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A-Team

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Re: The 2017/2018 freezing season
« Reply #650 on: January 15, 2018, 05:05:16 PM »
Here are a couple of movies that seem to be working for Mac/Window users over at DevCorner. The first is a synchronized display of the last four freeze seasons, from the Sept minimum up to 13 Jan 18. It looks like it can be bumped to 9 years of ASCAT data without the file size getting out of bounds (as it does with our more familiar gif animations). Note occasional satellite glitches (missing days) have been replaced by duplications of flanking dates.

The second shows UB SMOS thin ice development just for this season. That could also easily be bumped to 2x2=4 years, which allows comparison of freezing stages. Note a few of the frames have substantial radio frequency interference (gray flashes).

Note the forum mp4 controller offers a full screen mode that may or may not be beneficial. Some people will do better downloading the file and viewing on their own player.

Thanks to member Dryland, we now have automated plucking of netCDF files from daily packages, imaging them as specified with PanoplyCL scripts, animating in ImageJ, and saving out as mov --> mp4 videos.

We are thus in position, between ImageJ's montage compositing tricks and PanoplyCL, to provide some unprecedented internet offerings of historic and current cryosphere conditions at very reasonable file size with relatively little future effort.
« Last Edit: January 15, 2018, 05:28:19 PM by A-Team »

Ice Shieldz

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Re: The 2017/2018 freezing season
« Reply #651 on: January 15, 2018, 07:47:08 PM »
In addition to the snow, another big factor here is of course cloud cover. It appears be increasing during freezing season and potentially melting season too. Worst case scenario is more clouds along with less continental snow and more sea-ice-snow, followed by a melting season shift to less clouds and a rapid melting of snow. It may not matter that much if melting season clouds come to the rescue, the Arctic sea ice trend is clear. She's losing her winter power and, as others have indicated, the wimpy ice that's left does less and less to reverse any negative freezing season feedbacks at play.

Jim Hunt

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Re: The 2017/2018 freezing season
« Reply #652 on: January 15, 2018, 08:41:01 PM »
940 hPa now! With Iceland almost perfectly in the eye of the storm.

It looks have bottomed out at 939 hPa:

http://GreatWhiteCon.info/2018/01/the-january-2018-fram-strait-cyclones/#Jan-15



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jdallen

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Re: The 2017/2018 freezing season
« Reply #653 on: January 16, 2018, 04:59:50 AM »

...this is very incorrect.

Snow in southern latitudes does a much better job of reflecting sunlight back into space and reducing overall heat anomalies vs. snow in sunless high-latitudes (that are probably covered anyways).

Additionally, snowfall over thin ice can do a better job of insulating heat underneath, paradoxically creating warmer conditions if heavy snows occur when initial refreeze completes.

Yeah, then we should be heading into a Rebound Year according to ur Analysis.

All that snow and cold should have stayed inside the Arctic Fridge. But no, it is escaping into lower latitudes, where it will disappear and fast. Causing flash floods, inundations and a lot of erosion- not to mention wildlife damage.
Snow isn't escaping, cold is, which effectively detonates on contact with moist air at the mid latitudes when the air masses collide.  There's still plenty of moisture of snow pack on the ice, as this chart below seems to indicate.  20-40CM is plenty of blanket to slow down heat transfer significantly.  That's equivalent to a 10CM thick wall filled with fiberglass insulation, more or less.

https://i0.wp.com/www.stirimeteo.com/wp-content/uploads/2018/01/Snow-depth-North-Hemisphere-2.gif

Also found this cool article studying thermal transfer through snow on ice in the Beaufort:

http://onlinelibrary.wiley.com/doi/10.1029/2000JC000409/abstract

Over all, average thermal conductivity  of snow pack on arctic ice is about half that of the ice beneath it.  QED/Rule of thumb would be - 40CM of snow slows down ice thickening about as much as 80CM of ice.

Now to find some of last year's snow thickness plots from around this time...
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A-Team

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Re: The 2017/2018 freezing season
« Reply #654 on: January 16, 2018, 03:41:05 PM »
Quote
equivalent to a 10CM thick wall filled with fiberglass insulation, more or less.
If dry fluffy powder. But how does that stay in place given month after month of strong surface winds? More likely it will drift onto irregularities, leaving bare ice in some places and meter-thick snowdrifts on the lee of pressure ridges. There's only an even blanket of snow when viewed with 50 km x 50 km grid cell averaging. No one goes out there to measure snow transects Oct through May.

If rain on snow -- which we are seeing this week off Svalbard and likely off Alaska -- that will melt the snow entirely or form layers of weak ice within the 'snowpack'. The only recent extended winter in situ monitoring of the Arctic Ocean snow is N-ICE 2015. They documented warm moist air driven melt events as well as the effects of waves washing over the meagre freeboard of FYI-SYI.

For better or worse, comprehensive physical modeling programs like RASM-ESRL bake all this in to their near real-time daily state descriptions: snow, rain, water-ice-air heat equation transfer, wind, mid-latitude advection, high vs low clouds and up-and-down radiative energy transfers. Those netCDFs will resume 14 Feb 18.

Can we do better intuiting quantification?

Then there is bottom-line ice thickness observation by combined satellite altimetry and salinity. These have error issues in processing steps but are far better anchored in reality than pure models. (A snow-driven correction factor for Cryosat from upwardly extruded brine mentioned up-forum has not yet made papers like Stroeve 2018.)

Following the thinner ice on the periphery plus FDDAO for thermal thickening may be the best current guides to how the freeze season is going, as compared to recent years past. The peripheral seas are the last to freeze and the first to melt and so affect the core via ice mobility, long-fetch waves, and air moisture.

