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Author Topic: Home brew AMSR2 extent & area calculation  (Read 1559030 times)

crandles

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Re: Home brew AMSR2 extent & area calculation
« Reply #650 on: January 07, 2014, 11:29:53 AM »

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

01,06,14126244,13689257,13116894,-9999,13571020,13152013,12887212,12815784,12844393,12852098,12850810,12766882,12606948,12834052,12582524,12545921

is first lowest for quite some time.

Area however is higher than all of last 8 years.

Wipneus

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Re: Home brew AMSR2 extent & area calculation
« Reply #651 on: January 09, 2014, 07:58:19 AM »
My calculation joins that of IARC-Jaxa:

2014-2013 diff in: Total.Extent Total.Area

     20140106   0.11961720  0.2401091
     20140107   0.06502912  0.2042370
     20140108  -0.07332161  0.0239202

NSIDC and my calculation from UH SSMIS calculated sea ice concentration still are above 2013.

Hudson, Baffin and st. Lawrence are causing today's dip.

Wipneus

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Re: Home brew AMSR2 extent & area calculation
« Reply #652 on: January 09, 2014, 08:07:00 AM »
An irregular update of the Nares Strait animations.

Still no ice arch in the Smith sound. However, at the beginning of Nares, Robeson Channel, an arch has held for a couple of days now.

Andreas T

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Re: Home brew AMSR2 extent & area calculation
« Reply #653 on: January 09, 2014, 09:24:02 PM »
the IR image on DMI shows this is due to a large floe wedged in the channel
http://ocean.dmi.dk/arctic/images/MODIS/Lincoln/201401031302.NOAA.jpg
http://ocean.dmi.dk/arctic/images/MODIS/Lincoln/201401091336.NOAA.jpg
the floe seen on the 3rd broke into smaller pieces but seems strong enough to hold, with thinner ice forming behind it.

Wipneus

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Re: Home brew AMSR2 extent & area calculation
« Reply #654 on: January 11, 2014, 09:24:32 AM »
Thanks Andreas. The "arch" is still in place:


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Re: Home brew AMSR2 extent & area calculation
« Reply #655 on: January 11, 2014, 09:46:44 AM »
Time for a look at the Fram Strait. The transport has a "hiatus", causing the Greenland Sea Ice Extent to drop (see the regional graphs).
The ice to the north Svalbard seems to be reluctant to come any closer to the islands. This in contrast with the side facing the Barentsz Sea. Looking at the animations I can't help to think thatwinds are not enough explanation and currents are involved the West Spitsbergen Current

(Click on attached image to "animate")

jdallen

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Re: Home brew AMSR2 extent & area calculation
« Reply #656 on: January 11, 2014, 10:26:54 AM »
Time for a look at the Fram Strait. The transport has a "hiatus", causing the Greenland Sea Ice Extent to drop (see the regional graphs).
The ice to the north Svalbard seems to be reluctant to come any closer to the islands. This in contrast with the side facing the Barentsz Sea. Looking at the animations I can't help to think thatwinds are not enough explanation and currents....

Concur. If you look at the SSTs, west of Svalbard has consistently been 3-8C above zero. I think there is an upwelling of warmer water. I don't think ice *can* form there...
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werther

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Re: Home brew AMSR2 extent & area calculation
« Reply #657 on: January 11, 2014, 12:24:56 PM »
Interesting graph, Wipneus...
The remnants of the 'Barentsz Bite' still show (like on ASCAT). There's not enough volume/growth to fill up N of Svalbard....? Occurred several years since 2000....
And the West Spitsbergen Drift continues N of Svalbard, counterclockwise along the continental slope (getting more Atlantic water in all the time).

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Re: Home brew AMSR2 extent & area calculation
« Reply #658 on: January 11, 2014, 05:46:37 PM »
From that animation, transport through the Fram has slowed down but there looks to be a great deal of melting going on as well. Is this unusual for this time of year?

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Re: Home brew AMSR2 extent & area calculation
« Reply #659 on: January 11, 2014, 08:56:35 PM »
My 2c's Looks like the warm water flushing nares may have eroded a channel around to fram, if it continues the ice will thin and slam shut, then it open up nares again.
The new portal from Espen [thanks] has an ice temp link which shows up the warmer ice over by barrow and mackenzie +.

