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Messages - FishOutofWater

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1
Arctic sea ice / Re: The 2020 melting season
« on: September 15, 2020, 11:39:58 AM »
Today's images an animation.
Clear gains in the Beaufort and CAA outweighing losses along the Kara and Laptev facing ice edges.

2
Arctic sea ice / Re: The 2020 melting season
« on: September 15, 2020, 08:39:22 AM »
As a testimony of the disruption ongoing on the Atlantic front, the extraordinary heatwave is still ongoing for the Russian islands of the Barents and Kara. For weather stations with such a long record, this is crazy. Up to the 15th of Septembrer, the mean of temperature (the mean...) is above the old monthly record of September. And it is raining, raining, raining.
For Ostrov Vize, with the exception of the 10th, every day since the 14th of August is a record, and the old monthly record of 2015 has been broken twelve days as of now... The month of September is for the moment the warmest month ever recorded, ahead of August 2020  http://www.pogodaiklimat.ru/monitor.php?id=20069
For Ostrov Golomjanjy, every day of September has been a record, and the old monthly record of 2016 has been broken eleven times. http://www.pogodaiklimat.ru/monitor.php?id=20087

3
Arctic sea ice / Re: MOSAiC news
« on: September 07, 2020, 12:33:16 AM »
tbuoy update for those interested in data

4
Arctic sea ice / Re: MOSAiC news
« on: September 07, 2020, 12:26:45 AM »
The main tidal component is pretty close to zero at the pole.
Of course, there are other components, but they are amplified by being near land masses and submarine topography.
Probably topical. https://www.nature.com/articles/s41597-020-00578-z.pdf

https://forum.arctic-sea-ice.net/index.php/topic,2417.msg283489.html#msg283489

5
Arctic sea ice / Re: Home brew AMSR2 extent & area calculation
« on: September 06, 2020, 11:01:37 PM »
AMSR2_AWI continues to improve with the release of version 103 (though it's not 'there' yet). The new location for the twice daily files is provided below. The main change is explained in the ReadMe: the very latest sea ice concentration will appear at a fixed hour depending on your relative time zone. Rapid changes in concentration can be better resolved than with once-a-day products that use a full 24 hours of satellite swaths.

The winds have shifted to more off central Siberia and so differencing v103 shows that as the gold band in the upper Laptev. Surprisingly, these winds are not consolidating lower concentration ice as recognizable features persist for a week or more despite all the displacement on both OsiSaf light blue and AMSR2_AWI.

Quote
The product is generated twice daily for two different start times (filenames with AM or PM).

    [AM] ~22 UTC the day before until ~14 UTC. The AM product is available in the evening.

    [PM] ~10 UTC the day before until ~2 UTC. The PM product is available in the morning.

After about 16 hours the spatial coverage is almost complete. AM includes data mostly from before noon and PM after noon.

The advantage of this twice daily processing is A) a reduced latency and B) reduced time differences in the resulting ice concentration maps. A 24 hour difference as in traditional daily averaged products can cause displacement artifacts due to the ice drift. This effect can be observed along a moving ice edge which seems to be doubled in the 24 hours average.

The products so far often contain data gaps represented by gray swaths extending out from the pole hole (which never has data). These gaps can be repaired very simply as follows: open a time-ordered stack, switch mode to RGB, add a transparency alpha channel, select the gray, delete to let data from the immediately earlier file to show through, capture as a new layer, and merge down to retain file name. This can be done in one step if tiled. The dotted line in the illustrative image is not present in the actual repaired product. This process 'mixes' AM and PM but only to a very minor extent.

ftp://ftp.awi.de/sea_ice/product/amsr2/v103/nh/2020/09/

6
Arctic sea ice / Re: MOSAiC news
« on: September 05, 2020, 07:24:00 PM »
The time series below looks at how the moored Polarstern responded to the long-running mild anti-cyclone from Aug 23rd on to Sep 4th, with speed and displacement determined from floe buoys by Uniq and applied wind stress provided by GFS-nullschool three times a day.

There's quite a bit of hourly variation in wind details so the PS drift is correspondingly complex, though the 122 km of net displacement is surprisingly uniform in direction. Thus predicting overall motion of the ice pack (or just shape of ice edge) is difficult even with a good weather forecast since neither ridge nor keel drag is known nor ice plasticity response to pressure.

As first shown, the wind series was reversed relative to drift time. This effect arises from gimp and imageJ using opposite time ordering conventions. The last frame shows a major directional shift in the wind, now down from central Siberia over the NSI, rather than curling down from SevZem as it has been doing.

7
Arctic sea ice / Re: The 2020 melting season
« on: September 04, 2020, 12:18:16 PM »
Todays daily images and animation.
(Larger gif on the twitter page)

8
Arctic sea ice / Re: MOSAiC news
« on: September 03, 2020, 02:35:07 PM »
It is very easy to detect and perceive the bottom of the ice in the winter/spring due to the temperature gradient being positive from the top of the thermistor column to the bottom (very cold air: cold ice: warmer ocean).

Between us were setting the ice:ocean thermistor at the -1.8 to -2degC mark.

Unfortunately, during summer this temperature gradient becomes a U-shaped quadratic (warmer air: colder ice: warmer ocean) and eventually normalises to close to 0, which basically creates hell for analysis. Particularly given that the transition between ice and ocean at the bottom is probably muddied by supercooled water.

(the 2nd and 3rd figures represent different thermal conductivity sensors, you can just about perceive the bottom of the ice through summer)

9
Arctic sea ice / Re: Arctic Ocean salinity, temperature and waves
« on: August 29, 2020, 09:50:12 PM »
A very close look at axib buoy 91790, ~86.1N -45 (north of Greenland)

Somewhere near the middle of the clear worldview image from aug28 

I think arctic ocean 'waking up' might not have been too far off the mark

rammb nth greenland

10
Arctic sea ice / Re: Arctic Ocean salinity, temperature and waves
« on: August 27, 2020, 11:55:21 PM »
A quick look at the persistent low concentration area north of NSI/ESS, 80.7N 154.5

amsr2-uhh, aug17-26
today's worldview overlaid onto noaa bathymetry

11
Arctic sea ice / Re: The 2020 melting season
« on: August 27, 2020, 09:46:58 AM »
Latest images. The losses on the Laptev/Kara/Barents region have picked up, as expected with the southerly winds. Quite variable elsewhere.
Slow animation of change from the 23rd to the 26th too.

12
Arctic sea ice / Re: MOSAiC news
« on: August 23, 2020, 09:51:06 PM »
Quote
51 -- continuous light drizzle
28 -- fog
71 -- continuous light snow
You'd think a national weather service would have mouse-overs to the acronyms. Not rocket spreadsheet science to go through awiMet ship weather for the entire cruse (7561 entries) and pull out all the ones with weather comments (396 of them) sorted into class counts. So that's attached as a csv file below, ready for uniq(?) to process them further along the lines above, eg how many foggy days.

More challenging: go through the entire voyage on nullschool and do something with their 3hr precip claims (3HPA) for the whole Arctic Ocean. Not make a 5 hour mp4 but more of a summary. Rain is just devastating to snow and ice because of then phase change latent heat.
Quote
Oren: ice doesn't look all that thick overall but maybe locally
Very reasonable interpretation of the photo (which is all we have to go on).

Earlier in the year, 'Follow' did post a couple of raster thickness maps from above and below, in addition to near-horizontal mapping of topography. We have those above somewhere; they unfortunately forgot to include the numerical scale. Maybe this time they will!

The bow radar (above the upper bridge) just takes in surfaces reflections so maybe roughness and open water but not thickness. They unfortunately forgot to pair it with a camera or calibrate it with outings plus a Finnish student mistakenly cropped away the whole instrument parameter display for the entire cruise.