The second image below restricts the UH snow thinness product for 14 Jan 18 to ice between 0.25 and 1.25 m thick, which could be the Goldilocks range for tracking (in terms of intrinsic accuracy) in the post freeze-over winter. Open water in September can freeze to ~2m thickness by the end of winter so the deficit is of interest. (SMOS alone does not go out to that thickness.)

The third image shows the same date after the big melt summer of 2012 (which was followed by an unremarkable 2013 extent). The time series available is too short, relative to variation, for statistical trending. Further, later years might have used improved algorithms.

It's feasible also to use weekly or monthly averaging out of Panoply but ice acceleration this year in the western Beaufort means individual floes have moved on and their thickening isn't being followed. The bottom animation shows the last 30 days of motion, including a couple of feature trackers over a blowup of export to the Fram.

This is a very unfavorable pattern for retention of thicker remnant CAA ice which is getting stretched in two directions: into the warmer Chukchi and towards export.

These maps are only feasible to produce when a Geo2D thickness file within a netCDF bundle is provided to Panoply for range-picking (eg UH, not UB). Here ice <0.25 m is re-colored light blue (distinguishing it from open water) and ice >1.25m off-white in Gimp.

Technical note: it is feasible to replace the two bounding colors in Panoply continuum palettes with distinct colors from the ambient gradient. This would directly resolve situations where 0 and NaN conflict. The question really is whether long time series can be automated in Panoply (yes, see DevCorn) and wrapped in ImageJ to movies without invoking manual curation in Gimp (probably).

http://www.npolar.no/en/projects/n-ice2015.html
http://www.npolar.no/en/projects/n-ice2015.html
https://seaice.uni-bremen.de/data/smos/png/
https://icdc.cen.uni-hamburg.de/thredds/catalog/ftpthredds/smos_sea_ice_thickness/v3/catalog.html
« Last Edit: January 16, 2018, 06:50:29 PM by A-Team »

gerontocrat

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Re: The 2017/2018 freezing season
« Reply #655 on: January 16, 2018, 06:46:57 PM »
Quote
equivalent to a 10CM thick wall filled with fiberglass insulation, more or less.
If dry fluffy powder.

The thermal conductivity of snow is highly variable, just one among all the other variables quoted by A-Team. Given the paucity of data (rightly often bemoaned by A-Team) those teams doing the modelling are right on the edge of doability. But more credit to them for giving it a go.
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Jim Hunt

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Re: The 2017/2018 freezing season
« Reply #656 on: January 16, 2018, 07:27:56 PM »
Big Joe Bastardi was talking nonsense about the DMI >80N temperature graph on Twitter.

I figured I'd show him the error of his ways using an FDD graph, only to discover that the data on the last few days of December had already disappeared from the DMI web site. An email to Denmark has resulted in the entire data set now being available for download in a UNIX style .tar archive, should anybody else be interested.

ftp://ftp.dmi.dk/plus80N_temperatureindex/plus80n_temperatureindex_1958_2017.tar

DMI have asked me to point out that before using the data you should carefully read the enclosed documentation.
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Iain

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Re: The 2017/2018 freezing season
« Reply #657 on: January 17, 2018, 01:18:48 PM »
Jim,

There was some discussion around FDDs this time last year in the 16/17 freezing thread.

From memory, the gist was that for any given temp difference between cold air and above-freezing seawater, the Ice thickness tends to a particular value.

The upshot was that the dT in the period immediately prior to onset of spring melting was the most important for thickness and summer survivability. FDDs at the onset of Autumn freezing made much less difference.
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A-Team

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Re: The 2017/2018 freezing season
« Reply #658 on: January 17, 2018, 04:30:52 PM »
Dawn at Little Diomede yesterday (arrow). WorldView will be showing some of the Chukchi soon in its visible and IR channels. That may be soot in the lower left and center, third image.

The eastern Lincoln Sea area is being pulled apart by conflicting motions: rotation westward but eastward Fram export, animation. We've seen that many times before.

Two views of the Beaufort (thermal and radar brightness) emphasize different features, second image.

Technical note: NOAA AVHRR at DMI shows ice fractures better than higher resolution DTU Sentinel-1AB images, probably because open ice leads reveal water (or new ice) at a different temperature. The flip side is that heat escaping from opening ice can condense to 'black smoke' (fog) that obscures ice details. It then becomes difficult to disentangle the actual width of newly opening leads from the width of lead + black.

Arctic ice is sometimes treated as a viscous plastic which works well enough in describing ice pack motion at very low resolution but underlying this at higher resolution are rips in the fabric that are important heat vents but more difficult to model.
« Last Edit: January 17, 2018, 05:48:49 PM by A-Team »

Tor Bejnar

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Re: The 2017/2018 freezing season
« Reply #659 on: January 17, 2018, 04:51:31 PM »
Re: Jim's FDD chart, earlier today.  I wonder if a graph of the rate of change of FDDs would show us when different years really differ.
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Re: The 2017/2018 freezing season
« Reply #660 on: January 17, 2018, 08:46:53 PM »
Arctic ice is sometimes treated as a viscous plastic which works well enough in describing ice pack motion at very low resolution but underlying this at higher resolution are rips in the fabric that are important heat vents but more difficult to model. [/size]

Well, not entirely true. Lead occurrence can successfully simulated with (elastic) viscous plastic rheology. But I agree, high resolution is important:



http://onlinelibrary.wiley.com/doi/10.1002/2016GL068696/

A-Team

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Re: The 2017/2018 freezing season
« Reply #661 on: January 18, 2018, 02:29:40 AM »
Thanks, I had not come across this article! M Böttinger https://www.dkrz.de) can be credited for the remarkable animation -- we rarely see hillshading to represent a variable (here thickness) on these forums other than NASA SVS productions.

