Author Topic: The 2014 Melting Season (Read 1704842 times)

Jim Hunt · « **Reply #400 on:** April 25, 2014, 10:01:12 AM »

The frost has melted from O-Buoy 9, to reveal bright sunshine and an Ice Tethered Profiler:

Jim Hunt · « **Reply #401 on:** April 25, 2014, 10:25:37 AM »

Quote from: Nightvid Cole on April 24, 2014, 05:56:17 PM

"Water sky blink" is visible on the Barrow sea ice webcam now!!

Here's the latest shot from the Barrow webcam:

werther · « **Reply #402 on:** April 25, 2014, 10:56:06 AM »

Thanks, Jim,
It's the open stress lead, about 2 km into the sea, along the fast ice. Not unusual to see this. As the ice in the Chukchi Sea is very mobile, this 'opening' may be bound to become serious next week. Contrary to a couple of days ago, ECMWF doesn't forecast an eclipse in the present 'dipole' anymore. It shows the 10-day forecast as very volatile.
If true, the Barentsz-kara remain in easterly flow; some ice decay near the Kara Strait.
Most action in the Beaufort/Chukchi.

Jim Hunt · « **Reply #403 on:** April 25, 2014, 02:34:37 PM »

Some action in the Northwest Passage yesterday. The fractured Amundsen Gulf:

http://GreatWhiteCon.info/resources/arctic-sea-ice-images/winter-201314-images/#NW-Passage

Frivolousz21 · « **Reply #404 on:** April 25, 2014, 09:39:26 PM »

albedo dropping quickly all over the place.

Nightvid Cole · « **Reply #405 on:** April 25, 2014, 10:27:37 PM »

Quote from: frivolousz21 on April 25, 2014, 09:39:26 PM

albedo dropping quickly all over the place.

What color(s) are low/high albedo on this false color map?

icefest · « **Reply #406 on:** April 25, 2014, 11:23:14 PM »

Nightvid Cole: I suspect this isn't a simple linear color scale, but rather a multispectral image.

In this case we can see the (red) snow on northern Skandinavia; the (green) uncovered land south; the (black) ocean and the white clouds.

Looking at the edges of Greenland; a lighter red has a higher reflectance.

Rubikscube · « **Reply #407 on:** April 26, 2014, 12:44:48 AM »

Thank you for appreciating my work guys. I kind of agree with you Comradez that at this early stage of the season, snow cover is perhaps even more exiting to watch than SIA/SIE as snow cover extent often turn out to be very indicative for the magnitude of the summer ice melt desipte the chaotic nature of this system which generaly makes the severity of the summer melt very hard to predict.

As for the difference between 2012 and 2014 mentioned by jdallen, this is what the 2012 map looks like using the same technique (false color ice covered with blue this time).

The difference for this particular date doesn't seem very brutal, as opposed to the 2013 pic. I would like to have this same type of comparison for 2007 as well, but the CT picture displayed in their archive is shown from a slightly different angle, something which is beyond my limited skills to adjust for.

ChasingIce · « **Reply #408 on:** April 26, 2014, 05:34:03 AM »

We're talking about a 2deg. difference at this point. (like, today)

-17 vs -15

Frivolousz21 · « **Reply #409 on:** April 26, 2014, 10:32:07 AM »

Euro horrible tonight for next week oh my oh my

Frivolousz21 · « **Reply #410 on:** April 26, 2014, 08:09:29 PM »

The open water area in the Beaufort is exploding in size.

NeilT · « **Reply #411 on:** April 27, 2014, 04:30:51 PM »

Given the temperatures and weather around Barrow, is the greatly enlarging water around the area really about ice mobility or is there some heat budget in the water we are not fully seeing.

It just appears to me that -6C temperatures, in spring, should re-freeze the water even if it is moving around a lot. It would be thin ice to be sure, but not open water.

That should take heat and the heat is not in the atmoshpere and the sun is not driving enough w/msq to warm that water that much.

Just a thought.

Lord M Vader · « **Reply #412 on:** April 27, 2014, 05:18:14 PM »

Well, Barrow will actually experience 0-4 deg Celsius above zero during wednesday-sunday before somewhat colder air is returning temps below zero which certainly won't help the ice there... It will be interesting to see how much sunlight Barrow will get these days... All according to latest forecast..

