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Messages - subgeometer

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1
Arctic sea ice / Re: The 2019/2020 freezing season
« on: September 24, 2019, 08:36:16 AM »
Oe last look at the meltig seaso just past - I've posted a bunch of regional animations over on the test space thread , but here's one of the whole arctic drawn from Terra Modis on NASA worldview

2
Developers Corner / Re: Test space
« on: September 24, 2019, 05:17:21 AM »
A slightly longer version of the Beaufort Sea animation I posted on the melt thread a few weeks ago

This is at 720p  with h264 encoding. Its a bit large at 8MBfor ~150 images. I'll see how far I can push down the bitrate (doing 2pass encoding) without losing too much image quality. The alternative is to reduce size to 360p. I guess if you need the detail though, you pay in bitrate

EDit: Added the actual video

the h264 version here is twice the size of the h265 I made earlier though there are a couple of differences in -preset and -tune parameters - though the preset shd make it marginally more efficient. Its possible that "-tune animation" makes ffmpeg/libx264 consume heaps more bandwidth- I'll do some more experiments as time allows

Edit 2: Arggghhh padding. I added code to pad and force aspect ratio to deal with problems when sequencing clips for the video screens at the big Flea Circus show I mentioned in the post above, and which opens tonight, so I'll have to leave it for now. At least the H264 video displays fine on my system


3
Arctic sea ice / Re: The 2019 melting season
« on: September 14, 2019, 04:20:16 AM »
Another movie,( at a more reasonable 7MB) of the relentless conveyor feeding ice into the Beaufort Sea from 24-May through to 13 september. I should have gone a few weeks further back to breakup, and when I have time I'll grab the remaining frames to do so

4
Arctic sea ice / Re: The 2019 melting season
« on: September 06, 2019, 05:03:37 AM »
August Area, Extent & Volume losses may have been low, but SST anomalies continued to climb and expand.

I wish I had saved the images from the beginning of the melting season. But I did not. mea culpa.

The interface at DMI's site  is set up to step back and forward through the time series

5
Arctic sea ice / Re: The 2019 melting season
« on: September 05, 2019, 04:35:55 AM »
A few frames from Climate Reanalyser (at 33, 99 and 186 hours out)with yesterdays Bremen extent map marked to show where I think melt will cease very soon and freezing perhaps begin(perhaps I've drawn the area a little too large?), and where melt will continue.

Its looking like we're for a series of massive influxes of warmth (and storminess - N Pacific storms are showing signs of penetrating the Arctic  basin more often, wrapping around Chukotka)from the Pacific, and some from the Atlantic as well

6
Arctic sea ice / Re: The 2019 melting season
« on: September 04, 2019, 02:10:38 AM »
GFS's 10 day outlook shows a story of 2 arctics. Inside a triangle with corners at Axel Heiberg FJI and Fram strait we can expect refreeze to commence and the holes to ice over whereas everywhere on the other side of the pole will struggle to drop below freezing, so bottom melt will continue.

I've attached the 10day average temperature map from Climate Reanalyzer

Eurasia will start to get seriously cold soon so I expect plenty of fireworks generated by the warm water surrounded by cold in the next couple of months

7
Arctic sea ice / Re: The 2019 melting season
« on: September 04, 2019, 01:48:43 AM »
A clear view of the northern CAA yesterday shows very little ice obstructing Parry Channel, winds have pushed it all to the southern side. And the hole that's been appearing in the Lincoln Sea is as large as I've seen it.

Todays EC/Windy forecast ups the winds a bit, and indicates another round of storms at the back end of the forecast. Still plenty of interesting things going on despite the lateness of the date

Edit: oops, I double posted the image of the CAA, and left out Lincoln Sea - fixed

8
Arctic sea ice / Re: The 2019 melting season
« on: September 02, 2019, 03:24:40 PM »
I am eyeballing Worldview daily for evidence of freezing between floes in the CAB, as temperatures are beginning to dip into that region.

None as of yet.

Looking at GFS 10 day forecasts at Climate Reanalyser you see a small area of cold form repeated going down to around -7C and then dissipated again by another warm influx, all the way through the forecast, so refreeze is going to be limited for now- and then theres the wind to come with storms . Eve if losses are limited  nad the pack freezes over the gaps, after the long August lag the waters around are all anomously warm, so significant extent increases are a long way off

9
Arctic sea ice / Re: The 2019 melting season
« on: August 31, 2019, 03:02:32 AM »
The dispersal to the Pacific and Eursian sides which has driven the extent stall looks likely to turn around given the forecasts, The CAB adjacent to the western Beaufort and eastern Chukchi sea will have 20 knot winds pushing the ice north which should lead to extent drops. Any export will be via Fram strait and the Barents between Svalbard and FJI. The storms that may follow also seem likely to drive ice north from the Laptev region.