Although these are effective as scientific visualizations (especially the mp4 linked below), they lose frame by frame data. I myself don't plan to "Download dataset as tab-delimited text" because this is better distributed (like RASM-ESRL forecasts) as two Geo2D time series within a single netCDF that can be operationally combined within Panoply (for alternatives to hillshading).

The AWI announcement does not point to a follow-up animation -- four years have gone by -- nor to an actively maintained near-real time archive that covers the current freeze season. The UH sea ice concentration netCDF archives are up to date but not properly geo-tagged (in contrast to the SMOS archive).

While we can agree that 'improving previous resolution from 111 km to some 4 km' is an important advance, it is no longer state of the art, given 200x better resolution from the ~.020 km daily resolution of Sentinel-1AB composited by R Saldo at DTU.

However the question is, does this improved resolution already pick the low hanging fruit in terms of capturing significant heat loss and new ice formation, or do we need to include the many narrow width but very long extent leads? That issue is discussed in the 7 subsequent papers citing this 2016 publication, notably the 2018 paper at 1 km.

For a valid article link, Wiley wants 'abstract' or 'full' on the end of links, here since it open source:
http://onlinelibrary.wiley.com/doi/10.1002/2016GL068696/full

Sea ice leads in the Arctic Ocean: Model assessment, interannual variability and trends
Q. Wang, S. Danilov, T. Jung, L. Kaleschke, A. Wernecke 13 July 2016

https://tinyurl.com/ydh9nzsr AWI press release links to HD versions of youtube

1995-2004 MP4 29.8 MB   https://tinyurl.com/yd7rd9nb too big for forum
2005-2014 MP4 27.9 MB   https://tinyurl.com/yd4k9u4n too big for forum

Q. Wang et al: FESOM Arctic Ocean sea ice concentration and thickness 1995-2014, links to movies in mp4 format. PANGAEA, https://doi.org/10.1594/PANGAEA.860354
 
"Sea ice leads in the Arctic are important features that give rise to strong localized atmospheric heating; they provide the opportunity for vigorous biological primary production, and predicting leads may be of relevance for Arctic shipping. It is commonly believed that traditional sea ice models that employ elastic-viscous-plastic (EVP) rheologies are not capable of properly simulating sea ice deformation, including lead formation, and thus, new formulations for sea ice rheologies have been suggested.

Here we show that classical sea ice models have skill in simulating the spatial and temporal variation of lead area fraction in the Arctic when horizontal resolution is increased (here 4.5 km in the Arctic) and when numerical convergence in sea ice solvers is considered, which is frequently neglected.

...The scientists used a widely known theory, which describes the material qualities of the sea ice as an elastic-viscous-plastic medium. This was often criticised in recent years. But 'the new results show that the old theory for sea-ice physics still remains valid, if the calculation is performed with high accuracy'.

The model results are consistent with satellite remote sensing data and discussed in terms of variability and trends of Arctic sea ice leads. It is found, for example, that wintertime lead area fraction during the last three decades has not undergone significant trends.

Supplement: Northern Hemisphere sea ice from a Finite-Element Sea-Ice Ocean Model (FESOM) 4.5 km resolution simulation. Concentration is shown with color; thickness is shown with shading. A global 1 degree mesh is used, with the "Arctic Ocean" locally refined to 4.5 km. South of CAA and Fram Strait the resolution is not refined in this simulation. The animation indicates that the 4.5 km model resolution helps to represent the small scale sea ice features, although much higher resolution is required to fully resolve the ice leads.

Even in cold winters, more and more leads are forming due to wind and currents, which only adds up to a small amount of the total area, but is responsible for a large part of the growth in ice.'

Quote
A 4.5 km resolution Arctic Ocean simulation with the globalmulti-resolution model FESOM1.4
Q Wang et al  24 July 2017
https://www.geosci-model-dev-discuss.net/gmd-2017-136/gmd-2017-136.pdf

Quote
Scaling Properties of Arctic Sea Ice Deformation in a High-Resolution Viscous-Plastic Sea Ice Model and in Satellite Observations
N Hutter et al 8 January 2018

Sea ice models with the traditional viscous-plastic (VP) rheology and very small horizontal grid spacing can resolve leads and deformation rates localized along Linear Kinematic Features (LKF). In a 1-km pan-Arctic sea ice-ocean simulation, the small scale sea-ice deformations are evaluated with a scaling analysis in relation to satellite observations in the Central Arctic.... The agreement of the spatial scaling with satellite observations challenges previous results with VP models at coarser resolution, which did not reproduce the observed scaling. The temporal scaling analysis shows that the VP model, as configured in this 1-km simulation, does not fully resolve the intermittency of sea ice deformation that is observed in satellite data.

To summarize, our understanding of various Arctic Ocean ice physical processes is demonstrably improving, as is near-real time tracking of the current season, but the ability to make end-of-season or multi-year predictions is not advancing. We understand better what is happening (and why) but not what will happen in the future, other than trend lines.

The problem with unpredictability, given the phenomenon of Arctic amplification, is Arctic sea ice is a leading indicator -- indeed driver -- of global climate change. Lacking a solid foundation here, ambitious 'coupled' climate models are not in a position to reliably predict the future, notably because the onset and consequences of positive feedbacks from Arctic sea ice loss can't be anticipated.
« Last Edit: January 18, 2018, 11:51:13 AM by A-Team »

jdallen

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Re: The 2017/2018 freezing season
« Reply #662 on: January 18, 2018, 04:57:45 AM »
The thermal conductivity of snow is highly variable, just one among all the other variables quoted by A-Team. Given the paucity of data (rightly often bemoaned by A-Team) those teams doing the modelling are right on the edge of doability. But more credit to them for giving it a go.
The Beaufort Sea study I referenced elsewhere came up with an averaged value of about .33, which generalized effect of drifting, compaction, etc.

