Support the Arctic Sea Ice Forum and Blog

Show Posts

This section allows you to view all posts made by this member. Note that you can only see posts made in areas you currently have access to.


Messages - Michael Hauber

Pages: [1]
1
Arctic sea ice / Re: The 2019 melting season
« on: August 14, 2019, 06:25:25 AM »
Not sure I've ever seen +4 temps at 850hp reach all the way to the North Pole.



For a fun comparison the current 850hp temp where I live in the subtropics is about +6, and forecast top temperature at surface level is 21 C.

2
Arctic sea ice / Re: 2019 vs 2012
« on: August 09, 2019, 06:11:34 AM »


Why are you commenting if you don't understand the theory?

I know enough about ENSO to correctly identify which years were el nino influenced and which were not.

3
Arctic sea ice / Re: 2019 vs 2012
« on: August 09, 2019, 05:58:48 AM »

It is no accident the lows of '05, '07, '10, '11 '12 and '16 are all associated with EN's.

Nino 3.4 index for September for the above years:

2005 -0.08
2007 -1.04
2010 -1.56
2011 -0.76
2012 +0.44
2016 -0.46

Warmest nino 3.4 index for 12 months prior to September for the above years:

2005 +0.71
2007 +1.1
2010 +1.81
2011 -0.23
2012 +0.44
2016 +2.57

None of those minimums occurred during el nino events.  Four of those six minimums occurred within 12 months after an el nino event, which is only one more than half.

4
Arctic sea ice / Re: The 2019 melting season
« on: July 23, 2019, 12:07:34 AM »
Going Sea by Sea:

Beaufort - large amounts of dispersion, but also mostly larger floes, and weather has mostly been cooler in this region.  I suspect the ice is thicker and more durable than might be assumed at first glance looking at the broken appearance.  However the forecast high will hit this hard with heat and sun going into all that open water between the floes.  In 2012

Chukchi - the big story of the season with an ice boundary much further advanced than anything seen before.  Ice floes are much smaller than Beaufort, there is a lot of dispersion on the edge.  The forecast high will hit this area with heat, sun and wind, and the ice slaughter will continue.

ESS - Very weak ice, and an ice edge that has advanced further than 2012, but not as far as 2007.  Bore the brunt of early heatwaves, has been under low pressur and clouds since and the forecast continues this.  Ice would appear to be too weak to survive even under mostly favourable conditions.

Laptev - had a massive start early in June, but has been partly protected in the last few weeks.  A burst of warm air is pushed into this region with a sharp low early in the forecast which will do some more damage, but overall I see this region has fallen behind 2012 which had significant dispersion deep in the pack.  This year is a little like 2007 which had weaker melt in this region due to weather patterns pushing ice towards the Atlantic side, however NE passage remained blocked in this region in 2007 even at minimum and is now open (or at least very close to it).

CAB - the mystery.  Previous heat hasn't impacted this region as much, although there have been at least a couple significant warm incursions.  The forecast hits this region quite hard and it will be under serious assault from at least the Chukchi direction.  Perhaps the ice in this region is healthy enough to slow the melt down and prevent a record.  Or perhaps I'm clutching at straws.    Have a look at this region and compare to some other years.  Dispersion starting on top and left edge, 2012 maybe a little ahead, especially towards top right.  2016, 2008 and 2010 also have some significant dispersion much deeper into this region.  And 2010 wasn't a big melt year so no guarantees that this means anything.

5
Arctic sea ice / Re: The 2019 melting season
« on: July 19, 2019, 12:13:43 AM »
Since the 2012 GAC is being argued about, I thought I'd mention a couple of research papers into the question:

Parkinson and Comiso
Claim that the 2012 record was a result of the combination of preconditioning over previous decades of ice loss making the Arctic more vulnerable, and effectively put most of the blame for the record on the GAC.  The GAC sheared off a large area of ice which then melted and also made the remaining area of ice more vulnerable to melt.

Zhang et al
Claims that much of the sheared off ice would have melted anyway and that the GAC resulted in only a 150k reduction in final extent.  This is based on modelling the sea ice melt with and without the GAC.

Modelling of Arctic sea ice is off course far from perfect.  From my observations the process of shearing off the ESS section of the ice pack had well and truly begun from late June, with cyclones in June and July causing dispersion deep within the pack that enhanced melt in an area which eventually melted out totally in the GAC to shear off the ESS section.