The ship sails with a electromagnetic doohickey suspended off the prow that measured ice thickness (ie distance to saltwater) along the entire way from Greenland north. That would not provide representative ice thickness since they were always looking for a route involving minimal icebreaking. Be the same for a time lapsed smart phone lashed to the mainmast.

To answer your question though, we are somewhat at cross-purposes with the Polarstern.

The forums are terribly concerned with the current state of the ice ocean-wide, learning about the mysterious ice conditions in the pole hole, mapping features like melt pond extent below satellite resolution, getting spot measurements of ice thickness to compare with piomas and hycom models, describing how the melt season will end up, quantitating heat that will continue to be available into the fall, and understanding how it all compares to the trends of previous years.

Mosaic has a different agenda: trying to comply with the terms and objectives described in their massive grant. These stress goals such measuring this and that on the ice over a full year to improve interpretation of satellite imagery that will monitor the ice in future years when no ship is out there.

Indeed those improvements may already surfaced in the new AMSR2_AWI as that PI from leg 3 explained in a recent ticker. That's why we've dropped Hamburg and Bremen, putting all the effort in understanding to the new product and perhaps adding inclusivity and presentation value.

The ship is just a moving point on millions of sq km of ice; efforts to widen the swath with remote deployments and buoy swarms have had mixed results. There's been little mention of larger scale  ongoing sonar tomography that uses the ship as passive receiving station. This would map out oceanographic detail for the whole Nansen Basin top to bottom.

The PIs have said repeatedly that the top cruise priority now is documenting the onset and mechanisms of early freeze season to complete the funding terms of the mission. Since they moored on 04 Oct 2019, that probably means going out a week at most to 12 Oct 2020 before heading back to Tromsø.

So in by way of providing us better understanding of the current melt season, it will take some time (2023) before all the data can be corralled into print. N-ICE2015 just put out another paper modeling AW as it was five years ago.

In fairness though, the 25 years of mooring studies through 2018 just published by Polyakov et al are extremely relevant to the current melt season as the slowly but inexorably shoaling Atlantic Waters is taking over the energy budget from surface weather.

Will the lessons learned by the Polarstern still be relevant to the ice of that day or fall more into paleo?

Given the pace of climate change, especially in the Arctic, chewing of cud seems an unaffordable luxury. Darwin could spend 40 years polishing his snail monograph but today we need something closer to near real time. New satellites sound great but take years of planning to implement. Thus air-dropped buoys, undersea gliders and transect-flying drones may be more the way to go.

13
Arctic sea ice / Re: MOSAiC news
« on: August 19, 2020, 09:40:25 PM »
Quote
are these photos for real? how thick is the ice at the North Pole?
Yes, so far all the photos posted show the immediate area of the North Pole, not the usual Greenland icebergs or Antarctic penguins. It's astonishing to see it all extending out to the horizon, who knew?. The pole areas out to ~200 km are very difficult to observe because most satellites need to be in near-polar orbit and require fairly narrow swaths to have any resolution (or work in the visible and can't see through the clouds).

Mosaic does have some bad photo practices such as wiping Exif data including GIS, using unstated 'shipboard time' instead of UTC, showing date blogged instead of the photo timestamp, and not flattening the key data irreversibly onto the photo jpg file where it cannot be lost, forged or removed except by cropping. (Even the cheapest flip-phone will do all this.)

The first and fourth photos below from the press release shows freeboard and submerged ice a little more clearly; the ratio should be 1:9, but how do we calibrate an absolute scale? Note melt ponds are easily distinguished from 'leads' which are a mixture of leads and icebreaker paths. I don't see a floe suitable for six weeks of mooring but they have been looking around at the pole for 9 hours so far.

We've also located incoming data for the three new snow buoys re-launched at 89º in #993. I'll defer to Uniquorn on proper reading of buoy data for S93 but the green seems to be thickness and as marked by a little box on the y-axis, seems to be at 0.22 m below sea level. Live links to the data are provided above.

Mosaic is stating repeatedly that the NP is in the center of the TPD. This is false. The pole has rarely been included over the last ten years in the TransPolar Drift, better named the CircumPolar Drift as it primarily sweeps around from the Laptev to Frame about halfway to the SZ FJL SV line. This year though, the drift took in an extraordinary swath of Arctic Ocean including areas even beyond the pole. It's all been documented repeatedly on enhanced Ascat time series -- it's futile to argue with unambiguous satellite data but people still do.

The other take-away from these shocking pole photos: these melt ponds may be deepening and even draining but they are not new. Suppose half of the surface area shown has been ponded or open water since mid-July, the whole way up from Greenland. This means the albedo has been very low compared to snow on ice during the high insolation levels. In turn this means fractional BOE is already upon us in terms of not reflecting excess solar energy back to space regardless of how the next two months play out.

Melt ponds + leads take up 51% of the pixels in the photo after excision of the Polarstern; there is slant bias favoring the foreground but an overhead ratio may well be similar.

Quote
PI Markus Rex: “Up until 87.5ºN, for the most part we passed through open water, in some cases stretching to the horizon. Based on the satellite imagery, we weren’t sure whether the loose ice cover was due to wind and currents, and were concerned a change in weather conditions could compact it again. Once in the region, however, they found that much of the sea ice truly had melted away, and hadn’t simply been broken up by the wind.

Captain Wunderlich: “I’m very surprised to see how soft and easy to traverse the ice up to 88° North is this year, having thawed to the point of being thin and porous. Even after passing 88° North we mostly maintained a speed of 5-7 knots; I’ve never seen that so far north...Normally  it’s home to thicker and older ice and virtually impassable. But now we’re finding extended stretches of open water reaching nearly to the Pole.

Moving on from the Pole, the Polarstern may follow the Transpolar Drift a bit further (i.e. towards Siberia) until she reaches ~87° North. “Depending on the ice conditions, however, we’ll also start looking for a suitable floe in the vicinity of the North Pole.

Rex was quoted in a single news story as saying this -- all the other newspapers cropped it out:

“It's frightening to see how thin the sea ice is and how quickly it is melting. Something needs to be done urgently. The Arctic cannot wait long."

https://www.tellerreport.com/news/2020-08-19-little-sea-ice--"polarstern"-reaches-the-north-pole-faster-than-expected.Bkfeon39Gw.html

14
Arctic sea ice / Re: MOSAiC news
« on: August 19, 2020, 08:38:27 PM »
Pic taken at the Pole. Lovely ice conditions, eh?


15
Arctic sea ice / Re: MOSAiC news
« on: August 19, 2020, 06:18:42 PM »
They've arrived at the North Pole after making a smart decision to steam up through the unusual low concentratio ice north of Greenland. The ice is just one melt pond after another there. The Polarstern appears to be looking around for a suitable study floe as longitudes are varying wildly about the pole.

WorldView is currently cloudy; Sentinel-1AB and AMSR2 don't get up this far; Mosaic rarely releases any imagery of scientific interest. So the only sources of information on ice condition will come from awiMet and bow radar. The latter's last frame is 18:00 on the 18th when the PS was at 89.16º.
   
   Lat  Long  YY-MM-DD  UTC     Wind       T(C)  N  h  VV  wwWW  ICE  Pnn(hPa)
  90.0  132.3 20-08-19 15:00    3  360     -0.7  7  3  98  0222 58/98 1023.3
  90.0  147.7 20-08-19 12:00    5  150     -0.5  8  2  98  2054 58/98 1023.9
  90.0  115.6 20-08-19 11:00    3  200     -0.4  /  /  //  //// ///// 1023.9
  90.0  -20.0 20-08-19 10:00    3  170     -0.3  /  /  //  //// ///// 1024.0

16
Arctic sea ice / Re: The 2020 melting season
« on: August 17, 2020, 03:17:34 PM »
Mercator ocean shows a current at 100m running through the Nares strait and wrapping around the north coast of Greenland. The Coriolis effect turns currents with a northwards component to the right in the NH so the current is very likely a warm current running northeastwards through the Nares strait which then keeps turning right along the continental shelf of northern Greenland. The current maps for 30m and 0m show eddies, complexity and directional ambiguity but I'm confident that there has been some upwelling in areas where the ice has been transported away from the coast.
I very much doubt that there is a warm current flowing north through the Nares strait. There is a tidal current in the Nares, but the general flow is of cold water going south. See this paper for more details, "Propagation and Vertical Structure of the Tidal Flow in Nares Strait".