A long lag in extent drops is usually followed by a catch up period, altough since its so late it may be reflected in an extended stall in the freezing season. But temps have failed to fall much below 1C above 80N so far, and have bounced back upto about -0.5C again today - there has been nothiung to halt bottom melt, so we might see some nasty surprises in some gauzy low concentration areas if winds get as strong as (or stronger than) forecast

10
Arctic sea ice / Re: The 2019 melting season
« on: August 26, 2019, 11:59:57 AM »
By cutting clouds from the top image I made a crude composite of the past 2 days from Worldview of The Eurasian side across to a bit past the pole. There must be a million km2 of dispersed rubble and/or slush between the Laptev sector(where the Atlantic water is?) and the Pacific fringe.

But unlike some earlier years  no Wrangel arms or anything beyond the ESS Big Blob exposed to attack from all sides. Quite a bit of this stuff could survive(barely), and then be covered by a big dump of snow in the next storm.

GFS is also hinting at a bomb cyclone around Kara/Laptev late in the run

11
Arctic sea ice / Re: The 2019 melting season
« on: August 24, 2019, 03:36:11 AM »
HYCOM Ice Thickness August 22 - August 29



I feel like HYCOM must have changed their scale or something because that literally looks like the end of ASI as we know it.

A hole by the pole at the end of the month? hmmm, not sure about that. While that area is almost always cloud covered it hasn't seemed to have had low concentration recently, although ice a few degrees further south on the Eurasian side does have fissures and holes.

The gap opening again east of the CAA storm all the way to the Atlantic is more plausible. There's lot of wind around the big high over Greenland, which is getting cold while almost surrounded by warm SSTs(Baffin Bay is verywarm, much of it with 4C+ anomaly on the DMI chart.

Anomalies continue edging up in the ESS as well, and DMI also shows a growing area of elevated SSTs across the wide swathe of thinning ice adjoining the Laptev Sea. If correct the freezing season will be brutal, right now there still remains plenty of energy for melt and to propel storms

12
Arctic sea ice / Re: The 2019 melting season
« on: August 24, 2019, 03:03:16 AM »
Ice north of Svalbard shows thinning between the pack and the blob pushed(further) into the Barents recently.

This region is in for a lot more 20-30 knot wind from a parade of lows starting in around 3 days if the forecasts are correct - and this area melts and freezes late/on its own schedule - its very far north, but under the influence of the salty warm Atlantic

13
Arctic sea ice / Re: The 2019 melting season
« on: August 24, 2019, 02:42:20 AM »



Temperature is dropping like a rock...

Temps are down around the freezing temp of seawater above 80N now, but may struggle to drop much further for a while, that's what GFS forecasts are suggesting, with continuing warm air advection(though it flips around as to the points of attack) There's all the high SSTs ringing the ice, and half the pack itself is full of holes and tears. They will have to freeze over for temps to go down a lot further

Edit: fixed typo and hopefully ungarbled my english

14
Arctic sea ice / Re: The 2019 melting season
« on: August 21, 2019, 06:25:16 AM »
Another of this season's weird extent loss slowdowns (eg the heatwave in June saw an absolute flatlining!) continues, only 20000km2 lost today on the JAXA graph, after 30K yesterday, now 370000km2 behind 2012 and about the same in front of 2016. Losses must pick up again though. 2016 and 2012 both lost ~900K after this date(which surely puts 2016 out of running for 2nd, its minimum now only 490K away.)

Bremen though has 2019and 2012 still neck and neck on the extent graph(and it is higher resolution), and on the corresponding map little holes are starting to appear in the interior of the Laptev sector, as the gossamer shreds in the warm breeze after near continuous dispersal,. With the storms on the horizon there could still be a few big days ahead, with considerablelosses just before the cold descends, like 2016

15
Arctic sea ice / Re: The 2019 melting season
« on: August 21, 2019, 05:49:48 AM »
Only 2 days now till this storm is predicted to start bombing out over the CAA, EC/Windy now has central pressure getting down to 969 a day or so later as it crosses to the CAB, witha huge wind field, with 30-40 knot winds gusting well over 50kt in places. Could this open Parry Channel and the main NW passage route? The Lincoln Sea and areasnorth of Ellesmre Island and Greenland are in for another (last?) bout of strong southerly wind, well above freezing. The gap may widen again before refreeze

Anyway, its an interesting climax to the season. Both models havethe CAA low taking over the Pacific and Canadian of the CAB. With a lot of wind, not quite as strong, but pressure remains around 980 for a while. As that goeshe GFS sees a narrow ridge from Greenland to the New Siberian Islands by D7 and a 'double diplole' as lows also swirl in the Barents and Atlantic fringe. Its dispersal vs melt vs the clock, as temps inevitably drop