Wipneus

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Re: Home brew AMSR2 extent & area calculation
« Reply #660 on: January 13, 2014, 08:07:14 AM »
From that animation, transport through the Fram has slowed down but there looks to be a great deal of melting going on as well. Is this unusual for this time of year?

I think there is both melting and freezing in the Greenland Sea. The fact that slowdown of the Fram transport causes lesser ice cover, probably shows that melting is dominant.

Wipneus

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Re: Home brew AMSR2 extent & area calculation
« Reply #661 on: January 13, 2014, 08:15:04 AM »
Neven has a blog post, re-blogged from Chris Reynold's dosbat about the ice movement in the Beaufort.

Time for an animation. Cracks are vaguely visible, but give an idea of considerable ice movements. These are currently stopped as the anti-cyclone has gone.

(click on image to animate)

Wipneus

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Re: Home brew AMSR2 extent & area calculation
« Reply #662 on: January 18, 2014, 10:58:45 AM »
Nares: entrance is still blocked. An arch has formed in the Smith Sound, and held now for a couple of days. It is a bit north of last years arch though, no idea if there are more stable configurations.

 

Andreas T

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Re: Home brew AMSR2 extent & area calculation
« Reply #663 on: January 18, 2014, 10:17:48 PM »
Wipneus, I am intrigued by the changes in brightness ( in your post of the 13th ) of the landfast ice between some islands of the canadian archipelago. The same can be seen in the landfast ice on the north coast of Greenland (your animation of the11th). Striking is that  other ice nearby does not show these fluctuations with fairly sharp delineation. What makes this ice different? It probably has been deformed less, a look at the DMI satellite images (Greenland) shows that some of that ice is over two years old but not all, so maybe thickness is not what distiguishes it?
What else could affect its appearance in the imagery. Snow cover?

Wipneus

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Re: Home brew AMSR2 extent & area calculation
« Reply #664 on: January 19, 2014, 10:28:41 AM »
Wipneus, I am intrigued by the changes in brightness ( in your post of the 13th ) of the landfast ice between some islands of the canadian archipelago. The same can be seen in the landfast ice on the north coast of Greenland (your animation of the11th). Striking is that  other ice nearby does not show these fluctuations with fairly sharp delineation. What makes this ice different? It probably has been deformed less, a look at the DMI satellite images (Greenland) shows that some of that ice is over two years old but not all, so maybe thickness is not what distiguishes it?
What else could affect its appearance in the imagery. Snow cover?

Andreas,

At first, in these animations I exaggerate the concentration differences by applying a gamma correction. Sometimes a bit more aggressive, to make the differences and the movements more visible. In other words the differences are there, but not as big as you may think.

Second these ice concentration data are based on calculations that try to minimize the influence of the type of ice and snow cover. The ARTIST Sea Ice (ASI) algorithm is particularly good in this, due to the higher frequency microwave band that it uses (89 GHz). The downside is that water vapor in the atmosphere is a disturbing factor, I often see that high pressure over the ice gives lower concentrations.

Summarized, these animations are good to see ice movement, development of cracks, gaps and ice edges. For the surface conditions we should look at other microwave bands, Those are available but I lack the time at the moment to have a good look at them.

Andreas T

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Re: Home brew AMSR2 extent & area calculation
« Reply #665 on: January 19, 2014, 09:06:10 PM »
Thank you for that information which helps to 'read' those animations, and once more, I appreciate very much the time and effort you put into letting us see things more clearly.

Wipneus

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Re: Home brew AMSR2 extent & area calculation
« Reply #666 on: February 02, 2014, 09:52:22 AM »
Two week animation of Fram Strait sea ice concentration. Two weeks of near zero transport of voluminous ice.

(click on attached image to "animate")

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Re: Home brew AMSR2 extent & area calculation
« Reply #667 on: February 18, 2014, 07:53:56 AM »
Watch how the ice is retreating from Svalbard, Frans Josef Lands and the Barentsz sector.
The Fram Strait transport is slowly taking up again.

