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Author Topic: Home brew AMSR2 extent & area calculation  (Read 1720663 times)

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Re: Home brew AMSR2 extent & area calculation
« Reply #600 on: October 14, 2013, 04:43:29 PM »
Lots of ice on the move in this part of the Canadian Archipelago.

(login and click to see attached image)

I cannot shake the feeling that we have transitioned to a new phase state in the Arctic. This new state is characterized by dramatic sea ice mobility. With less MYI, land fast ice and mass, the sea ice is much more reactive to weather in the arctic.

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Re: Home brew AMSR2 extent & area calculation
« Reply #601 on: October 16, 2013, 09:35:33 AM »
The East Siberian Sea has an almost 100% ice cover by extent, Laptev will follow very soon. It is mostly new ice of course with lots of mobility.

(login and click on the picture to see the animation)

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Re: Home brew AMSR2 extent & area calculation
« Reply #602 on: October 25, 2013, 06:56:30 AM »
Baffin Bay is starting to fill seriously with sea ice. In the center of the animation the parked remnants of PII iceberg are visible. Also watch the "whirl pool" at the entrance of Parry Channel.

(log in and click on attached image to animate)

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Re: Home brew AMSR2 extent & area calculation
« Reply #603 on: October 25, 2013, 09:03:18 AM »
Baffin Bay is starting to fill seriously with sea ice. In the center of the animation the parked remnants of PII iceberg are visible. Also watch the "whirl pool" at the entrance of Parry Channel.

(log in and click on attached image to animate)

I see a problem in what I perceive as those CAA flow rates in that animation. The fast flows at Nares are to be expected, but contrary to some people, I've suspected the last of the ASI will exist in the CAA, AB and not north of Greenland near it's coast, where Fram and Nares can take it, based on my analysis of recent ocean currents. I remember being told by people who lived in Canada about the conditions of MYI in the CAA. In my mind's eye, MYI can only exist within a certain neighborhood and ASI going south of CAA is either doomed or lucky enough to get stuck for awhile clogging the pipes that will remove it. I would hope the pipes would be clogged at this late of a time in the year, regardless of weather and the Arctic not be losing any MYI. It's not something easy to replace it. 

This is only the second year I've examined the refreeze in some detail, but last year I remember the gyre direction taking MYI away from CAA. I still can't find that Navy Arctic data to get a better picture. I guess paying a University a few pennies to do cheap work for the government is just too costly. <grumble>

Wipneus, is the export of ASI I'm seeing normal to the Arctic at this time of year in that area?   

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Re: Home brew AMSR2 extent & area calculation
« Reply #604 on: October 25, 2013, 09:41:37 AM »
Quote
Wipneus, is the export of ASI I'm seeing normal to the Arctic at this time of year in that area? 

The ice is still very mobile, and the influence of the winds can be observed everywhere. So I don't think this is unusual, especially in recent years.
The resolution and quality of the AMSR2 makes this much easier to follow, unfortunately it is not so easy to compare with previous years.

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Re: Home brew AMSR2 extent & area calculation
« Reply #605 on: October 25, 2013, 12:15:16 PM »
wipneus, some features in the animation seem to disappear and reappear, is that a result of changing ice reflectivity / thickness or problems caused by cloudcover? I also noticed that on the animation you posted in the Nares Strait thread where visibility of PII was much reduced in some frames.   It is of course great to see these animations and it would be foolish to expect the kind of resolution of clear sky visisble or IR images, but I am trying to learn how to "read" what I see.
Thank you very much for the work you do!

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Re: Home brew AMSR2 extent & area calculation
« Reply #606 on: October 25, 2013, 02:03:01 PM »
The ice is still very mobile, and the influence of the winds can be observed everywhere.

Certainly not easy to compare with previous years, but ice mass balance buoy 2013C has been very mobile recently. It now seems to be whizzing around in "the 'whirl pool' at the entrance of Parry Channel":
Reality is merely an illusion, albeit a very persistent one - Albert Einstein

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Re: Home brew AMSR2 extent & area calculation
« Reply #607 on: October 26, 2013, 08:20:56 AM »
wipneus, some features in the animation seem to disappear and reappear, is that a result of changing ice reflectivity / thickness or problems caused by cloudcover? I also noticed that on the animation you posted in the Nares Strait thread where visibility of PII was much reduced in some frames.   It is of course great to see these animations and it would be foolish to expect the kind of resolution of clear sky visisble or IR images, but I am trying to learn how to "read" what I see.
Thank you very much for the work you do!

