The 2018 melting season

[uniquorn]

I think the 'Greenland ratchet' is temporarily disabled.
Mar25-29
[edit]-just checked and there was similar movement in 2017, without the open water event.

Worldview viirs brightness temperature band15,night,squashed pallette

[bbr2314]

The situation in Bering is obviously worsening each passing day, and now another major injection of Pacific saltiness is about to enter Chukchi. This one should be bigger than any to date and may be sustained for quite some time. I wonder if we see complete melt-out of Chukchi and Beaufort by 6/1?

[jdallen]

The situation in Bering is obviously worsening each passing day, and now another major injection of Pacific saltiness is about to enter Chukchi. This one should be bigger than any to date and may be sustained for quite some time. I wonder if we see complete melt-out of Chukchi and Beaufort by 6/1?

Not ready to predict *that*, but for sure, current conditions are at least 6 weeks ahead of a "typical" melt season.

[A-Team]

It's easy to track the train of thick ice that was in the CAA that has rotated around the displaced Beaufort gyre this fall and winter on the JAXA RGB map. Tracking other features is not so easy because of zones of compression, extension and shear. The ice pack is constantly deforming.

Right. While the Jaxa polarized radar gives some very interesting effects, it does not have nearly the feature resolution of Ascat in newer ice regions where it lacks recoverable contrast. Minor weather artifacts can also be seen passing over the ice, as with many other radar products such as DMI ice surface temperature.

As described up-forum, the best/easiest quantitative approach to describing ice pack motion over an 8 month season is via a delauney feature tesselation. The real question though is how to optimally expand the motion into components, for example zonal and radial, as these would allow more nuanced year-on-year comparisons. Another approach is through plasticity as compression and extension are largely localized to thinner peripheral FYI and SYI, with central MYI undergoing more brittle shear but retaining inter-feature relational geometry over much longer time frames.

Technical note: Jaxa provides a very sophisticated web site, with good control over various animation services. These are in the new webm format developed by google which is not yet portable here. The products are scaled up effectively but way beyond their actual ground resolution which is just ~350 pixels from the Bering Strait to Svalbard. The graphics need a 135º rotation to orient them with Greenland down. They do not readily rescale to Ascat and may be in another projection.

https://ads.nipr.ac.jp/vishop/#/gallery/&time=2018-02-18%2000:00:00

[JayW]

100 hour loop, Beaufort region, March 25-29.

https://weather.us/model-charts/euro/usa-east/significant-weather/20180401-0600z.html

[A-Team]

100 hour loop, Alaskan coast, March 25-29.

Nice resource, thx for regular tracking of this. Jay.

[slow wing]

  Concerning the discussion above, I really like the vectorized sea ice motion maps we see that are plotted for 1 day's motion if I recall correctly.

Question: does anyone do them for longer time periods? Weekly, or even monthly or for an 8 month melt season?

Would showing such ice vector displacement maps be instructive or not? For example, would they inform discussions on trends and tendencies in seasonal ice motion?

Technically I suspect they are doable, given that the daily maps exist and that the human eye can easily follow the ice motion in the plots above that A-team has kindly posted. (I realise that it is in 2 dimensions that humans have traditionally best out-performed computers.)

Sorry I don't have the skills or commitment to do them myself but I'm guessing they would be interesting 

[A-Team]

really like the vectorized sea ice motion maps we see that are plotted for 1 day's motion if I recall

There are an 80-day and 202 day animations of OSI SAF on the Page One section of this forum that could easily be extended or updated; it takes two-day intervals in order to reduce errors with small measurements. There is another version at Jaxa that has speeds colored as well as the vector overlay. NSIDC also has a version that is not so convenient. I don't know if these were derived independently. RASM-ESRL also offers a forecast for five days out.