The value for new snow (A-Team's "powder") is much lower - .071.  Even slab snow (which has compacted into sheets which resist blowing is lower at .29.  However, the extra I think accommodates what A-Team was driving at in his comments.

As I'm pondering ways to apply this to gridded data, I will have to fudge and will likely choose to err in favor of the effective measured coefficient, as it similarly summarizes widely varying conditions across the pack.

As imperfect as that is, If we can start from some sort of direct measurement I agree with A-Team that this would put estimation a step up from the models, however clever.
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jdallen

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Re: The 2017/2018 freezing season
« Reply #663 on: January 18, 2018, 05:12:14 AM »
Dawn at Little Diomede yesterday (arrow). WorldView will be showing some of the Chukchi soon in its visible and IR channels. That may be soot in the lower left and center, third image.
Indeed, returning with effectively no ice in the Bering to keep albedo high and prevent heat uptake.

The exchange is still strongly postive outbound, but in a few weeks it will start to balance out, sooner if we continue to see moisture and heat inputs from further south into the Bering.

I'm wondering now if we may see exceptionally early opening of the Bering strait and Chukchi - possibly as early as late March.  I'm also wondering what consequences *that* could have on the ESS and Beaufort as a cascade.
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Jim Hunt

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Re: The 2017/2018 freezing season
« Reply #664 on: January 18, 2018, 09:52:43 AM »
The Sea Ice Prediction Network post season report has just been released:

https://www.arcus.org/sipn/sea-ice-outlook/2017/post-season

Quote
It is important to note that NSIDC changed their averaging method this year such that the monthly mean sea ice extent is now the average of all the daily sea ice extent values rather than the sea ice extent derived from the monthly average sea ice concentration. As a result, sea ice extents are slightly lower than before (i.e. 2016 extent previously was 4.70 and now is 4.51 million square kilometers).

This year, the observed mean extent for the month of September was 4.80 million square kilometers with the new averaging method compared to 4.87 million square kilometers using the old method. This represents a September sea ice extent that was 1.6 million square kilometers below the average September extent for 1981–2010, but 1.23 million square kilometers above the record low in September 2012 and 300,000 square kilometers above that in 2016.
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Re: The 2017/2018 freezing season
« Reply #665 on: January 18, 2018, 03:51:51 PM »
My experience of the snow on the sea ice is that you don’t get bare patches except where new ice formed (at a lead). There’s some undulation but it’s pretty flat. Snowmachines fly along at 120 km/h, which implies there’s little risk of a big bump.

It is definitely not light and fluffy. It’s hard and compacted; you cut it with a knife to build bricks for your igloo. The bricks are about 10cm thick, but provide sufficient insulation to live in while it’s -40C outside. I don’t know the R value.

A-Team

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Re: The 2017/2018 freezing season
« Reply #666 on: January 18, 2018, 04:04:42 PM »
Quote
not light and fluffy. It’s hard and compacted
Meaning little trapped air to provide insulation. It sounds like the corners of hexagonal plate snowflakes have broken off, leaving rounded cores that pack much tighter.

Quote
may see exceptionally early opening of Bering strait and Chukchi as early as late March with knock-on consequences for ESS and Beaufort.
Quite plausible. For mid-January, the peripheral freeze season seems weak (except for the central Laptev-ESS). The Beaufort still shows extensive regions of thin ice, though by tracking individual CAA floes frozen into its matrix, we know cold air at a fixed position there sees a rapidly moving target to thicken.

Very little can be learned about this region from FDD80º as parts of these seas are in a different weather regime 1400 km to the south of that parallel. Indeed even the reanalysis wind seems to have a so-so correlation with ice velocity, suggesting it is mostly guesswork or that Beaufort currents dominate because floes have been consistently moving westward for 117 days (since day 266 of 2017).

The velocity accelerates markedly up a swath from Banks Island to eastern Chukchi, reminiscent of ice getting caught up in the Fram. Indeed, export there resumed around the same date following a massive intrusive squeeze from the Kara. A slug of ice almost 600 km long has been exported, mostly off the Laptev/SZ but with some north of Morris Jesup streaming in. A streak develops leeward of the small island, Ostrov Ushakova. [Note FJL is mislabelled as SZ on the final frame.]

One has to wonder how the volume being exported over the last 50 days compares to that newly created (and retained) by ice thickening.
« Last Edit: January 18, 2018, 11:59:28 PM by A-Team »

jdallen

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Re: The 2017/2018 freezing season
« Reply #667 on: January 18, 2018, 09:57:55 PM »
One has to wonder how the volume being exported over the last 50 days compares to that newly created (and retained) by ice thickening.
Your Kara ice intrusion animation speaks to that.  It's new ice which is displacing 2nd year+ ice in the CAB, quite definitively.
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gerontocrat

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Re: The 2017/2018 freezing season
« Reply #668 on: January 19, 2018, 12:22:31 PM »
Suddenly a really cold spell in the northern Bering Sea and into the Chukchi ?
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Re: The 2017/2018 freezing season
« Reply #669 on: January 19, 2018, 01:49:10 PM »
Quote
Kara ice intrusion volume being exported over the last 50 days?
The intrusion is not picked up by SMOS ice thinness or AMSR2 concentration but it's seen clearly (at much improved detail) in Sentinel-1AB. Overlaying a rescaled lat lon grid from Panoply and using an online grid cell calculator, the intrusion area works out to about 40,000 km^2. UH SMOS has a fairly large pole hole here but is showing the ice being displaced averaging maybe 1.4 m in thickness. So that would be roughly 56 cubic km of export. That would be 3.8% of wipneus' 2017-12-31 PIOMAS volume of 14,418. The event isn't over (see one day change of 8 km below) so it might worth doing this more carefully when it is.
« Last Edit: January 19, 2018, 11:39:32 PM by A-Team »

jdallen

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Re: The 2017/2018 freezing season
« Reply #670 on: January 19, 2018, 06:15:57 PM »
Suddenly a really cold spell in the northern Bering Sea and into the Chukchi ?
From the looks of it, not really.

