The 2018 melting season

[FishOutofWater]

Ok. http://www.whoi.edu/page.do?pid=160136



That's very cold water sinking off the shelf penetrating deep in to the Atlantic water layer around day 540. That's not warm water mixing up. It will not cause melting. It is a form of convection, but it's intermediate to deep water being formed.

[Pagophilus]

I am not qualified to comment on the details below ("so don't!" I hear you say  ), but I think that the ongoing Atlantification that is now stretching out past Svalbard towards FJL and perhaps beyond should be taken into account.  That process does not seem to be stalling, and if it is going to roll onwards it would leave the ice of the entire Atlantic and western Siberian sides more and more vulnerable, particularly in any strong melting year.

Given the trend and forecast, this year could contend with 2013's cool summer and end up over 5M on extent. I'm also thinking around 3.5M for area.

I don't see how we're going to break out of this pattern without significant changes in the North Atlantic SST pattern or a big Nino (or both). We may see this "stall" continue for a few years until deep ocean convection in the NATL corrects the large SST anomaly and helps flip the NAO/AO state back into negative territory. I suspect we'll see a relatively rapid drop in sea ice cover when that happens, but it could take 5-15 years (as it did in the 80s to early 90s).

The difference by that time will be the warming winter temps and significantly weakened spring volumes. 2016 was a small preview of that. I don't think much of the pack would survive a 2012 or 2007 style dipole with another 1C of winter warming.

[Hyperion]

Yeah. The colour bars are difficult to interpret due to different ones for shallow and  deep charts. And for different itps for that matter. Sorry for the gif s of confusion.

[Hyperion]

Ok. http://www.whoi.edu/page.do?pid=160136



That's very cold water sinking off the shelf penetrating deep in to the Atlantic water layer around day 540. That's not warm water mixing up. It will not cause melting. It is a form of convection, but it's intermediate to deep water being formed.

I don't think its that simple fish. There's definitely signs of warming near surface, and look at the dissolved oxygen plot. 20 days of up and down mixing through the whole column. And there, like I said, is signs this has been already happening to a smaller degree for months. And this is the most Beaufort central of the three 2017 ones. They stopped reporting the other two when they got anywhere near nares and Chukchi rise.108 is still well over the abyss. Though starting to speed for the CAA, on the very rapid flush  Current that's been running in recent months

[FishOutofWater]

The oceanography of the Arctic ocean is quite complicated. I have read a number of papers, studied basic oceanography on-line and looked at web sites for years, but it's no substitute for coursework on the topic. I'm not completely befuddled because I took graduate level courses in geophysics. Perhaps there is someone posting here who can explain the Arctic ocean circulation better than I can, but I know enough to see that many people here are badly confused about the dynamics of the water layers in the Arctic ocean.

I strongly recommend watching the full length animations at Mercator Ocean to get an idea of what's been happening for the last 16 months at various levels. Set it to the highest speed possible and focus on the salinity and sea surface height model runs. Here's the link to the animation of salinity over time at the 30 meter level.

http://bulletin.mercator-ocean.fr/en/permalink/PSY4/animation/3/20170228/20180714/2/2

Water near the surface generally flows a path pretty close to sea surface height contours but it is deflected to the right by the Coriolis effect as it moves towards or away from the pole. Thus the west sides of passageways to/from the Arctic ocean are cold and the east sides are warm. Thus incoming near-surface Atlantic water tends to begin to flow towards Siberia.

However it only gets so far before it cools and sinks. The incoming paths of Atlantic water are strongly affected by the weather. Storms in the Arctic and subarctic seas on the Atlantic side blow Atlantic water into the Barents sea. High pressure directs it mostly towards the Fram strait. Lately storms have increased the flow into the Barents sea.



One really confusing thing is that there's eventually a reversal of the direction of flow of the water that pushed into the Arctic from the Atlantic. And also it sinks to 300 to 600 meters depth. Thus water that flowed towards Siberia is blown out to sea and heads back in the general direction of Greenland. A strong Beaufort gyre drives salty water from north of Greenland along the continental shelf of the CAA at the 300 to 600 meter level. That's what happened last fall and winter. The previous winter the Beaufort gyre was weak and last winter it strengthened.