I believe we could roll our own one-days in contrast-enhanced Ascat since multiple high-end tools are a strong feature of ImageJ. As mentioned, gridded motion vectors do not give integrable solutions (particle trajectories) but those are again easy to do in ImageJ on Ascat.

https://forum.arctic-sea-ice.net/index.php/topic,2278.msg146696.html#msg146696
https://ads.nipr.ac.jp/vishop/#/gallery/&time=2018-02-18%2000:00:00
ftp://ftp1.esrl.noaa.gov/RASM-ESRL/ModelOutput

[Neven]

  Concerning the discussion above, I really like the vectorized sea ice motion maps we see that are plotted for 1 day's motion if I recall correctly.

Question: does anyone do them for longer time periods? Weekly, or even monthly or for an 8 month melt season?

Something like this? edit: the link doesn't work because http:// keeps getting put in front of the address: ftp://ftp.ifremer.fr/ifremer/cersat/products/gridded/psi-drift/quicklooks/arctic/merged-ascat-ssmi/30-days_missing_values_filled/

I use these images for the annual winter analysis.

[numerobis]

Big storm over Hudson Bay the past couple days. Not particularly strong but its arms have swept by southern Baffin and got us some strong, warm southeasterlies.

It’s dying off now, but a system coming off Labrador this weekend is forecast to bring us near-freezing temperatures, even a risk of rain.

[be cause]

there's an unusually good view of the pole using Uniquorn's favoured night view on Worldview ..see reply 152 for better guidance . As such a view seems unavailable for previous years (or recent days) there is little to compare it with .. but the ice is certainly mobile and very fractured .. b.c.

[A-Team]

Neven, I've looked at that before and don't think 30-day jumps are a good approach to ice motion trajectories (the daily Ascat animations for their time periods are below, Ascat is what they are using). The September through March trajectories do not correspond to stringing together these monthlies: all the intermediates are missed, including the late February storm. Note the archive skips over the months of June, July and August which are difficult but not impossible to track centrally.

The T Lavergne daily two-day product now over at OSI SAF is a better starting point; it has error analysis and corresponds very closely both with nullschool GFS winds and what the eye sees flashing consecutive days. His twitter site sometimes animates these and provides updates to his earlier motion publications (provided up-forum).

Not sure why you posted January as the February product to March 03 is also available. The Feb looks properly chaotic but the Jan seems just plain wrong. The freeze season 2018 SONDJFM are below. I wonder if they are just adding up gridded dailies (which will accumulate hopeless levels of error) rather than comparing two 30-day jump images which would take misleading vector shortcuts to net motion.

We could have the whole daily Ascat series of the last 11 years quantitatively trajectorised in triplicate with self-correcting error, updated in NRT by remote sensing human PhD's over in India for a small fraction of what is being spent on unsatisfactory ice motion AI:

Video shows moments before fatal Uber crash in Tempe

Mar 21, 2018 - Tempe police have released two angles of a fatal crash involving a self-driving Uber SUV and a pedestrian on March 18, 2018. Uber. Tempe ... Elaine Herzberg of Mesa was walking a bike across Mill Avenue outside of a crosswalk near the Marquee Theatre when she was hit, police said. [The driver was looking at her cell phone, the road is adequately lit at this location, the car uses Lidar in any event.]

Mobileye, which makes chips and sensors used in collision-avoidance systems and was a supplier to Aptiv Plc, the auto-parts maker that supplied the vehicle’s radar and camera, said it tested its software on the crash video and found it detected the cyclist:

“The video released by the police seems to demonstrate that even the most basic building block of an autonomous vehicle system, the ability to detect and classify objects, is a challenging task,” Mobileye CEO Amnon Shashua wrote on Intel’s website.

http://ktar.com/story/2003896/report-uber-disabled-collision-avoidance-tech-in-tempe-crash-car/?

http://ktar.com/story/2003896/report-uber-disabled-collision-avoidance-tech-in-tempe-crash-car/?