The satellites show a far amount of anchored pack ice along the Bering shore of Alaska, which explains some of the"blue", but actually mostly the image suggests mostly normal to warm temps over the Bering. 

Interior AK looks colder, but not over the water. 

The Chukchi looks slightly cooler, but doesn't exactly look like a cold snap.
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subgeometer

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Re: The 2017/2018 freezing season
« Reply #671 on: January 20, 2018, 01:14:21 AM »
Suddenly a really cold spell in the northern Bering Sea and into the Chukchi ?
From the looks of it, not really.

The satellites show a far amount of anchored pack ice along the Bering shore of Alaska, which explains some of the"blue", but actually mostly the image suggests mostly normal to warm temps over the Bering. 

Interior AK looks colder, but not over the water. 

The Chukchi looks slightly cooler, but doesn't exactly look like a cold snap.

The GFS forecast has relatively cold conditions developing for a few daysover an area in the Basin south of a line from the ESS to the Mackenzie delta, as well as really cold in Alaska. But by about 60 hrs in the cold is being pushed out into the North Pacific, bypassing the Bering Sea, and by 120 hrs its all gone from everywhere but Alaska , pushed out by warm cloudy air from the Atlantic side which is anomolously warm all week.

The huge cold airmass that has developed over Siberia has also almost totally avoided going over any sea ice area, and is about to head south

gerontocrat

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Re: The 2017/2018 freezing season
« Reply #672 on: January 20, 2018, 10:13:35 AM »
WINTER 2017-18 SNOW

"Environment Canada" has data on snow at https://ccin.ca/home/ccw/snow/current  .

Below are (for the Northern hemisphere) -
- a map of extent and variations from average depth,
- snowfall extent graph,
- snowfall mass graph.

If nothing else the contrast between extent - below average, and mass - above average is consistent with a warming world with increasing precipitation predicted especially at higher latitudes.

What this means for the remainder of the freezing season and for the 2018 melting season I leave for others to say.
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Re: The 2017/2018 freezing season
« Reply #673 on: January 20, 2018, 11:27:20 PM »
The GFS forecast has relatively cold conditions developing for a few daysover an area in the Basin south of a line from the ESS to the Mackenzie delta, as well as really cold in Alaska. But by about 60 hrs in the cold is being pushed out into the North Pacific, bypassing the Bering Sea, and by 120 hrs its all gone from everywhere but Alaska , pushed out by warm cloudy air from the Atlantic side which is anomolously warm all week.

The huge cold airmass that has developed over Siberia has also almost totally avoided going over any sea ice area, and is about to head south

Climate Reanalyzer is now also offering mp4 videos of their forecasts, and given that this Forum now supports mp4, here's the temperature anomaly forecast for the coming 10 days (and look at all that global warming moving over to the US East Coast, right where President Trump wanted it; amazing, innit?  ;)):

Il faut comparer, comparer, comparer, et cultiver notre jardin

A-Team

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Re: The 2017/2018 freezing season
« Reply #674 on: January 21, 2018, 12:51:04 AM »
Quote
Climate Reanalyzer is now also offering Forum-supported mp4 videos of their forecasts...
It just keeps getting better!

Here is a pair of high resolution Sentinel-1B separated in time by only 12 hours. It shows the lower tongue of that Kara ice intrusion. Note the ice rearranging itself like a jigsaw puzzle. There was an additional translational component, towards the Fram, which was removed by shifting the second image back up to the sub-central fixed point to which the residual motion is relative to.
« Last Edit: January 21, 2018, 02:38:16 AM by A-Team »

subgeometer

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Re: The 2017/2018 freezing season
« Reply #675 on: January 21, 2018, 02:15:28 AM »
Thanks for the tip Neven

subgeometer

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Re: The 2017/2018 freezing season
« Reply #676 on: January 21, 2018, 02:35:19 AM »
Quote
Climate Reanalyzer is now also offering Forum-supported mp4 videos of their forecasts...
It just keeps getting better!

Here is a pair of high resolution Sentinel-1B separated in time by only 12 hours. It shows the lower tongue of that Kara ice intrusion. Note the ice rearranging itself like a jigsaw puzzle.

Very elastic pack. There's a lot of shatter lines like last winter where leads open effortlessly.

I agree with Gerontocrat that sometimes` the framerate could be a bit slower on these short sequence and comparisongifs. ImageMagick sets it with a delay setting (eg 'convert -delay 100 [input files] output.gif' - the value is in milliseconds) , with other software I don't know how. Its a matter of preference I guess, but the slower rate allows the eye to linger a little on each frame

I played with your file and found convert will change the framerate without apparent issues.