There is apparently a current flowing from the mouth of the Nares north-east along the Greenland coast. I have suggested that this is the northward pulse of the tidal current, similar to what I have experienced alongt he coast of Sicily south of the Messina strait, a narrow and periodic, but at times surprisingly vigorous, current.
I am currently reading a paper from 2015 link. Random extracts attached..
My take on it..
Ice Arches matter - none this year?
The main current is heading south, at the western edge when there is landfast ice, on the centreline when ice is mobile or non-existent..
A narrow current heads north.

With global heating+arctic amplification say goodbye to landfast ice for longer periods of the year?

But much better for people who know what they are talking about to comment.

https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2015JC011091
Modeled ocean circulation in Nares Strait and its dependence on landfast‐ice cover

Quote

Ice conditions typically alternate between landfast and mobile states that are associated with the formation and breakdown of ice arches across Smith Sound and northern Robeson Channel [Kwok et al., 2010]. In years in which neither ice arch forms, such as 2007, ice fluxes roughly 2–3 times those of a typical year have been inferred [Kwok et al., 2010] and modeled [Rasmussen et al., 2010].

The multiyear Canadian Archipelago Throughflow Study [CATS; Münchow and Melling, 2008] maintained a mooring array across southern Kennedy Channel (roughly 80.5°N, Figure 1) from 2003 to 2012.

In the annual mean, flow across most of Kennedy Channel is southward with a vertically averaged magnitude of about 7 cm s−1 on the western side of the channel. On the eastern edge of the channel (south of Franklin Island located at 80.8°N, 66.5°W), a narrow current heads to the north with a depth mean of roughly 4 cm s−1. Rabe et al. [2012] showed that the mean structure of the main southward current is markedly different under landfast and mobile ice conditions, with important implications for seasonal and interannual variability of freshwater transport through the strait.

17
Arctic sea ice / Re: MOSAiC news
« on: August 15, 2020, 08:46:03 PM »
Very fortunate to having a well-appointed research vessel enter the baffling area of ice decay between Greenland and the North Pole.

It's not at all clear what the final destination is though the publicist writing 'Follow' suggests it is out of satellite range which for Sentinel-1AB is 87.5ºN (WorldView satellites don't have a pole hole but clouds often preclude imaging). The PS is moving rapidly, a full degree of latitude north in the last 12 hours (111 km by 20-08-15 19:00 ) plus 2º of longitude west.

They're fixing the helicopters but may or may not share those photos (or much else en route). The bow radar is no longer reporting at 6 hrs frequency, having stopped on Aug 9th. If restarted upon mooring, it would benefit from synchronous overhead views and shipboard commentary.

https://data.meereisportal.de/maps/animations/Iceradar/?C=M;O=D

Let's hope the PS focuses on the current melt season rather than searching for another meaningless ice jumble. (N-ICE2015 already followed four of them to oblivion.)

The PS reached the rarely studied Wandel Sea a couple years back after a strong narrow cyclone blew up the Fram, pushing the ice well north of the flux gate. The captain toyed with the safety of continuing through the Lincoln Sea and around Greenland via the Nares. The PI wrote me that the ship is equipped to do CTD tests on its own and did so (but the data could not yet be shared).

Fram export winds ceased in mid-May, not displaying a consistent pattern since. Despite the lack of a dramatic storm in the Straits this season, the 'cumulative impact' of moderate but generally non-northerly winds could possibly explain both the lift-off from the CAA, churning of Lincoln Sea ice, and the remarkable deterioration towards the Pole.

Since the ice has not been notably pushed, southerly winds would have needed to bring some mix of sunshine, warm air and overturned warm water acting on dodgier-than-realized ice.  Morris Jesup is not favorably located for katabatic winds off the Greenland summit ridge. No one here has systematically examined online daily records of the automatic weather station there.

This same 'Follow' publicist wrote in a double falsehood yesterday that the ship had passed through the offshore wind-created Northeast Water polynya. The facts and location concerning  that water opening have been established from 90 years of arduous on-site field work, beginning with Lauge Koch in 1933.

Read about it here:

http://www.issibern.ch/teams/Polynya/

https://sci-hub.se/10.1007/bf00240265

https://www.tandfonline.com/doi/abs/10.1080/00167223.2010.10669503?journalCode=rdgs20

https://www.researchgate.net/publication/226224526_The_Northeast_Water_polynya_Greenland_Sea

The Sentinel-1B below was colored by embedding a small fiducial black square, setting the colorpicker after some trial and error to radius 5, and clicking to find black elsewhere in the image. The selection was then filled with 'open water blue' though parts may have small floes or be half-slush.

18
Arctic sea ice / Re: The 2020 melting season
« on: August 13, 2020, 10:05:37 PM »
Quote
dnem asks: is the 15 Sep 2020 slide in #4796 your actual best guess scenario for that date? What would the extent of that scenario be?
No. It is better to focus on weather that has actually happened and document what that has done to the ice. For example, we do not have a grip on what is causing the unprecedented opening between Ellesmere-Greenland and pole so no have clue what comes tomorrow, much less Sept 15th. Even the better ‘operational’ forecasts like hycom haven’t been able find ice physics that reproduces what we can plainly see happening.

Sept 15 will come soon enough, it’s grossly over-weighted in posts. The melt forum is not really concerned with melt season but rather with loss of the planet’s refrigerator, the darkening solar reflector of high latitude northern hemisphere. Open water having only a tenth the albedo of sea ice, it carves out the lion’s share of growing energy imbalance as it fits increasingly better to seasonal insolation inputs. So it gets a forum.

‘Extent’ isn’t extent but rather a bare number that has forgotten its ice distribution picture. The bizarre opening this summer will go down the rabbit hole of a line graph. Multi-decadal trend lines are a much better use of extent numbers but even there, the x axis intercept has provided a dangerous upper bound to BOE oo far out in the future whereas the end game will likely be vastly faster and different process from the trend.

The 15 Sept scenario in #4796 isn't ‘photoshopping the future’ for the sake of an extent visualization stand-in because there is a physical basis to it: lowered concentration feeds on itself as enhanced lateral melt takes edges and smaller floes down to open water. So nipping away successively at the lowest concentration remaining in the palette does mimic the dominant process creating open water. However there’s no ability to anticipate less-than-boring weather.

This visualization method also works on hycom thickness though the physical basis is different (bottom melt). Because the embedded palette is so complex, it is harder to progressively infill the thinnest ice remaining with open water gray but still doable with lots of back and forth on the color picker radius. Hycom goes out six days on the weather so again a 30 day visualization will be thrown off by weather.

Ascat in late-May can supply surprisingly realistic visualizations based on yet another physical basis, residual brine channel salinity. The grayscale images are whiter on older matured ice and darker on newer FYI and SYI and systematically so. Thus iterated stepping of the contrast slider can incrementally erode higher dielectric ice, mimicking summer melt-off. Ascat does not provide useful images from mid-June to mid-Sept.

Despite the differing physical bases and gimp operations to exploit them, what the three future visualizations have in common is a stepping number. If that’s overdone or underdone, the visualization won’t look much like the actual future, especially if there’s unexpected weather. That departure is of interest in itself. However the images will remain a big step up from bare extent numbers or photoshop artwork.