Minor points that suggest an unattended French autonomous vehicle: a lost ice boundary in the February (all blue background) and text 'd' still running off the margin, a bug already in the Jan 2007 (though ftp mod dates indicate Nov 2016).

ftp://ftp.ifremer.fr/ifremer/cersat/products/gridded/psi-drift/quicklooks/arctic/merged-ascat-ssmi/30-days_missing_values_filled/

[A-Team]

unusually good view of north pole on Worldview .. view seems unavailable for previous years so little to compare it with .. but the ice is certainly mobile and very fractured

Right, the north pole is an unfavorable area because of clouds, the off-center orbits of near-polar sun-synchronized satellites and especially by the way WV tiles up images with different time stamps  like day-old pizza slices. Sentinel-1AB has far better resolution but its swath is not wide enough to include the pole, https://www.polarview.aq/arctic.

The NP is mostly political theater: it is not the cold pole, it is not in the center of the Arctic Ocean, it has the same daylight hours over a year as everywhere else, it is only a singularity in selected coordinate systems, it has no special role in the ice pack's future.

Overall, while fractures are important to melt pond drainage and floe separation, it has proven very difficult to compare year on year or quantitate fracturing to get at changes in late season mean floe 'caliper' size, (with the AI for that done quite well in ImageJ). Ice ridges and freeboard edges act as sails that catch the wind and put the ice in motion in more direct proportion to a seasonally changing power law of wind velocity.

[Neven]

Neven, I've looked at that before and don't think 30-day jumps are a good approach to ice motion trajectories (the daily Ascat animations for their time periods are below, Ascat is what they are using). The September through March trajectories do not correspond to stringing together these monthlies: all the intermediates are missed, including the late February storm. Note the archive skips over the months of June, July and August which are difficult but not impossible to track centrally.

You're probably right. It was the only thing I could think of when slow wing asked his question. I wish there was something better that was easy to get for a guy like me, who can't make it himself. Same for ice age. Or melt ponds.

Not sure why you posted January as the February product to March 03 is also available.

I just wanted to post an example. The March image looked a bit weird (no ice).

[Neven]

Barentsz is still going up, and might go up some more, given the current forecast. But Hudson has started to go down a bit, and Okhotsk is probably going to drop very fast from now on.

[A-Team]

guy like me, who can't make it himself.

We are to believe this after seeing that elegant new graphic with all the years from 2006-2017 circling around a large 2018? Not!

http://neven1.typepad.com/.a/6a0133f03a1e37970b01b8d2e5c4c1970c-800wi

Per request from FishOut, Jaxa and Ascat are compared below for 208 days, from Sept 1st of last year through March 28th of this year. Between the two of them, we have a very good idea of how recognizable ice features moved, rotated, elongated, compressed, broke apart, left or entered the area or were otherwise distorted over this time frame.

[Shared Humanity]

Just wow!

[Tor Bejnar]

I don't know the cause (my MacBook Air running Yosemite or internet provider?), but most of your GIFs give the equivalent of this (screenshot of center of GIF):

[A-Team]

MacBook Air running Yosemite or internet provider

That's unfortunate. These are in the common .mp4 format, converted by a very experienced formatting conversion service, https://www.online-convert.com/. The other forum options were mpg mp4, m4v, mov, avi and did not seem to work.

Jaxa is using webm for html5 as that gets around a lot of issues that patent trolls like Nokia have. Does that format work for you?  https://ads.nipr.ac.jp/vishop/#/monitor

We had to move on from .gif because of file size issues. Some of the season-long files are over 100 MB as gifs, unworkable on the forum.

The mp4 don't always load for me right away so I try a reload, or hit the start button. But your attachment suggests you are not even reaching the forum's video player controls. But 'network error', that sounds like your provider. Have you never gotten any of the mp4's to play or is it just today?

Try downloading the file to your hard drive. These have all been tested on QuickTime for the Mac and all work right away. Even for someone running four operating systems behind the curve, it should certainly work.

I use Opera 52.0 on an iMac 13.3.3 High Sierra. The mp4 do not load in Safari 11.03 which lags in many other respects, though I do get a different controller. They load fine in Chrome 65.0.3325 as dnem notes below. So it appears Safari is the problem. Desktop development has not been a priority since the iPhone took off.