Therefore, the Mercator animation shows a strong increase in salinity over the past 16 months in the waters of the Canadian Archipelago and on the continental shelf of the Arctic ocean north of the CAA.

So, if we had high pressure over the Arctic this June and July, that warm salty water would have welled up along the shelf and melted out a huge volume of sea ice. However, this summer's cold stormy weather is keeping most of that warm salty Atlantic water, that might have welled up, locked up at 300 - 600m.

We're likely to see a big melt out on the Siberian side with all the warm air advection, but the Canadian cold and Arctic ocean storms will lead to a good year for ice preservation on the Canadian side of the pole.

http://bulletin.mercator-ocean.fr/en/permalink/PSY4/animation/3/20170228/20180714/2/2

[Pagophilus]

Thanks for your highly cogent, informative post.   Do you see ongoing 'Atlantification' as contributing towards that meltout on the Siberian side?

We're likely to see a big melt out on the Siberian side with all the warm air advection, but the Canadian cold and Arctic ocean storms will lead to a good year for ice preservation on the Canadian side of the pole.

http://bulletin.mercator-ocean.fr/en/permalink/PSY4/animation/3/20170228/20180714/2/2

[uniquorn]

<snippage>
I strongly recommend watching the full length animations at Mercator Ocean to get an idea of what's been happening for the last 16 months at various levels. Set it to the highest speed possible and focus on the salinity and sea surface height model runs. Here's the link to the animation of salinity over time at the 30 meter level.
http://bulletin.mercator-ocean.fr/en/permalink/PSY4/animation/3/20170228/20180714/2/2
<snippage>

that 30m animation, every third frame to reduce size

[oren]

Thanks FOOW (and uniquorn), indeed my eyes start to glaze over at the mention of salinity and sea surface height, due to lack of background in oceanography. That salinity animation is certainly educational.

[Frivolousz21]

Modis and Bremen amsr2 graphics show parts of the chuchki and ESS getting smoked.

It extends further North but visible is obscured by clouds and amsr is obscured by higher clouds with frozen vapor.

If my back of the envelope math is right.

Having 2-4C surface temps with 20-30km winds not even accounting for insolation can melt upwards of 10-15cm a day off the top.

If the dews are also 1-2C with Smoke and decent insolation.

Incredible melting can really go nuts because the sub surface will also see a massive influx of heat.

Even in a couple days this massive heat intrusion could leave the subsurface a degree or two warmer than before.

0 to 0.5c sub surface water in low psi conditions is essentially 2c Above the freezing point

Also the ESS is still shallow almost all of the heat dumped into the sub surface will go to melting the ice or warming the sea bed.

[jdallen]

Modis and Bremen amsr2 graphics show parts of the chuchki and ESS getting smoked.
<snippage>

This is going to be *very* interesting to watch.

If your 10-15CM/day is on target, there's a lot of ice in the Pacific side of the CAB, along with the ESS and Chukchi is that is going to disappear within two weeks.

[Hyperion]

Modis and Bremen amsr2 graphics show parts of the chuchki and ESS getting smoked.
<snippage>

This is going to be *very* interesting to watch.

If your 10-15CM/day is on target, there's a lot of ice in the Pacific side of the CAB, along with the ESS and Chukchi is that is going to disappear within two weeks.

SMOS is showing it too. And the Beaufort. But you'll have to go to the SMOS thread Nevz started to see the pics and wind and temp animations. Since he thinks SMOS not respectable enough to be on here. 

[Hyperion]

Zooming in on that 30m year to date salinity animation. And trimming it to even less frames for better file size. Last frame freezes before repeat so you know when is now.
You can see the Beaufort Gyre contract off Mackenzie bay, pushing the dark blue low salinity stuff deep as its angular momentum speeds up the core, then it slides along the Alaskan coast until it collides with the Chukchi rise, and starts to unravel.
The unraveling appears to entrain Pacific water, that floods onto the ESAS to meet the east flowing Atlantic. In the last few months extra fingers of Pacific water extend parallel to the ESAS out into the basin.
It would not surprise me if this has progressed further than the model represents. We have so little actual data on subsurface current and salinity behavior.