Don't take as a criticism, your work is setting the bar here

Your movies you posted play fine on Linux as well - with Firefox on Ubuntu anyway
« Last Edit: January 21, 2018, 02:59:15 AM by subgeometer »

A-Team

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Re: The 2017/2018 freezing season
« Reply #677 on: January 21, 2018, 03:07:49 AM »
Quote
Very elastic pack. lot of shatter lines
These irregular shear lines are not elastic deformations as those terms are defined at english language wiki or used in classical 19th century continuum mechanics. This ice is brittle. Features  like embedded MYI floes are not changing shape. What we are seeing is more like a crystal dislocation or diffusely distributed earthquake strike-slip faulting than a Glen's law smooth deformation of ice deep under Jakobshavn.

Elastic too is used very differently in physics; here kinetic energy was not conserved but went off entirely into frictional heat, nothing is left to drive a rebound. However viewed at the very much lower resolution of say Ascat, you can get away with a viscoelastic perspective (see up-forum).

The ice here is experiencing a torque because the wind is pushing harder on the inbound side of the Kara tongue. In response, ice is trying to rotate regionally. That's really problematic because it is caught up in the overall AO ice pack which is mightily constrained in an asymmetric basin (with respect to shape, the north pole and coriolis force) bounded by immovable islands. We see consequences of this all the time. The only really large scale rotation possible for the Arctic Ocean is about the so-called pole of inaccessibility. A favorable MSLP pressure pattern for driving this is not uncommon but not that persistent either.

Sentinel-1AB shows opening leads quite well (as bright white) but ridging and over-riding floes not at all since it's viewing almost straight down. Between these three processes, there's no day-to-day conservation of ice surface area even outside of melt season.

Thanks for the animation rate suggestion. I've added some additional frame rates to the 200ms one above, having no idea whether various web browser actually switch between the two frames at the advertised rate. These are 600ms, 1000ms and 2000ms.

Myself, I've come to the opinion that mousing ImageJ stacks offline is by far the best viewing option for climate science time series. (That would involve a download of the forum gif and opening in ImageJ freeware for your platform.) Mousing can be varied from fast to slow, notably for some interior subset of interest. Elsewhere on the screen, several Gimp playback windows could be looping more conventionally through the animation at various fixed speeds.

The other thing ImageJ does very well is montage all the frames at any combination of rows x columns (eg 360 frames as 24x15 or 30x12). This makes optimal use of rectangular monitor displays: you can see all the animation frames at once. Further, contrast improvements consistently affect all the frames in the montage. The result can be sliced and diced back into the animation stack.

ImageJ will also subset an animation or concatenate or combine several. Somehow someone got all this to happen in milliseconds whereas Gimp can take several minutes on high frame count products.
« Last Edit: January 21, 2018, 04:15:22 AM by A-Team »

oren

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Re: The 2017/2018 freezing season
« Reply #678 on: January 21, 2018, 08:26:57 AM »
Thank you as usual A-Team. The GIFs refresh as advertised on my Windows Chrome browser. I think the 1000ms rate is useful for short animations such as this, and the 600ms is probably better for longer ones. 2000ms is too long, and 200ms usually too short.

Tor Bejnar

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Re: The 2017/2018 freezing season
« Reply #679 on: January 21, 2018, 04:28:51 PM »
oren speaks my mind.  (Quakerese for "I agree with oren.)
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Re: The 2017/2018 freezing season
« Reply #680 on: January 21, 2018, 05:54:58 PM »
Thanks for the feedback!

Here is a 100 frame false color gif at 120ms with a 1200 ms pause at the end, Ascat to 20 Jan 2018. This uses the 'phase' color table at ImageJ. It simplifies quite a bit of detail present in the original but does ok at retaining features for purposes of tracking their movement over time. (ImageJ offers many tools for quantified tracking but each has a substantial learning curve.)

In addition to the huge pulse of Kara ice, look at the stretching out of the MYI floes as they get caught up in accelerating motion towards the Chukchi. Ice in the central Arctic most manages to stay put despite what is going on around it but ice 'SE' of the pole appears to thin out as it gets drawn into the Fram.

The Kara ice makes up about 4% of the surface of the Arctic Ocean proper on 20 Jan 2018. Should it be lumped with other FYI or tracked separately?

If this keeps up, the ice pack will be very damaged before we even get around to melt season.
« Last Edit: January 21, 2018, 07:08:49 PM by A-Team »

gerontocrat

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Re: The 2017/2018 freezing season
« Reply #681 on: January 21, 2018, 06:33:44 PM »
These animations demonstrate so well that the Arctic ice pack is not a solid lump - the energy, the dynamic, the movement, even in 100 days are amazing.  It is a great pity that these animations are not part of what the general public gets to see as a rule.
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Re: The 2017/2018 freezing season
« Reply #682 on: January 21, 2018, 08:40:12 PM »
A-Team's 100-day animation shows that, no matter how hard the little engine tries (that is: Nares Strait), it is no match for the big guy (Fram Strait).  Years ago I read that Nares export (when open) is about 10% of Fram's.
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Re: The 2017/2018 freezing season
« Reply #683 on: January 21, 2018, 08:59:45 PM »
I dont think that the late refreeze of chucki is the problem.
The reason is, if you look for estimated temperatures till april, they will stay much below zero.
So if this area refreeze a little later, it will not melt the same, because thicker ice insulate, so for example if an area refreeze 2 weeks later at same condition, it wil lose more heat, so the melt should be less then two weaks earlyer, say only 10 days earlyer.
The hole problem is not the temperature or radiation in the arctic but the transposing heat effect of lower attitude.
The arctic itself has rather a negative feedback, you can see this when looking that after porr low ice minimums the next year is better, so it seems to overcompensate this in the winter.
This dont mean the ice is surviving forever, because there are other factors.
There is more heat around and because a surface that is is the middle gets much more impact from ouside.
Look at a little circle and think about an area,a ring surrinding.
This ring has a much larger surface, so if you take it mathematically, a circle with r=1 and a bigger circle with r=1,5.
Lets say the ring from r=1,5 to 1 has the number 1 and the inner circle has the number 0.
So the total circle is 2.25 larger (1.5*1.5) and this 1.25 lets say have the value 1 and the inner ring the value 0.
If you mix this the hole circle has 0.65 even you can compare it with Say N80 and N75.
So the extra energy is coming from a lot larger surface then the inner circle and this is the most import efffect in my opinion, the ice albedo and winter insulation is more or less not cooling the water at all, but keep it warm, but this effect, you can observe after poor ice years (more extend instead of keeping low or lower) is quite strong, resulting in not low records last year, this negative feedback is as stronger as you go north but all the extra heat from climate change is surrinding this negative feedback area with extra heat all the time.
« Last Edit: January 21, 2018, 09:16:48 PM by 2phil4u »

