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Messages - RoxTheGeologist

Pages: [1] 2
1
Arctic sea ice / Re: The 2020 melting season
« on: July 02, 2020, 06:34:20 PM »
In case anyone is interested in an on-the-ground perspective on this year's melting season, I put together a time-lapse video using still images from the observatory's webcam here in Alert.  The video covers 12 days from June 18-30, which includes the record-breaking June high temperature of 18.6°C recorded on the 28th.


2
Arctic sea ice / Re: The 2020 melting season
« on: June 17, 2020, 10:02:56 AM »
June 12-16.

2019.

3
Arctic sea ice / Re: The 2020 melting season
« on: April 20, 2020, 10:35:19 AM »
April 14-19.

2019.

4
Antarctica / Re: PIG has calved
« on: January 25, 2020, 07:46:45 PM »
I can't believe i didn't think of that one...  ;D

Well played, Rox.

5
Science / Re: Where are we now in CO2e , which pathway are we on?
« on: January 25, 2020, 06:09:44 AM »
<snip, no need for this at all, don't do it again, please; N.>

You know Jan concentrations are not reflective of what the year average will be.

6
Greenland and Arctic Circle / Re: The Nares Strait thread
« on: December 03, 2019, 08:37:26 PM »
Yeah, winter doesn't really show so far.  :-\
We're definitely noticing it here on station.  We're still getting fog rolling in off the ocean occasionally, which doesn't normally happen by December...

7
Arctic sea ice / Re: The 2019/2020 freezing season
« on: November 19, 2019, 07:32:32 AM »
November 14-18.

2018.

8
Arctic sea ice / Re: The 2019/2020 freezing season
« on: November 03, 2019, 07:07:42 AM »
October 29 - November 2.

2018.

9
Arctic sea ice / Re: The 2019/2020 freezing season
« on: November 01, 2019, 07:05:23 AM »
October 27-31.

2018.

10
Arctic sea ice / Re: MOSAiC news
« on: October 24, 2019, 10:34:54 PM »
Deformation test suggesting there is still significant movement up to 7am this morning. A few buoys reported till 10am but not really enough to run a separate subset. There are 32 in this animation.
The iabp page updates a few times a day(not sure of the exact times yet), the mosaic buoy data less often.

11
..
ASLR, I find your post troubling.
Interesting how you juxtapose 'skill of analysis' to 'peer reviewing'. Is there some systematic bias here, so that peer reviewing implicates a lack of skill of analysis? Or maybe this regards only MICI issues?
Also, would be very interesting if you could say some more on those 'vested interests', as you explicate that AR6 is 'subject to manipulation' here.
While this can be made into a very complex topic as hinted at by RoxTheGeologist's reply, the primary points that I was thinking of include:

1. The dynamics of MISI models are currently poorly understood, and MICI models are only at the beginning of their refinement/calibration process; thus all of this uncertainty means that ice sheet models currently have a wide range of outputs and papers on these different ice sheet models can easily pass peer review by merely stating their input and assumptions that determine their various outputs, whether or not the outputs windup matching what actually occurs in the future.  Thus by 'skill of the analysis' I mean the future correction between the various model projections and what actually occurs (say this century).

2. By 'vested interests' I primarily mean the fossil fuel industry that heavy influence government policies and research funding; where such policies can encourage the conduct of numerous simplified models that do not include the complexity to correctly match MICI-types of required conditions (such as those currently occurring in the Thwaites gateway); and which err on the side of least drama but which easily pass peer review.  If a sufficient number of such overly simplified models are included in the AR6 review, this could/will bias their projections on such topics as sea level rise and ice-climate feedbacks.

12
Arctic sea ice / Re: The 2019/2020 freezing season
« on: October 20, 2019, 08:23:11 AM »
October 12-19.

2018.

13
Greenland and Arctic Circle / Re: The Nares Strait thread
« on: October 07, 2019, 10:54:37 PM »
The winds in the last 24 hours have opened up plenty of water off shore of the station.  I took this this morning on the drive to the lab.  The winds are supposed to continue the rest of the week, which could push things quite a ways out.