[F.Tnioli]

Looks like we will find out the effects of smoke on ice through observation soon

I would very much like to think so, but I have come to realize that it may be difficult.  Given that this area of the ESS/Laptev coast is scheduled for very high temperatures at the same time as the smoke is present, then those two variables might be hard to separate.  In addition, there is a good deal of precipitable water in this area.  If rain results then that rain may also have a melting effect on the ice (and produce a change in albedo by itself).  ...

"May" have a melting effect - how so? I mean, wouldn't liquid water poured over a piece of ice always have a melting effect? Or are you considering possibility of such effect being insignificant due to minimum possible temperature of rain water or somesuch?

[Pagophilus]

You are correct, my English was at fault  -- the 'if' should have been followed by 'will'.  Thanks for picking it up.

Looks like we will find out the effects of smoke on ice through observation soon

I would very much like to think so, but I have come to realize that it may be difficult.  Given that this area of the ESS/Laptev coast is scheduled for very high temperatures at the same time as the smoke is present, then those two variables might be hard to separate.  In addition, there is a good deal of precipitable water in this area.  If rain results then that rain may also have a melting effect on the ice (and produce a change in albedo by itself).  ...

"May" have a melting effect - how so? I mean, wouldn't liquid water poured over a piece of ice always have a melting effect? Or are you considering possibility of such effect being insignificant due to minimum possible temperature of rain water or somesuch?

[Csnavywx]

Well, the EPS and GEFS don't exactly look good for melting over the next 5-10 days. After this brief torch on the Pacific side, it appears a -AD sets in followed by a pole-centered TPV pattern. This year feels more 2013'ish all the time.

[Ned W]

This year feels more 2013'ish all the time.

This year's June slowdown was eerily similar to 2015, both at the whole-basin scale:



and in terms of geographic distribution of ice:

[Pagophilus]

And 2015 ended up looking like this.  Which would correspond with the low melting this year on the Canadian side, and the compactness of the ice in the CAB.  Long term speculation, I know, but still not an unlikely scenario...

This year feels more 2013'ish all the time.

This year's June slowdown was eerily similar to 2015, both at the whole-basin scale:
and in terms of geographic distribution of ice:

[FishOutofWater]

The large scale synoptic weather patterns & El Niño development are fairly similar to 2015 and I suspect the sea ice minimum will look a lot like that map of the 2015 minimum.

[Ned W]

Here's a comparison of the change in NSIDC concentration over the month of June, in 2015 (left) and 2018 (right):



The black areas are "no change", including areas that were open water on both dates, but also areas that were 100% ice on both dates.  2018 seems to have had a much greater area in the CAB that didn't see any change in concentration during June.  Other than that, they're remarkably similar.

[Hyperion]

2013 and 2015 were totally different worlds. This year the Beaufort gyre has disgorged its protective lid of fresher water through the CAA, sucked in a high SST Pacific flood, which is in the process of colonisation of the east Amerasian basin. The flood out the CAA is continuing. A back eddy into the Beaufort from the south CAA is causing the Beaufort to be constantly refilled with low concentration beaten up and partially melted and quickly melting ice. As well as the increase in Pacific inflow, the Atlantic inflow has accelerated, in volume and heat. As is necessary to replace a volume of water similar to the great lakes being  expelled into the Atlantic.
Low pressure over the basin, particularly the Beaufort will only accelerate this process. And these cyclones and the temperature differential enhanced by bottom melting In a high surface salinity regime is drawing in unprecedented levels of heat and moisture over the continents. Which enhances the temperature differential still more in a feedback loop.

Comparing with previous years extent figures and distribution will only delude you. 😢😰

And don't expect comparison with previous years weather patterns and indices to be helpful either.
US Navy melt animation:

[cesium62]

This year feels more 2013'ish all the time.

The Slater Projection has been dropping fast the past few days and is currently suggesting a 2016-like minimum.

[Tor Bejnar]

Remarkable graph by Jim Pettit:

[Stephan]

My actual monthly post about the deviation of sea ice extent from the long term linear trend for June 2018 is ready.
The linear trendline is now 0,41 mio. km² below the actual value. This is an increase of this difference (in comparison to may 2018) due to the "slower than average" reduction of sea ice extent in June.
See attached graph.