The first animation below shows major changes are going on every day, just not ones that manifest on the low resolution extent/area forums

The five slides below start with the alarming OsiSaf of 11 Aug 2020, a 48-hour measure of ice pack displacement captured by well-tested AI. The background dark blue is open water; the inner light blue is not quite fully open as it still has vulnerable ice. There’s advantages to simplicity in terms of capturing a good overview; it’s sometimes hard to find a basic take-away from AMSR2 displays with 1% concentration increments that need a hundred colors.

The second slide overlays a reinitialized GFS wind display at 850 hPa in the middle of the OsiSaf date range. This shows winds a couple kms above the surface which again captures the main story without getting into complexities of actual surface air movement. It shows an unremarkable central anti-cyclone surrounded by three even less remarkable small cyclones. A confused jet stream far above has introduced not just surface highs and lows but given angular momentum to them.

The third slide drops the weather pattern onto the ice motion display. It’s a fairly good fit — the ice is moving right along under the anti-cyclone) — considering the 3-hr nullschool dynamic is on a 48-hour OsiSaf summary. The three cyclones are over open water, making waves but not directly moving ice. Persistent winds over long reaches can create swells that greatly damage the ice pack many hundreds of km away if they hit head-on. We have no idea if the next six weeks will bring extreme winds like these.

Air pressure differences per se don’t bring strong cyclonic winds, the gradient between the pattern of highs and lows has to be steep (close isobars). It follows that merely giving the low (970 hPA for the 27 July 2020 event) doesn’t adequately describe the strength, persistence, and ice impacts of the storm.

The fourth slide shifts to where the rubber meets the road: wind power density (WPD) vs frictional resistance of the ice (from pressure ridges, surface roughness and exposed freeboard edges). Wind tunnel data has established that the force exerted on the ice is better fit to the cube of wind speed (rather than speed). That means a mild Arctic zephyr of 5m/s (often seen by the Polarstern) provides 1/8 the push of a brisk 10m/s wind and 1/64 that of a 20m/s gale (rather than the 1/4 expected from assuming a linear relation).

A key feature of WPD in an Arctic cyclone is its strong variation with location and timestamp. Because of the cube, this is exaggerated for WPD relative to plain wind. On this fourth slide, the wind is seen acting very unevenly on the ice, the gold color indicating extreme forces above Ellesmere and Greenland and the blue a far more moderate impulse. Since we have no real idea of the level and distribution of friction across the ice surface, we have no real idea how the ice pack will respond to forces that vary so markedly in magnitude, direction and persistence.

Strong persistent non-cyclonic winds off Siberia brought a most unusual TransPolar Drift in late winter, causing havoc for the Polarstern, putting it months ahead of schedule and prematurely flushing it down the Fram. How does do cyclonic wind gyres differ in ice effect from straight southerlies? A tight radius of curvature means over a short distance through the eye that the wind has reversed direction by 180º. The ice, being pushed in opposite directions, forms a shear zone when cold and thick but more just a jumble of floes when thinner and weakly matrixed. A straight southerly has no curvature but may vary across a transect.

The ice also picks up on the overall cyclonic rotation as seen in this fourth slide. However the torque is not evenly applied. If the ice pack has open leads or polynyas, some of this can be adsorbed by compression or dispersion; if not, by ridging and over-rafting. In summary, though cyclonic events don’t necessarily bring extreme winds (or WPD), the ice pack is stressed in more complex ways. In late summer, on thinning ice, the effects can be dramatic.

The major 27 July 2020 cyclone will have a huge effect on the overall melt season. Even though much of the devastated ice might have melted out anyway just barely before Sept 15th, the early melt wrapping up now has exposed the perimeter of the central older thicker icepack both to enhanced lateral melt and to extreme wind exposure (so far unrealized).

19
Arctic sea ice / Re: The 2020 melting season
« on: August 10, 2020, 02:00:17 PM »
-3- The whole icepack does not rotate CW with the TPD but rather participation is demarcated by immense  curvilinear leads, newly visualized in a dockside posting by L Kaleschke and enhanced on the Mosaic forum by directional convolution. These fracture lines, coincidentally or causally, approximately delimit the puzzling openings to the pole above Morris Jesup. A lot of MYI ice between Greenland and the pole was fractured by lead formation.
The first animation of Kaleschke SIC-LEADS overlaid onto gmrt bathymetry in February when the ice was much thicker shows the location of those fracture lines. Accepted that drift will be different now that Lincoln Sea is not land fast.
The underlying ocean currents will still be there but the recent prevailing winds are preventing southerly drift so the ice north of Greenland is melting in situ and beginning to show the turbulent ocean beneath. The continuous rotation during July and the abrupt halt could also have contributed to the lower concentration in that area.
The second animation shows the rotation and some of the underlying turbulence. Rammb might do a better job over a shorter timescale

20
Arctic sea ice / Re: Arctic Ocean salinity, temperature and waves
« on: July 30, 2020, 12:40:09 PM »
Two active ITP buoys 113 & 114 in the Beaufort sea are worth watching during the storm, both showing a massive mixing event in the form of a decreasing salinity gradient, down to a few hundred meters below sea level. It's destroying the freshwater lens while temps in the upper layers have been increasing. I expect rapid melt out of what's left in Beaufort and Chuckci seas in the coming days.



21
Arctic sea ice / Re: The 2020 melting season
« on: July 30, 2020, 07:42:05 AM »
About wave activity, it can be noted that Indian Ocean was a strong source until lately. Pacific convection was a bit muted, but a dipole dominated over Indian Ocean, and a stationary MJO stucked in phase 2- 3 in June and July, with propagation of a wave train over Pacific and a reinforced subtropical jet here. But what is really curious is the strong source of wave activity from Arctic. I mean, I really don't remember seeing such a source independently from the mid latitudes and tropics.

22
Arctic sea ice / Re: The 2020 melting season
« on: July 29, 2020, 08:48:10 AM »
The Beaufort low is clearly visible on Worldview today. Unusually clear spiral pattern.
So far up north the Coriolis forces are pretty small.
The storm forms further south, and besides I'd think the Coriolis plenty strong enough to create a revolving pattern at that latitude. But I'd guess that how "clear" the spiral is when seen from above is more to do with happenstance than theory. Not that I would know.
Or it might be an indicator of an arctic cyclone reaching mature stage: coupling with the stratosphere, accompanied downdraft at the lower stratosphere, resulting in extremely clear conditions around the (very peculiarly shaped) tropopause. See https://www.sciencedirect.com/science/article/pii/S1873965216300056 . BTW Coriolis effect (force) is max at pole.

23
Arctic sea ice / Re: The 2020 melting season
« on: July 27, 2020, 01:00:37 PM »
It's unfolding as foreseen. In the first stages, weather has forced a big reduction on extent loss. To remember the 2012 GAC; it hit from the Sakha Republic, Siberia, right into the slush and goodbye waves in the ESS. From that direction, there wasn't the noticeable slow down in extent reduction. Within two days, under the clouds, GAC spreaded everything out over 2Mkm2 ocean, pushing the ice content under 15% in the grid-count. It was called 'flash melt' then.
The present Beaufort-chaser storm creates a different pattern. The 10-day ECMWF shows it teaming up with a Eurasian side anticyclone, thus setting up what could be called a reversed dipole.

In that situation, measured extent-loss will remain reduced for that period. That doesn't mean the pack-ice will be safe. While a lot of debris will seem to regain sea in the Chukchi, the ESS and Laptev, area will nose-dive and I have no doubt volume does the same.

In the coming 10 days, volume might loose up to 1500 km3. PIOMAS will report up to 15 July. So in about 10 days their graph will reflect the strong July melt. It will take the line at pair with 12, 17 and 19; about 6500 km3. After that, the coming 10 days will bring a decisive reel down for volume, taking it to a new dramatic low come september.