Change reflectivity by emissivity, as these instruments measure thermal microwave emission of ice and water. Fortunately in the microwave bands used by the ASI algorithm, the emissivity is not very variable (which is not so true for other algorithms).

Liquid water in cloud and water vapor certainly influence the results. There is another factor affecting the PII iceberg(s), that is movement. The satellite makes multiple passes over the iceberg each day, and I presume the final pixels are an average of these passes. When the iceberg is moving sufficiently fast, the apparent brightness is reduced.

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Re: Home brew AMSR2 extent & area calculation
« Reply #608 on: October 26, 2013, 11:25:25 AM »
wipneus, some features in the animation seem to disappear and reappear, is that a result of changing ice reflectivity / thickness or problems caused by cloudcover? I also noticed that on the animation you posted in the Nares Strait thread where visibility of PII was much reduced in some frames.   It is of course great to see these animations and it would be foolish to expect the kind of resolution of clear sky visisble or IR images, but I am trying to learn how to "read" what I see.
Thank you very much for the work you do!

Change reflectivity by emissivity, as these instruments measure thermal microwave emission of ice and water. Fortunately in the microwave bands used by the ASI algorithm, the emissivity is not very variable (which is not so true for other algorithms).

Liquid water in cloud and water vapor certainly influence the results. There is another factor affecting the PII iceberg(s), that is movement. The satellite makes multiple passes over the iceberg each day, and I presume the final pixels are an average of these passes. When the iceberg is moving sufficiently fast, the apparent brightness is reduced.

I tried to find information on salinity of ASI following the fragmentation event, with limited success. Do you or does anyone having knowledge, know of studies to measure the tensile stress of ASI, or just sea ice in general? Concept:

http://en.wikipedia.org/wiki/Tensile_strength

Atlas was complaining about his back hurting again today and he wants to know.

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Re: Home brew AMSR2 extent & area calculation
« Reply #609 on: October 26, 2013, 12:19:52 PM »
Do you or does anyone having knowledge, know of studies to measure the tensile stress of ASI, or just sea ice in general? Concept:

The conventional wisdom is that you should be looking here first:

http://en.wikipedia.org/wiki/Rheology

I have a little book on this sort of stuff - "Drift, Deformation, and Fracture of Sea Ice: A Perspective Across Scales" by Jerome Weiss

It includes many references, the vast majority of which I haven't read! If you can be a bit more specific maybe I can suggest something? Part of the concluding chapter says:

Quote
Brittle rheology implies a strongly non-linear response of sea ice to mechanical forcing, with the consequence of reinforcing the intermittency and spatial localization, and modifying the scaling properties.

together with:

Quote
The failure strength of the ice cover depends linearly on its thickness. consequently a thinner ice cover will break up and crumble more easily for the same wind/current mechanical forcing.
Reality is merely an illusion, albeit a very persistent one - Albert Einstein

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Re: Home brew AMSR2 extent & area calculation
« Reply #610 on: October 26, 2013, 08:47:18 PM »
Thank you, Wipneus, could you point me (and others) to a place to read up on AMSR2?
This, I guess, reinforces your point about mobility of the ice:
 http://ocean.dmi.dk/arctic/images/MODIS/MorrisJessup/201310260353.NOAA.jpg in conjunction with Ice Speed and Drift from the graphs page (what is the name under which I should refer to it? CICE? ARC? HYCOM? not sure how to link). I interpret that as older ice from north of Greenland heading for the Fram Strait drain, increasing extent now but will be figuring as a volume loss in 2014.
« Last Edit: October 26, 2013, 08:57:35 PM by Andreas T »

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Re: Home brew AMSR2 extent & area calculation
« Reply #611 on: October 26, 2013, 10:40:21 PM »
Do you or does anyone having knowledge, know of studies to measure the tensile stress of ASI, or just sea ice in general? Concept:

The conventional wisdom is that you should be looking here first:

http://en.wikipedia.org/wiki/Rheology

I have a little book on this sort of stuff - "Drift, Deformation, and Fracture of Sea Ice: A Perspective Across Scales" by Jerome Weiss

It includes many references, the vast majority of which I haven't read! If you can be a bit more specific maybe I can suggest something? Part of the concluding chapter says:

Quote
Brittle rheology implies a strongly non-linear response of sea ice to mechanical forcing, with the consequence of reinforcing the intermittency and spatial localization, and modifying the scaling properties.

together with:

Quote
The failure strength of the ice cover depends linearly on its thickness. consequently a thinner ice cover will break up and crumble more easily for the same wind/current mechanical forcing.