16
Arctic sea ice / Re: The 2019 melting season
« on: August 19, 2019, 08:45:53 AM »
A fractal swirl of more concentrated ice north of the the ESS gets stirred over the past week-now it being pushed into the warm SSTs in the wetern Beaufort Sea

17
Arctic sea ice / Re: The 2019 melting season
« on: August 19, 2019, 03:49:50 AM »
Just before cold air dominates the Arctic, this beautiful inverted dipole promises 40-80 km/h winds over the Laptev-ESS side for a couple of day. This is Thursday according to ECMWF.

assuming that the pressure gradient is 3000 Pa over 1 million meters, and that this is near enough to the NP, then the associated geostrophic wind is 3600x24/4/pi x 3000/1000000 = 20 m/s ~ 40 knot ~ 80 km/h, that’s a max. limit, near the surface it will drop considerably

As well as wind temps will be well over 0 and dewpoints of 0-3C the next few days over the Laptev sector and eastern Atlantic front, where the ice is looking bad, melting and dispersed and very grey. While freezing altitudes are up to 3km, there will be thick cloud so I am imagine a substantial longwave flux as vapour condenses within them, there's up to 30kg/m2 in these pulses coming in. Bremen's 'daygrid swathe' temporary shows holes appearing in the Laptev ice north west of the bite, so I guess they'll also be in their final AMSR2 for today

The Atlantic front is being turned by the conditions, advancing( into warm SSTs) around Svalbard, and rapidly retreating further east

I've attached an image of the Laptev sector, and one of ice east of Svalbard, and a gif of thinning ice north of the Laptev bite from 13-18August, doubleframed on the 18th, and skipping the 17th as it was solid cloud. I've also included Windy's dewpoint(not temperature - temps are generally about 0.5C higher!) forecast for thursday

Keep the forecasts coming Freegrass. It would be great though if we could collectively work out how to embed movies (eg MP4, avi) when possible rather than GIFs, which are great for encoding 8bit data, but don't compress efficiently. It would help limit server costs and energy consumption, and also those of us with crap internet connections. I've had difficulty in embedding them directly, I'll try using youtube sometime soon

18
Arctic sea ice / Re: The 2019 melting season
« on: August 16, 2019, 11:23:22 AM »
Laptev bite and ice north of it - 8 August and 16 August.

19
Arctic sea ice / Re: The 2019 melting season
« on: August 16, 2019, 04:41:32 AM »



There's also a pressure gradient and strong winds from the North Pacific and Bering, which will continue, which may have an impact on the Bering Strait throughflow. Some very warm water in the N. Pacific. Not a huge deal, but may be interesting to consider.

Water is also very warm inside the straits, 8-11C for hundreds of km north. The water flowing in is much more saline though. Uniquorn posted some salinity model charts from Mercator earlier in the season that matched closely with melt patterns there in recent years(2016 and after?) and help to explain why the Chukchi struggles to freeze, and especially, why (expanding)parts of it melt out so easily even in mid winter.

Pressure builds to over 1040 for a couple of days, as the high moves to hover over the Chukchi Sea

20
Arctic sea ice / Re: The 2019 melting season
« on: August 16, 2019, 04:26:13 AM »
There's only one place for the ice to go, into hot water...

This will restrain the advance of the melt edge, and the hot water, at least at the surface. And areas with cold surface waters and remnant ice can refreeze quickly once atmospheric temperatures drop sufficiently. If the weather is kind in a couple of weeks maybe the freezing thread can get off to a good start with a larger than normal dump of energy to space as a large amount of new ice forms. That requires high pressure and minimal clouds though.

In the meantime the disprsal can only further expand the holes and  ragged tears in the interior of the pack. Eg at 87N on the Eurasian side its already looking pretty bad, as we approach minimum the pack will look worse than we've ever seen it.

EC sees another 7 days of warm air from Eurasia pushing right across the pack, before(finally) indicating an end to it, to be replaced by the low over the pack sucking in other lows from Europe and the Atlantic, one of which may well bomb out. The N Atlantic cyclone cannon has been silent till now

21
Arctic sea ice / Re: The 2019 melting season
« on: August 15, 2019, 10:31:51 AM »


Heat blowing in from the continents will have a minimal effect, as it isn't accompanied by significant insolation or long-wave radiation.

All hinges now on bottom melt, and to a certain degree, on how much heat is pulled from depth by wind.

I think a 2nd place finish is pretty close to being "in the bag".  I'm doubtful that we will pass 2012 - *UNLESS* the melt season continues into late September, driven by bottom melt.

Unfortunately, that store of heat - what's already in the water - is an aspect of the Arctic we probably have the least information on.  We can only wait and see what transpires.