[dnem]

I can't run A-Team's .mp4s in Safari on my Macbook but they run perfectly in Chrome.  FYI.

[uniquorn]

The first few frames of large mp4's play ad then I get a video stopped loading error:). They run ok when I download them.

Lovely view of the Sea of Okhotsk today on Worldview. A few days of warmer weather forecast.

[A-Team]

The first few frames of large mp4's play ad then I get a video stopped loading error:).

Ads for what, in which mp4 above? Browser and operating system? Sounds like your mp4 player has been hijacked, with remote ads injected and kickbacks to the browser company. Whatever the Mac browser, obnoxious strangers can turn up the volume on a movie audio without your permission and without any means of revoking permission enabled.

Early melt ponds are so important to the overall melt season, what are the best online tools for following their development?

Good question. RASM-ESRL does offer daily melt ponds and albedo plus their forecasts; whether these correspond to ground condition reality is another matter.

Summer imagery s overwhelmed by passing weather in both Ascat and Jaxa so I've been looking at extending them to year-round utility via color space deconvolution into a weather-minimizing channel.

The ones that ImageJ has "in stock" have to do with optimizing immunohistochemistry stain visualization; the one below uses the 3rd channel of alcian blue & hemolysin basis vectors on Jaxa for June, July and August 2017. This does quite a good job on suppressing noise past the sea edge but is likely far from optimal. (I have not gotten around to the two 'rational' options that base off user-picked regions of interests or an inspired/deduced RGB rotation matrix.)

Channel mixing was discussed here many many moons ago, in the context of petroglyph enhancement where it has revolutionized photographic preservation of faded and vandalized artwork. The approach was to rapidly scroll through many dozens of color spaces, then zoom in on a good one, rather than proceed from model and theory.

Here Jaxa has 3 channels of color whereas Ascat has 1, or 256³ vs 256. While the Jaxa channels are fairly well correlated, they can be maximally de-correlated.

[uniquorn]

Sorry.

The first few frames of large mp4's play and then I get a video stopped loading error:). They run ok when I download them.

[Tor Bejnar]

MacBook Air running Yosemite or internet provider

...These are in the common .mp4 format ... [I used "GIF" generically, for "movie".  Sorry for my sloppy communication.]

Jaxa is using webm for html5 as that gets around a lot of issues that patent trolls like Nokia have. Does that format work for you?  https://ads.nipr.ac.jp/vishop/#/monitor  [I clicked on this link, clicked "Save as animation", and could see frames getting added to the picture behind the status/progress box.  After about 2 minutes it got to 97% when it stopped progressing (no additional progress after 5 more minutes).]

... But 'network error', that sounds like your provider. Have you never gotten any of the mp4's to play or is it just today?  [Has never worked from home.  I see them fine at work.  Living rural, my Centurylink is slow: Download 3.06 Mbps Upload 0.63 Mbps.  I use Firefox, by the way.]

...

I'll watch them at work (during breaks, of course).

[Jim Hunt]

A new open access paper in GRL from Alek Petty:

"A Possible Link Between Winter Arctic Sea Ice Decline and a Collapse of the Beaufort High?"

A new study by Moore et al. (2018, https://doi.org/10.1002/2017GL076446) highlights a collapse of the anticyclonic “Beaufort High” atmospheric circulation over the western Arctic Ocean in the winter of 2017 and an associated reversal of the sea ice drift through the southern Beaufort Sea (eastward instead of the predominantly westward circulation). The authors linked this to the loss of sea ice in the Barents Sea, anomalous warming over the region, and the intrusion of low‐pressure cyclones along the eastern Arctic. In this commentary we discuss the significance of this observation, the challenges associated with understanding these possible linkages, and some of the alternative hypotheses surrounding the impacts of winter Arctic sea ice loss.

[uniquorn]

A partially refrozen lead in the Svalbard and FJL area. Probably not significant yet. Nullshool has temperature <-20C so it should freeze over completely. Mar31

Worldview Terra Modis

[A-Team]

Firefox 58.0.2 works just great on forum mp4's. In fact it offers speed controls. Initially though I got the same fail screen that you had.