I have a solid background in rheology, including working on the development of the world's most sensitive rheometer, many years ago. It is true that materials like ice and glass have fluid properties, but they also have properties like tensile strength that can be measured like solids. My experience in that field is somewhat limited to metals.

Using the word stress instead of strength was a poor choice and was confusing.

In simple English, has testing of sea ice been accomplished to determine it's strength under various conditions of formation? My reasons for wondering about such details is trying to assess how sea ice will handle the changes it's future will subject it to.

Various governments have an interest in an ice free Arctic, but I don't share their concerns. I'm more concerned about the canary being removed from the coal mine and blocking it's entrance.

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Re: Home brew AMSR2 extent & area calculation
« Reply #612 on: October 27, 2013, 03:01:57 AM »

looking at http://ocean.dmi.dk/arctic/images/MODIS/Joekelbugt/201310250624.NOAA.jpg it seems that the mobility of the ice has more to do with the rheology of solid / liquid two phase flow with variable grain size in two dimensions. Strength of the ice probably has an influence on size of floes, but most ice will not be uniform with frozen over leads and ridges. Only a good model which incorporates a lot of parameters which are based on previous conditions of the ice would be able to describe that.

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Re: Home brew AMSR2 extent & area calculation
« Reply #613 on: October 27, 2013, 04:56:05 AM »

looking at http://ocean.dmi.dk/arctic/images/MODIS/Joekelbugt/201310250624.NOAA.jpg it seems that the mobility of the ice has more to do with the rheology of solid / liquid two phase flow with variable grain size in two dimensions. Strength of the ice probably has an influence on size of floes, but most ice will not be uniform with frozen over leads and ridges. Only a good model which incorporates a lot of parameters which are based on previous conditions of the ice would be able to describe that.


and?

I wasn't looking for information on present sea ice floes and wanted information on sea ice tensile strength to form the basics of an understanding on how sea ice will respond to future weather conditions and make judgments about whether good or bad conditions are present during it's formation.

If I wanted to look at the materials of sea ice in these similar terms, I'd be looking at relative viscosity and not rheology, though the subjects are related to the point of being all inclusive, if someone has that perspective.

I seriously doubt if anything other than a government lab has investigated the sea ice based on tensile strength, because there isn't a profit motive involved in such research. My guess is such research was done in the past by our Navies putting nuclear submarines under that Arctic sea ice and other useful pre-satellite ASI information is archived as well.   

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Re: Home brew AMSR2 extent & area calculation
« Reply #614 on: October 27, 2013, 04:14:10 PM »
We seem to be drifting further and further from AMSR2, but....

Andreas - I think the acronym you are looking for is ACNFS (Arctic Cap Nowcast/Forecast System). Is this the sort of image you were looking for? I've grabbed the GIF and attached it here since the direct links to the drift archives don't seem to be updating properly. The ones for thickness seem be utilising some sort of time machine!

ggelsrinc - I'm no expert in these matters, but the emphasis in the past seems to have been on compression rather than tension. Does this paper from Weiss help at all?

"Sea ice rheology from in-situ, satellite and laboratory observations: Fracture and friction"
Reality is merely an illusion, albeit a very persistent one - Albert Einstein

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Re: Home brew AMSR2 extent & area calculation
« Reply #615 on: October 27, 2013, 06:41:55 PM »
Thank you, Jim, this conversation should definitely move into a seperate thread, I feel. Can the moderators do this, or do we need to stop and start again elsewhere?
 Tracking motion and moveability of the ice over the coming months seems worthwhile to me especially when considering the fragmented state of some of the ice which has survived the summer. The article talks about the behaviour of "perennial ice", looking at the ice age maps there are scattered crumbs of multiyear ice. I read the whiter specks in the IR images such as http://ocean.dmi.dk/arctic/images/MODIS/MorrisJessup/201310270342.NOAA.jpgas such fragments with colder surfaces, is that correct? (you see I have taken your advice)
 In that state (before winter increases thickness of the "infill" substantially) it looks to me like the "granular plastic" material mentioned in the text you linked. Lots more to say but not here?