The evidence is on worldview that this longlasting atmospheric infkux is adding extra oomph to bottom melt. The warmth comes with a high dewpoint, significant atmospheric moisture and wind( which is also moving the ice around and enhancing bottom melt. The longwave from clouds can take cm oiff even in midwinter. It all enhances and extends the momentum - aka bottom melt. Apart from enough ice melt, atmospheric cooling is about the only way to stop momentum

2016 is totally in the bag, its only 750K away on JAXA

Edit: JAXA is 750K behind 2019 minimum, not 720 , an average 37500 km2/day for the next 20 days to tie if minimum comes really early, as in 2016.We need a major slowdown right now and even then I can't see the minimum not going below 4 million km2. In the absence of major storms 2019 might bottom out a bit above 3.5 million, but I wouldnt bet my house on it

22
Arctic sea ice / Re: The 2019 melting season
« on: August 15, 2019, 04:13:17 AM »
SST's north of laptev are turning orange. That would be under the ice. Could this be a result of all that hot rain hitting this area? How does this get measured? By buoys?

Edit; The rain actually hit the ice more to the west of this area, so probably not because of the rain. Just hot temperatures.

The ice is dspersed and melting there. Open water between the rubble could be observed by a microwave instrument, maybe.though it seems unlikely the SST could be above -1.5C with so much ice around, even if the water some metres beneath was considerably warmer.

I think its probably spurious, unlike ESS SSTs which have increased significantly over the past week since most of the ice melted, now showing lots of positive anomalies on the same DMI mapsSome of that must be warmth beneath the surface accumulated in June and July and now raising the surface temp once the ice is gone

23
Arctic sea ice / Re: The 2019 melting season
« on: August 15, 2019, 03:57:56 AM »
Some nasty surprises are starting to wink thru the cloud as heat keeps pouring in from Eurasia.

A worldview image of ice near Severnaya Zemlya, showing rapid retreat and melt in a spot where thick ice apparently was just recently.

The various extent and especially area graphs are all over the place, they don't seem equipped to handle a state where so much of the pack is in a state of melt, cascading into rubble as it disperses. There's very little 95% coverage on the maps

The forecasts don't let up. DEwpoints over the ice are close to the surface temp, at the spot indicated on the Windy screenshots dewpoint ranges from 0-2C for the next week with temps about a degree higher. Both GFS and EC show the heat continuing, and hint at the beginning of some weather action from the Barents and Atlantic. One big difference is that GFS appears to be modelling a lot of ghost ice in the ESS, temps in the southern part are much cooler than on the ECMWF. Adjacent regions in Chukotka are ~10 degrees different in the 2 models, freezing in GFS, ranging from 7-15 on EC.



This all as the basin should be cooling - 80N is due to go through 0C on the DMI graph in another day, but, surprise, surprise, temperatures have gone back above the green line and it looks like another week before we go through the freezing point of water in that region

There's not much to slow momentum anytme soon

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Arctic sea ice / Re: The 2019 melting season
« on: August 12, 2019, 07:52:28 AM »
Can this ice around 85-6N survive another month? If the waether cools quickly, and its calm, maybe, though it will look awful.

JAXA dropped 110K to 5million km2 today. The average drop from now to minimum in 2010s has been about 1.3 million, so its unlikely to not beat 2016 (4.03million)into 3rd. We're currently 110K above 2012 on this chart(about even on NOAAs, and 2019 retains a dwindling lead according to Bremen), so 2019 remains in the hunt for the record.

There's a lot of vulnerable ice. I've included an edited Bremen map from 11 August to show the location of the Worldview image(red square) and the ice that I think will likely survive(inside purple line) and that which is at risk of melting out, as a tentative stab at a minimum projection

25
Arctic sea ice / Re: The 2019 melting season
« on: August 12, 2019, 04:57:46 AM »
Area data is notoriously difficult to interpret this time of the year. The graphs that Gerontocrat posts show what they show, but it is difficult to draw conclusions about melting or freezing based solely upon the graphs. 

 

Yesterdays Bremen AMSR2 also shows high concentration north of the Laptev bite, despite the clear fraying visble on earlier days on the map and worldview, and the warm temps under thick cloud. The cloud is fooling the instrument - weather artifacts are often visible. Animations by Aluminium etc show the passage of cloud bands as areas of fleetingly increased concentration- phantom area

Temps have to drop well below freezing for new ice to form, -11C is the figure usually quoted, and nowhere has been anywhere near that cold yet, and won't be for at least a couple of weeks yet. Regional area increases can come from transport. Any absolute area increases now are spurious, solid floes collapsing to rubble, and the effects of dispersal combined with quirks of the algorithm and low resolution of the instruments, as well as the effects of thick clouds

26
Arctic sea ice / Re: The 2019 melting season
« on: August 10, 2019, 05:37:50 AM »
I post 6 to 10 day forecasts when the models are indicating a large scale phenomenon such as a a change in the Arctic oscillation. I know that the models are unlikely to get the details right and will the ECMWF often overdevelops storms and ridges near the pole in those forecasts, but I find that the European model does pick up large scale features pretty well on the 5 to 10 day scale.