14

Thus, I reject calling any of these models "the best".
https://isccp.giss.nasa.gov/role.html
I prefer to think of the scientific method as a process that is continually improving climate change models, and as an example of the next generation (of new & improved) climate change models, I provide the following link to special issues of the JGR Atmospheres publication, update September 13, 2019, focused on the Energy Exascale Earth System Model (E3SM), which is one of the CMIP6 preliminarily indicating that the mean value of ECS is currently over 5C (as discussed earlier in this thread):
Title: "The Energy Exascale Earth System Model"
https://agupubs.onlinelibrary.wiley.com/doi/toc/10.1002/(ISSN)2169-8996.ENERGY1

ASLR, thanks for providing those references to the open source project E3SMv1. I read some of the articles that disclose various details about the modelling work, and want to provide some further insights here.

Unsurprisingly, the model makers continue to have insurmountable difficulties to handle the hydrological cycle/convection issues, as evidenced in the previous generation of CMIP5 models.

It's not astonishing that this particular GCM displays a high ECS, over 5.
"E3SMv1's high climate sensitivity is solely due to its large positive cloud feedback, which causes its net feedback parameter (which quantifies how strongly the 4xCO2 forcing is radiatively damped) to be less negative than all but two CMIP5 models"

My impression is that the model makers delibaretely set this model on a trajectory that is sure to yield a high ECS, starting in around 1990, but that is rather inconsistent with GSTs from around 1960, see the attached figure.
https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2018MS001603

Digging deeper, we go into the art of tweaking/tuning of the models:
"...two adjustments were made to the deep convection scheme in EAMv1. One is to reduce the number of negative buoyancy levels (capeten) that deep convection is allowed to penetrate from 5 to 1. The other is to lift the air parcel launch level (liftlevel) from the model bottom level to 2 levels above. Results showed that these two adjustments, and particularly the rise of parcel launch level, could have significant impact on high clouds and precipitation as well as their vertical structure. They typically act to suppresses deep convection over tropical oceans and enhance convection over lands.
...
Similar to what we saw over the TWP, these EAMv1 configurations have substantially underestimated clouds below 6 km and only show one peak in the upper troposphere. The lack of middle and low clouds over deep convection regions is an issue that needs to be addressed in the future development of EAM"
https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2018MS001350

The model manipulators would like to be able to include 'more convection', but instead have to suppress convection. Convection is not allowed to be as deep in the model as it is in nature - model makers delibaretely chose to suppress convection.

 "The physical processes associated with deep convection, shallow convection along with cloud macrophysics and cloud microphysics are treated via separate parameterizations in EAMv1. In each parameterization scheme there are multiple, often dozens of, uncertain parameters that cannot be constrained by using direct measurements and so they can be tuned within a reasonable range to improve model fidelity."

What they say here is that they have a lack of data on convection, so they have to guess and tune the models with a range of free parameters.

ASLR, you prefer to think of this as a "scientific method"? Is the art of tweaking and tuning a GCM really science? The modelling magicians themselves describe their method in terms of educated guesses that necessitates physical intuition:

"...combining experience, physical understanding, and educated guesses has difficulty anticipating nonlinear relationships between parameters and model output as soon as the number of parameters exceeds a few (Hourdin et al., 2017). The procedure relies heavily on experienced climate scientists and their physical intuition, and the outcome is not always as expected.
https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2018JD028927

I don't deny that GCM models can be useful to get a hunch about where climate is going, but at the end of the day they are nothing more than the educated guesses built on intuition that go into the tweaking and tuning efforts.

15
Arctic sea ice / Re: The 2019/2020 freezing season
« on: September 29, 2019, 07:26:50 AM »
September 24-28.

2018.

16
Arctic sea ice / Re: The 2019 melting season
« on: September 21, 2019, 08:45:06 AM »
In Kane Basin, refreeze becomes obvious.

