge.  Delayes surface melting means lots of the sunshine is bouncing of shiny ice.  Also a decent portion of the Arctic is covered by two low pressure systems.  These low pressure systems have stronger upper signatures and weaker surface signatures.  So less surface winds, dispersion, ekmann pumping.  But stronger uppers means more cloud and reflecting sunshine away from the ice.  The Siberian low seems to be a bit cut off and not drawing in any substantial warm air, whereas the Laptev low is connected to a strong mass of warm air over Russia and pulling in quite a lot of warm air into Laptev, where substantial surface melt is visible.
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bbr2314

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Re: The 2019 melting season
« Reply #1580 on: June 07, 2019, 09:59:13 PM »
I think one of the things slowing down surface melt is that the high pressure is shallow and not reflected in the uppers.  So plenty of sunshine, but no warming from forced air decent from an upper ridge.  Delayes surface melting means lots of the sunshine is bouncing of shiny ice.  Also a decent portion of the Arctic is covered by two low pressure systems.  These low pressure systems have stronger upper signatures and weaker surface signatures.  So less surface winds, dispersion, ekmann pumping.  But stronger uppers means more cloud and reflecting sunshine away from the ice.  The Siberian low seems to be a bit cut off and not drawing in any substantial warm air, whereas the Laptev low is connected to a strong mass of warm air over Russia and pulling in quite a lot of warm air into Laptev, where substantial surface melt is visible.

None of this makes sense to me. Surface temps have been far higher than 2012 in May. I would continue to assert that most of the ice is incapable of supporting substantial melt ponding and this is why it is less visible than previous years. 

Alphabet Hotel

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Re: The 2019 melting season
« Reply #1581 on: June 07, 2019, 10:55:58 PM »
PSA:

When you do return [B8A*2,B03*1,B02*1] in Sentinel Playground, it makes it pretty easy to spot melt ponds. Ice has a reddish tint while melt ponds are very blue.


Hey that's a great trick. Jakobshavn looks amazing with those settings. I found this way upstream in the main channel:

Neven

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Re: The 2019 melting season
« Reply #1582 on: June 07, 2019, 11:23:34 PM »
Here is almost all of the near real-time evidence we have for melting momentum. I could also post SMOS maps, or even Uni Bremen SIC maps, but that's just too much work.
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Neven

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Re: The 2019 melting season
« Reply #1583 on: June 07, 2019, 11:30:21 PM »
The latest ECMWF forecast shows that high pressure domination is over, but the open water in the Laptev Sea is going to get larger, lots of isobars are pointing towards the Atlantic, there will be small cyclones over the Beaufort and Kara Seas, and things aren't looking good at all for the Greenland Ice Sheet (as already mentioned earlier today).
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Neven

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Re: The 2019 melting season
« Reply #1584 on: June 07, 2019, 11:44:51 PM »
Not unimportant: Northern Hemisphere snow cover almost lowest on record.
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CameraMan

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Re: The 2019 melting season
« Reply #1585 on: June 08, 2019, 02:03:57 AM »
I would continue to assert that most of the ice is incapable of supporting substantial melt ponding and this is why it is less visible than previous years.

Thanks, that was rather my take as well.  Visible ponding is one sign of melt, but given the fragmented and loose state of so much ice, I wouldn't assume fewer ponds automatically signifies less melt.   We'll know soon enough.
« Last Edit: June 08, 2019, 03:51:11 AM by CameraMan »

Rod

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Re: The 2019 melting season
« Reply #1586 on: June 08, 2019, 02:13:47 AM »
I think one of the things slowing down surface melt is that the high pressure is shallow and not reflected in the uppers.  So plenty of sunshine, but no warming from forced air decent from an upper ridge.  Delayes surface melting means lots of the sunshine is bouncing of shiny ice.  Also a decent portion of the Arctic is covered by two low pressure systems.  These low pressure systems have stronger upper signatures and weaker surface signatures.  So less surface winds, dispersion, ekmann pumping.  But stronger uppers means more cloud and reflecting sunshine away from the ice.  The Siberian low seems to be a bit cut off and not drawing in any substantial warm air, whereas the Laptev low is connected to a strong mass of warm air over Russia and pulling in quite a lot of warm air into Laptev, where substantial surface melt is visible.

None of this makes sense to me. Surface temps have been far higher than 2012 in May. I would continue to assert that most of the ice is incapable of supporting substantial melt ponding and this is why it is less visible than previous years.