CenturyLink 

That explains a lot right there. Gifs are animations. Single frames that fly by one at a time. When you download and open, each frame shows up as an independent layer. They can be compressed but only to the extent that frame n+1 reuses a lot of material from frame n. Mp4s are videos. They are eye-foolers, compressed in 2D+T. You can stop-action but not recover the frames from which it was made.

Gifs are preferable scientifically because each frame represents a day of data, presented without loss, and thus conveyed to the next person to work with. Videos can convey ideas very well using much small files but lose data details, so they are just climate theatrics and not an acceptable way to distribute data.

Jaxa has the most sophisticated code I've seen to date on a climate science portal. They are using the webm format for videos, open source codecs championed by google. Neven would have to enable that in admin attachment permissions. I converted some of the mp4 here into webm and tested them on Opera, Chrome, Firefox and Safari. Again, all but Safari worked perfectly.

The Arctic Ocean occupies only a third of the Jaxa video area. However free online cropping is available at https://ezgif.com/crop-video as well as https://www.online-convert.com. However rotations are restricted to multiples of 90º whereas Jaxa animations need 135º.

[Neven]

We are to believe this after seeing that elegant new graphic with all the years from 2006-2017 circling around a large 2018? Not!

I can do some basic copy/Paste stuff in Photoshop. I know how to create 'actions', so I don't have to repeat the same operations for each image. But I don't know how to squeeze out extra information by using filters, like you do, let alone set up scripts that retrieve data and turn them into visual graphs and maps, that are easy to grasp (like dryland is doing with RASM project).

I wish I could , though. I'd be rocking hard. We could even join forces and create WAN University (Wipneus, A-Team and Neven) to compete with the real science institutions. 

[A-Team]

we could compete with the real science institutions?

That would be a lark. We can definitely get some decent stuff out the door in near-real time. That's the future, not 36 months of chewing cud that our forums could have spewed out while still at sea (N-ICE2015?).

JimH brought attention in #176 above to a well-written commentary piece on an interesting Arctic Ocean gyre piece. The analysis below only gets as far as Fig.1b which "averages" ice motion vectors over Jan-Mar 2017.

That didn't make a great deal of sense to me because averaging loses all track of time ordering (scramble the order, get same result) so with many grid points averaged separately and potentially relatively scrambled, it doesn't follow that vector field correlation would be retained. Sure enough [Frobenius 1877], the outcome is only so-so as an overlay on real data.

The January-only story of Fig.2 is very wrong, which favors the original Moore 2018 story and Zabolotskikh 2018 discussed in #1474 of the freezing season forum.

Technical note: Motion detection algorithms have received an incredible amount of development, not only from science side (cell  and organelle movement, ice sheets advancing, asteroids moving against fixed stars ) but also video games and commercial AI applications such as security cameras, robotic computer vision and autonomous vehicle object recognition and classification.

These algorithms work by identifying scene changes, in the case here from a pair of consecutive grayscale Arctic Ocean images in the Ascat daily time series. The central problem is reliable displacement vectors are very unevenly distributed across the scene, first because the ice pack does not move uniformly as a rigid body but notably deforms, and second because of uneven availability of local contrast.
For example, if a pixel is say gray 128 and part of a large dull patch of gray 128±3, it won’’t be possible to tell where the point went on day 2 because it lacks the distinct local signature that’s key to its recognition in the displaced image.

Because both the displacements and the Ascat images are pixelated (ie integers rather than continuous), round-off errors are especially serious with small displacements. This cannot be overcome by fitting splines or bumping to much higher resolution with say bicubic enlargement to make the displacements larger because those processes have limits tied to the original resolution. That is, over a day, a feature might only move half a pixel but that would have to be treated as 0 or 1 pixels of displacement. If it moved 5.5 pixels, round-off to 5 or 6 wouldn’t be so serious in percentage terms.