We have reached the point in the melting season where bottom melt dominates and heat in the ocean has more impact than insolation in the central Arctic. There is sufficient ice around the pole that we can now be certain that there will be no "blue ocean event" this year.

The heatwaves the models saw coming well out, since the Mackenzie in May. Even if they turn out wrongI think its worth posting the far off forecasts when something big is signalled.

A BOE is totally improbable from here, too much ice. Perhaps if conditions didn't ease off at times in July. But there is a lot of vulnerable ice on the Eurasian and Pacific sides, pretty much to the pole. There's a huge amount of rubble, vulnerable to bottom and side melt Then there's the gap, and thinning Lincoln Sea etc.The next week will see rapid advances in the Laptev region and the thinning ice north of there. It's going to start looking very ragged as all the FYI struggles to survive. And there is still plenty of time before the minimum for serious storms to wreak havoc, something the forecasts seemingly aren't so good at predicting

27
Arctic sea ice / Re: The 2019 melting season
« on: August 05, 2019, 05:13:30 AM »

 while some CAB ice is constantly driven south to melt in the warm waters of the Chucki.


With the exception of a narrow band of water extending over the shallow Chuchki Plateau, the warm water in the Chuchki hasn't reached the 75N line.

CAB ice N of 80N will need to make a journey of at least 300km and perhaps over 600 km to reach warm water in the Chuchki.

It takes a lot of wind for a lot of days to push ice that far.

Currents from the Chukchi are pushing directly at the ice edge in the western Beaufort. More importantly I think, for the atmosphere 800km is not so far. Being ringed by warm SSTs will extend the melt season in the centre of the pack as the air above will struggle to cool. At the same time the warm water will likely feed storms

28
Arctic sea ice / Re: The 2019 melting season
« on: August 05, 2019, 04:54:54 AM »
GFS and EC are both forecasting another monster heatwave rolling over the Laptev sea pushed by a high on one flank, and another strong low advancing into the Kara sea, which also drives a large area of 20-30 knot winds pushing ice into the Barents sea. The Laptev bite will advance rapidly for a few days if it plays out.

The real action starts about 5 days out, so its still a bit far off.

A bunch of Pacific typhoons are forecast this week, hopefully none of them head our way next week

29
Arctic sea ice / Re: The 2019 melting season
« on: August 05, 2019, 03:46:02 AM »
Unfortunately Sentinel doesn't have coverage of the Arctic Ocean much beyond land (or above 82.8 degrees) with the partial exception of the CAB north of the CAA. I went out as far as I could to sea to find a recent clear image. I've included a gif comparing July28 and 31 at about 82.6, -119, showing the ice spreading a little in the interval, (and moving from top right towards bottom left)

click to play

30
Arctic sea ice / Re: The 2019 melting season
« on: August 05, 2019, 03:36:39 AM »
The crack, the persistent southerlies and the warmth released by descending air(foehn winds and high pressure ridges) are enough to explain the thinning on the Greenland/CAA edge of the basin, though warm water seems to be affecting NE Greenland, EC shows 2C water in part of the crack there, right at NE tip of Greenland..

I had a bit of a look on Sentinel.  I've attached a close up and wider view of ice in the Lincoln Sea, near the open water on its west shore, showing worn pebble shaped floes peppered with open water.

I also attached a couple of views centred on about 82.6,-102, about 100km NW of Axel Heiberg Island, also showing somewhat dispersed ice

Edit: The closeups are at Sentinels 500m resolution, I hadn't realised its screenshot tool left the scale out

31
Arctic sea ice / Re: The 2019 melting season
« on: August 01, 2019, 06:06:22 AM »
The 18Z GFS run on Climate analyser sees a big storm taking over most of the basin later in the run, not quite a GAC, but lots of fairly strong wind. The EC today on Windy disagrees, so we'll have to wait and see. (both see continuing injections of heat and moisture especially over the Canadian and Pacific sectors and adjacent CAB).

If the AO turns negative now, with an increase in cloud and possible storms, just as the sun is getting low at high latitudes, especially if combined with further incoming physical or latent heat, I don't think that is the best news. The N Hem tropical cyclone season is just about to crank into action. GFS also foresees an Atlantic hurricane missing Florida, and beginning a swing north, Again a long shot, but its a sign of the dangers the cooling after summers peak may bring

32
Arctic sea ice / Re: The 2019 melting season
« on: August 01, 2019, 05:48:27 AM »
Plants might help us find variables for interpreting the climate. I for one find this correlation pretty obvious.