Just as a interesting note the SIE is almost at the same numbers as last spring.. The next date to keep an eye on is may 15 which is the earliest day the SIE have dropped below 12 million km2..

jdallen · « **Reply #413 on:** April 27, 2014, 07:32:50 PM »

Quote from: NeilT on April 27, 2014, 04:30:51 PM

Given the temperatures and weather around Barrow, is the greatly enlarging water around the area really about ice mobility or is there some heat budget in the water we are not fully seeing.

It just appears to me that -6C temperatures, in spring, should re-freeze the water even if it is moving around a lot. It would be thin ice to be sure, but not open water.

That should take heat and the heat is not in the atmoshpere and the sun is not driving enough w/msq to warm that water that much.

Just a thought.

The SSTs are going to be volatile, and the key to refreezing isn't air temp as much as it is heat loss out of the atmosphere. Low SST are also fighting against rapidly increasing insolation. Add to that, -6 C is only about 4C cooler than the water. -6C air doesn't have the heat carrying capacity necessary to let the seahwater do much more than build a transient skin of nilas, if that. Cloudiness now will produce warmer temperatures (albeit more slowly) as well, as that while reducing insolation, it also retards re radiation.

Nightvid Cole · « **Reply #414 on:** April 27, 2014, 08:58:11 PM »

Quote from: jdallen on April 27, 2014, 07:32:50 PM

Quote from: NeilT on April 27, 2014, 04:30:51 PM
Given the temperatures and weather around Barrow, is the greatly enlarging water around the area really about ice mobility or is there some heat budget in the water we are not fully seeing.

It just appears to me that -6C temperatures, in spring, should re-freeze the water even if it is moving around a lot. It would be thin ice to be sure, but not open water.

That should take heat and the heat is not in the atmoshpere and the sun is not driving enough w/msq to warm that water that much.

Just a thought.

The SSTs are going to be volatile, and the key to refreezing isn't air temp as much as it is heat loss out of the atmosphere. Low SST are also fighting against rapidly increasing insolation. Add to that, -6 C is only about 4C cooler than the water. -6C air doesn't have the heat carrying capacity necessary to let the seahwater do much more than build a transient skin of nilas, if that. Cloudiness now will produce warmer temperatures (albeit more slowly) as well, as that while reducing insolation, it also retards re radiation.

I have a hard time believing that cloudiness makes it warmer now, with the sun having a declination of 13 degrees North, well over half the maximum value in June. Would it be unreasonable for me to ask how you concluded such a thing?

ktonine · « **Reply #415 on:** April 27, 2014, 09:03:38 PM »

Quote from: NeilT on April 27, 2014, 04:30:51 PM

It just appears to me that -6C temperatures, in spring, should re-freeze the water even if it is moving around a lot. It would be thin ice to be sure, but not open water.

Wayne Davidson pointed out several years ago that bottom melt typically begins once the air temperature rises above -14ºC. There is a large thermal mass (the water) sitting at ~-2ºC. If you examine buoy data you can see that -14ºC is a boundary temperature between growth and loss. Likewise the DMI graphs for temps north of 80º typically show a brief plateau in both spring and fall when temps rise/fall to -14ºC. Again this would be indicative of the change from a growth regime to a loss regime and vice versa.

Hubert · « **Reply #416 on:** April 27, 2014, 09:28:36 PM »

This will be the apocalypse, massive melting of snow and positive feedback.

sofouuk · « **Reply #417 on:** April 28, 2014, 12:35:47 AM »

I think Wayne also said refreezing of open water usually starts at around -11C? wouldn't expect any significant new ice to be forming around barrow at this time of year

pearscot · « **Reply #418 on:** April 28, 2014, 04:47:23 AM »

Quote from: Hubert on April 27, 2014, 09:28:36 PM

This will be the apocalypse, massive melting of snow and positive feedback.

I do see how the dipole is set to develop again but can you explain why it will be quite so bad? I'm not disagreeing with you at all, I would just like to know more about what is setting up.