24
Arctic sea ice / Re: The 2020 melting season
« on: July 27, 2020, 12:33:45 PM »
Watch the unfolding Low on the Barrow webcam. Wind-swept waves on the coast, steady rain... The report speaks of wind gusts 33 mph. That's 6 - 7 Beaufort.

The wave height is more than a meter. I will save it in case the camera site crashes due to too many visitors.

25
Arctic sea ice / Re: The 2020 melting season
« on: July 27, 2020, 08:54:24 AM »
Thankfully these crazy predictions of 2.5million are now gone. Looks like a stall will mean we finish in the pack. Though probably whether we come 2nd or 3rd will be the only question. Think 2019 and 2020 will be very close at the end despite everything. Hopefully August will be a boring month for the ice.

So you expect the endless torching over the CAA and Eastern CAB to not keep melting the ice??  Which is already showing up on modis when the clouds clear out filled with holes...

What do you think this 972MB vortex puking out rain all over the Beaufort, Chuckchi, and Western CAB in concert with 20-30KT winds over 36-48 hours is going to do to ice that is truly 50-60 percent Concentration with MILES of OPEN WATER between the DECIMATED CHUNKS of ice?

And when that system winds down we still have another 40 days of ice loss to go.

You literally call predictions for new record lows crazy while giving no evidence to back up your new prediction of 2nd or 3rd lowest. I assume you are talking about extent.

Well you did cite a few days of slower losses while winds are in the reverse dipole position.  Which hasn't stopped melting.  Just compaction.


I'm not trying to be a dick but people post here putting huge effort and time backing there opinions and thoughts with great depth and thoughtfulnes and you dismiss that as crazy while offering no empirical evidence. 


I guess you have historical precidence on your side.  It would be nice if you would back up why you think 2020 is probably going to end up tied with or below 2019.

You may be right.  But it's pretty cheap to call the incredible analysis that dozens of members here contribute as crazy and then not actually offer any substance to back youe position.  Please no hard feelings.  Have a good night/day

 





26
Arctic sea ice / Re: The 2020 melting season
« on: July 27, 2020, 08:25:31 AM »
What's with closet deniers making multiple usernames... Being disingenuous reeks through every crack that it can.  In other words it's easy to spot.

Anyways the DMI 00z surface temp map isn't out.

But the 80N map shows temps above the long term average.

Pretty wild. Might go even higher the next few days.

Also at 00Z Alert, NU reported a 17C SURFACE temp.

With a pure Southerly wind at 17KTS.

Mid 60s heading into quasi night time with a Southerly breeze pumping incredible warmth into the CAB.

On the DMI ssts graphic.  It's hard to see but the Beaufort is showing above freezing ssts slightly throughout the rubble. Which has continued to weaken under the canopy.  The sst graphic is always 2 days behind.  I look forward to seeing how much the open water in the far Southern CAB warms.

Also Barrow Alaska must be in the warm sector of the organizing system.

At 00Z Barrow was rocking a 7.4C temp and 6.5C DP with a 15-20KT pure Southerly wind.  With a decent deep and deepening mixing ratio.

So over the next 2 days in the warm sector of this system warm deep moisture will bring some rain to the rubble.

At Inuvik near the mouth of the Mackenzie delta ..at 00z...  20C with 10C DP and deep mixing.

At Resolute 5.6/5.6C so deep fog at that temp which is ice bye bye.

Eureka, NU was 18C at 00z.  Our friends there in the science community can get outside in shorts today

Also the GFS has a wide area of 0 25-1.0" of rain over a large region from the vortex. Only 1-2" of snow in a very small spot.

Also it shows 20-30KT sustained winds directly over the weakest rubble region for 36 hours.




27
Arctic sea ice / Reversal of the Siberian Coastal Current
« on: July 26, 2020, 06:13:35 PM »
When you look at the Siberian Coastal Current (SCC) for the last few days on Nullschool, you can clearly see that the SCC is reversed. The current coming out of the Bering Strait is now flowing into the ESS. I'm wondering if this is a glitch in the data, or if something else is going on here.

Looking at the salinity data in this area this phenomenon seems to be confirmed.

Is there a simple explanation for this, or can we start speaking about the pacification of the ESS?

Attached are 2 GIFs with salinity at 30 meters and the surface comparing 2019 with 2020.

28
Arctic sea ice / Re: The 2020 melting season
« on: July 25, 2020, 06:32:43 PM »
21.7C at Longyearbyen, Svalbard today, thus "shattering" the previous max dating back to July 1979! Another poor year for the retreating glaciers up there...

29
Arctic sea ice / Re: The 2020 melting season
« on: July 25, 2020, 06:04:20 PM »
I believe this more of a coincidence than meets the eye. In normal years the deep Beaufort is much emptier of ice, the shallower ESS often has lots of ice at this stage. And this year the deep Laptev/CAB sector is ice-free.
amsr2-uhh overlaid onto gmrt bathymetry, minimum jaxa dates, 2012-2018
must add 2019 sometime.
edit:Perhaps someone will put together all the nsidc minimums one day. I think they go back a lot further. If they do, I will attempt to overlay them onto bathy.

30
Arctic sea ice / Re: The 2020 melting season
« on: July 25, 2020, 01:09:00 PM »
There was a bit of a discussion yesterday about Albedo Warming Potential (AWP) . Here is some further speculation.

I attach graphs of accumulated AWP anomalies from NICO Sun 's website https://cryospherecomputing.tk/NRTawp.
It is high, close to the 2016 and 2019 values.

This is potential, not actual, energy being applied to and absorbed by the surface of the Arctic Seas. However, the GAAC during a period of high insolation giving more than usual clear skies surely means that actual energy applied to the ocean surface was higher than usual. .

The last graph has the cumulative AWP potential of each sea. The Kara Sea AWP is through the roof. With clearer skies than usual, surely it is no wonder SST's are so high in that sea.

Perhaps there is momentum for further melting simply because of high energy absorption in the last month or so.

Wouldn't it be marvellous if the data on clouds and its effect on insolation reaching the surface was good enough to produce Albedo Warming Actuality.
______________________
ps: Nico Sun has documented everything he has produced at https://cryospherecomputing.tk/doc.html

Here is his explanation of the AWP calculation

The Albedo-Warming Potential (AWP) quantifies the additional ocean warming from a lower ice cover at the poles. These calculations don't include cloud cover, therefore it is called "Warming Potential" and not actual warming. However, over the six-month period weather tends to average out and warm areas correlate well with low ice extent in September. The basis of all calculations is a global surface radiation model and NSIDC Sea Ice Concentration data.

Formula per gridcell
AWP Daily = ((1-SIC) * MJ) + 0.15 * MJ * SIC
AWP Accumulated = sum(AWPdaily)
MJ = incoming surface radiation per square meter
SIC = Sea Ice Concentration

The calculated values are arithmetic averages over the whole maximum possible ice extent (shown in light blue). All lakes and some marginal seas (Baltic Sea, Gulf of St. Lawrence) are not considered because their coastline to total area ratio is too high. Coastline measurement errors introduce just random noise.



31
Arctic sea ice / Re: The 2020 melting season
« on: July 23, 2020, 10:28:07 AM »
Beaufort thinning out already. Big block in the middle 'pulverised'
amsr2-uhh, jul12-22 click

32
Arctic sea ice / Re: The 2020 melting season
« on: July 22, 2020, 11:28:03 PM »
Note that worldview shows cracks up and down the main channel and ice may be beginning to flow through the Davis strait. It certainly is cracking up and moving at the south end towards Baffin bay.
The dominoes are beginning to fall on the north American side of the Arctic.
Yes. Looking weak all the way to the Mclure Strait. Heavy linear contrast to show fractures.