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Re: Home brew AMSR2 extent & area calculation
« Reply #616 on: October 28, 2013, 12:09:10 PM »
This conversation should definitely move into a seperate thread, I feel.

I'm not sure if the moderators can move stuff or not. In the meantime I've started a new thread in which to continue (and if necessary restate) the conversation. Here it is:

"Drift, Deformation and Fracture of Sea Ice"
Reality is merely an illusion, albeit a very persistent one - Albert Einstein

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Re: Home brew AMSR2 extent & area calculation
« Reply #617 on: October 31, 2013, 12:49:01 PM »
A Fram export animation based Uni Hamburgs AMSR2 3.125 km ice concentration data.

Export is well on its way (but ice extent in the Greenland Sea is still behind 2012). Watch the vortices where the ice is moving south. More north, the edge between the ice pack and the Ocean is quite sharp, resembling a fluid surface held by gravity.

(click on attached image if it does not "animate")

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Re: Home brew AMSR2 extent & area calculation
« Reply #618 on: November 01, 2013, 09:18:45 AM »
Thank you muchly for the image, Wipneus!

I'm betting part of the reason behind the sharp delineation may be northward-moving warm water that's still a couple of degrees above freezing.  That would tear apart the ice we see (probably much not more than a meter thick) at the rate of 5-10 CM/day.  If the flow doesn't have much of an E-W component to its movement, that might tend support the boundary we see, along with other factors like surface wind and current.
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Re: Home brew AMSR2 extent & area calculation
« Reply #619 on: November 01, 2013, 09:54:13 PM »
I am not sure how to interpret these patterns, but they do look wind driven to me.
source http://ocean.dmi.dk/arctic/nord.uk.php
The ice nearer the edge is moving southwards at a higher rate than that nearer the coast. That itself with faster movement further south could result in a thinning of the region near the edge, thereby stopping floes drifting towards the east.
That is the sort of thing I hope to discuss on Jim's new thread
"Drift, Deformation and Fracture of Sea Ice"

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Re: Home brew AMSR2 extent & area calculation
« Reply #620 on: November 03, 2013, 09:31:36 AM »
Kara sea is where most of the ice increase has been in the past two weeks. It is also the region where the growth is more earlier than other regions, compared with the timeline in 2012.
The animation shows most of the growth is "in situ", but the northern winds that bring the cold also transport ice from the central pack.

(click on attached image if it does not "animate")

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Re: Home brew AMSR2 extent & area calculation
« Reply #621 on: November 03, 2013, 08:15:18 PM »
Was PIOMAS volume data for September released - did I miss it?


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Re: Home brew AMSR2 extent & area calculation
« Reply #622 on: November 03, 2013, 09:33:53 PM »
Was PIOMAS volume data for September released - did I miss it?

You didn't miss a thing Bob. The Arctic Sea Ice Volume Anomaly page still says:

Quote
September Update Delayed:  Required data not available due to US Government shutdown.
« Last Edit: November 03, 2013, 11:10:46 PM by Jim Hunt »
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Re: Home brew AMSR2 extent & area calculation
« Reply #623 on: November 03, 2013, 09:39:23 PM »
Thanks.

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Re: Home brew AMSR2 extent & area calculation
« Reply #624 on: November 05, 2013, 02:45:31 AM »
Try my link again Bob. PIOMAS now seems to be back in action, and the September numbers are available at long last.
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Re: Home brew AMSR2 extent & area calculation
« Reply #625 on: November 08, 2013, 09:56:44 AM »
The growth of sea ice seems to have "paused". In the last couple of days the ice most regions either retreated or at least stooped increasing. Only Baffin and Hudson kept increasing.

Attached image shows the "retreat" is mostly on the Atlantic side, particularly in the Kara sea.

(log in to see attached image)

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Re: Home brew AMSR2 extent & area calculation
« Reply #626 on: November 12, 2013, 09:05:19 AM »
The filling of the Baffin Bay continues steadily. What surprised me in this animation is that the transport from the Nares Strait continues strongly. I have no idea when the blockade is supposed to start.