CraigsIsland · « **Reply #419 on:** April 28, 2014, 05:40:00 AM »

I think the scary part is having warmer air over vulnerable parts of where snow normally is. Past posters have indicated that this year has been bad for snow cover and thus contribute to more sunlight hitting darker parts of the globe. We'd rather see "normal temperatures" than extremes to help alleviate the snow cover recession. It's just not helping that this pattern is developing rather strongly. A lot of negative feedbacks; warmer air, more methane release possibility, more heat content in oceans/land potentially.

sofouuk · « **Reply #420 on:** April 28, 2014, 06:16:19 AM »

... still, it won't be the apocalypse, and the hyperbole is not especially helpful to people are beginning the process of learning how the arctic melts

jonthed · « **Reply #421 on:** April 28, 2014, 07:29:19 AM »

Quote from: Nightvid Cole on April 25, 2014, 10:27:37 PM

Quote from: frivolousz21 on April 25, 2014, 09:39:26 PM
albedo dropping quickly all over the place.

What color(s) are low/high albedo on this false color map?

I think it is actually simply showing the change in albedo, i.e. red is negative change (becoming less reflective) and the darker the red, the greater the change. Likewise green would be an increase in albedo, becoming more reflective due to fresh snow etc.

Frivolousz21 · « **Reply #422 on:** April 28, 2014, 07:35:10 AM »

Holy crap.

17 days ago versus yesterday.

Frivolousz21 · « **Reply #423 on:** April 28, 2014, 07:37:12 AM »

jdallen · « **Reply #424 on:** April 28, 2014, 08:16:53 AM »

Quote from: Nightvid Cole on April 27, 2014, 08:58:11 PM

<snippage>

I have a hard time believing that cloudiness makes it warmer now, with the sun having a declination of 13 degrees North, well over half the maximum value in June. Would it be unreasonable for me to ask how you concluded such a thing?

I think others covered it pretty adequately, but let me expand.

First, its a question of rate of transfer of heat out of the atmosphere, not rate of transfer from water to air. Even with cloudiness, the sunlight still heats the atmosphere, and reduces the lost from exchange.

Second, clouds are a net insulator - increased H2O will significantly increase heat retention.

Third, as indicated, the ocean itself is a huge heat reservoir, on the order of 100 times greater heat content per unit volume that atmosphere. Further that the temperature of that reservoir is right at -2C, generally even a little higher, so loss of sunlight does not eliminate the heat available to prevent a surface phase change. ktonine notes that bottom melt may actually start at around -14C (Reference? I can see how it would happen mechanically, but references are good.)

So, in short, at this point of the season, I don't see lack of sunlight permitting refreeze.

Jim Hunt · « **Reply #425 on:** April 28, 2014, 10:28:46 AM »

Friv seems to have covered the Bering/Chukchi Seas more than adequately, so here's an interesting artefact from the US Navy's ACNFS thickness forecast for May 5th. Notice the fracture that runs all the way from Banks Island to the New Siberian Islands?

sofouuk · « **Reply #426 on:** April 28, 2014, 12:02:19 PM »

(Reference? I can see how it would happen mechanically, but references are good.)

think the numbers were based on Wayne's own in situ observations and intended as a rule of thumb

Jim Hunt · « **Reply #427 on:** April 28, 2014, 12:29:21 PM »

Quote from: ktonine on April 27, 2014, 09:03:38 PM

If you examine buoy data you can see that -14ºC is a boundary temperature between growth and loss.

I've spent a lot of time looking at buoy data, and whilst air temperatures above -14ºC might typically stop growth, they certainly don't start bottom melt. By way of example hunt around in the blue pushpins and look at the temperature profiles for this buoy from the Beaufort last year:

http://GreatWhiteCon.info/resources/ice-mass-balance-buoys/summer-2013-imbs/#2012H

Bottom melt doesn't get going until the whole floe is above -2ºC, which doesn't (usually!) take place until July.

seattlerocks · « **Reply #428 on:** April 28, 2014, 04:46:10 PM »

Quote from: Jim Hunt on April 28, 2014, 10:28:46 AM

Friv seems to have covered the Bering/Chukchi Seas more than adequately, so here's an interesting artefact from the US Navy's ACNFS thickness forecast for May 5th. Notice the fracture that runs all the way from Banks Island to the New Siberian Islands?