33
Arctic sea ice / Re: The 2020 melting season
« on: July 22, 2020, 04:05:53 PM »
I took the 07/28 HYCOM sea ice thickness forecast and filled in green most everywhere where it is more than 50-70 cm thick (supposing that August will likely be able to melt 50 cm but not 1 M). This is what should remain by Sep 1. I don't know how much in million sq km the green area is:

Somewhere between 2 and 2.5 million, I'd say.  It's roughly a right triangle, the top edge runs from 80N across the pole and back to 80N on the other side, that's about 2200 km.  The other leg is a bit shorter, but there's some that's outside.   If it were 2200 on each leg, you'd get an area of 2.42x10^6.  Another handy number for eyeballing area in the Arctic is that the entire area N. of 80 is just under 4x10^6 km^2.

34
Arctic sea ice / Re: The 2020 melting season
« on: July 22, 2020, 03:49:25 AM »
OK, this is it.  This is our compact, unrubbled extent.  Our CAB Bastion if you will.

It's due north of Ellesmere.  The lower left hand corner is grounded on an island in the CAA.

To the left, it is bounded by the Beaufort, which *is* rubble, and the upper left hand corner is where the ESS and Chukchi melt in-situ are chewing into it.

Directly above, the Laptev ice boundary is chewing northward at as much as 50km/day, and will almost certainly be passing 85N before the end of this.

To the right, you have a combination of ice being rubbled, melting in situ as it is dumped into the Fram conveyor, or shoved into the emerging killing zone along the Atlantic front to the north of Svalbard and FJL.

This image is about 1.5 million km2.  There is far too little that will survive outside of it for my comfort.

35
Arctic sea ice / Re: The 2020 melting season
« on: July 21, 2020, 03:48:40 AM »
The CAB may be more compacted, but that is not thanks to high area, it's simply a result of lower extent. While we do not know the UH area for 2012 for this date, one can surmise the 2D situation was quite similar, and not something that can be considered good. The big question is if August will bring CAB area crashes as it did in 2012 and 2016. Considering the roasting under clear skies in the past few weeks, I expect the answer is yes.

36
Arctic sea ice / Re: The 2020 melting season
« on: July 20, 2020, 09:06:26 PM »
Area as well as PIOMAS volume is flawed during summer. The ice isn’t ‘holding up well’. Just look at Worldview at a well visible spot some 1500 km NW of Prince Patrick Island. That used to be part of ‘the safe structured haven’ of about 1,8 Mkm2 pack ice. If situated on the rim, I’d call the visible structure ‘goodbye waves’.

Bremen Uni’s colours in this phase of the melt season doesn’t reflect the situation in a reliable fashion. It isn’t completely wrong too. But it needs interpretation. That is why I studied the MODIS tiles in detail for years. Worldview is a means too, but, hélas, doesn’t fit my original method (so I gave up in ’17).

A large part in the creation of the current situation is terrible conditions for sea ice survival on the Siberian sector, rapid melt-out of Hudson and Baffin Bay and serious pre-conditioning over the Arctic during May. What saves the day is ‘winter power’ over Beaufort and CAA last winter.

Hard core warming is all over the place under the 415 ppm CO2 cover and even higher total greenhouse gas content. In thirteen years (since '07) the remaining time lapse to prevent a major climate reset has passed. And with it, the small chance to prevent a BOE. It could happen any year now. In ’07, strong compaction saved a lot of volume. In ’12, enough MYI remained to withstand a complete collapse in the Laptev sector. Those advantages now have faded out. The survival of pack ice in the Arctic is completely in the hands of weather. A GAC could be devastating, an August dipole could, whatever. Don’t pay to much attention to DMI-2 meter temps N of 80 degrees. Those reflect melt conditions. Look for temps on 950 MB and large swirls in the jet stream. It is on the rim of the Rossby-waves that Nemesis for the ice will ride…

37
With current sea ice records shattered already during the midst of the season, as well pronounced in the East Siberian Arctic Shelf ESAS region - basically just open waters, we ought to be particular cautious about the current environmental change opening up in front of our eyes.

via https://twitter.com/ZLabe/status/1284595460766707712

Quote
This scenario is now further fueled by prolonged record setting heatwaves. ..prolonged high average temperatures over 6 months and the record-breaking high of 38 ℃ recorded in Verkhoyansk on 20 June - a town roughly 600 km from the ESAS coast line. http://climatestate.com/2020/07/19/further-evidence-suggests-arctic-ocean-methane-storage-getting-more-unstable

Baked by midsummer sun, Arctic sea ice could face worst losses on record
Quote
Relentless high pressure and cloud-free skies have allowed the Arctic Ocean’s sea ice to plummet to its lowest mid-July extent on record. The persistent pattern sets the stage for what could be unprecedented losses by September – a long-feared next step in the Arctic’s erratic, climate-change–fueled lurch toward a potential “blue ocean” mode. https://www.yaleclimateconnections.org/2020/07/baked-by-midsummer-sun-arctic-sea-ice-could-face-worst-losses-on-record/
Quote
NSIDC: Air temperatures at the 925 mb level (about 2,500 feet above sea level), as averaged over the first half of July, were unusually high over the central Arctic Ocean—up to 10 degrees Celsius (18 degrees Fahrenheit) (Figure 2b). These above average temperatures were associated with high sea level pressure, centered over the East Siberian and Chukchi Seas (Figure 2c).

Arctic temperatures along the Russian coast were near to slightly above average. This is a sharp change from June, when, as part of the Siberian heat wave that has garnered much attention in the media, temperatures along the Siberian coast of the eastern Laptev Sea were 8 degrees Celsius (14 degrees Fahrenheit) above average.

It is likely these high temperatures, combined with ice motion away from the coast, initiated early ice retreat along the Russian coast, leading to the present low ice extent (Figure). Based on imagery from AMSR-2 processed by colleagues at the University of Bremen, the Northern Sea Route along the Russian coast appears to be largely open. https://nsidc.org/arcticseaicenews/2020/07/siberian-downward-slide/



Further Evidence suggests Arctic Ocean Methane Storage getting Unstable

At the ocean and atmosphere interface, the upper layer albedo effect vanishes with a lack of sea ice cover, subsequently creating a warmer surface layer, and perhaps altering the halocline https://www.sciencedirect.com/topics/engineering/halocline saltiness, temperature gradients, currents - shifting into a mode of a more productive melting regime.

The authors of the 2019 French study, Using ship-borne observations of methane isotopic ratio in the Arctic Ocean to understand methane sources in the Arctic, noted, ‘..in addition to increased CH4 emissions from wetlands and thawing permafrost, increasing ocean temperatures could lead to the destabilization of methane hydrates on the Arctic continental shelf, potentially emitting large quantities of CH4.’

Further previous research highlights a new mechanism for subsea permafrost deglaciation

Quote
The scientists found that one of the reasons for extensive methane release from the bottom sediments of the East Siberian Arctic Shelf is the destabilization of underwater permafrost gas hydrates that interact with the salt solutions (sea water) migrating into the thawing submarine permafrost. http://climatestate.com/2019/06/19/new-mechanism-for-methane-hydrate-dissociation/

Salinity at 34m, jul18 2018-2020


Quote
New research explores how lower-latitude oceans drive complex changes in the Arctic Ocean, pushing the region into a new reality distinct from the 20th-century norm. https://uaf-iarc.org/2020/07/10/arctic-ocean-changes-driven-by-sub-arctic-seas/

38
Arctic sea ice / Re: The 2020 melting season
« on: July 20, 2020, 07:13:58 AM »
72 hours until we see what happens when low pressure system takes over the Arctic.  In my opinion we will see the most dramatic slow down in extent drop in history.  Largely because the recent drop has been unprecedented (so a drop even to normal is a very big drop), and also because such a strongly compacted ice pack will accentuate the slow impacts of a switch to cool and cloudy conditions.

A wrinkle in the forecast is that there is hints of a high pressure system building into the Arctic from the Atlantic side in around 7 days time.  At this stage it looks a long way from a return to the extreme melt conditions we have seen recently.