[Pagophilus]

Hyperion, I guess some of us are discussing matters in terms of possibilities ahead, the way scientists usually make predictions, but you seem to be in possession of absolute knowledge.

2013 and 2015 were totally different worlds.

Comparing with previous years extent figures and distribution will only delude you. 😢😰

And don't expect comparison with previous years weather patterns and indices to be helpful either.

[uniquorn]

Algal bloom in the Svalbard hotspot?
Worldview terra/modis true color and enhanced jul6.

Last image: imagej brightness contrast 9,122

[A-Team]

Same area, gimp. It is fairly difficult to determine the extent or onset these algal blooms, first because of cloud cover and second because they can also occur on the bottom side of sea ice (see article in N-Ice2015). The species mix is complex and highly variable and cannot be determined from satellite, someone has to go out there to sample repeatedly. This is not only an odd area for a bloom but an inexplicable pattern if it reflects currents.

One consequence to algal blooms is that the vertical distribution of solar energy capture changes, to favor the upper surface over the depths. Note blooms go with long summer days of sunlight, not so much with warm water temperatures (like the more familiar eutrophic pond) as quite a few species are ok with the -1.8ºC at the ice-ocean interface. FYI ice lets more light through so that has been a major change.

There is usually a growth-limiting nutrient with blooms, depending locally on currents, upwelling and dgree of mixing. In the Arctic, nitrogen and phosphorus are often mentioned, iron not so much. Earlier melt, thinner peripheral ice, later freeze-up will increase  open-water blooms, with large, changing and unpredictable consequences for the overall ecology.

[FishOutofWater]

That bloom was visible on 22 June in the 3-6-7 imagery on Terra. 3-6-7 enhances the visibility of algal blooms. 7-2-1 makes algae and sea water both turn black. I suspect that the swirls are caused by the mixing of cold fresh meltwater with warm, salty Atlantic water. The algae would be growing fastest in the nutrient rich meltwater. Click to enlarge/enhance.

[uniquorn]

So, is the bloom related to the nullschool hotspot?

At risk of salinity overload here is mercator salinity at 0m,34m,92m,318m ~201703-201807.
Every 5th day to reduce file size.

34m is missing the forecast
edit:there is no salinity clause

[RoxTheGeologist]

could it be there is some vertical convection going on?. I have no idea what the density profile would look like between the light an dark areas. Is the top layer cooling and sinking, or is it a warm upwelling?  The later seems the most likely considering the hotspot we have observed.

[FishOutofWater]

If we look at the east side of Svalbard today we can see the algal bloom there is associated with melt water that flowed off the island.

[Ned W]

2013 and 2015 were totally different worlds.

Comparing with previous years extent figures and distribution will only delude you. 😢😰

And don't expect comparison with previous years weather patterns and indices to be helpful either.

Nope, same world, with just the normal differences in winds and currents and clouds.  Each year varies a bit in these things, but not wildly so.  We continue through a long, slow transition from an icy Arctic ocean to an intermittently and then seasonally ice-free Arctic ocean.  Along the way there will be occasional outlier years on the high or low side (e.g., 2012) but most years are pretty similar to most other years close to their point in time. 

Here are 39 years of daily observations of Arctic sea ice extent.  I see no reason why the 40th year will turn out to be so utterly, radically different from the previous 39 as to negate any possibility of comparison:



[Edited to add graph]

[A-Team]

These new autonomous sea gliders will usher in a whole new era of measurement-driven oceanography... but who here can keep up with oceanographic research? Look at all these papers, from just one conference of many this year:

https://agu.confex.com/agu/os18/preliminaryview.cgi/Session27542

Upper Ocean Evolution Across the Beaufort Sea Marginal Ice Zone Captured by Seagliders
Craig Lee et al February 14, 2018

The observed reduction of Arctic summertime sea ice extent and expansion of the marginal ice zone (MIZ) have profound impacts on the balance of processes controlling sea ice evolution, including the introduction of several positive feedback mechanisms that may act to accelerate melting. Examples of such feedbacks include increased upper ocean warming though absorption of solar radiation, elevated internal wave energy and mixing that may entrain heat stored in subsurface water masses (e.g., the relatively warm Pacific Summer and Atlantic waters), and elevated surface wave energy that acts to deform and fracture sea ice. Spatial and temporal variability in ice properties and open water fraction impact these processes.