As a practical matter, much of the central ice pack is hardly moving whereas peripheral areas can see displacements of a km/hr. For this reason, OSI SAF uses 48 hour intervals instead of 24 to reduce error. (These overlap oddly: day n is determined by differencing day n-1 and day n+1, the following day by day n and day n+2.)

Consequently, starting with the mindset of a fixed rectangular gridded array (ie a certain resolution), the grid points themselves won’t often be assigned displacement vectors directly. Instead, whatever favorable points in the scene that can be assigned accurate displacements are interpolated onto the grid, typically by kriging. We’ve seen this before in Greenland bedrock determination — polygons of 10,000 sq km that never received an over-flight with ice-penetrating radar.

So not only does each displacement vector have variable associated error, interpolation to the grid brings in additional error, with very uneven accuracy over the scene depending on the distribution of favorable regions for motion detection. The gridding process gets repeated for each pair of consecutive days to produce the daily OSI SAF gridded vector graphic, even though the set of favorable points is not time-transitive (ie, the trajectory of an initially favorable point won’t necessarily be followed across the time series).

Here the central issue is optimal pre-processing of Ascat contrast prior to applying the displacement algorithm to the daily pair. If the pair is used ‘as-is’, errors will be horrible because the original contrast is uncorrected and the central ice pack is uniform gray. A much more effective method is to first change the initial RGB gif to 8-bit gray to 32-bit gray. This seems strange since the image actually only has 7-bit information but three rounds of bicubic enlargement, contrast stretching and moderate adaptive contrast adjustment all involve round-off errors , dumbing down to the prevailing bit depth bins. It is better to do a single round-off step back to 8-bit at the end. The adaptive contrast step is very important to increasing the availability of accurate local displacement vectors, as is bicubic vs bilinear 2x enlargement. Done in moderation, these steps do not introduce artificial displacements, as can be seen from the internal consistency of the product across 200 days of imagery.

Thus over a month, the interpolation process will have been carried out 30 separate times, so averaging the 30 vectors at each grid point will accumulate all the initial and interpolation errors there. Since the averaging process loses all track of time order, all correlation to other grid points being averaged is lost. Note too, gregorian months are arbitrary time divisions out of synch with natural seasonal divisions; it is imperative to test such slicing for bias by rolling 30-day winds to assure robustness of a particular calendar month view.

 For these reasons, it is better to determine a reasonably dense set of actual particle trajectories because positional error self-corrects (resets each day) instead of accumulating. Further the subset of daily points for the set of trajectories retains positional correlation (delauney triangulation) and provides the polygons that measure ice pack deformation.

[uniquorn]

Chukchi Sea Mar23-Apr1

Worldview Terra/Modis

[Neven]

Now that the month is full, here's the final bar graph showing March average for Bering Sea SIA. And here's the top 5:

2001: 401 K
2015: 369 K
1996: 341 K
1989: 310 K
2018: 172 K

[Shared Humanity]

If I were to look at this data without anything else to inform my analysis, I could not conclude that this years record low was anything more than random variation, an outlier that happens but only rarely.

Heck, the cluster of 4 record highs in a 6 year span from 2008 to 2014 seems to suggest we are moving towards more ice coverage not less.

[Archimid]

I was reading a bit on Arctic sea ice melt dynamics and stumbled upon this paper.

Winter-to-summer transition of Arctic sea ice breakup and floe size distribution in the Beaufort Sea
https://www.elementascience.org/articles/10.1525/elementa.232/

For brevity sake I will not post the abstract but this paper discusses ice melt in the Arctic using  buoys and satellite imagery.  They discuss melt in all directions and at different stages of the melting season in 2014. I find this graph from the article to be very insightful as we head into the melting season:

[be cause]

having a good look again on Worldview at the fracturing/freezing going on across the Arctic .. all this fresh freezing must affect the under ice water temps . It is also allowing for growth and spread of the Arctic to replace export as it happens . It looks to me that this activity is increasing as the ice becomes younger and thinner ( also a cause .. ) . Any analysis of what is happening would be appreciated .. b.c.