6
Arctic sea ice / Re: The 2019 melting season
« on: July 05, 2019, 07:43:21 AM »
I've often suspected a repeat of 2007 conditions may result in near ice free conditions, considering that 2007 had to contend with a much larger proportion of thicker multi-year ice than has been around since then.

With a lot of heat in June, a strong retreat in the Pacific and with more compaction and less dispersion evident this year seems to have some similarities to 2007.  In general there is more dispersal of ice currently in the ESS region than there was same day 2007

NSIDC ice comparison shows a strong retreat in the Pacific centre.  Compared to 2007 this year is retreating faster towards Chukchi and not as fast towards ESS.  Similar speed of retreat in Laptev which suprises me due to the severity of both wind and heat in that sector this year.



Temps at 925hp show how much hotter this year is than 2007.  The strongest heat is more towards Laptev this year, but is overall noticeably warmer.





Wind driven compaction and export was an important factor in 2007.  There were some quite strong winds over the Pacific sector that drove the ice towards the Atlantic.  Keep in mind Ekman transport will push the ice to the right of the wind vector so the ice will travel much more away from the Chukchi region than the roughly right angle winds suggest.



In contrast this year winds have definitely been milder over the Pacific sector, although there have been some very strong winds towards Kara and some moderate winds near Laptev.



Overall more heat, but less help from winds than 2007.  Assuming the pattern continues, is that enough to set up a similarly devestating melt season as 2007, and what impact would that have with the multi-year ice greatly reduced?

Is the fact that ice retreat towards Laptev is only similar to 2007 and not well ahead despite apparently much hotter conditions and solid wind important?  Was the ice there thicker this year?  Or was the heat perhaps not as strong as shown in the models (I believe a lot of extrapolation is involved producing these temperature maps).





7
Arctic sea ice / Re: The 2019 melting season
« on: July 03, 2019, 12:08:47 AM »

This is not something that needs to be 'balanced'. The implication is that things aren't really that bad, because look, 2012 was much worse. This is what annoys people and brings out the troll accusations. Because practically no one is saying - as of yet - that 2019 is looking much worse than 2012 in every respect. Things simply look very bad, that's all, but we don't know what the next weeks will bring.


But I'm not saying things are not as bad as 2012 in every aspect either.  I'm saying that in one aspect things aren't as bad as in 2012, and definitely acknowledge than in at least one other aspect - mid to late June heating this year is substantially worse.  Balance is to take note of both facts.  And then the hard part is how to put them together, one person might see the heat as being more important and think it likely that we are overall worse than 2012, and another might think dispersion is more important and think we are overall not as bad as 2012.  I'm leaning towards second, but its far from certain and people who think the heat is more important could easily be correct.

8
Arctic sea ice / Re: The 2019 melting season
« on: July 01, 2019, 06:52:37 AM »

I don't know about the trolling, but I agree that calling a shift of bad conditions from one location to another 'improved conditions for ice retention' is pushing it.

It is a shift of the heat from an area where it is easy to melt the ice to an area where it is hard to melt the ice.  It is an overall reduction in the intensity of the heat with the area forecast to be at or above +10C anomalies a fraction of what we say several days ago.  It is an increase in cloudiness due to upper level low pressure activity which is already very obvious in MODIS vies of the Arctic.

I'm puzzled as to how anyone could not recognise the substantial reduction in intensity of heat within the arctic evident in these two frames:





Quote
When everything falls silent, and low pressure/clouds takes over completely, no dipole, no clusters of isobars, that's when we have 'improved conditions for ice retention'. I'm not seeing it in the D1-D6 forecast. Maybe after that.

Considering how extreme conditions were for much of June we don't need perfect ice retention conditions to note an improvement.  Pretty much any type of weather would actually be an improvement.

9
Arctic sea ice / Re: The 2019 melting season
« on: June 28, 2019, 01:16:17 AM »
Forecast for 850 temps is a signfiicant drop, from extreme values that appear to be close to peak now, to something still warm, but probably reasonably close to average for the last 5 years.  At extended range low pressure takes over, reminding me of 2010 which had a blistering start in June, but stumbled to be an also ran as cloudy low pressure weather took over in July.  Cooler low pressure is set to take over in ESS/Laptev which will test the area hit hardest by the heat with potential dispersion and mixing, but will cool and slow down surface heating.  Warmer conditions will move towards Chukchi and Beaufort.  Beaufort has been quite cool through June but had a really early melt in May, and has a fair bit of dispersed ice.  I think the ice is likely in quite good condition for being as dispersed as it is, and now it will be tested with heat, which will be able to take advantage of all the open water in between the floes.