17
Arctic sea ice / Re: The 2019 melting season
« on: September 21, 2019, 07:33:18 AM »
September 15-20.

2018.

18
Arctic sea ice / Re: 2019 sea ice area and extent data
« on: September 20, 2019, 09:44:18 PM »
A timely point for me to say thank you Geronto and to Juan and ... +1

19
Arctic sea ice / Re: The 2019 melting season
« on: September 12, 2019, 09:15:20 PM »
According to Jim's graphs, ice volume has decreased from 14.9 to 4.7 * 1000 cu. km from mid 80's to now
This represents approx 0.35 * 1000  cu km change / year  at time of minimum volume. Assuming a BOE occurs  when there is 15% of the 16,000,000 max in 1980 and an average thickness of remaining ice of 1 metre, the volume at a BOE would be 2.4 cu km
Therefore , at 0.35 * 1000 loss in vol / year , we could expect a BOE in (4.7-2.4)/0.35 = 6.6 years
This makes a big assumption - that system behavior will be consistent as we reach that limit.

Based on the surprising end of season slowdown this year, I'm not sure that's safe. I'm still mulling hypotheses for what we are seeing and why the dynamics are not falling more in line with your assumptions. 

"Blue Ocean" is a boundary condition, and the retreat of the ice to where it stands now - post 2007 - suggests to me that the dynamics for the ice north of 80 are significantly different from those of the peripheral seas, which is were most significant visible changes in the Arctic have unfolded.

The ice in the CAB and along the CAA by dint of higher latitude appears less influenced by the effects of insolation and atmospheric heat.  It is also *somewhat* protected by the deeper waters of the central basin.

I  think it will require more import of oceanic heat - from the Atlantic side in particular - to push the system out of the state I think it may have settled into.

I think we may see quite a number of years like this - following the pattern of post 2012 - with the ice retreating to the high-latitude bastion we see.

We *could* see a weather driven event driving a season below 2012, but am leaning more and more to a conclusion that this would be anomalous rather than a signal of impending BoE.

I think we need a lot more data on changes in Arctic ocean enthalpy changes, as I'm thinking that and attendant changes in water column structure are what will drive us to a BoE.

20
Arctic sea ice / Re: Home brew AMSR2 extent & area calculation
« on: September 04, 2019, 09:07:31 AM »
A late century drop in extent shows there are still possibilities for second lowest place ( in my limited data set).

Here is an animation of the Arctic Basin compared with 2012. Click to start.

21
Arctic sea ice / Re: Latest PIOMAS update (September 2019)
« on: September 04, 2019, 08:52:08 AM »
The thickness map on 2019-08-31, compared with previous years and the differences. All need a click for full size.

22
Arctic sea ice / Re: Latest PIOMAS update (September 2019)
« on: September 04, 2019, 08:46:25 AM »
Fram volume export was about normal for August: low.

23
Arctic sea ice / Re: Latest PIOMAS update (September 2019)
« on: September 04, 2019, 08:28:36 AM »
PIOMAS gridded thickness data has updated (official volume data not yet). Volume on 31st August was 4.17 [1000km3], second lowest behind 2012 (3.93[1000km3]).

Here is the animation for August.

24
Arctic sea ice / Re: The 2019 melting season
« on: August 27, 2019, 03:28:11 AM »
Heat is radiating out from the cloudtops and above so the polar atmosphere is becoming increasingly unstable as we move into September. The models are struggling to capture what's happening more than 3 or 4 days out.

There's still the potential to melt out dispersed ice on the Siberian side of the pole but the horse race is now for the second or third position. It's a good thing that 2012 is looking unbeatable. The fires in Siberia and the Amazon have been depressing enough. We don't need to see any new sea ice records this year to get the message across that the climate is in trouble.

25
Arctic sea ice / Re: The 2019 melting season
« on: August 13, 2019, 02:53:53 PM »

It would be interesting to know how much ice the Barnes Ice Cap lost this yet. It seems to have been under blue sky for most of July and August.