(click on the image if there is no animation)

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Re: Home brew AMSR2 extent & area calculation
« Reply #627 on: November 12, 2013, 11:43:20 AM »
The filling of the Baffin Bay continues steadily. What surprised me in this animation is that the transport from the Nares Strait continues strongly. I have no idea when the blockade is supposed to start.

(click on the image if there is no animation)

Wipneus, I'm not trying to take your thread off topic, but I've been watching that and other similar areas for years, thinking what would it take to plug up those ASI transport leaks around this time of year. Your animation has inspired me again to speak my mind.

If I had the cooperation of two of my childhood heros, Dudley Do-Right and Hans Christian Andersen (and I mean no disrespect for the fine people of Canada and Denmark by my sloppy use of metaphor), I'd make an ice bridge to plug up that ASI transport. Cooperation with the Inuit people living in that area also needs to be considered.

The concept is simple enough, if nature can make an ice bridge, why can't we do it, but some of the methods I've considered are strange? I've pondered, is it possible to "borrow" a piece of Petermann glacier or some of the old Ellesmere ice shelf, rig it with sail and move it to plug up those ASI leaks? Is it possible to "weld" ice together using liquid nitrogen? What base of operation should we use, well Camp Century, of course?!

Now, I only put that in a question form to illustrate how your animations make people think of things as a function of time, when before it was static, lifeless data. There are better places to discuss these and other ideas, but I just wanted to say thanks again for your efforts and accomplishments. Even a humble warrior such as yourself is worthy of our praise. 

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Re: Home brew AMSR2 extent & area calculation
« Reply #628 on: November 12, 2013, 07:14:00 PM »
The filling of the Baffin Bay continues steadily. What surprised me in this animation is that the transport from the Nares Strait continues strongly. I have no idea when the blockade is supposed to start.

Me neither. I'm sure Andreas Münchow does.
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Re: Home brew AMSR2 extent & area calculation
« Reply #629 on: November 12, 2013, 10:45:39 PM »
Wouldn't the answer to that question have to be found at the northern end of the strait?
here http://ocean.dmi.dk/arctic/images/MODIS/Lincoln/201311081308.NOAA.jpg
is a clear sky view from Friday.
If Andreas Münchow does comment on this, I would like to ask him whether his measurements of tides in Nares Strait http://icyseas.org/2013/10/24/ruins-of-fort-conger-in-the-high-arctic/ suggest a role of tidal movement in breaking ice at the northern entrance?

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Re: Home brew AMSR2 extent & area calculation
« Reply #630 on: November 13, 2013, 01:16:13 AM »
The filling of the Baffin Bay continues steadily. What surprised me in this animation is that the transport from the Nares Strait continues strongly. I have no idea when the blockade is supposed to start.

Me neither. I'm sure Andreas Münchow does.

Fun discussion and animations ;-)

The ice-bridge or ice-arch across Smith Sound separating Nares Strait from Baffin Bay forms generally somewhere between November and February of each year. Last year it was extremely early, because Petermann's 200-m thick, grounded ice island partially anchored the bridge. There were years in the 2006-2009 timeframe (I'd have to look up the numbers and dates) when no ice-arch formed in Smith Sound.

It appears to me, that the Smith Sound ice-arch is always preceeded by an ice-arch at the northern entrance to Nares Strait in the Lincoln Sea. That one appears to be forming right now, as thermal (MODIS) imagery shows the concentric rings of thinner (warmer) ice before it all compacts into a solid ice-plug. It showed most dramatic in 2009 when only the northern end was plugged and ice was thin and mobile all winter. [I have posted a complete 2000-present set of daily Nares Strait thermal MODIS imagery, if someone wants to dig in.]

Tidal currents are weak (less than 1/2 kts amplitude) in the north, however, they are much larger in the south of Nares Strait (more than 1 kts), so the southern ice-arch (or ice-plug) forms preferentially near neap-tide. And yes, tensile strength of the ice has something to do with, too, but tensile strength is temperature dependent and a group of floes has different tensile properties than does an individual piece of ice (I know nothing of ice and rheology, so take this with a grain of salt). The ice in Nares Strait is always a melange of vastly different types of ice and, I believe, the fraction of thicker multi-year to thinner first-year to thinner-yet new ice may matter also in when and how this melange congeal into a solid mass that blocks all ice motion for months.