(assuming you clicked the attached animation)

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Re: Home brew AMSR2 extent & area calculation
« Reply #668 on: February 18, 2014, 08:30:30 AM »
Watch how the ice is retreating from Svalbard, Frans Josef Lands and the Barentsz sector.
The Fram Strait transport is slowly taking up again.

(assuming you clicked the attached animation)

Astonishingly, I see melt as well as compaction, if you look at the ice immediately to the east of Svalbard at the start of the animation.  Not a lot, but significant in context, I think.

I notice also that Fram export was still active during the time of the animation, if not that high.
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Neven

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Re: Home brew AMSR2 extent & area calculation
« Reply #669 on: February 18, 2014, 09:31:28 AM »
Wow, spectacular.
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wanderer

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Re: Home brew AMSR2 extent & area calculation
« Reply #670 on: February 18, 2014, 10:09:08 AM »
Svalbard:
"Last 30 days: Average temperature was -1.2 °C, 14.8 °C above the normal."

Crazy!
http://www.yr.no/place/Norway/Svalbard/Longyearbyen/statistics.html

LarsBoelen

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Re: Home brew AMSR2 extent & area calculation
« Reply #671 on: February 18, 2014, 10:23:53 AM »
Wow that is spectacular, is this a flow of "hot" Atlantic water doing this? The path to the pole seams weak already, it'll be interesting to sea what spring is going to bring if this continues.

werther

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Re: Home brew AMSR2 extent & area calculation
« Reply #672 on: February 18, 2014, 10:56:54 AM »
Thanks Wipneus,

Reading Neven, Wanderer, Lars... yes, there's nothing even remotely close to the impact of invading warmth in mid Feb since at least '97.
I checked 11-15 Feb anomaly on NCEP/NCAR on that. It seems to be related to the latest SSW flash, the split cold poles on 500Mb and the SLP pattern. There is no extreme cold on 850Mb over the Arctic Basin, allowing the concentrated influx of warmth from the S to get to a mean +8C anomaly over the whole 7.3 Mkm2 Basin.
I'll check Ascat metop again to find out if the 'Barentsz Bite', that has remained visible all winter, is showing signs of weakening. Wipneus' animation does...

Lars, that Atlantic water is at work on a constant basis. I think it allows the Barentsz Sea to perform 'Atlantic' for at least the latest 10 years. It progressively strengthens the ice-free zone N of Svalbard (prolonged near surface flow of the West Spitzbergen current). The present temp anomaly  is an atmospheric phenomenon though.

werther

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Re: Home brew AMSR2 extent & area calculation
« Reply #673 on: February 18, 2014, 11:32:34 AM »
Here’s a detail from ASCAT 17 Feb:



The ice front is now 380 km N of Nordaustlandet/Svalbard, at its farthest. Through compaction it shows up as a white rim. North of that rim is the mark of last summers’ Barentsz Bite, showing less reflective, young ice with older splinter floes. Less reflective probably from lesser snow cover, snow less dry because of the close to zero temps.
The main pack to the Pole is more reflective through thickness/dry snow cover. The weakness on a band through the Pole, dating from last summer, still visible.

Shared Humanity

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Re: Home brew AMSR2 extent & area calculation
« Reply #674 on: February 18, 2014, 02:04:34 PM »
Svalbard:
"Last 30 days: Average temperature was -1.2 °C, 14.8 °C above the normal."

Crazy!
http://www.yr.no/place/Norway/Svalbard/Longyearbyen/statistics.html

Looking at this chart, it seems there was a similarly anomalous warm period last February as well. While not as warm, it still deviated sharply from historical averages. What did January of 2013 look like?

werther

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Re: Home brew AMSR2 extent & area calculation
« Reply #675 on: February 18, 2014, 02:29:45 PM »
Hi SH,

Sure, there were several anomalous temp periods in Longyearbyen winter '12-'13. But those were more local than the one we're seeing this Feb.

For Jan 2013, IIRC there was an enduring warm anomaly up to +8dC in the central Arctic Basin, due to a 'warm high' induced by the main SSW event late Dec-early Jan.
Feb was very cold. That's why there's a good chance that 'winter power' will be less this year.

But lets just wait a little; ECMWF does project a restauration of the 'cold pole' over the CAB after 20 Feb. Although that can hardly be severe, because there's not that much cold (and another bite, diluting what's left, will be heading for the US...).