I think ironically, a huge slow down is perhaps worse for the ice long term as it would suggest huge spreading out of the ice and possibly weakening the CAB ice as a result. I would prefer if its a more gradual process of trying to rejoin the pack.

There was perhaps some surprise and even suspicion of the PIOMAS volume charts, I do think we got to remember, alot of the rapid melt occured where ice thicknesses were below normal to start off with so whilst alot of extent has been reduced, there has been less volume loss because that part of the ice was not all that thick.

I know the compactness debate has been talked about alot but the theory would suggest a compact ice cap should be harder to melt than a more diffused one but like last year, I do fear SSTS will overrule any compactness especially on the Atlantic/Laptev edge. I also think Area has some positives of measuring during summer and there does seem to be link that if extent is high but area is low, a rapid drop is due but perhaps its more inconclusive the other way round?





What are you talking about????  The SOUTHERN CAB has been blow torched.

This pattern started back in june.

I just can't understand how you can come to that kind of conclusion. 

You are a really INTELLIGENT contributor here. 

You know better than to say that.

You know the Northern half of the CAA has been warm at times.

But the CAB has been decimated everywhere.

ONLY the far far Western reach has gotten slightly less warmth because of more persistent clouds.

Even tho it's still above freezing 24/7 expect a few hours here and there for like 6
50+ days.

The CAA & CAB IN JUNE BLOW TORCHED.

THE CAA HAD 3-4C+ 925mb temp anomalies in June

The Southern CAB had 4-5C+ for the entire month of June.






FOR JULY THROUGH THE 19TH(WHICH IS ALMOST 2/3RDS OF THE MONTH. )  CANADIAN ARCTIC ARPICHELAGO HAD ANOMALY OF 3-4C+ SO FAR IN JULY.


THE SOUTHERN CAB HAS HAD TEMPS ANOMALIES OF 2-7C+.THE CLOSER TO THE POLE YOU REACH THE 6-10C+ RANGE. 

THE NORTHERN 1/2 OF THE CAB HvAS HAD:

9-10C+ TEMP ANOMALIES FOR THE ENTIRE MONTH!!!


ON PIOMAS THE ATLANTIC SIDE WAS WAYYYYY ABOVE NORMAL NOW ITS ALL GONE.

ALL OF IT.

THE SOUTHERN CAB WAS THE ONLY OTHER BIG AREA OF POSITIVE THICKNESS!!



39
Arctic sea ice / Re: The 2020 melting season
« on: July 20, 2020, 12:50:00 AM »
Why are extent numbers dropping like a stone, and extent is #1, while area numbers are just bumbling along in #3 position?

Sea Ice Area, as captured by passive radar from satellites, is not an especially reliable metric (read: noisy) for sea ice loss (the underlying variable of interest) during the Summer months:
  • melt ponds form slowly (which can appear to reduce area), then drain suddenly (appearing to increase area), all without capturing much of the underlying melt dynamics
  • variable clouds can block observations making obscured areas seem more concentrated
These problems (and more I'm sure the researchers know about that I don't), are literally the reason the concept of Sea Ice Extent (SEI) was invented. It's an attempt to give a more reliable measurement of the state of the sea ice.

Once the pack firms up with the refreeze, then area once more becomes a reliable measure, it's just that we want to know about the Summer minimun above all else. Drat!

Cheers!

40
Arctic sea ice / Re: The 2020 melting season
« on: July 18, 2020, 04:18:12 PM »
mercator 0m (ocean) temperature with amsr2uhh overlaid at 80% transparency. amsr2 0% concentration has been set to fully transparent. jun1-jul17

41
Arctic sea ice / Re: The 2020 melting season
« on: July 17, 2020, 06:50:45 AM »
I think the three remaining question marks for this season, besides the obvious unknown weather, are:
* As Friv asks - How much of the CAB ice reaches final melt-out? My gut feeling says this will happen on a wide scale. The thickness lost during the GAAC is way higher than any possible winter advantage the CAB may have had. Besides  massive ice movement during Feb-Mar resulted in the replacement of a lot of ice near the pole and Greenland with FYI that came from the Laptev area. This FYI can only take so much before it becomes water.
* Will the CAA break open early enough to allow transport and export of the rather thick ice there? Considering the constant sun and high temperatures experienced by the CAA in the past month or more, my gut feeling says this will happen, and perhaps even enable export of thick ice from the CAB towards the end of the melting season. Currently the breakup in the main channel is faster than the cold years and slower than the very warm years (2011, 2012, 2015, 2016), but considering the amount of thickness that must have been lost I suspect the speed will be enough to carry it to completion on time.
* Will the Beaufort ice succumb to the crazy melting season around it and crash? Due to abnormal transport patterns this year, sea ice area and modelled volume have been consistently high. However, the ice does not look so good and at some point import from the CAB could shrink considerably. In addition, any movement by the Beaufort ice will result in extreme damage due to expected open water all around. Again, my gut feeling is the Beaufort cannot survive on its own with the mayhem going on.

Bonus question - will the weather produce some ice-preserving miracle? Is it even possible at this stage, with so much bottom melt already secured, and only that much thickness remaining? Perhaps the best thing the weather can achieve is an early minimum.

Points which I find unquestionable:
* Laptev is dead and will pursue into the CAB, the only question is how deep.
* ESS ice will soon disappear completely, before the end of the month. It looks terrible on Worldview.
* Chukchi will reach zero in the first half of Aug, despite being fed by the Beaufort.
* Greenland Sea which has been running cold and swollen with ice will lose lots of area and volume in August, as it does every year.
* All the rest (Kara, Barents, Baffin, Hudson) should reach zero during July.

i will go publicly here to predict a record low PIOMAS volume this year. Admittedly it's just a model with its own limitations, but I find it hard to believe that the relentless unprecedented insolation we have seen over huge parts of the CAB will go unnoticed. I have never seen so many clear days on Worldview during peak insolation.
I also expect record low area, with somewhat less certainty. GAC or no GAC, enough damage has been done that will be hard to stop in time. AS for extent, this depends on compaction during the September end-game, harder to predict.

At most, my gut predictions will turn out wrong. Good for the planet.

42
Arctic sea ice / Re: The 2020 melting season
« on: July 16, 2020, 11:37:28 PM »
Perhaps it would be best to research how such models work, before making comments in the future.

Dude,

Back in the good old days I discussed the then novel SPIE model with Andrew Slater in these hallowed halls:

https://forum.arctic-sea-ice.net/index.php/topic,778.msg25903.html#msg25903

If you had clicked the link I helpfully provided above you would have seen that I recently stated that the 2020 blue line "seems rather 'non physical' to say the least".

Nonetheless it is still "currently showing a very early minimum". See below.

Do you suppose that the red line will continue to closely follow the blue line for the second half of July?


 


43
Arctic sea ice / Re: The 2020 melting season
« on: July 16, 2020, 04:43:53 PM »
LOL, i was just making a GIF with D&N band! Coincidence? I think not!  ;)

The Lincoln suffers swisscheeseification. Note how there is no export via Nares so far. (Click to play)

44
Arctic sea ice / Re: The 2020 melting season
« on: July 14, 2020, 04:48:26 PM »
I have no hope for the ice in the Beaufort and the Laptev bite is already at 80N. The weather is so bad for ice that 2020 could beat 2012 without a GAC in August or September. You are right, Friv that the ECMWF forecast is brutal for the ice.

if you click this link https://clima.caltech.edu/files/2018/11/Timmermans.pdf
you will see 20 pages of images by Prof Timmermans which describe the current patterns and the build up of heat in the Chukchi and Beaufort seas. Sustained easterly winds cause upwelling that brings up some of the stored heat. The Beaufort is a death zone for late summer ice now.

And no 'recovery years' in 2021 and 2022. The GAC vented a lot of oceanic warmth.