Overall in 2 dimensions the ice looks more like 2007 for this date, and in better shape than 2012.  Hard to be sure about what the 3rd dimension is doing, but I think it if it was really bad then we'd see evidence in 2 dimensions with worse conditions around the edges.  If the ice is a good distribution of thicker in the middle and thin around the edges than extent and area should drop with similar speed as thickness.  If the ice is uniform thickness everywhere then you can get all the ice melting at once as can happen in a small lake.

I expect July will see a continuation of top 3, with 1st possible, but a large lead in 1st unlikely.  If low pressure takes over as hinted at by extended maybe even dropping out of top 3.

10
Arctic sea ice / Re: The 2019 melting season
« on: June 26, 2019, 12:22:14 AM »
I think it has no chance.

5th or 6th IMO

In what criteria?

Thats almost impossible at this point.

The weather would have to abruptly go to cloudy and cold and not change back.

I recall 2010.  That was a massive year for volume drop, with a substantial record set for PIOMAS.  June 2010 was a brutal melt month and at about this time extent was well clear of 2007, with a record well on the cards.  Most of the drop in volume anomaly happened in June, and I remember looking at the numbers at the end of June and noting that if the anomaly drop was repeated in July we would be getting pretty close to 0 volume.  The size and speed of the drop caused a few comments in the blogosphere at the time.

First week in July cooler low pressure dominated weather set in, and the melt season stuttered.  2010 found its way to 3rd at the time for extent, or 10th if you include the years 2011-2018.  I think a repeat this year might put us somewhere near 6th this year.  The break from pre-2007 to post 2011 was huge so I think a repeate would put us further back then 3rd, but given 9 years of general warming since 2010 I'd think we'd do better than 10th.  The volume record set in 2010 was beaten in both 2011 and 2012, but has not been beaten since.

I certainly consider top 2 a much better prediction than 5th or 6th, but I wouldn't go so far as to say 5th or 6th is almost impossible.  Maybe a roughly 1 in 10 chance.

Extended GFS does have a low pressure taking over around day 10, but EC doesn't agree.  Extended GFS has forecast something similar for a while, but it seems to be something that is staying out near day 10 and not coming closer.

11
Arctic sea ice / Re: The 2019 melting season
« on: June 21, 2019, 12:27:00 PM »

My understanding was that high pressure means clear skies so high insolation. But is 1040 hpa worse for ice than 1030 hpa, all else being equal ?

Larger high pressure means either colder denser air (the strongest high pressures on earth are ultra cold air over Siberia), or a stronger upper ridge.  If its a stronger upper ridge it means stronger descent of air, and air heats up as it sinks.  This high has a strong upper ridge associated with it.

12
Arctic sea ice / Re: The 2019 melting season
« on: June 21, 2019, 01:46:24 AM »
850hp air temps over last 7 days:



I had a look at 4 weekly periods (1st to 7th, 8th to 14th, 15th to 21st, 22nd to 28th) from each of 2007,2010,2011 and 2012, being years I remember having strong surface melt in June.  Hottest I could find was 2007:



13
Arctic sea ice / Re: The 2019 melting season
« on: June 20, 2019, 06:34:30 AM »
Michael Hauber. If there's a real increase in area in the Beaufort Sea it came from elsewhere, there's no new ice forming. It came from the CAB, which hasn't had an area reduction, so trhe concentration has to have decreased.

Definitely came from CAB..  CAB has not had a decrease in area detected by incidents - therefore concentation as measured by instruments did not decrease.  Two possibilities.  The ice moving from CAB to Beaufort was replaced.  Current weather patterns suggest that ice from Laptev is moving towards the CAB, so I am sure this accounts for at least part of the reason why the CAB did not lose area.  Its also possible that CAB lost real area, but this was not detected by instruments.  I can't see anything on MODIS, but thats no guarantee.  Either way there is no contribution to dispersal as measured by instruments due to this effect.

14
Arctic sea ice / Re: The 2019 melting season
« on: June 20, 2019, 02:25:29 AM »

Quite a little cyclone this created! As others pointed out, the primary reason is clear in the data: dispersion. E.g. Look at Wipneus' regional extent charts for the Beaufort.