Buddy

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Re: Home brew AMSR2 extent & area calculation
« Reply #676 on: February 18, 2014, 02:33:29 PM »
Here's two charts that show the "average temperature above the 80th parallel" for both 2014 (so far) and 2013 (full year).  The difference between 2014 and 2013 for the first 50 days of the year is DRAMATIC.   Look at the 2nd and 3rd graphics on this link:

https://www.blogger.com/blogger.g?blogID=3668502585335462792#editor/target=post;postID=3138607357704998522;onPublishedMenu=allposts;onClosedMenu=allposts;postNum=12;src=link



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werther

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Re: Home brew AMSR2 extent & area calculation
« Reply #677 on: February 18, 2014, 03:48:48 PM »
I can't open that link without signing in, Buddy.

But I have a general idea of what your graphs show.
NCEP/NCAR also presents a major difference for the first six weeks of 2014 compared to last year. Over the whole Arctic Basin (I mean the CAB with its peripheral seas, but without the CAA and Barentsz) the average anomaly was between +1/+2 dC in '13. It is about +5dC now.
This extends well into the Bering Sea, Baffin Bay and the Barentsz Sea too.

The only 'compensation' was the colder than usual autumn refreeze.

Just the S. Laptev and Kara Seas had some decent freezing. But looking on MODIS r05c05, just available by the first spring sunlight, ice quality in the Laptev doesn't look great. You'll see lots of wide cracks, barely refrozen, between the usual polynia N of the Lena delta, Tiksi and Great Lyakhovsky Island.

Buddy

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Re: Home brew AMSR2 extent & area calculation
« Reply #678 on: February 18, 2014, 04:04:43 PM »
Werther:

Going to be an interesting year for weather.....THAT is for sure (and already HAS BEEN for January and February).  You "scientific ice watcher guys" are going to have your hands full this year (unfortunately).

With the SST and air temps much higher than normal (and forecast to stay that way for the next week)......that isn't going to help.

In my mind I keep "fast forwarding" to about 3 years from now when I believe MOST of the Arctic ice sheet will melt out.  More heat absorption can't be good:(

And now the SST anomaly along the east coast of the US has been ramping up over the past several weeks....and all that warmer than usual water is being pumped UP to Greenland and the Arctic......and over to our friends in Britain (just what they need).

Makes a "bean counter" wish he was "science geek" instead...:)



 

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Wipneus

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Re: Home brew AMSR2 extent & area calculation
« Reply #679 on: February 21, 2014, 07:42:46 AM »
A sharp increase in extent in the last two days. Most of this is in the Barentsz sector. Beyond the pack with near 100% concentration, a field with low (near 60-70% according to Uni Hamburgs calculation) concentration has formed.

The ice north of Svalbard also shows a large area extending to the pole with lower concentration, 75-85%.

Some of the boundaries are quite sharp.

werther

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Re: Home brew AMSR2 extent & area calculation
« Reply #680 on: February 21, 2014, 08:04:26 AM »
Remarkable, Wipneus!
Yesterday I thought the SIE gain was concentrated mostly in the Bering Sea. But indeed, the Barentsz Sea is kicking in... +150K in two days!
BTW it fits with the ECMWF prognosis for a 'cold pole' restauration over the Arctic Basin.
A low level high is shutting off influx from the S.
AAMOF, winds are supportive for growth on a lot of fringes. Bering, Baffin and Barentsz... a threefold B dash for a late season maximum!

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Re: Home brew AMSR2 extent & area calculation
« Reply #681 on: February 21, 2014, 09:58:13 AM »
A sharp increase in extent in the last two days. Most of this is in the Barentsz sector. Beyond the pack with near 100% concentration, a field with low (near 60-70% according to Uni Hamburgs calculation) concentration has formed.

The ice north of Svalbard also shows a large area extending to the pole with lower concentration, 75-85%.

Some of the boundaries are quite sharp.