Four long-endurance autonomous Seagliders followed the retreating Beaufort Sea ice edge to repeatedly occupy sections that extended from open water, through the marginal ice zone, deep into the pack during summer 2014. Gliders penetrated up to 200 km into the ice pack, under complete ice cover for up to 10 consecutive days.

Sections reveal strong fronts where cold, ice-covered waters meet waters that have been exposed to solar warming, and O(10 km) scale eddies near the ice edge. In the pack, Pacific Summer Water and a deep chlorophyll maximum form distinct layers at roughly 60 m and 80 m, respectively, which become increasingly diffuse as they progress through the MIZ and into open water.

The isopynal layer between 1023 and 1024 kgm-3, just above the Pacific Summer Water, consistently thickens near the ice edge, likely due to mixing or energetic vertical exchange associated with strong lateral gradients in this region. This presentation will discuss the upper ocean variability, its relationship to sea ice extent, and evolution over the summer to the start of freeze up.

Interaction of the Mackenzie River Plume with Beaufort Shelfbreak Jet, Wind Forcing, and Offshore Eddy
D Gong et al February 14, 2018

The Mackenzie River is the largest source of riverine freshwater input for the western Arctic Ocean. Peak discharge occurs during the spring melt season, but a high discharge rate of over 10,000 m3 s-1 is maintained throughout the summer open water season.

The downstream evolution of the nutrient-rich Mackenzie river plume can significantly affect upper water column stratification and lower trophic level abundance and distribution in the eastern Beaufort Sea. As part of the Marine Arctic Ecosystem Study (MARES), we used an underwater SLOCUM glider to conduct season long, high resolution hydrographic survey in the Mackenzie Trough region downstream of the mouth of the Mackenzie River.

We found that the spatial distribution of the Mackenzie plume is in part controlled by the direction of the coastal flow and the Beaufort shelfbreak jet. Dynamical factors such as sea surface height gradient and wind forcing further control the flow pattern in and around Mackenzie Trough. In addition, wind-driven mixing acted to entrain the Mackenzie plume water and deepen the seasonal pycnocline. Rapid changes on the order of hours in upper water column stratification and shelf-break flow direction were observed.

Multi-year analysis of the data-assimilative HYCOM ocean model output indicates that 2016 was an anomalous year (along with 2012 and 2008) with a strong, well-defined, eastward flowing shelf-break jet into late summer and fall that limited the westward extent of the Mackenzie plume.

However, a persistent offshore cyclonic eddy, identified in the model, may have acted to entrain some of the plume water and directed it westward further offshore. In other years, predominantly westward transport along the Beaufort slope serves to entrain more of the Mackenzie River plume into the Beaufort Gyre. The application of a well-instrumented underwater glider in MARES uniquely enabled dynamical and ecological observations across a range of spatial and temporal scales in this challenging and difficult to access region.