45
Arctic sea ice / Re: The 2020 melting season
« on: July 14, 2020, 02:59:31 PM »
Somehow Andrew Slater's model isn't responding to the current melting conditions. It moved its predictions upwards over the last week and is still trailing at 4,72 mi. km per 2nd of september. Meanwhile the general impression here at the forum is that this season will end up with (well) below 4 mi and maybe even around 3 mi. sq. km.
Slaters model only has about two weeks left of revising its numbers downwards. While it has done remarkably well in predicting september minimum over the last years, this year it might be off by quiet some margin. It seems to imply that what's happening at the moment is rather unusual and not in incorporated in the model.

Maybe the Slater model, and some other models, did not anticipate the massive heat punch that has been delivered this year from central Siberia, which has been expressed most dramatically in the virtual destruction of the Laptev sea ice.
https://www.ncdc.noaa.gov/sotc/global/202006 

46
Arctic sea ice / Re: The 2020 melting season
« on: July 13, 2020, 02:24:48 AM »
Latest Five Day Forecast
Wind @ Surface + Total Cloud Water
Wind + Temp @ Surface

Large GiFS!

47
Arctic sea ice / Re: Arctic Ocean salinity, temperature and waves
« on: July 11, 2020, 10:09:58 PM »
Rough check of Beaufort buoy drift timing with worldview, apr1-jul10 4.6MB

48
Arctic sea ice / Re: Temperatures at Eureka, Nunavut, Canada
« on: July 09, 2020, 12:20:28 PM »
Hello folks,

I did contact EC Canada and I received a reassuring reply that all is well. This basically confirms what we have outlined in this thread. It is always nice to get confirmation and thanks to EC Canada.

       Hello Niall,

 
 Thank you for sending your message to Environment and Climate Change Canada.  I checked with one of my colleague familiar with the weather in Eureka and here’s the reply he sent me:

  “While the stations are within 2 KM of each other, they differ from each other physically.  NAV Canada’s station (71613) is situated on a hill 30m higher in elevation than our surface station (71917; as well, our surface station is located quite a lot closer to the fjord. Depending on which direction the wind blows we have seen a large discrepancy between the two sites due to their locations.

I looked over our surface site date between June 21 and July 3 and do see some temperature swings of about 5C between the max and min reported temps, but these are similar to the swing between max and min we see in Svartevaag and Alert over the same period.

We have a climate program on site with different instruments located about 3m away from our surface sensors, I spoke with the staff on site and they mentioned that the values differ by about 0.5c at times but are generally similar to our surface station values.

 The equipment in the Eureka surface station is standard across Canada and failures are extremely rare.  We compare the sensors against our regional standard at least once a year and require tolerances of +/- 0.5 degrees.  The last comparison was done in August of 2019 and showed a deviation of 0.05 degrees from our reference.  I am not sure of Nav Canada’s maintenance schedule, or if they go out to check their equipment at all.

 For the reasons discussed, I am confident in the accuracy of our sensors and that these temperatures are indeed correct.”





49
Arctic sea ice / Re: The 2020 melting season
« on: July 08, 2020, 06:33:51 AM »
Phoenix, you are being intentionally obtuse.

When FOW calls someone out, you know things are bad! He is the nicest guy on the planet. 😂😂😂
FOoW also knows Arctic climate better than most of us would dream of.

He's pointing out very explicitly you (Phoenix) are drilling down further into a dry hole, and gently telling you that you really don't understand the atmospheric dynamics of heat exchange which are currently taking place.

I've tried to do a bit of the same, but you do not appear to be listening.

To be succinct, again, the heat exchange to ice from atmosphere this time of year by way of direct thermal transfer is measured in 10s of watts per square meter, whereas insolation is providing 350-400.  A drop of a degree or so at 2 meters or the surface is not material.  The "250kilo gorilla" is still pounding away at the ice.

To use a somewhat different metaphor, talking about air temperature dropping and reducing heat transfer is like getting excited about someone no longer throwing gravel at you.

Meanwhile someone else is *still* shooting at you with a high calibre handgun.  The reduction in gravel is not going to make a lot of difference in how badly you'll be shot up.
 

50
Arctic sea ice / Re: Arctic Ocean salinity, temperature and waves
« on: July 07, 2020, 05:03:09 AM »
Oren, I was thinking the creation of white ice as surface ponds drained and the reduction of visible and UVR resulted in less heat to surface water below the ice via a reduction in insolation. Here is an excerpt from an article I posted month ago.

Stage I Prior to Melt Pond Onset on 15 June

Only 0.02 ± 0.01 of incoming PAR was transmitted through the snow-covered ice and spatial variability of light transmission did not change noticeably.

Stage II From 15 to 22 June

Once melt water became visible in large stretches at the ice surface, T¯(PAR)
increased by an order of magnitude to 0.31 on 22 June, while under-ice irradiance became increasingly variable.

Stage III From 23 June to 2 July

A short snowfall event followed by an enhanced surface melt resulted in discrete areas of white ice and melt pond, defining stage III. PAR transmittance and its spatial variability did not increase further during this stage. In fact, T¯(PAR)
 measured along the ND transect decreased from 0.23 to 0.16.

The observed large drop in T¯(PAR)
 measured along the ND transect on 28 June was attributed to the snowfall event. Unfortunately, surface albedo was not measured that day. Repeated measurements along this transects also showed more pronounced transmittance peaks beneath melt ponds while PAR transmittance below white ice became less variable over time (Supplementary Figure S3). These high transmittance values of discrete surface ponds became pronounced as outliers in the boxplots after the surface flooding in stage III. The larger areas of white ice transmitting less PAR compared to ponded ice also resulted in a skewed distribution and the median to be less than the calculated mean for most of the days within stage III. On the last sampling day, the variability in measured under-ice PAR levels decreased while T¯(PAR)
 remained unchanged at 0.20. As shown in the aerial drone image of the sampling area on 2 July (Figure 4E), more white ice had emerged at the surface due to ongoing drainage of melt ponds, leading to a drop in the melt pond coverage and a more uniform sea ice surface. It should be noted that the proposed stages of changes in T¯(PAR)
 are different from the stages of melt pond evolution described elsewhere (Eicken et al., 2002).

For the comparison of measured mean PAR transmittance and length-weighted average transmittance, T¯LW(PAR)
 was calculated for all D transects. To do so, T(PAR) values of 0.16 to 0.24 beneath white ice and 0.25 to 0.40 beneath ponded ice, measured along four destructive transects, were used. As shown in Figure 5B, T¯(PAR)
 and T¯LW(PAR)
 were not significantly different (t(12) = 0.005, p = 0.996) over the sampling period.

The increase in the transmission of one wavelength (305 nm) in the UVB spectrum and three wavelengths (325, 340, and 379 nm) in the UVA spectrum at 2 m is shown for all transects over the sampling period (Figure 5C). Beneath snow-covered sea ice in stage I, T¯(UVA)
, ranged from 0.01 to 0.02, while UVB radiation was not detectable. It is noted that surface and transmitted irradiance were integrated over the UVA wavelength spectrum (320–400 nm) prior to estimating T¯(UVA)
. With melt pond onset, T¯(UVA)
increased to 0.26 by the end of stage II on 22 June. Also, UVB radiation was detectable beneath the ice cover with a T¯(305nm)
 of 0.01. In stage III, transmission of UVA radiation did not increase further, displaying a mean of 0.21 ± 0.05 for D and ND transects. However, T¯(305nm)
 was on average greater during stage III than stage II, reaching a mean value of 0.07 ± 0.06. During stage III, UVR transmittance remained relatively consistent, while the variability in measured under-ice UVR levels decreased. Furthermore, UVR transmission through melt ponds was twice as high than through white ice. TWI(305nm) and TMP(305nm) ranged from 0.03 to 0.08 and 0.11 to 0.14, respectively

https://www.frontiersin.org/articles/10.3389/fmars.2020.00183/full

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