That is really, really disturbing to look at.
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Shared Humanity

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Re: Home brew AMSR2 extent & area calculation
« Reply #682 on: February 21, 2014, 04:44:06 PM »
Wipneus.......that image seems to suggest both compaction and early melt or, more likely, weak winter freeze on the Atlantic side. The 100% concentration on the Atlantic side of FJ and lower concentration on the CAB side has to be due to compaction. Similarly the thin barrier of 100% concentration that borders the lower concentrations over the pole suggest the same thing.

jdallen

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Re: Home brew AMSR2 extent & area calculation
« Reply #683 on: February 21, 2014, 07:00:04 PM »
Wipneus.......that image seems to suggest both compaction and early melt or, more likely, weak winter freeze on the Atlantic side. The 100% concentration on the Atlantic side of FJ and lower concentration on the CAB side has to be due to compaction. Similarly the thin barrier of 100% concentration that borders the lower concentrations over the pole suggest the same thing.

Good analysis (as usual), Shared Humanity.
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Wipneus

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Re: Home brew AMSR2 extent & area calculation
« Reply #684 on: February 26, 2014, 09:25:08 AM »
Gulf of St. Lawrence is most southern of the 14 regions. The ice cover is probably at or just past maximum winter extent. Most of the ice has concentration well below 100%, a clear ice pack is not to be seen with the "blues" and "reds" scattered all over the place.


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Re: Home brew AMSR2 extent & area calculation
« Reply #685 on: February 26, 2014, 09:34:27 PM »
Gulf of St. Lawrence is most southern of the 14 regions. The ice cover is probably at or just past maximum winter extent. Most of the ice has concentration well below 100%, a clear ice pack is not to be seen with the "blues" and "reds" scattered all over the place.

The Gulf of St. Lawrence also makes up a big slug of the extent which in total numbers is keeping 2014 from falling to the lowest maximum extent and area on record.  I think drops in area/extent there may explain the retreat we've seen in numbers over the last few days.
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Re: Home brew AMSR2 extent & area calculation
« Reply #686 on: February 27, 2014, 09:31:54 AM »
Yes, but also the Baffin, Barents, Bering and Okhotsk regions are very volatile at the moment. Today it is the Sea of Okhotsk with the largest delta, far larger than the net change (1000 km2):

Extent:
           Arctic Basin       East Siberian Sea              Laptev Sea
                   -5.6                     0.0                     0.4
               Kara Sea             Barents Sea           Greenland Sea
                   -4.8                   -14.0                     4.3
Baffin/Newfoundland Bay            St. Lawrence              Hudson Bay
                  -10.4                    -2.1                     0.1
   Canadian Archipelago            Beaufort Sea             Chukchi Sea
                    0.2                    -0.1                     2.7
             Bering Sea          Sea of Okhotsk            Total Extent
                   -8.6                    40.6                     2.7




jdallen

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Re: Home brew AMSR2 extent & area calculation
« Reply #687 on: February 27, 2014, 11:25:42 PM »
Yes, but also the Baffin, Barents, Bering and Okhotsk regions are very volatile at the moment. Today it is the Sea of Okhotsk with the largest delta, far larger than the net change (1000 km2):

You are as usual, faultlessly accurate.  The key take away for the entire season seems to revolve around the word "Volatile".
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Wipneus

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Re: Home brew AMSR2 extent & area calculation
« Reply #688 on: March 02, 2014, 10:22:24 AM »
Two animations for the Laptev Sea, to compare 2013 with 2014. Movements of the ice are bigger in 2014, and the lower (darker) concentration is noticeable.

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Re: Home brew AMSR2 extent & area calculation
« Reply #689 on: March 08, 2014, 10:28:46 AM »
Today's  dip is mostly by the ice in the Sea of Okhotsk, with a bit of help from far away Barents Sea.

The Okhotsk region is very volatile at the moment, in a few days all those reds could be ice again.

 

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Re: Home brew AMSR2 extent & area calculation
« Reply #690 on: March 09, 2014, 08:17:10 AM »
Total drop in extent today (20140308) : -158k8.

Of that the Sea of Okhotsk takes the lions share, -112k7. A century break for a region is remarkable, even in the middle of summer, but in March?

The Barents Sea corner is also "under a torch", so to speak. Attached is the difference map.