And what is the reason that Beaufort extent jumped quickly up? A storm dispersed ice from a compact region into open water --  see any of the several recently posted animations of the region. The end result of this dispersion will almost certainly not be less ice melt, but more.

I realize that all this has been pointed out previously, but I agree with TeaLight and just want to make sure that these obvious points have not been obscured successfully.

Don't hang your hat on extent values, especially short-term blips.

Look at both the extent and area charts for Beaufort.  They both jumped up.  So not more dispersion, just more ice in general in that location.  Recent weather patterns have been pushing ice from Laptev direction (where rapid ice loss is evident) and towards Beaufort.  If you compare concentration maps of today with those a week or so ago the obvious increase in low-concentration ice is around Laptev and ESS, and corresponds to melt ponds.

I put zero importance in short term changes in extent, but do suggest that they be attributed to the correct reason, being cloudy weather in Kara delaying ice melt in that region for a short period of time.  The region will melt out soon enough, and slow melt in Kara is due to cold air being exported from Arctic in that direction allowing warm air to move into the Arctic from elsewhere.

15
Arctic sea ice / Re: The 2019 melting season
« on: June 19, 2019, 12:50:30 PM »
Following the recent accusations directed at me, Neven suggested I state that I am concerned about AGW, do believe the ice is melting.  I believe that the IPCC reports are the best scientific assessment of what is likely to happen in the future.  I also accept that there are serious risks associated with climate change.  While I believe it is unlikely that impacts of climate change will be dramatically worse than what IPCC predict, I believe that the low possibility of such extreme aspects should be taken into consideration, and we should act strongly on climate change to reduce the risk of nasty surprises.

If some are surprised by the intensity of the reaction to my recent comment, my opinion is that the intensity was motivated by past arguments that I have pursued very strongly in the consequences section of this forum, especially around claims that IPCC is seriously understating the risks. 

16
Arctic sea ice / Re: The 2019 melting season
« on: June 11, 2019, 08:54:27 AM »
A tale of two Arctics.  Warm air has pushed into Siberian and Laptev sectors in a big way with serious surface melting.  Beyond that the Arctic is mild with minimal surface melting.  Beaufort amazes me with many large floes and little to no small floes - Little visible sign of melting but plenty of open water.

Forecasts show a strong temperature contrast with the coolest air still at -8C at 850HP according to GFS, and the warmest air above +12C.  Definitely one of the larger temperature contrasts I've seen.

17
Arctic sea ice / Re: The 2019 melting season
« on: June 05, 2019, 01:17:46 AM »
June 4 Channel 3-6-7.  Significant amount of red showing in Laptev area.  I'd say 2012, 2015 and 2016 all have more red (Arctic wide) as at June 4 than 2019.  Hard to be sure about 2012 due to cloud cover, but given the events of that year I'm more bullish guessing on red below the clouds for that year.  Red reflects surface melting.


18
Arctic sea ice / Re: The 2019 melting season
« on: May 24, 2019, 01:32:41 AM »
For those interested in what happened in the Beaufort, back in 2016 (so as to compare to this year's siutation), I wrote about it extensively on the ASIB. Here's a blog post from May 21st, with links to previous blog posts in the first paragraph.

The maps look very similar, so much so that one would be tempted to think there is something causing the ice to stay glued to the coast, all the way up to Utqiaġvik. But there's no "Chukchi polynya" now, with open water all the way to the Pacific and far into the Chukchi, meaning there is less ice to be blown back towards the coast, should the winds turn.

And the winds are another similarity. Both the weather forecast back then and the one this year show a change in the set-up that caused the early Beaufort opening, around the same time. However, this year there may be a return to that set-up next week.

So, wondering if there will be open water all along the Alaskan-Canadian coast before July this year...

My guess there are two factors behind this 'ice bridge'.  First there seems to be more fast ice on the coast - presumably the sea bed is shallow and/or perhaps currents favour colder water below the ice.  Second I suspect the beaufort gyre and shape of the coast line combine.  Ice I think tends to move away from the coast towards Chukchi and towards CAA, but towards the coast near this ice bridge.  As soon as temps warm enough that ice can't form these two areas become ice free as ice moves away from the coast, but the ice bridge area needs temps to warm enough that substantial ice in the Beaufort at large is melted and there is no longer enough ice to move towards the coast.