I love to see some more data on this do you have any.

Wikipedia says it averages about a meter year lost.

This year probably way abbve that

Here is a timelapse from 1984 - 2018 (Will be interesting to see when they add 2019/2020)

https://earthengine.google.com/timelapse#v=70.08059,-74.06429,6.626,latLng&t=0.03&ps=100&bt=19840101&et=20181231&startDwell=0&endDwell=0

Here you are:

26
Arctic sea ice / Re: 2019 vs 2012
« on: August 12, 2019, 08:11:51 AM »
Looking at the most recent extent graphs in the data thread, using a cycling analogy: It kinda looks like the 2012 GAC amounts to a breakaway while 2019 is the peloton, going steady. Will 2019 chase it down? Did 2012 break too early & lose steam? Very interesting!

Here's my graphical scientific representation of 1 potential outcome (exaggerated for clarity):


27
Arctic sea ice / Re: 2019 sea ice area and extent data
« on: August 11, 2019, 08:06:06 PM »
You picked not the relevant chart. Past days at ESS and the Pacific side in general were really cold with massive surface refreezing, but winds have already shifted.

Any evidence of this massive surface refreezing in the ESS or the Pacific side in general would be appreciated.
Yes, your pattern recognition ability to observe the increase in concentration in the pacific edge between the 4th and the 10th of August.
I think you are being rude and you are also incorrect, there was no increase in concentration, but there has been an increase in CLOUDS which creates the artifact you incorrectly attribute to refreeze.

28
Killian, it is not OK because he is doing it too. I think you know that is not an excuse. Be above it.

Covert agression.
Quote
You both have a weird sense of what is aggressive and rude
I'm not going to engage further, sorry to have disturbed the discussion, but these phrases are abrasive and covert agressive in my view:
"First, cherry picking is the domain of the intellectually dishonest"
"This should be obvious."
"Your problem is, rather than be curious, research, investigate,"
"If you are claiming any skill whatsoever in math, analysis, ASI, "
"you should seriously consider not spending any further time on the issue of ASI"

29
Killian, your insults outweigh your insights by a great margin.

30
Arctic sea ice / Re: 2019 sea ice area and extent data
« on: August 07, 2019, 06:51:49 AM »
When your going down the highway at 100mph and another vehicle goes past you at 150mph. :o

31
Arctic sea ice / Re: The 2019 melting season
« on: July 31, 2019, 10:42:18 PM »
I think ESS resistance may also be partly the result of the Beaufort gyre and the southern winds in from the Bering pushing Chukchi ice toward the ESS.

The gyre sends the strongest ice that doesn't melt in the Beaufort toward the northern reaches of the ESS where some at least gets shifted south most years into the ESS.

The winds coming from the pacific into the Chukchi and at least some of the current part of the time are shifting Chukchi ice west on both sides of Wrangel Island.

And if the winds are from the east, some ice arrives from the shift of ice from the Laptev.

The ice in the Chukchi is attacked from the Bering, the Ice in the Laptev is hit with whatever causes the Laptev bite, and the Kara is attacked from the Atlantic - the ESS (in a similar fashion as how everyone talks about the CAB being 'protected' late into the season) is the arctic coastal sea most protected by the other seas around it and can more easily import ice regardless of whichever direction the bias of the melt season is tilted toward.

32
Arctic sea ice / Re: The 2019 melting season
« on: July 26, 2019, 12:29:54 AM »
Repeating myself, the continuation of the current wave, days 6 to 10 can be evaluated using 5-day average over ensemble of forecast, to fail in the conservative side.
What the EC ensembles say is that the Greenland ridge will be strengthened, and the corresponding high will be strongly reinforced. Not as bad circulation as present, but not party time for the pack either. And a very bad news for Greenland

33
Arctic sea ice / Re: The 2019 melting season
« on: July 25, 2019, 09:50:17 AM »
Thanks again Aluminium. Any chance you can increase the height of the cropping so that we can watch the potential collapse of CAA ice in your updates?
I like this size and long sequences of similar data or images. Maybe I'll try to make something another when i have finished trip.