Can you, Philopek, preclude such a correlation? If so, please explain.

Interesting, but a discussion for another thread, there's a lot going on with the ice right now, as the denouement draws near , let's stay on topic, please

33
Arctic sea ice / Re: The 2019 melting season
« on: July 30, 2019, 05:22:08 AM »
There's a really clear view of the ice on Worldview for yesterday(29 July), with some spectacular images of melt

Swirls of goodbye waves speckled with confetti-like small floes must present quite a challenge for the microwave instruments and their operators/programmers.

This region of the ESS - about 40000km2 just north of Wrangel Island is now mostly open water as far as NOAA and Bremen are concerned, I've attached their current extent or concentration map with the area marked.

The other Worldview image shows the ice to the west of the northernmost part of the Laptev bite, which is in a bit better condition/will melt out slightly later, and still counts for extent.

There's a band of thinning ice from here all the way to the head of the bite north west  of FJI which seems to reflect the salinity map Uniquorn posted a few days ago. Anyway I think all the ice south of this band will soon start becoming isolated from the main pack.

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Arctic sea ice / Re: The 2019 melting season
« on: July 30, 2019, 05:04:49 AM »
SSTs are a lot easier to determine when there's no clouds to confuse or obscure the instrument? (They also rise quickly if its June or July) The DMI figures seem to often jump after a couple of days of clear weather in a region. Or drop as well - Chukchi sea SSTs are a couple of degrees below their peak a few weeks ago. In the Bering Sea Norton Sound is down to 16C from 18 in June and 20 in early July, despite weather remaining mostly warm - mixing with water from deeper and further offshore must be going on. In the Chukchi sea currents push it into the ice edge.

The Laptev Bite area has remained fairly steady at 4-8C as it melted out the ice around.

The tongue of open water north of Svalbard has gone up to 4C and is again a death trap for any ice that wanders nto it. How much effect the salty Atlantic water is having underneath the ice is something we may see revealed as August proceeds, and whether all the ice pushed into the area over the past 6 months have turned back the Atlantification trend significantly


35
Arctic sea ice / Re: The 2019 melting season
« on: July 29, 2019, 06:43:44 AM »
A gif of a region of the pack north of the ESS. The aquare is centred at 82N, 169E and spans about 20 degrees of longitude from top right to bottom left. It shows melt proceeding and a highly mobile pack. I get the impression that collapsing rubble is spreading in the gaps closing them to a degree - maybe this kind of process is part of what is causing the odd area numbers.

I left out some days as they were totally filled with cloud, using the 22nd, 25th, and 27-9 July. I doubled up the start day so it pauses there a bit

36
Arctic sea ice / Re: The 2019 melting season
« on: July 26, 2019, 10:00:07 AM »
...
So what evidence would you look for to prove that a massive heat influx is actually taking place?

The simple answer seems to be that we should see a rapid increase in area loss, reflecting the onset of surface melt.
For area to start dropping, there must be openings larger than grid size for any given method of observation -


Norsex Arctic ROOS (https://web.nersc.no/WebData/arctic-roos.org/observation/ssmi_ice_area.png) has flatlined over the past few days despite the melt apparent on Worldview, the momentum etc. It has a coarse grid of over 10km

WE'll have a good opportunity to observe the Beaufort and CAB ice to see how it fares under high pressure with warm air and cloudless skies. What can be seen from yesterday and today don;t inspire huge confidence.

I've included a worldview image of about 500,000 km2 of extent in the Beaufort Sea and CAB between 74 and 82N, with the approximate area marked on todays AMSR2 map from Bremen, as well as a section of the Arctic ROOS sea ice area graph

Greenland looks to be in for a bad week, possibly one for the record books. and areas to its north wont escape, with the Lincoln seeing 4C surface temps from D3 on Windy and 2 days of 5-6C about D6 and D7. There's some wind and dewpoints are also above freezing. The apparent worst is still a way off so I'll wait till tomorrows forecast

37
Arctic sea ice / Re: The 2019 melting season
« on: July 22, 2019, 03:05:53 AM »
I do think the polar cell is failing outright.  Richard Alley said we'd have time to respond to it, that it wouldn't be SO ABRUPT that it would happen before we could do something about it.  Not 3 years, but more like 10 or 15...  well can we get started already

*third image requires click to run

It seems to me like its bifurcating between states. For the past week say, it looked a bit more like itself again, with high temps and levels of moisture kept neatly  outside the Arctic basin. Now a big blast of precipitable moisture is about to punch right through its guts from the Pacific, as well as  substantial heat being sucked in from the continents.