Upper Ocean Evolution Across the Beaufort Sea Marginal Ice Zone Captured by Seagliders (323672)
Greater Role of Geostrophic Currents on Ekman Dynamics in the Western Arctic Ocean as a Mechanism for Beaufort Gyre Stabilization (302895)
Microstructure Measurements and Mixing in the Strongly Stratified Beaufort Sea (307329)
Microstructure observations of turbulent heat fluxes in a warm-core Beaufort Gyre eddy (312649)
Role of Eddies in Shaping the Vertical Structure of the Beaufort Gyre Halocline and its Geostrophic Circulation (314222)
Investigating Steady States of the Beaufort Gyre (310039)
Energetics of the Beaufort Gyre and its link to freshwater dynamics (322091)
Negative Feedbacks Between Wind, Sea-Ice and Ocean Currents Damps the Response of the Beaufort Gyre to Changing Winds (322089)
Interaction of the Mackenzie River Plume with Beaufort Shelfbreak Jet, Wind Forcing, and Offshore Eddy(321271)
Energy flux from the wind to mixed layer inertial motions over a lengthened open water season in the southern Beaufort, Chukchi, and Bering Seas (325750)
Feedback of dynamic ocean topography measured with satellite altimetry on ice-ocean stress and Ekman pumping: a theory for Beaufort Gyre equilibration (314609)
Impacts of Baroclinic Instabilities Derived from Bering Sea Inflow on Chukchi Shelf Sea Ice (321278)
Spatio-temporal property changes of the Atlantic water in the Chukchi sea (319324)
Turbulent controls on properties of water entering the Arctic through the Bering Strait (313123)
Observations of Atlantic Water subduction below Polar Water at a submesoscale front in Fram Strait(321788)
The Yermak Pass Branch: a major pathway for the Atlantic Water north of Svalbard? (302354)
Under-ice internal wave climate north of Svalbard (302393)
Sea-ice variability and convection processes in the Greenland and Iceland Seas (326133)
The stability of the Norwegian Atlantic Current before it enters the Arctic Ocean (317683)
Evaluation of kilometer-scale ice-ocean simulations in the Svalbard Archipelago region (317389)
Tidal conversion and mixing poleward of the critical latitude (an Arctic case study) (311651)
Variability of internal wave-driven dissipation, diffusivity, and stratification in the Canadian Arctic Ocean(303093)
Causes and Implications of a Warming Canada Basin Halocline (323078)
Barents Sea Atlantification Induces Frontal Constraint on Winter Ice Extent (322231)
Low internal wave energy in the Arctic Ocean: It’s not just the presence of sea ice. (303124)
Layering in the Arctic Ocean: the interplay between entrainment and fluxes (323024)
Small-scale Upper Ocean Variability and Surface Forcing in the Arctic Ocean (324537)
Observations of horizontal stirring and eddy diffusivity in the Arctic Ocean (318035)
The Arctic Ocean Surface Layer: Submesoscale Restratification Observed by Ice-Tethered Profilers (308852)
Thermohaline Layering in Dynamically and Diffusively Stable Shear Flows (303812)
Symmetric Instabilities in Dense Shelf Overflows (308018)
Direct observations of atmosphere – sea ice – ocean interactions during Arctic winter and spring storms(308645)
New Layer Thickness Parameterization of Diffusive Convection (309633)
Breakup of dipoles and the formation of sub-surface anticyclones (310444)
Diffusive convection under rapidly varying conditions (316847)
Ventilation of the Halocline in the Canada Basin (317156)
Thermohaline staircases in the Eurasian Basin and their relations to thermohaline intrusions (317393)
Field observations and results of a 1D boundary layer model for developing early and late summer near-surface temperature maxima (317537)
Signatures of submesoscale ocean flows in sea ice patterns in marginal ice zones (318962)
Small-Scale Modeling of Wave Attenuation in the Marginal Ice Zone (311471)
Can we detect subsurface eddies in the ice-covered Arctic from space? (316612)

[Ned W]

A-Team, your last two posts there are connected, in that one of the especially cool applications of AUVs (autonomous underwater vehicles) is looking at free-floating and ice-attached algae blooms under the ice. 

This spring I had the chance to see a couple of talks by a PhD student who has been working on this, and who has lots of cool photos of algae blooms under first-year and multi-year ice.  From what I have seen in their talks, modeling this is phenomenally complicated, as it involves everything from brine flushing to snow depth to the fine-scale structure of the skeletal layer at the ice-water interface.  Plus, the environment they're trying to study is constantly changing, and often varies radically over even short distances. 

Until now, most of what's known about this has been learned by people walking around on the ice and drilling cores.  With the introduction of AUVs this sub-field is jumping from 18th to 21st-century technology in the blink of an eye.

[Hyperion]

<snip, off-topic and inciting more off-topic reactions; N.>

[bbr2314]

<snip, off-topic and we've been over this a couple of times now; N.>

[bbr2314]

Denier drivel bullshit... where is Neven?

<snip, here is Neven, don't be so touchy and paranoid; N.>

[Rob Dekker]

Most of you will know that since 2013, I use I use the "whiteness" of the Arctic in June as a predictor for how much ice will melt out between June and September.

http://neven1.typepad.com/blog/2013/07/problematic-predictions-2.html

Specifically, I use three variables to make this prediction :
- Land snow cover in June
- Ice 'area' in June
- (Extent - Area) in June, which represents the amount of 'water' in the ice pack in June.