I shifted window by 30 px.

34
Arctic sea ice / Re: The 2019 melting season
« on: July 25, 2019, 05:00:36 AM »
I suspect that melt ponds lasted later in July before the year 2000. The thick multiyear ice would have kept its below -1.5C temperatures longer into the melt season supporting melt ponds later into the year.

I think that explains the paradox of 80N temperatures being lower after Y2k than prior to it. Melt ponds support warmer surface temperatures. An saltwater ice mixture supports negative 1.5 C temperatures at the surface.  The effects of solar heating and atmospheric heat may lead to a higher 2m temperature. The paradox is that melt ponds over thick ice support higher 2m temperatures than drained melt ponds over ice that's almost melted out.

Observe that there has been a significant dip in temperatures the past few days, but 80N to the pole is still above freezing on average.



Yes, I'm sitting in a dining room chair in North Carolina. It has been sweltering here but today we got relief from a cold front that passed through. I am very frustrated by the paucity of data out of the Arctic. I know that my hypotheses could be wrong and would like more data.

35
Arctic sea ice / Re: The 2019 melting season
« on: July 23, 2019, 09:11:25 PM »
Insolation at 90 degrees is greater than at the Equator until the first week in August.

Ought to settle this question.
Except that the albedo of the underlying surface is in large part a function of the angle of incidence of the solar radiation. This is true not just for water but also for sea ice.


Source: Hudson, 2011 https://doi.org/10.1029/2011JD015804

At 90°N latitude at this time of year the solar zenith angle is about 70° so that all the time is spent in the high-albedo part of the curve. South of 30°N, once the sun rises, almost all daylight hours have a solar zenith angle less than 70° and for much of the day less it's than 40°; at tropical latitudes it can obviously reach 0° at high noon. The end result is a great deal of time is spent in the low-albedo part of the curve.

I have no idea how to quantify this difference. My point is that it's not as simple as calculating the theoretical 24-hour solar insolation based on latitude alone and calling it a day.

36
Arctic sea ice / Re: The 2019 melting season
« on: July 23, 2019, 07:21:02 PM »
It is important because we usually assume that the last bit of sea ice will be northward of Ellesmere and Greenland. But after all, perhaps it is not going to the case ? Last year also, sea ice quit the Greenland coast. And studies have found evidences of beaches along northern coast of Greenland during Holocene : https://science.sciencemag.org/content/333/6043/747

Anthropology had long suggested otherwise. We know that both the Dorset and Thule cultures had a presence up the Nares Strait. For the Thule, that presence continued east along the north coast of Greenland, past Cape Morris Jesup, and at least some distance down the east coast, all aided by the Medieveal Warm Period.

AGW has exceeded the climate forcing of the MWP, so there's no reason to expect that Greenland's north coast will be the final refuge of sea ice. For near-shore ice, that honor will almost certainly go to a section of the CAA, bounded on the east by Axel Heiberg Island and on the west by Eglinton and Prince Patrick (essentially, this comprises the Sverdrup Islands). These areas were never settled by the Arctic indigenous peoples, even during the MWP.

It's probably worth noting that the ice in the Sverdrup Islands functions more like fast ice than like sea ice, even in relatively large open bodies of water like the Prince Gustav Adolf Sea. The transition between that CAA fast ice and the CAB sea ice is what allowed the CAA/CAB crack, in fact. The sea ice has become sufficiently unmoored that Arctic-wide winds have applied torque this season, shearing the sea ice away from the CAA boundary. It's difficult to judge the current condition of the crack in the vicinity of the Sverdrups because the area has been under heavy cloud for awhile now. As of the 20th, there was about 50km of almost completely open water to the north of Brock, and I can almost convince myself there's about that much ice rubble north of Ellef Ringnes on the 22nd, under the cloud deck. At some point, clear skies will out. In any case, the PGAS and adjacent channels seem quite robust again this year, but that crack lowers regional albedo and portends their eventual failure.