38
Arctic sea ice / Re: The 2019 melting season
« on: July 18, 2019, 05:10:30 AM »
The DMI volume chart is hopeless, at best a week or 2 out of date. It's showing a ice over half a meter in open water in the Laptev bite today, and great swathes of ice in Baffin Bay in these 2 maps dated 16 July from Bremen and DMI - though what date the DMI really refers to, who knows

I've attached the comparison as both a gif(click to and an mp4. The MP4 plays fine locally but its been a bit of a lottery trying to get them to play on the forum, at least in my browser

39
Arctic sea ice / Re: The 2019 melting season
« on: July 17, 2019, 09:57:57 AM »
A lot of the cloud on Worldview today is thin enough to peer through, and wherever you look ,from the Pacific to the Atlantic across half the basin, is dispersed ice,and  in many areas showing telltale signs of melt

I've attached images of 2 areas, colour coded 2 match  with the squares at 77 and 81 N in todays Bremen extent map

Edit: I forgot to add that the images have had the contrast enhanced by monkeying around with levels in Gimp

40
Arctic sea ice / Re: The 2019 melting season
« on: July 17, 2019, 02:30:30 AM »
Holes are developing all over on the Eurasian and Pacific sides as dispersion takes its toll and areas of FYI start to melt out.

The area shown is about 84-85N, north of the Laptev Sea, and a few hundred km from the Atlantic Front. If I can find time I'll have a closer look with Sentinel as things progress

41
Arctic sea ice / Re: The 2019 melting season
« on: July 15, 2019, 01:16:05 AM »
The Lincoln Sea is pretty warm the next couple of days as winds blow up Nares strait and off Greenland etc. Those  huge areas of bare rock must drive a lot of thermals, adding turbulence, as well as more heat to the foehn wind this area is subject to?

I've added the Windy forecast for about now, as well as a Worldview image of the area yesterday

42
Arctic sea ice / Re: The 2019 melting season
« on: July 08, 2019, 07:15:10 AM »
More greying ice in the ESS

I copied the cloud free area in the square in gimp, resized the image to one pixel, then looked at the level, which is 107.

In 8 bit graphics mid-grey is 127 or 128 (0 is black and white 255), so this ice is closer to black than white.

Naively dividing 107 by 255 to get a value in the range from 0 to 1, that comes out to an 'albedo' around 0.42 That ice is pretty good at collecting light energy, Given the ice darkens as it deteriorates, it's going to accelerate the final meltout of that and similar areas.

The pack is nowhere as grey as this coastal stuff, a, but its visible greying after melt onset gives an extra kick to insolation potential(moreso in bad years), and there is a long stretch of seas off the Russian coast that can collect continental dust etc

43
Arctic sea ice / Re: The 2019 melting season
« on: July 06, 2019, 07:49:36 AM »
The ESS former fast ice ice is in no shape for the blowtorch its about to go under. Nor is the Laptev ice which is extremely grey, and collapsing now. A lot less cloud on worldview today

44
Arctic sea ice / Re: The 2019 melting season
« on: July 06, 2019, 06:54:21 AM »
Currently it's 21C at the weather station at Niuqsuk Airport, just east of Barrow,  with the dewpoint at 11C, with the breeze blowing straight out onto the sea
Those dewpoints mean the ice will be literally sweating the moisture out of the air even without rainfall, with the attendant transfer of heat.  Same applies to any open water as well, assuming SSTs of around zero.

Windy says that, right now temps are up to 25C on Wrangel Island, with similar maximums each day.

(Like the temperature) the dew point drops once the air gets over the ice(3C at the surface, it rises to 6C at 950hPa and 8C at 925, at the pt indicated), but a large and increasing area will experience dew points of 2-4C in the days(and days) to come.

I've attached bunch of screenshots from Windy to illustrate, of surface dewpoint, temperature and humidity. as well as clouds for daytime on the 8th(ie 2 days out). 3C dewpoint, 4C temp and 98% humidity, which as it turns out is predicted to mark the edge of clouds - a lot of ESS ice will be undrr full sun as well. This is going to be interesting to watch

45
Arctic sea ice / Re: The 2019 melting season
« on: July 05, 2019, 02:43:42 AM »
For the next few days, at least, high pressure and warmth dominate from Kara through the central CAB to the CAA/eastern Beaufort. These are the parts of the Arctic that have been relatively protected so far, and now they will be exposed to surface melt/melt ponding and high insolation.




I think this pattern will be bad for the ice. The southern Laptev and ESS are already in such bad shape that they will melt out anyway over the next few weeks, particularly with the help of warmish river water, while Chuckchi and the western Beaufort have the high SSTs and southerlies through Bering to contend with. Add in continuing Fram export...