(using paint so hard to get a nice curve to better illustrate the ice flow)

19
Arctic sea ice / Re: The 2019 melting season
« on: May 23, 2019, 12:05:05 AM »
Here is a recent photo of sediment.



From Cat 6 blog.

Of course not all sediment will look exactly the same.

20
Consequences / Re: Weird Weather and anecdotal stories about climate change
« on: November 29, 2018, 02:22:38 AM »
The Sydney floods (plus gales and hail and fairly cold conditions, none of which were exceptional but still unusual), Intense heat in Cairns, serious bushfires, dust storms yesterday, dust storms mentioned a week or so ago in this thread.  All related to the same pattern of an unusual sequence of low pressure systems through Australia and out into the Pacific, which may be related to Southern Polar Vortex issues.

21
Antarctica / SH Polar Vortex
« on: November 23, 2018, 06:34:28 AM »
Also posted in weird weather thread in consequences.

Furthermore there is a remarkable string of strong low pressure systems belting across Australia and well into the Pacific.  Got some members of the weatherzone forum scratching our heads not sure what to make of it.  The pattern might have implications for ENSO, as I think its part of why a significant WWB is forecast to commence shortly.

I've been doing some hunting around to see if I can explain it as some sort of polar vortex variation.  Due to this forum I know more about the northern polar vortex than the southern which impacts on my weather.  Of course Antarctica hasn't had no real trend towards reducing sea ice, but has had a couple years of fairly low values.  Start of a similar change in SH to what has happened in NH?  Maybe some connection to changes in the Ozone hole....

Does anyone follow the SH polar vortex much and know if anything is going on that might explain part of this weird weather?

22
Arctic sea ice / Re: The 2018 melting season
« on: September 04, 2018, 11:33:26 PM »
Not sure if this is the correct thread; forgive me if it is not!

What happened to the predictions of a GAC from the last week of so?

There is still a pretty decent cyclone going on around Laptev/Barents.  Not far off the intensity forecast a while back.  Pretty large system getting up towards the GAC 2012 size, but a fair gap in intensity.

The forecast Friv and I commented about just a day or so ago of a huge heat influx has moderated.  The forecast had a perfect alignment of strong high and low plunging a strong warm front in between directly into the Arctic.  The alignment has shifted a bit and the warm front now strikes a fairly glancing blow.  Until the next model run....

23
Arctic sea ice / Re: The 2018 melting season
« on: August 29, 2018, 11:01:54 PM »

I don't think it is fair to say this year was GAC-less, the June event was about as impressive as 2012, it just happened far earlier in the melt season.

The June event was close when considering minimum pressure.  Not very close when considering size of circulation, or duration.

24
Arctic sea ice / Re: The 2018 melting season
« on: August 29, 2018, 12:02:07 AM »
MODIS 3-6-7 channel shows nearly total cloud cover of the Arctic, but what shows in between the clouds suggests that the surface is mostly frozen and that the surface melting season is mostly over.

A thought on the current cyclone, forecast to continue for the forseeable future.  SSTs are close to their seasonal max now, mixing and winds will cool them faster (but clouds keep the heat in).  But mixing may also push some of the heat below the surface to impact the start of the freeze season.  In contrast if the heat is left undisturbed near the surface in calm conditions it might be lost much quicker as Arctic night falls.  Ekman pumping will produce upwelling mostly in the central ice pack and presumably this will need to be balanced by downwelling somewhere in the Arctic fringes which might also push heat below the surface.

25


Even volume? Even volume? You are aware the world does occur in 3D, right? How could you prefer extent more than volume?

I think I explained it just fine in my last post.  Is there some part of it you didn't understand.

There is a place for it, but the top indicator has to be volume...cuz it is, like,  the actual amount. Takes a certain amount of energy to melt a certain volume of ice.

Winter maximum isn't about melting ice, it is about conditions being cold enough for sea water to freeeze.

Speaking of madness...saying "well this is what is going to happen cuz a  few models say so..." is effectively like pontificating about what would happen in a zombie outbreak cuz thats what happened in Fortnite or Call of Duty waves. How good do you believe the models are? Can any models tell me what the weather will be like in a month?

Climate deniers don't like what the models say so run exactly the same argument.  Seems you don't like what the models are saying and so are running exactly the same argument.  This is a science based forum and not Watts Up with That.  The models are certainly imperfect, but whats a better method for predicting the future? 

26

How does the model maintain the cold halocline layer despite the lack of sea ice cover?