[Alexander555]

If I were to look at this data without anything else to inform my analysis, I could not conclude that this years record low was anything more than random variation, an outlier that happens but only rarely.

Heck, the cluster of 4 record highs in a 6 year span from 2008 to 2014 seems to suggest we are moving towards more ice coverage not less.

I think that's the result from the weaker Vortex. 2012 had the highest extent in the Bering Sea and the lowest arctic summer extent in a long time . And this year the Bering Sea is at a record low. Some volatility is kicking in.

[FishOutofWater]

La Niña favors a jet stream track across the Pacific that tracks farther north than normal at the dateline. The Rossby wave pattern from strong convection in Indonesia and the western Pacific transports heat in the direction of the Aleutians, and the Aleutian low is weakened.

This winter's low sea ice extent in the Bering sea is consistent with La Niña. There's other stuff, such as climate change going on, of course. Beware of drawing lines through small data sets.

[Shared Humanity]

La Niña favors a jet stream track across the Pacific that tracks farther north than normal at the dateline. The Rossby wave pattern from strong convection in Indonesia and the western Pacific transports heat in the direction of the Aleutians, and the Aleutian low is weakened.

This winter's low sea ice extent in the Bering sea is consistent with La Niña. There's other stuff, such as climate change going on, of course. Beware of drawing lines through small data sets.

I think that was my point...that the record low reveals little.

[Neven]

If I were to look at this data without anything else to inform my analysis, I could not conclude that this years record low was anything more than random variation, an outlier that happens but only rarely.

Heck, the cluster of 4 record highs in a 6 year span from 2008 to 2014 seems to suggest we are moving towards more ice coverage not less.

Random variation or extreme volatility? 

[oren]

The Bering is indeed volatile, but a look at long term ice coverage statistics of its downwind brother the Chukchi (some of which I have posted recently one of the threads) reveals an unmistakable long-term decline trend, which I am certain will see another record season this year.

[A-Team]

Got melt ponds?

May and June melt*ponds and albedo are important to the summer season but who is tracking them  with what satellite and daily web service -- or is this another product that we can do better ourselves?

One way of going is level 3 MODIS bands 1,3,4 because melt-ponds, sea ice, snow on sea ice and open water have sufficiently different reflectance profiles. Given a calibration set tied to ground observation of typical melt stages, the contributions of each to a given image pixel (or rather grid cell) can be obtained by inversion. Dividing by the sea ice concentration of that grid cell then gives the melt-pond fraction relative to the current sea-ice concentration.

The question is, how much of the Arctic Ocean will have clear skies over the eight days? (More recent methods use polarized radar.)

So far, so good -- the 8-day netCDF files are available by open ftp. However they only extend to Sept 2011 though the program mentions a correction made on 25 Oct 2017. The last seven years of data seem to be restricted to insiders.

At any rate, I ran day 137 -161 through Panoply and compared them to Ascat and Jaxa averaged over eight days for the 17 May 2011 date, below. No correlation with melt ponds can be seen. (NOAA's Ascat server was broken down as it often is, so the eight day averaging couldn't be done.)

https://www.the-cryosphere.net/6/431/2012/ original article
https://icdc.cen.uni-hamburg.de/1/daten/cryosphere/arctic-meltponds.html description
ftp://ftp-icdc.cen.uni-hamburg.de/arctic_meltponds/ the netCDF files to Sept 2011

MODIS__MeltPondFraction__UHAM-CliSAP-ICDC__v02__12.5km__2011137.nc  17 May 2011
MODIS__MeltPondFraction__UHAM-CliSAP-ICDC__v02__12.5km__2011145.nc  25 May 2011
MODIS__MeltPondFraction__UHAM-CliSAP-ICDC__v02__12.5km__2011153.nc  02 Jun 2011
MODIS__MeltPondFraction__UHAM-CliSAP-ICDC__v02__12.5km__2011161.nc  10 Jun 2011

Integrated Climate Data Center - ICDC Restricted Access - What does that mean?
This data set is only available for a restricted user group. In the CEN network of the University of Hamburg or from the outside via Login for CliSAP members, you can access links of the restricted area and use the data.  Please contact us, if you are not member of this user group and would like to access these data.