I agree with bbr on this one.  Zack says that the May 2019 arctic air temperatures were the highest on record.  I'm going to go with him when it comes to evaluating arctic conditions. 

magnamentis

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Re: The 2019 melting season
« Reply #1587 on: June 08, 2019, 02:17:50 AM »
I would continue to assert that most of the ice is incapable of supporting substantial melt ponding and this is why it is less visible than previous years.

Thanks, that was rather my take as well.  Visible ponding is one sign of melt, but given the fragmented and lose state of so much ice, I wouldn't assume fewer ponds automatically signifies less melt.   We'll know soon enough.

+1

something that i'm trying to convey for the last 3 years, floes are small and ice is fractured, hence water will drain into the ocean on a large scale.

further as far as i can see temps are at or above 0C 23-24h per day and no-one can tell me that at 0-1C ice does not melt, especially at the edges where salty sea-water helps in the process and edges there are many nowadays.

Rod

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Re: The 2019 melting season
« Reply #1588 on: June 08, 2019, 02:20:20 AM »
I also agree that different types of ice support different types of melt ponding.  The visible satellite has a limited resolution.  The below image is a close up of the east side of the Hudson. In it, you can see lots of melt ponding on the fast ice along shore and on the fast ice attached to the islands. 

The ice floes in between do not show melt ponding even though they are receiving the same weather. But, that does not mean they are not wet on top.  It just means the satellite can't see it.  Take a look at the Barrow webcam earlier this spring.  That ice had lots of small melt ponds, but they did not show up in the satellite imagery.
« Last Edit: June 08, 2019, 02:39:09 AM by Rod »

magnamentis

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Re: The 2019 melting season
« Reply #1589 on: June 08, 2019, 02:52:36 AM »
I also agree that different types of ice support different types of melt ponding.  The visible satellite has a limited resolution.  The below image is a close up of the east side of the Hudson. In it, you can see lots of melt ponding on the fast ice along shore and on the fast ice attached to the islands. 

The ice floes in between do not show melt ponding even though they are receiving the same weather. But, that does not mean they are not wet on top.  It just means the satellite can't see it.  Take a look at the Barrow webcam earlier this spring.  That ice had lots of small melt ponds, but they did not show up in the satellite imagery.

100% correctly observed.

after it takes a certain size of meltpond to be visible with current sat-resolutions and for this to happen melt ponds have to sit on stable and large enough floes.

often meltponds are in or build some kind of "valleys" on such floes, hence they have a very much lenghty form factor and floes that allow for all this to happen exist less and less and if they do exist they can perhaps hold 1-5 smaller ponds while in the old times when the ice was one
homogeneous shield that water simply stayed on top and could not drain so easily over one of the edges and/or through one of the leads and holes.

GoSouthYoungins

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Re: The 2019 melting season
« Reply #1590 on: June 08, 2019, 03:10:42 AM »
The latest ECMWF forecast shows that high pressure domination is over...

Yes. I wonder if the worst weather for ice is long periods of high pressure followed by some cyclones to stir things up, and then back to high pressure, etc.
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Sterks

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Re: The 2019 melting season
« Reply #1591 on: June 08, 2019, 04:08:31 AM »
I would continue to assert that most of the ice is incapable of supporting substantial melt ponding and this is why it is less visible than previous years.

Thanks, that was rather my take as well.  Visible ponding is one sign of melt, but given the fragmented and lose state of so much ice, I wouldn't assume fewer ponds automatically signifies less melt.   We'll know soon enough.


+1

something that i'm trying to convey for the last 3 years, floes are small and ice is fractured, hence water will drain into the ocean on a large scale.

further as far as i can see temps are at or above 0C 23-24h per day and no-one can tell me that at 0-1C ice does not melt, especially at the edges where salty sea-water helps in the process and edges there are many nowadays.
Wow the pseudo-science cavalry join together.
The SMOS info, see SMOS thread, or the high compactness also not good enough?
And why can we see many places (of limited extent at the moment) where the 2019 degraded soup that you describe can hold surface melting in the traditional way?

binntho

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Re: The 2019 melting season
« Reply #1592 on: June 08, 2019, 05:06:14 AM »
Wow the pseudo-science cavalry join together.