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Re: Home brew AMSR2 extent & area calculation
« Reply #691 on: March 09, 2014, 09:29:29 AM »
Thanks for the visualization, Wipneus.
As predicted by ECMWF, strong Southern influx on the Barentsz side. Now starting to be visible on MODIS too. The ice stacks up on the S side of the Frantsa Yosefa Islands, Ushakov etc. In the wake on the N side open sea is emerging (with little indication of new ice formation, it was just a few dC below zero there last week).
Yesterday had a strong storm in the Okhotsk.
There's a lot to say for the extent max being 6 March, although winds change.

Rubikscube

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Re: Home brew AMSR2 extent & area calculation
« Reply #692 on: March 09, 2014, 01:42:44 PM »
There's a lot to say for the extent max being 6 March, although winds change.

Agreed. It seems like there is a pattern change going on as the constant southerly flow that have been feeding the atlantic arctic with warm air is going to be cut of for some time, and cold will also be digging in over Bering. A late spring rebound should not be ruled out. Though, I'm getting increasingly worried about what will happen to the russian snow pack this spring if the warmth starts flowing in to Russia instead of the Arctic.

werther

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Re: Home brew AMSR2 extent & area calculation
« Reply #693 on: March 09, 2014, 11:39:27 PM »
Rubikscube, yes, ECMWF sure shows a changing pattern. But it also shows there's just not enough cold over the Arctic to really have a lasting impact.
Meanwhile, MODIS reveals more and more, FI this 'slaughterhouse' N of Frantsa Yosefa:



The 'wake' is about 100 km deep, to the S a 100 km of piled left-overs from the Barentsz Sea.

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Re: Home brew AMSR2 extent & area calculation
« Reply #694 on: March 10, 2014, 07:33:31 AM »
Rubikscube, yes, ECMWF sure shows a changing pattern. But it also shows there's just not enough cold over the Arctic to really have a lasting impact.

Very much so.  I think even more crucial is,  "Sunrise" is well above 80N now. So I believe the rapidly increasing energy budget of the region will be unfavorable for shedding heat fast enough to permit anything beyond surface freezing. 

Meanwhile, MODIS reveals more and more, FI this 'slaughterhouse' N of Frantsa Yosefa:
...
The 'wake' is about 100 km deep, to the S a 100 km of piled left-overs from the Barentsz Sea.

It may be very small compared to the energy which will start being delivered after the equinox, but those regions of open water are now *already* picking heat from sunlight which otherwise should have been reflected back out. 

It will be significant in as much as this isn't just "leads" being opened up on a small scale, but rather thousands of KM2 of ocean being directly exposed as light is increasing, rather than decreasing.
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Andreas T

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Re: Home brew AMSR2 extent & area calculation
« Reply #695 on: March 10, 2014, 08:01:13 PM »
don't forget that at shallow angles water reflects.

icefest

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Re: Home brew AMSR2 extent & area calculation
« Reply #696 on: March 10, 2014, 09:26:54 PM »
Does water or ice reflect more light/heat at shallow angles?

If the water has a significant amount of chop/waves, would it reflect less?
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jdallen

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Re: Home brew AMSR2 extent & area calculation
« Reply #697 on: March 10, 2014, 10:42:34 PM »
Does water or ice reflect more light/heat at shallow angles?

If the water has a significant amount of chop/waves, would it reflect less?

Ice has higher albedo, and so would reflect more.  Even at shallow angles, absorption of sunlight would provide notably more energy than it would striking ice.  There is a question of whether ice would prevent more heat loss, but in the end, even freezing, the ice produced at this stage will be quite thin, most likely well under a meter  in thickness.  There just isn't enough time for the heat to be lost.

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Re: Home brew AMSR2 extent & area calculation
« Reply #698 on: March 10, 2014, 11:07:56 PM »
don't forget that at shallow angles water reflects.

Only one polarization. 
This is the result for air/water:
http://tinyurl.com/mykxfr7

Andreas T

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Re: Home brew AMSR2 extent & area calculation
« Reply #699 on: March 11, 2014, 11:40:50 PM »
http://weather1.pme.gov.sa/applied-studies/majala9.pdf
has measurements showing high reflectivity (>0.9) at low sun angles. Waves reduce this strongly. I don't claim that open water is no different from ice but it seems that early in the year the difference can be significantly less than what it is later.