The last refuge of actual open sea ice will probably be somewhere north of the Lincoln sea, in a narrow triangle described by the Ward Hunt Ice Shelf - Kap Kane Ice Shelf - North Pole.

37
Arctic sea ice / Re: The 2019 melting season
« on: July 23, 2019, 04:01:54 PM »
This looks like the Great Arctic Anticyclone with strong winds and waves and clear skies. The sun still be high in the sky. I expect singnificant ice drop in any metrics.

High in the sky ? Under the anticyclone centre area (at 85N) the sun elevation angle will vary between 15 and 25 degrees.

Ok I know the sun does not set but from elevation angle POV, this is something similar to a January 10th afternoon in Boston, Mass.



Umm....Keywords are I know the sun don't set.

Will you post the Boston graphic so we can count how many hours there literally is no solar Insolation.

That's a bad comparison

38
Arctic sea ice / Re: The 2019 melting season
« on: July 22, 2019, 04:08:56 PM »
Mercator doesn't show evidence of much heat in that saline 30m water. The salinity, alone, will impact melting, however. Thanks for the outstanding animations, Uniquorn. That observable information shows that the Mercator model is pretty damn good in that region despite the paucity of data. Mercator's color gradients are not subtle enough to help us track Atlantic water heat that's possibly contributing in melting the ice.

In 2012 waters were warmer in late July on the Atlantic side but cooler on the Pacific side. Warm air advection into the Arctic from air masses originating from above these above normal temperature waters may play a major role in the late summer melting season. The forecast dipole pattern will import anomalously warm humid air from the Pacific.

Note that the cold water pool that was located southeast of Greenland for several recent years is gone, replaced by warm salty Gulf Stream water. The thermohaline circulation has recovered from the effects of the big Greenland melt years of 2010 and 2012.


39
Arctic sea ice / Re: The 2019 melting season
« on: July 22, 2019, 12:50:17 PM »
First semi-clear view on the ice in the ESS in a good week or so.
Looking for reasons for the low concentration area in the ess, nw of wrangel island prompted an overlay of yesterday's amsr2-uhh and noaa bathymetry.
This also highlights how far open water is developing over deep ocean. Notably in the beaufort but possibly also north of laptev.

40
Arctic sea ice / Re: The 2019 melting season
« on: July 20, 2019, 07:58:48 PM »
After testing yesterday here is large version of unihamburg amsr2-uhh, jun1-jul19.
mercator(model) SST inset, also jun1-jul19.
Best viewed full screen.   edit:click on the square arrows icon bottom right.thanks Niall

41
Arctic sea ice / Re: The 2019 melting season
« on: July 19, 2019, 02:12:28 PM »
Stay on topic please.
unihamburg amsr2-uhh, CAA, jun1-jul18

42
Arctic sea ice / Re: The 2019 melting season
« on: July 17, 2019, 03:09:03 AM »
One interesting thing they did provide, was an updated ice age map. One more argument for 2019 not breaking the record, is that arm of MYI positioned way into the pack. In most other years, it was closer to the edge, where it was much more prone to melt out. By the time open water reaches that MYI, it will probably be too late in the melting season to completely melt it out and reach further into the CAB.
Also - not sure if there is a 2012 version of this chart but I suspect it did not look 'better' in terms of distribution or extent of multi-year ice.
Neven I beg to disagree. I think 2019 is uniquely poised to break the record, given the distribution of sea ice age and subject to the weather of course. Friv may be right about what will happen, but this year is certainly highly vulnerable should the weather turn again.