You're talking about a model of arctic sea ice decline, not a model of a blue ocean event.  We have no clue what that looks like, but the hypotheses floating around suggest papers in the next couple of years that begin to test the subject.  Models of arctic sea ice disappearance may be able to be sourced in such discussions right about the time it's happening right in front of our eyes.

I'm sure the model programmed by Arctic experts does a better job of predicting the influence of the cold halocline on sea ice than the guesses of members of this forum.

27
Ice free in winter is not going to happen in the next few centuries.


28
Arctic sea ice / Re: The 2018 melting season
« on: August 04, 2018, 12:47:30 AM »
Quote
Even after a summer BOE, ice will still form in the Arctic during the dark, polar winter for many decades
So, this being merely 2018, it surely follows that Svalbard-FJL-SZ corridor froze over this winter?

Except it never came close. And this year was only a continuation of a long-term regional trend, not a variational swing attributable to unusual weather, cycle, oscillation, phase or teleconnection event.


Big difference between this region with deep water, and directly in the path of one of the warm currents from the Atlantic.  Compare to say Laptev with shallow shelfs and no direct exposure to warm Atlantic waters.  I note also that in this corridor the edge of the ice is pretty much in the same spot as it was at maximum.  Not exactly representative of general Arctic sea ice behaviour.

29
The current Arctic cyclone has been quite intense.  968 vs 963 for the GAC.  Looking at Canadian Analysis charts it covers only a fraction of the Arctic basin, compared to GAC covering the majority.  However the squeeze against the high pressure towards the Siberia Sea looks to have produced tighter wind gradients and presumably stronger maximum winds than the GAC, but over a relatively small area.

What struck me with this cyclone is the intensity of the associated warm air mass over Siberia.  After the central Arctic has generally been a little on the cooler side (compared to recent years, but still warm compared to longer term stats).  Temperature contrast plays a big role in cyclogenesis.  And while much has been said about Arctic amplification, and warm arctic cold continents, I think the situation may be reversed in summer.  During summer, particularly early summer the Arctic is still dominated by ice. This pins the surface air temperature close to 0 and the basin is pretty similar to what it was several decades ago.  The surrounding regions are getting warmer, thus we have warm continents, cold Arctic, and increasing frequency/intensity of Arctic cyclones.

And some seasons we see a transition from strong high pressure dominated weather early in the melting season to low pressure dominated weather.  2010 and 2011 really stood out as seasons that early on had severe melting weather, with some dramatic (at the time) early season stats, but then fell flat quite significantly as cyclone dominated weather took hold.  2013 was the year of the persistent arctic cyclone where the cyclones started early and just kept going.  While the surface temperature may be pinned close to 0, the atmosphere above has been getting warmer (eg 925hp temps).  But when we get a significant cyclone, mixing of the air column with the surface pinned at 0, plus clouds etc result in the relatively cool surface extending through a more significant portion of the atmosphere, thus increasing the warm continent cold arctic temperature contrast and making further cyclones more likely.

So negative feedback.  But perhaps only sometimes.  In 2012 we saw both early season cyclones that failed to establish a more persistent cyclone shield, but spread the ice and allowed intermittent high pressure weather to pump lots of heat into the mix of ice and open ocean, and then the very severe GAC.  The GAC was of course followed by massive loss of ice, although there is an argument that the ice had already been set up to melt by previous conditions and the GAC played a relatively minor role.

30
Arctic sea ice / Re: Don't read this thread
« on: July 10, 2018, 03:24:27 AM »
Took me a while but I eventually read this thread, and was amused. 

Maybe if the thread was titled '10 reasons why you must read this thread - no 7 will blow your mind' I would have refused to read it.

31
Arctic sea ice / Re: The 2018 melting season
« on: July 04, 2018, 05:08:15 AM »
Whatever the final outcome will be, I'm fairly sure that we'll see an early September minimum this year.
Why? Early summer minima are due to cloudy weather (while the sun still shines). If there are open skies, there won't be an early freeze onset. So what is convincing you of the contrary?

Not sure what Lord Vader's reasoning may be, but I think we might be biased towards an early minimum because the core ice has been somewhat cooler and the fringe ice much warmer.  So late in the season the easy to melt ice will be gone and whats left will be stronger.  Still my personal opinion is that the weather near minimum would be more important.