A combination of these variables, each one of which affects the 'albedo' of the Northern Hemisphere, represents how much solar energy gets absorbed by the Northern Hemisphere in summer, and this correlates remarkably well with September sea ice cover.

Details of this method is described in one of my entries into Arcus Sea Ice Prediction Network :

https://www.arcus.org/files/sio/25738/sio-2016-july_dekker.pdf

This year, land snow cover in June was quite high compared to recent years :



Also, ice 'area' is quite high in June (in between 2014 and 2015) and the ice is still fairly compact.

As a result, prediction for Sept 2018 September sea ice extent is quite high at 5.19 M km², with a standard deviation of 340 k km².

My gut feeling this year tells me that this an upper bound, but it's fairly clear that given the past performance of this method, it is highly unlikely (less than 2.5% chance) that Sept 2018 will end up below 4.5 M km².

Here is what this hind-cast method did for the past 26 years :



Comments and suggestions on this method are welcome in the "Re: Land snow cover effect on sea ice" thread :

https://forum.arctic-sea-ice.net/index.php/topic,292.msg162415.html#msg162415

[A-Team]

We can applaud the people who put this resource together even as we hope others will have the time to do something good with it. While autonomous sea gliders will soon swamp CTD cast, buoy, mooring and profiler data with newer and more extensive observations, gliders can't go back in time to create the necessary contextual baseline.

However that is exceedingly biased in its geographical distribution as the graphic below illustrates. Indeed, one has to wonder what exactly went into creating some of the detailed Mercator Ocean displays (not to single them out).

UDASH – Unified Database for Arctic and Subarctic Hydrography
A Behrendt et al 20 June 2018
https://doi.org/10.5194/essd-10-1119-2018

UDASH is a unified and high-quality temperature and salinity data set for the Arctic Ocean and the sub-polar seas north of 65◦ N for the period 1980–2015. The archive aims at including all publicly available data and so far consists of 288,532 oceanographic profiles measured mainly with conductivity–temperature–depth (CTD) probes, bottles, mechanical thermographs and expendable thermographs.

The data were collected by ships, ice-tethered profilers, profiling floats and other platforms. To achieve a uniform quality level, suitable for a wide range of oceanographic analyses, approximately 74,000,000 single measurements of temperature and salinity were thoroughly quality checked. A large number of duplicate and erroneous profiles were detected and not included in the archive. Data outliers were flagged for quick identification...

In total, we excluded 81,441 profiles and additionally nearly 70,000 single values because of quality problems. We therefore strongly recommend taking caution when using oceanographic data from public archives without detailed quality tests... 90% of the data does not exceed the 1000m depth. Our knowledge about the deep Arctic Ocean is still very poor, particularly for the winter months and the central Arctic Ocean.

The final archive provides a unique and simple way of accessing most of the available temperature and salinity data for the Arctic Ocean and can be downloaded from:

https://doi.pangaea.de/10.1594/PANGAEA.872931.

[Hyperion]

And now the Beaufort is taking a whupping.
Interestingly this beast has a well defined tropical style hot core at low level.
Right now, nullschool/gfs:

[Aluminium]

July 2-6.

[uniquorn]

Kara sea, worldview jul3-7.

[Neven]

Current storm at 970 hPa:

[bbr2314]

Current storm at 970 hPa:

GAC-classification worthy? Wonder what things will look like when the smoke clears.

[Shared Humanity]

Most of you will know that since 2013, I use I use the "whiteness" of the Arctic in June as a predictor for how much ice will melt out between June and September.

http://neven1.typepad.com/blog/2013/07/problematic-predictions-2.html

The prediction for Sept 2018 September sea ice extent is quite high at 5.19 M km², with a standard deviation of 340 k km².

My gut feeling this year tells me that this an upper bound, but it's fairly clear that given the past performance of this method, it is highly unlikely (less than 2.5% chance) that Sept 2018 will end up below 4.5 M km².

Here is what this hind-cast method did for the past 26 years :



Comments and suggestions on this method are welcome in the "Re: Land snow cover effect on sea ice" thread :

https://forum.arctic-sea-ice.net/index.php/topic,292.msg162415.html#msg162415

You have a good track record and, given the current slow melt, I am inclined to agree that we will end this melt season around 5.00 M km².