I provide 3 animations:
* What happened in 2012 between end-June and the late minimum. Lots of old ice was eaten up, especially in the Beaufort/Western CAB. FYI from the direction of Siberia was eaten up despite small initial Laptev bite. Note age was advanced by 1 year in the second image.
* What happened in 2016 between end-June and the early minimum. Lots of old ice was eaten up, especially in the Beaufort/Western CAB.  FYI from the direction of Siberia was eaten up despite small initial Laptev bite.
* Comparing end-June between 2012, 2016 and 2019. This year has much less old ice, and a lot of it is at the border of the Atlantic. With a bit of wind or current, this ice could be gone, the Western CAB could be eaten faster than previous years, and the FYI from Siberia to the pole might offer no resistance, with a larger initial Laptev bite.

Click to animate.

Edit: modified language, fixed 3rd animation.

43
Arctic sea ice / Re: The 2019 melting season
« on: July 15, 2019, 06:19:55 AM »
July 10-14.

2018.

44
Arctic sea ice / Re: The 2019 melting season
« on: July 14, 2019, 02:32:56 PM »
It's still growing.

45
Arctic sea ice / Re: "Stupid" Questions :o
« on: July 04, 2019, 06:53:39 AM »
Interesting questions Rox. A couple of general points (based on my understanding, and I'm happy to be contradicted) before trying to answer some of your specific questions. Sea ice, particularly first-year ice, contains pockets of salty brine. This initially remains liquid when the sea ice freezes, as it has a lower melting point, and some of it then drains out, leaving air pockets. Some remains as trapped pockets of brine, which melt at a lower temperature than the surrounding ice. This, as well as other factors, mean that there are weaker and stronger points within the ice, including potential routes for the water to escape from the surface to the sea. When melt water refreezing blocks these cracks/passages, it doesn't necessarily block them at the base of the floe. If surface melt has started before the ice is all at 0C, the water will refreeze at some point on its way through the floe.

The water in melt ponds can reach temperatures above zero.

Fresh water coming into contact with subzero salt water won't necessarily freeze on contact. It may manage to mix sufficiently before losing enough energy to its surroundings to change state.

Now to your questions:

1. Yes, probably in general, but only at the column where the water drains. The whole floe won't be the same temperature. It is also possible that "warm"  (1 degree?) melt water is able to escape before refreezing through a larger crack produced by dynamic processes.
2. Usually, but not always, I think. From observation, sometimes you see melt ponds drain in areas where it is unlikely that the water has reached 0. The buoy temperature profiles could help with this.
3. Not sure, but I don't think so. See 2 and the point about losing energy to change state.
4. Yes, it must be thick and strong enough, but I think the depth implied by this varies a lot. Sometimes floes melt out very quickly after melt ponds drain, sometimes slowly.
5. Floes are massive, and they are constantly losing and gaining heat in different places, and heat is being transferred through them. The temperature won't be uniform when the pond drains. Either way, the energy needed for the change of state is much greater than the energy needed to raise the temperature a degree or two, so I don't think this has a huge impact on the subsequent rate of melt.

Overall, I think you're underestimating the dynamic nature of the process and the variation in conditions within avsing floe.

46
Arctic sea ice / Re: "Stupid" Questions :o
« on: July 04, 2019, 06:51:31 AM »
Sometimes, I'm sure, a floe with a melt pond 'cracks in two' and the pond drains 'over the new edge', with no regard to how cold the ocean is under the floe.

As provided in this GIF.

Here we see cracks holding meltwater in it in the first frame. In the next frame, we see meltwater on top of the surface but in the crack and around them, it has already drained.

(also the Inglefield Bredning fjord)

47
Arctic sea ice / Re: 2019 sea ice area and extent data
« on: July 03, 2019, 09:26:15 AM »
JAXA ARCTIC EXTENT :-  8,782,986 km2(July 2, 2019)

- Extent is 2nd lowest in the satellite record.
- Extent loss on this day 131 k, 34 k more than the average loss on this day of 97 k.
- Extent loss from maximum 5,488 k, 251 k (4.8%) greater than the average of 5,237 k loss from maximum by this day,
- On average 53.0% of the melting season done, with 73 days to average date of minimum (13 September).