Well said sir!
because a thing is eloquently expressed it should not be taken to be as necessarily true
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subgeometer

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Re: The 2019 melting season
« Reply #1593 on: June 08, 2019, 05:28:07 AM »
Interesting info on the onset of surface melt from Neven. At least there may be one factor in melt that's not maxxed out and might retard things to a degree. 2007 and (and esp)2012 spent most of the season among the lowest in the NSIDC compactness chart, whereas 2019 is in the middle, though its early days yet(and large areas of open water are growing and warming into potential death traps for mobile ice)

I disagree with Magnamentis etc that melt ponding can no longer occur significantly The advancing blue zone in the Laptev Sea fast ice shows how far surface melt is advancing into the pack from that direction. And beyond the fact ice  there are plenty of floes >5km across amongst all but the most parlous mush, and much larger eg in the Beaufort. How can something that size not support ponding and hold together at all? Swirls of slush melting in the water are apparent, but ponding, at least to my eye, is not yet(either in the northern Laptev, or the Beaufort etc).


Rod

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Re: The 2019 melting season
« Reply #1594 on: June 08, 2019, 05:51:25 AM »
Wow the pseudo-science cavalry join together.

Well said sir!

Fair enough.  Tell me more about SMOS in the summer and how accurate it is.  And Compaction?  Please explaine how microwave data works?   Dividing one uncertain number by an even more uncertain number does not give you any real data.

That is pseudo-science.   But carry on please. 

Rod

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Re: The 2019 melting season
« Reply #1595 on: June 08, 2019, 05:58:42 AM »
Interesting info on the onset of surface melt from Neven. At least there may be one factor in melt that's not maxxed out and might retard things to a degree. 2007 and (and esp)2012 spent most of the season among the lowest in the NSIDC compactness chart, whereas 2019 is in the middle, though its early days yet(and large areas of open water are growing and warming into potential death traps for mobile ice)

I disagree with Magnamentis etc that melt ponding can no longer occur significantly The advancing blue zone in the Laptev Sea fast ice shows how far surface melt is advancing into the pack from that direction. And beyond the fact ice  there are plenty of floes >5km across amongst all but the most parlous mush, and much larger eg in the Beaufort. How can something that size not support ponding and hold together at all? Swirls of slush melting in the water are apparent, but ponding, at least to my eye, is not yet(either in the northern Laptev, or the Beaufort etc).

I think you misunderstood the point.  No one is saying melt ponding can not occur - it clearly does.  The issue is whether it can be seen in the satellite data.

Tor Bejnar

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Re: The 2019 melting season
« Reply #1596 on: June 08, 2019, 06:03:05 AM »
There was a comment in the Nares thread about how much snow appears to top the floes moving through the strait.  I wonder if one component of "less apparent melt ponding" is thicker snow cover.
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Re: The 2019 melting season
« Reply #1597 on: June 08, 2019, 06:22:47 AM »
Thankyou b_lumenkraft for those Sentinel settings. Something  I've been wanting to explore

Here are some images using them of the Laptev region with a section of fragmented ice north of the bite blown up to so 1cm is about 500m. Are those melt ponds on the blocks or some other feature?


Michael Hauber

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Re: The 2019 melting season
« Reply #1598 on: June 08, 2019, 06:39:28 AM »
Channel 3-6-7 has no problem seeing wet surfaces on the thinnest of ice.  Have a look at the url=https://worldview.earthdata.nasa.gov/?p=arctic&l=MODIS_Terra_CorrectedReflectance_Bands367,VIIRS_SNPP_CorrectedReflectance_TrueColor(hidden),MODIS_Aqua_CorrectedReflectance_TrueColor(hidden),MODIS_Terra_CorrectedReflectance_TrueColor,Reference_Labels(hidden),Reference_Features(hidden),Coastlines&t=2019-06-07-T00%3A00%3A00Z&z=3&v=-2661509.2245357623,1060293.7737951968,-1262725.2245357623,1710533.7737951968]Bering Strait[/url] at the moment.  Very thin ice, clearly on its last legs and fractured into individual floes to small to be spotted individually is still clearly red and wet on the surface. 

I do also look at Microwave imagery for evidence of melt ponds, but that is much less sensitive and picks up only strong surface melt ponds.  Too early to spot anything this year or other years as at this date using this method, and from past experience thick ice can hold deeper melt ponds that show up much better on this method, with occasionally fast ice nearly disappearing from sensor view due to the amount of melt water it can hold on top.  In contrast I have very rarely spotted melt ponds  using Jaxa near the edge of the ice field, and its usually only early in the season that melt ponds can be seen in such imagery as the ponds drain later in the season.
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binntho

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Re: The 2019 melting season
« Reply #1599 on: June 08, 2019, 06:54:55 AM »
There was a comment in the Nares thread about how much snow appears to top the floes moving through the strait.  I wonder if one component of "less apparent melt ponding" is thicker snow cover.

I was thinking the same thing.
because a thing is eloquently expressed it should not be taken to be as necessarily true
St. Augustine, Confessions V, 6