32
Arctic sea ice / Re: The 2018 melting season
« on: July 01, 2018, 09:57:56 AM »
Here is 6/19-28 2018 minus 2012. I would call this severe abrupt and apocalyptic climate change. We have clearly hit an inflection point re: continental albedo and sea ice. Maybe the Mayans were right after all and this occurred in 2012?  :o

Also ^ data directly refutes the notion that the weather has been beneficial to the ice. It has been the worst June on record.



Two points.  Firstly there are no direct observations of surface temperature in the arctic,  the output is not observational data, but a weather model output.

Secondly 19th to 28th of June is not all of June.  My reading of MODIS images is that the early part of June 2012 was much sunnier with lots more surface melting than we've seen this year, and then around the 21s a low pressure system moved in causing cloudy conditions in 2012 for much of your analysis period - and by the time the cloud cleared at the end of June a significantly dispersed pack was revealed and sunnier conditions early in July did a lot of damage on this weakened pack. 

33
Arctic sea ice / Re: The 2018 melting season
« on: June 29, 2018, 03:04:35 AM »
I know that it is overwhelmingly likely that you are correct, Michael, but I have a novice's question to ask.  If the Arctic ice is fresh, then its melting point is 0 C, I presume.  If the ocean water below is saltwater, then it can be up to -1.8 C, which means that it is then colder than the melting point of freshwater ice.  So in this simplistic formulation, the ice should not melt -- it should even form during these conditions at the bottom of the ice, even without a lot of heat being sucked way at the interface between the ice and the atmosphere.  Now, I suspect that salinity/entropy has got something to say here, but what exact physical principle is at work?  Is it ultimately entropy -- that the salt ions and water molecules will tend to become as mixed as possible?  And/or is it that the ice has a lot harder time growing when salt ions are present?  Or... (I often discover something I never thought of...)   


I hadn't thought about that angle.  The salty water below would not freeze and neither would the ice melt.  It is the multi-year ice that is fresh and the first year ice is much saltier, and there is a good amount of first year ice north of 80N. 

Looking through some MODIS images, channel 3-6-7 shows quite a lot of red in the high Arctic at the end of June in 2007,2008, 2010, 2011, 2012, so some substantial surface melt.

Current conditions - its almost a tale of two Arctics.  The Pacific side has some significant ice dispersal deep in the Beaufort, and plenty of red suggesting surface melt.  From Greenland towards Laptev there is quite an area of solid looking ice that is still supporting a crack/lead pattern instead of separating out into individual floes, and little reddening/surface melt.  I'd say the Pacific side is well on the way to a major meltout, and the Atlantic side will hold up quite well, suggesting that an extreme outcome in either direction is less likely than normal this year.

34
Arctic sea ice / Re: The 2018 melting season
« on: June 29, 2018, 12:39:22 AM »
I'm a bit late to the friv bashing session.  But I'll add that if the ice isn't freezing, it is melting.  The ocean below is always warm enough to melt the ice, and freezing only happens when the air above is far enough below 0 to more than balance out the slow addition of energy from below.  I would say that there is never any freezing happening in June, and that the ice north of 80N is basically always melting in June, but that the melting except possibly in rare circumstances (and near the Atlantic edge around Svalbaard) is too small to matter.

35
Arctic sea ice / Re: The 2018 melting season
« on: June 08, 2018, 02:55:43 AM »
Should the current cyclone be compared to the GAC?  Or to cyclones that occur in the north Atlantic or north Pacific.  Cyclones outside the arctic can get a lot stronger than the GAC, for instance Bering Sea cyclone at 943hp, with a note that cyclones reach below 930hp one or twice a year.  Or an Atlantic Cyclone that managed to reach 914 hp.

Impacts?

Will make a mess of the Atlantic front, but much of this is doomed ice anyway.  Perhaps it will accelerate warm water from the Atlantic into the Arctic, but I don't have a good handle on that current.  Lots of upwelling on the Atlantic/Arctic boundary.  Will that warm or cool the surface?  Upwelling = warming in the Arctic proper, but cooling in most of the Atlantic.  Where is the boundary between these two opposing trends?  Longer term the cyclone seems to hang around as a weaker system and looks to me like it will help to cool things down in the central/Canadian parts of the Arctic.

More concern to me is moderate high pressure ridge setting up in the Pacific sector, and the strong import of warm air between the ridge and this low.  I see strong sunshine and surface melting kicking off from Laptev to Chukchi/Beaufort.

Pages: [1]