A-Team

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Re: The 2017/2018 freezing season
« Reply #684 on: January 22, 2018, 01:03:04 PM »
Quote
Arctic ice pack is not a lump - the energy, dynamic, movement, even in 100 days are amazing
Endlessly fascinating to watch! We may be seeing an increase in ice mobility this January, as expected from the increasingly FYI composition of the ice pack and continuing thinness in the Beaufort-Chukchi.

Check out the 'lift-off' of the entire ice pack from the western CAA especially east of Banks Island as well as ill winds elsewhere pushing the top of the floe stringer south towards the Bering Strait. The animation runs forwards and backwards in time.

Other satellite products like AMSR2 and SMOS are 'missing out' on these events as they do not image individual floes and features, though there's some interest in the last three weeks of SMOS blur (bottom). Sea ice age would pick them up but seems to always lag by months. WorldView could pick up Bering Sea events provided it were not cloudy. The ice is on the move though there's no export through the Bering Strait at this time.
« Last Edit: January 22, 2018, 05:08:29 PM by A-Team »

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Re: The 2017/2018 freezing season
« Reply #685 on: January 22, 2018, 01:16:24 PM »
If this mobility keeps up- and why wouldn't it?-
 there won't be enough Ice left in September to cool down a Champagne Bottle.

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Re: The 2017/2018 freezing season
« Reply #686 on: January 22, 2018, 01:37:09 PM »
That's not a problem because Disneys version is outdated, Santa sacked all of us dwarfs in the 90s and moved to Rovaniemi, Finland.
https://santaclausoffice.com/story-santa-claus-office/
Even the Danes gave up on their claim, that Santa lives on Greenland, in December.
https://www.dr.dk/nyheder/udland/groenlands-turistorganisation-opgiver-julemanden-finland-maa-gerne-faa-ham
Omnia mirari, etiam tritissima.
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Science is a jealous mistress and takes little account of a man's feelings.

meddoc

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Re: The 2017/2018 freezing season
« Reply #687 on: January 22, 2018, 02:59:55 PM »
That's not a problem because Disneys version is outdated, Santa sacked all of us dwarfs in the 90s and moved to Rovaniemi, Finland.
https://santaclausoffice.com/story-santa-claus-office/
Even the Danes gave up on their claim, that Santa lives on Greenland, in December.
https://www.dr.dk/nyheder/udland/groenlands-turistorganisation-opgiver-julemanden-finland-maa-gerne-faa-ham

Yes the climatological NP is being tossed into Siberia these Days. & partly Greenland.

http://cci-reanalyzer.org/wx/DailySummary/#t2anom

Lord M Vader

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Re: The 2017/2018 freezing season
« Reply #688 on: January 22, 2018, 05:33:47 PM »
NSIDC came back today after not updating yesterday. The most recent numbers reveals that 2018 sea ice extent is now the lowest on record, 30K below 2017. I shouldn't be too surprised if we'll continue to be lowest on record for at least a couple of days, or maybe the rest of the month.

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Re: The 2017/2018 freezing season
« Reply #689 on: January 22, 2018, 05:55:51 PM »
That 30k difference is the 5day number? Daily extent spreadsheet says 2018 150k below 2017.0
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Lord M Vader

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Re: The 2017/2018 freezing season
« Reply #690 on: January 22, 2018, 07:40:01 PM »
Gerontocrat: exactly! The 5-day average is better as it removes daily variations. But daily numbers are ofc of interest too :)

gerontocrat

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Re: The 2017/2018 freezing season
« Reply #691 on: January 22, 2018, 08:03:12 PM »
Gerontocrat: exactly! The 5-day average is better as it removes daily variations. But daily numbers are of interest too :)

I am in two minds about the 5 day versus 1 day question. Jaxa data (to confuse things more) is the two day average (?) and at the moment is showing a far more dramatic divergence in SIE between 2017 and 2018. 2018 is shown as 297 k less than 2017, about one week's average gain at this time of year.

Is some of this difference (and that JAXA SIE is always lower than NSIDC's figure) due to NSIDC data including places (such as Baltic, Okhotsk Sea?) that JAXA ignores?

But after a week or so the picture will become clearer.
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oren

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Re: The 2017/2018 freezing season
« Reply #692 on: January 22, 2018, 09:06:45 PM »
JAXA data shows less extent thanks to its much better resolution.

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Re: The 2017/2018 freezing season
« Reply #693 on: January 23, 2018, 04:08:23 PM »
Comparing current concentration maps to the forecast temperatures, do we or do we not expect the ice to play a bit of catch up over the next few days in the Barents / Bering / Okhotsk?