Gothic cathedrals and their stability characteristics come to mind, e.g., http://icyseas.org/2012/06/11/ice-arches-and-gothic-cathedrals/
« Last Edit: November 13, 2013, 01:24:32 AM by Andreas Muenchow »
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Re: Home brew AMSR2 extent & area calculation
« Reply #631 on: November 21, 2013, 09:34:38 AM »
Werther pointed yesterday to the region North of Svalbard/Frantsa Yosefa. High (anomalous) temperatures IIRRC. Indeed there is an impressive darkening in the Ice concentration to be seen. If I didn't know better, I's suggest surface melting there.
Ice is continuing exported through the Fram.

(click on the attached image for an animation)

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Re: Home brew AMSR2 extent & area calculation
« Reply #632 on: November 21, 2013, 06:10:44 PM »
Werther pointed yesterday to the region North of Svalbard/Frantsa Yosefa. High (anomalous) temperatures IIRRC. Indeed there is an impressive darkening in the Ice concentration to be seen. If I didn't know better, I's suggest surface melting there.
Ice is continuing exported through the Fram.

(click on the attached image for an animation)

That... Is just SO wrong...

But it makes sense anecdotally when looking at atmospheric flow and surface temps.  The cold pole(s) are currently about 10-15 degrees south - in the CAA.  I was about to add Siberia, but temps there seem anomalously high as well.
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Re: Home brew AMSR2 extent & area calculation
« Reply #633 on: December 06, 2013, 08:55:15 AM »
Baffin Bay, Nares Strait animation. The ice-arch can be seen forming and collapsing again. The north of Baffing Bay gets surprisingly ice free, even a remnant of PII iceberg can be seen by the keen observers.

(click on attached image if it does not animate)

Wipneus

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Re: Home brew AMSR2 extent & area calculation
« Reply #634 on: December 19, 2013, 07:08:27 AM »
Nares Strait transport continues...

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Re: Home brew AMSR2 extent & area calculation
« Reply #635 on: December 19, 2013, 07:21:54 AM »
Hudson Bay has reached near 100% extent. The time is about normal as far as I know.

(click on the attached image if there is no animation)

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Re: Home brew AMSR2 extent & area calculation
« Reply #636 on: December 20, 2013, 01:37:31 AM »
Is it imagination on my part, or is the steady flow through Nares Strait anomalous? 

Seems like the Baffin refreeze is slow as well.
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Wipneus

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Re: Home brew AMSR2 extent & area calculation
« Reply #637 on: December 21, 2013, 08:53:30 AM »
Hudson bay is full, and as a consequence the increase of the Arctic Sea Ice has entered a "pause". A pause that happens about every year at this stage in the progression of the ice cover.

Most activity has since been in the Barentsz and the Bering Seas. They are opposite: the extent in the Barentsz  is a bit ahead than in 2012, but has been retreating these days. Even the ice North of Svalbard that was approaching the islands has been driven north.
In the Bering Sea, the ice has been slow this season, but it seems to be making up a bit.

(attached image can be seen only when logged in, click on it for a full view)

jdallen

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Re: Home brew AMSR2 extent & area calculation
« Reply #638 on: December 21, 2013, 09:11:41 AM »
@wipneus - looks like a very bad year for polar bears on Svalbard...
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Re: Home brew AMSR2 extent & area calculation
« Reply #639 on: December 26, 2013, 09:53:19 AM »
The Gulf of st. Lawrence has not been discussed much, if at all, in this thread. If it was, it was often the false ice reported by the different instruments and algorithms. The lower resolution SSMIS sensors in combination with the NASA Team algorithm employed by the best known NSIDC sea ice data series are affected most by this problem.