Thank you for the update on this thread.

[Hyperion]

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You have a good track record and, given the current slow melt, I am inclined to agree that we will end this melt season around 5.00 M km2. 

I am continually gobsmacked by comments like this. Volume is taking a hammering. Bottom melt and fragmentation is going at a record pace. The fast changing weather systems and winds are sprawling the pack and mixing in the unprecedented incoming ocean heat like never before. Are people so stuck in their habits that they only make a skin deep quick look at extent and area figures compromised by incapacity to distingush between fields of shrapnel and solid ice, and charts drawn by the artist algorithm. And don't look at the underlying processes going on.
These Amsr2 datasets cannot resolve even sub 200m wide continuous leads of long length. And even thickness products are giving misleading results due to measurement of the gap between sea level and the tops of chunks of floating rubble.
Incoming heat is attacking the ice basin wide. The energy flux into the ice and sea surface is  enormous. It REALLY stands a chance of slushing into almost nothing in one major prolonged storm.

[Dharma Rupa]

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You have a good track record and, given the current slow melt, I am inclined to agree that we will end this melt season around 5.00 M km2. 

I am continually gobsmacked by comments like this. Volume is taking a hammering. Bottom melt and fragmentation is going at a record pace. The fast changing weather systems and winds are sprawling the pack and mixing in the unprecedented incoming ocean heat like never before. Are people so stuck in their habits that they only make a skin deep quick look at extent and area figures compromised by incapacity to distingush between fields of shrapnel and solid ice, and charts drawn by the artist algorithm. And don't look at the underlying processes going on.
These Amsr2 datasets cannot resolve even sub 200m wide continuous leads of long length. And even thickness products are giving misleading results due to measurement of the gap between sea level and the tops of chunks of floating rubble.
Incoming heat is attacking the ice basin wide. The energy flux into the ice and sea surface is  enormous. It REALLY stands a chance of slushing into almost nothing in one major prolonged storm.

And it may or may not mean anything this year....I don't think there is any way to know if it will or will not.

[Pagophilus]

As of now the storm is centered above the relatively compact, continuous CAB ice, where there is reduced capacity to generate wave action.  The surface winds may mainly sweep above that ice.  Nullschool has this storm waning rapidly over the next couple of days.  So effects caused today and in the near future may be less than one would expect. 

Following A-Team's advice to look at our predictions once we have made them, and given the comments ahead of this storm, I am curious to see what damage the storm did in its earlier stages, particularly in the Laptev and ESS areas.  Looking at the Bremen AMSR2, dramatic effects are not visible to me.  Worldview images are pretty much obscured by clouds.  It may be of course that there has been thinning and preconditioning of the ice in these areas.  Perhaps others see effects I have not noticed? 

Current storm at 970 hPa:

GAC-classification worthy? Wonder what things will look like when the smoke clears.

[Stephan]

I would appreciate if these kinds of predictions are re-visited after the storm has left or faded.
Has the compact ice broken up? Were high waves eating away the edge of some floes? Did falling rain (or was it snow?) damage the surface? And a comparison of other less or non-affected areas close by (wouldn't all these things not have happened anyway?) should be included...

[gerontocrat]

Following A-Team's advice to look at our predictions once we have made them, and given the comments ahead of this storm, I am curious to see what damage the storm did in its earlier stages, particularly in the Laptev and ESS areas.  .......  Perhaps others see effects I have not noticed? 

Last 5 days area loss in the ESS - 2 July was pretty average loss.

02-Jul   -2,688 03-Jul   -18,268 04-Jul   -21,746 05-Jul   -41,835 06-Jul   -42,077

Laptev showed no real change in area loss

[Tor Bejnar]

As of now the storm is centered above the relatively compact, continuous CAB ice, where there is reduced capacity to generate wave action.  ...

What, if any, affect will Ekman pumping have on bottom melt under the 'continuous CAB ice'?

On smaller scales, cyclonic winds induce Ekman transport which causes net divergence and upwelling, or Ekman suction, while anti-cyclonic winds cause net convergence and downwelling, or Ekman pumping. Ekman transport is also a factor in the circulation of the ocean gyres.

Do I have this right:  the storm should cause (Ekman) downwelling? And the consequences for the ice?