Jan 22nd Bremen concentration map:



Jan 24th ClimateReanalyzer forecast surface air temperature:



Jan 25th ClimateReanalyzer forecast:



Jan 26th ClimateReanalyzer forecast:



Further forecasts: https://sites.google.com/site/arcticseaicegraphs/forecasts2

I'm thinking potentially yes in all three, but what do I know?

Stephen

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Re: The 2017/2018 freezing season
« Reply #694 on: January 24, 2018, 05:36:23 AM »
Waaay back when I first got interested in climate chaneg science I recall the following as proof of global warming when caused by an intensifying greenhouse effect.

  • the nights will warm faster than the days
  • the winters will warm faster than the summers
  • the poles will warm faster than the equatorial regions

But then I got fascinated by the dramatic sea-ice decline of 2007 and 2012 and forgot about those fundamental proofs.

In my opinion a record hot summer temperate is more exciting but less significant than a record warm winter.  So I am thinking that these record low winter extents may be more significant than record low summer extents.  Not nearly as exciting - sure - there won't be any headlines in the NY Times.  But I am now follwoing  these winter extents with the same fascination I used to follow the summer extents.
The ice was here, the ice was there,   
The ice was all around:
It crack'd and growl'd, and roar'd and howl'd,   
Like noises in a swound!
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Daniel B.

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Re: The 2017/2018 freezing season
« Reply #695 on: January 24, 2018, 05:08:55 PM »
Waaay back when I first got interested in climate chaneg science I recall the following as proof of global warming when caused by an intensifying greenhouse effect.

  • the nights will warm faster than the days
  • the winters will warm faster than the summers
  • the poles will warm faster than the equatorial regions

But then I got fascinated by the dramatic sea-ice decline of 2007 and 2012 and forgot about those fundamental proofs.

In my opinion a record hot summer temperate is more exciting but less significant than a record warm winter.  So I am thinking that these record low winter extents may be more significant than record low summer extents.  Not nearly as exciting - sure - there won't be any headlines in the NY Times.  But I am now follwoing  these winter extents with the same fascination I used to follow the summer extents.

I agree.  This is due to the increased cloudiness, which leads to warming in all seasons, but the summer.  See the following presentation:

https://atmos.washington.edu/~rmeast/BarrowPresI.pdf

magnamentis

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Re: The 2017/2018 freezing season
« Reply #696 on: January 24, 2018, 10:52:27 PM »
Waaay back when I first got interested in climate chaneg science I recall the following as proof of global warming when caused by an intensifying greenhouse effect.

  • the nights will warm faster than the days
  • the winters will warm faster than the summers
  • the poles will warm faster than the equatorial regions

But then I got fascinated by the dramatic sea-ice decline of 2007 and 2012 and forgot about those fundamental proofs.

In my opinion a record hot summer temperate is more exciting but less significant than a record warm winter.  So I am thinking that these record low winter extents may be more significant than record low summer extents.  Not nearly as exciting - sure - there won't be any headlines in the NY Times.  But I am now follwoing  these winter extents with the same fascination I used to follow the summer extents.

you name it, not much else to add, should be bookmarked and posted on each page once the summer discussions about minima are in full swing ;)
« Last Edit: January 25, 2018, 11:41:05 PM by magnamentis »

Dharma Rupa

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Re: The 2017/2018 freezing season
« Reply #697 on: January 24, 2018, 11:26:08 PM »
Waaay back when I first got interested in climate chaneg science I recall the following as proof of global warming when caused by an intensifying greenhouse effect.

  • the nights will warm faster than the days
  • the winters will warm faster than the summers
  • the poles will warm faster than the equatorial regions

But then I got fascinated by the dramatic sea-ice decline of 2007 and 2012 and forgot about those fundamental proofs.

In my opinion a record hot summer temperate is more exciting but less significant than a record warm winter.  So I am thinking that these record low winter extents may be more significant than record low summer extents.  Not nearly as exciting - sure - there won't be any headlines in the NY Times.  But I am now follwoing  these winter extents with the same fascination I used to follow the summer extents.

you name it, not much else to add, should be bookmarked and posted on each page once the summer discussions about minimal are in full swing ;)

Does seem that for those of us here this time of year he is preaching to the choir.

I can only add that all of this is because the major greenhouse gas is H2O.

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Re: The 2017/2018 freezing season
« Reply #698 on: January 25, 2018, 12:58:05 AM »
Waaay back when I first got interested in climate chaneg science I recall the following as proof of global warming when caused by an intensifying greenhouse effect.

  • the nights will warm faster than the days
  • the winters will warm faster than the summers
  • the poles will warm faster than the equatorial regions

But then I got fascinated by the dramatic sea-ice decline of 2007 and 2012 and forgot about those fundamental proofs.

In my opinion a record hot summer temperate is more exciting but less significant than a record warm winter.  So I am thinking that these record low winter extents may be more significant than record low summer extents.  Not nearly as exciting - sure - there won't be any headlines in the NY Times.  But I am now follwoing  these winter extents with the same fascination I used to follow the summer extents.

you name it, not much else to add, should be bookmarked and posted on each page once the summer discussions about minimal are in full swing ;)

Does seem that for those of us here this time of year he is preaching to the choir.

I can only add that all of this is because the major greenhouse gas is H2O.

And the more CO2/GHGs, the more H2O. Feedbacks suck.
I am more ears than mouth.

Paddy

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Re: The 2017/2018 freezing season
« Reply #699 on: January 25, 2018, 05:24:13 AM »
At least if we do get more clouds it should reduce the impact of lost albedo from ice, right? (Although I've no idea how the numbers stack up on this)
« Last Edit: January 25, 2018, 04:17:50 PM by Paddy »