Beyond this, the models seems a bit unsure whether high pressure will dominate the whole central Arctic or whether the high pressure will drift across to the Eurasian side, allowing a low to develop over Beaufort, creating a reverse dipole.

Based on the emerging pattern, I expect high losses for the next 2-3 weeks, but I wouldn't dare to predict whether they will be steady or occur in fits and starts.

Its not just the rivers. The areas under cloud may be protected from sun, but temperatures are high, and the precipitable moisture levels are nuts - not much of an arctic desert this week coming. One huge blob of moisture is being pushed from Eurasia via the Kara to rotate north of Svalbard, with surface temps around 2C, while the Alaska and Chukotka heatwave pushes warmer air and more moisture in from the Pacific. The melt over the past few days has been very aggressive on that side as we see in the Bremen animation, and that's only going to continue, if not worsen. (Warm?) rain and a lot of longwave radiation, as well as very high SSTs close by

I've attached 5 day GFS forecasts for NH max(cor blimey, that's a lot of red) and avg temperatures, as well as precipitable moisture and rainfall(precipitation, ~20mm in places, but not much will be snow).

46
Arctic sea ice / Re: The 2019 melting season
« on: July 01, 2019, 06:50:36 AM »
The darkening of the pack thru June is pretty stark in this movie. of worldview images. I've also attached the June 1 and June 30 for comparison.

We need a lot of bright white cloud

Edit: replaced the movie with one half the size to see if it displays the Atlantic side on the page

47
Arctic sea ice / Re: The 2019 melting season
« on: June 30, 2019, 03:25:02 AM »
Talking of longwave radiation and latent heat: there is a 30kg/m2 river of moisture flowing in through the Bering Strait all week, and the air column will be warm, freezing altitude varying from ~2000-3500 m over the Chukchi sea according to Windy( the freezing altitude map is nuts right now). The clouds thicken and cloudbase drops as the air hits the ice edge.

Surface temps at the spot indicated stay around 6-7C (dropping to 2C over ice) through the forecast, and the air above is about the same temp or slightly warmer up to around 900hPA and about 2C at 800hPA. Wind from the south, a 15knot breeze at the surface, about double that aloft

Does anyone have an idea how much of that moisture is arriving at the ice edge as vapour? How much latent heat is being transferred to the ice?

48
Arctic sea ice / Re: The 2019 melting season
« on: June 30, 2019, 02:40:55 AM »
A quick and dirty insolation calculation could made by making a grayscale version of Worldview's truecolor image for the date, ...

It would definitely be quick and dirty.  Gerontocrat was not kidding when he talked about the cost of developing a model that would accurately account for the cloud effects on albedo. 

Clouds are very, very, very complicated.  They are all different.  Different clouds let in different wavelengths of light that have different energy.  Different clouds also block upwelling wavelengths of light and reflect them back to the surface.

There are many papers on this topic.  The take home message is that it is not a simple matter of saying it’s cloudy so the Ice is protected.  Sometimes the clouds make things worse.

Sure, clouds are complicated, hence the desire to not have to handle them

My suggestion is for a method to calculate raw insolation, not longwave and other processes. Quick and dirty, but also simple. My thought is that the whiter clouds are, the more sunlight they reflect,

49
Arctic sea ice / Re: The 2019 melting season
« on: June 28, 2019, 04:06:33 AM »
Laptev SSTs are now up to 10C in the bite according to WindyTV/EC. Most of the open water is between 6-9C. (Around the Lena delta water is an insane 17C). Have SSTS ever been this high there? Let alone on 27 June? For the next few days winds turn around and start blowing ice from the north into those warm waters, while the Chukchi will warm up some more as Alaska heats up.

Meanwhile half the basin is above freezing at the 800hPa level, all week long(The CAA, and adjacent areas of CAB, as well as the Kara Sea, the Atlantic front all take a clobbering) Even where the lows are its barely freezing at this height(2000m)

My personal not really scientific(though testable) theorem is that when a sea ice region starts looking like a head, its the beginning of the end for it, soon to distort, fall apart , and ultimately melt. We've all seen the baby elephant head that forms in the Chukchi sea the past few years. The mouth widens, the trunk narrows, and then, ... poof. The southern Beaufort starts out with more human features. So it's been with growing alarm that I've watched the whole Pacific sector take on the appearance of a bearded face in recent days.

50
Arctic sea ice / Re: The 2019 melting season
« on: June 26, 2019, 07:05:15 AM »
Volume is key for us here maybe, but I wouldn't write off 2D measurements as necessarily secondary for everything. Eg in its effects on the the weather and climate, extent/area measures  (where ice is) are the key thing. That sets the albedo, in part determines location of the jetstream, etc

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