The Perils of Projections.
Average remaining melt would give a minimum of 4.14 million km2, 4th lowest in the satellite record, and 0.96 million km2 above the 2012 low of 3.18 million km2.
Looking at the last 5 years average remaining melt gives a result of 4.19 million km2, also 4th lowest, and 1.01 million km2 above 2012.

The first 2 days in July had much above average extent loss after a mixed picture in the last days of June. Not so much a cliff, more a bumpy steep slope.
2010 has the lowest extent for this date, but quickly faded out of the picture. Another year that promised but did not deliver mega ice loss.


Other Stuff
Weather
A messy picture but mostly unchanged. GFS showing temperature anomalies in a narrow and very slightly lower temperature range of +0.6 to +1.6 degrees celsius. with a mostly modest +ve anomaly over most of the Arctic Ocean for most of the time.

The CAA, Baffin Bay and Hudson Bay are mostly warm, while Western Canada stays mostly coldish.
High +ve anomalies most of the time in Central Siberia and Western Siberia contrasting with long periods of cooler weather over land bordering the ESS.
By Friday Alaska and the far Eastern Siberian Chukotka Autonomous Okrug warm up and stay warm.

The GFS 5 day wind outlook from GFS still show persistent strongish southerly winds from The North Pacific entering the Arctic Ocean via the Bering Strait, but now bending more towards the Alaskan shore. This combined with warmth must impact the Chukchi and the Beaufort to the West and maybe threaten the edge of the CAB.

This 5 day outlook also shows persistent even stronger winds from Western Siberia travelling across the Arctic into the North Atlantic. This wind stays West (looking it from a Russian view) of the island chain stretching from the Russian shore at Ostrov Bol'shevik via Franz Josef Land and Svalbard to the NE corner of Greenland and then down the East coast of Greenland. i.e. likely to help clear out the Kara and Barents and shovel ice into the Greenland Sea to die.  I don't see it significantly pulling ice towards the North Atlantic from the CAB. Indeed the high in the middle of the CAB may send ice north of Greenland from East to West towards the Lincoln Sea. Much of the central arctic also looking dry.

A complicated picture inadequately described above.

We are now in the period of maximum daily extent loss that lasts until mid or late July and then very gradually declines. Extent loss on this day again just above average.
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Tealight's AMSR2 volume and thickness data for June is bad enough to frighten the horses. The PIOMAS volume data for June should be available by this Friday (hopefully). It will be interesting to see if this backs up Tealight's analysis. If yes, what has happened to volume and from that, perhaps more importantly, thickness during June must be a factor in guesstimating the 2019 minimum.
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48
Arctic sea ice / Re: The 2019 melting season
« on: July 03, 2019, 07:10:31 AM »
June 28 - July 2.

2018.

49
Arctic sea ice / Re: The 2019 melting season
« on: July 02, 2019, 05:36:23 AM »
I've included a couple of archived Bremen concentration maps (earliest I could get for July was the 23rd), and as you can see, 2012 and 2016 don't appear definitively "holier" than 2019; at least from what I can tell. (edit - though 2019 has a lot more purely open water.)
Here's the Bremen map for the 3rd July 2012.

50
Antarctica / Re: Sea Ice Extent around Antarctica
« on: July 01, 2019, 11:40:12 AM »
JAXA ANTARCTIC Sea Ice Extent :  13,717,589 km2(June 30, 2019)

The last week started with very high extent gains and finished with - very low extent gains. 2019 is now 2nd lowest in the satellite record, 85 k above 2017 and 668 k below 2018.

- Extent gain on this day 40 k, 46 k less than the average gain of 86 k on this day.
- Extent gain from minimum is 11.293 million km2, 0.731 million km2 (6.1%) less than the average of 12.024 million km2 by this day,
- 75.5% of average extent gain done, with 78 days to the average date of maximum (16 Sept).

The Perils of Projections
Remaining average freeze of the last 10 years gives a max of 17.65 million km2, 0.41 million km2 less than 2017 (the record low maximum year).
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