But now increasing ice extent and area are even seen in the much higher resolution images from the AMSR2 instrument from Jaxa, either using their Bootstrap algorithm (10km resolution) or the ARTIST Sea Ice (ASI) algorithm with resolutions down to 3.125km.
There are still differences:

NSIDC SSMIS NASA Team 25km: ~70k extent
Uni Hamburg AMSR2 ASIv6 3.125km: ~14k extent
Jaxa AMSR2 Bootstrap 10km: ~21k extent

The attached image (click on it for the full view) shows the AMSR2 3.125 image with MODIS Terra close-ups over the st. Lawrence river created with the NASA Worldview tool. In the false color images ice and clouds are separated well. In the highest resolution ice floes can be seen, so this is not false ice as far as I can tell.
 

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Re: Home brew AMSR2 extent & area calculation
« Reply #640 on: December 31, 2013, 01:50:50 PM »
Two animations of the Nares Strait. The first one at the beginning of 2013 shows the blocking arch in the Smith Sound firmly in place. The second is the current situation: no arch established and ice transport continues.

 

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Re: Home brew AMSR2 extent & area calculation
« Reply #641 on: December 31, 2013, 07:03:47 PM »
Wipneus - nicely done!  This strikes me as a major state change in the system.
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Re: Home brew AMSR2 extent & area calculation
« Reply #642 on: December 31, 2013, 10:08:23 PM »
jdallen, I don't think it's as big as that, as Nares has remained open all winter in previous years as well (can't remember which ones though).
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Re: Home brew AMSR2 extent & area calculation
« Reply #643 on: December 31, 2013, 10:49:04 PM »
Believe Nares was last open all year in 2009 (just before the huge 2010 volume drop). Last season PII2012 plugged things up well past the normal dates for opening & we had a positive volume spike.
While Nares Strait doesn't have a large outflow I do think that it's positioning means that when even a small amount of MYI takes this route it weakens the rest of the Lincoln Sea ice allowing far more mobility when melt commences.
If the ice-bridge does not form I'd venture a guess that PIOMAS numbers will come in low for 2014.
Terry




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Re: Home brew AMSR2 extent & area calculation
« Reply #644 on: December 31, 2013, 11:16:49 PM »
From Dr. Munchow's blog:
http://icyseas.org/2012/06/19/nares-strait-ice-bridge-and-arctic-ice-thickness-change/



"I processed and archived maps of [/size]Nares Strait satellite images[/font][/color][/size] to guide 2003-2012 analyses of how air, water, and ice change from day to day. Ice arches formed as expected during the 2003/04, 2004/05, and 2005/06 winters lasting for about 180-230 days each year. In 2006/07 no ice arch formed, ice streamed freely southward all year, and this certainly contributed to the 2007 record low ice cover. In 2007/08 the arch was in place for only 65 days. In 2009/10, 2010/11, and now 2011/12 ice cover appear normal as the arches formed in December and lasted until July."[/color][/size][/color]

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Re: Home brew AMSR2 extent & area calculation
« Reply #645 on: January 02, 2014, 02:01:23 PM »
To clarify your last post

"I processed and archived maps of Nares Strait satellite images to guide 2003-2012 analyses of how air, water, and ice change from day to day. Ice arches formed as expected during the 2003/04, 2004/05, and 2005/06 winters lasting for about 180-230 days each year. In 2006/07 no ice arch formed, ice streamed freely southward all year, and this certainly contributed to the 2007 record low ice cover. In 2007/08 the arch was in place for only 65 days. In 2009/10, 2010/11, and now 2011/12 ice cover appear normal as the arches formed in December and lasted until July."

TerryM

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Re: Home brew AMSR2 extent & area calculation
« Reply #646 on: January 02, 2014, 02:33:23 PM »
RalphW


Thanks so much for straightening that out. No idea why my posts sometimes get eaten up that way.
Terry

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Re: Home brew AMSR2 extent & area calculation
« Reply #647 on: January 03, 2014, 07:31:12 AM »
No update for 2014 yet from Uni Hamburg...

Graphs are still maintained, see the top post

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Re: Home brew AMSR2 extent & area calculation
« Reply #648 on: January 06, 2014, 07:08:06 PM »
No update for 2014 yet from Uni Hamburg...

The updates have started again. 1st and 5th are currently available.
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Re: Home brew AMSR2 extent & area calculation
« Reply #649 on: January 07, 2014, 08:01:20 AM »

The updates have started again. 1st and 5th are currently available.

Indeed: days 2, 3, 4 and 6 make the set complet now. Also IARC-IJIS has begun updating (version 2).

So we can have a look at a possible day record low now.