[A-Team]

Chukchi reveals an unmistakable long-term decline trend, which I am certain will see another record season this year.

Good call. Right now though, UH SMOS is showing the Beaufort to have thinner ice than the Chukchi. The Arctic north of the Barents may also have a lot of open water early.

[uniquorn]

Yes, beaufort looks bad. Look forward to Jayw next update.
I did a quick reality check on Chukchi going back to 2004. Some clouds, but good enough for comparison.

Worldview Terra/Modis (some differences pre2013)

[jdallen]

Chukchi reveals an unmistakable long-term decline trend, which I am certain will see another record season this year.

Good call. Right now though, UH SMOS is showing the Beaufort to have thinner ice than the Chukchi. The Arctic north of the Barents may also have a lot of open water early.

Concur.  I *really* don't like how that ice is breaking up north of Svalbard.  That's more like what it might look like in May or June, not now.

[sofistek]

Heck, the cluster of 4 record highs in a 6 year span from 2008 to 2014 seems to suggest we are moving towards more ice coverage not less.

What record highs? As far as I can tell, the highs for all of those years were below the median high.

[oren]

Just to back up my claim of Chukchi trend. NSIDC data of monthly extent and area averages.
I agree other locations currently look worse though.

[Espen]

Chukchi reveals an unmistakable long-term decline trend, which I am certain will see another record season this year.

Good call. Right now though, UH SMOS is showing the Beaufort to have thinner ice than the Chukchi. The Arctic north of the Barents may also have a lot of open water early.

Concur.  I *really* don't like how that ice is breaking up north of Svalbard.  That's more like what it might look like in May or June, not now.

It is not only north of Svalbard, but the break up of sea ice of Jøkelbugt (North East Greenland) is at least 3-4 months ahead of normal, Scoresbysund further south is well ahead too?

[uniquorn]

Winter-to-summer transition of Arctic sea ice breakup and floe size distribution in the Beaufort Sea
https://www.elementascience.org/articles/10.1525/elementa.232/

Thanks for this Archimid.
For those who don't have time to read the link. c1 to c4 on the charts are the 4 clusters of buoys. w1 to w7 are wind events.

[subgeometer]

It won't be long before the last ice in the Bering Sea gives up the ghost, and the Chukchi Sea doesn't look good. A lot of the ice there must be pretty thin, given that there was open water and sub 0.5m ice only 6 weeks or so ago

[jdallen]

It won't be long ebefore the last ice in the Bering Sea gives up the ghost, and the Chukchi Sea doesn't look good. A lot of the ice there must be pretty thin, given that there was open water and sub 0.5m ice only 6 weeks or so ago

Also to factor, we are with in a week or so of reaching "break even" where incoming insolation will balance outgoing long wave radiation from the top of the atmosphere.  The current predicted spasm of inflowing heat will only exacerbate the problem.

[Thomas Barlow]

" 'Usually you see a bit of sea-ice along the coasts and if you happen to fly the drone far enough, you may capture some icebergs much further away' Beyzaei told Global News. So Beyzaei was in for an early April Fool's shock on March 27, when he flew his drone off the Newfoundland coast and recorded astonishing footage of sea ice stretching over Brighton, Newfoundland, Global News reported Sunday. "

'Stunning Drone Video of Sea Ice Reveals Unexpected Climate Change Effects'
"..the Arctic has just experienced its warmest winter on record. Arctic sea ice also reached its second-lowest extent on record this year, just barely inching out 2017's ice coverage to avoid being the lowest year for Arctic sea ice ever.
But according to research published in Geophysical Research Letters on March 15 and cited by Global News, footage like Beyzaei's is exactly what you can expect from the impacts of climate change on the Arctic."

https://www.ecowatch.com/sea-ice-drone-newfoundland-2555583953.html