That's probably a numerical issue, right ...? Or did any artifact of this sort become something real in the past? I read (here and in Neven's blog) several posts trashing this model very badly, but I've been watching it lately, and it has been predicting the ice boundary changes very well.

ChrisReynolds · « **Reply #429 on:** April 28, 2014, 06:20:34 PM »

SeattleRocks,

Check out wind movement.
http://www7320.nrlssc.navy.mil/hycomARC/navo/arcticicespddrfnowcast.gif

HYCOM (some people cal it ACNFS) has a tendency to have ice that is too 'sticky'. So when it pulls away from the coast it may move as a mass and open a coastal flaw lead that is bigger than in reality. In reality what happens is that a series of fault fractures open up across the ice as the ice is 'pulled apart' by the movement away from the coast.

I've not been following the IR images but I think this can be seen here:
http://weather.gc.ca/data/satellite/hrpt_dfo_ir_100.jpg
There's a set of parallel fractures visible off the Alaskan coast reaching well into the pack - not as obvious as sometimes becuase the pack is so heavily fractured.

BornFromTheVoid · « **Reply #430 on:** April 28, 2014, 06:39:58 PM »

An interesting week coming up for the Arctic.

First off, from mid-week until the weekend, it looks like there will be some very mild conditions around the Bering Strait area, especially toward toward the Beaufort sea.
Southerly winds, upper air temperatures above 0C and surface temperatures often above 0C should cause some rapid melting of the ice remaining in the Bering Sea (about 450k left in extent), while some minor early melting in the Chukchi and Beaufort sea could be expected.

The Sea of Okhotsk looks like remaining cool to the north, but bouts of very mild air should whittle away the last of the ice in southern area.

Hudson Bay looks like seeing it's first mild spell of the year, with surface temps and uppers climbing above 0C for much of the next week. This may cause some slow melting, though I would expect a whole lot as it's not exceptionally warm, and the ice is probably quite thick.

All the while, the general dipole pattern continues, with this month looking remarkably similar to Apr 2007.

2007

2014

seattlerocks · « **Reply #431 on:** April 29, 2014, 12:09:48 AM »

Chris, thank you. So if i understand... the winds cause strong shearing stresses that in the real world will be alleviated by a complex web of fractures; but the model within its limitation cannot but show a single lead. Which means that the model is qualitatively correct in predicting a real phenomenon... I'm curious to see this in a few days, if the wind forecast doesnt change in the meantime.

jdallen · « **Reply #432 on:** April 29, 2014, 12:24:47 AM »

Not so far off as one might think.

Weather is quite clear over the Beaufort. Here's yesterday's Lance-Modis imagery.

The whole arctic first.

http://lance-modis.eosdis.nasa.gov/imagery/subsets/?mosaic=Arctic.2014117.terra.4km

http://lance-modis.eosdis.nasa.gov/imagery/subsets/?subset=Arctic_r05c03.2014117.terra

http://lance-modis.eosdis.nasa.gov/imagery/subsets/?subset=Arctic_r05c02.2014117.terra

jdallen · « **Reply #433 on:** April 29, 2014, 01:25:48 AM »

Another contrast.

http://igloo.atmos.uiuc.edu/cgi-bin/test/print.sh?fm=04&fd=25&fy=2012&sm=04&sd=25&sy=2014

Jim Hunt · « **Reply #434 on:** April 29, 2014, 11:20:29 AM »

Quote from: seattlerocks on April 28, 2014, 04:46:10 PM

That's probably a numerical issue, right ...? Or did any artifact of this sort become something real in the past? I read (here and in Neven's blog) several posts trashing this model very badly, but I've been watching it lately, and it has been predicting the ice boundary changes very well.

Here's an article of mine from March 2013, which includes an ACNFS forecast that did "become something real" (see below)

http://econnexus.org/the-ice-cap-crack-d-from-side-side/

However the pan Arctic fracture visible yesterday seems to have disappeared from the latest forecast.

Getting pedantic about nomenclature, the Arctic Cap Nowcast/Forecast System (ACNFS) couples the HYCOM (ocean), NAVGEM (atmosphere) and CICE (sea ice) models using the Navy Coupled Ocean Data Assimilation (NCODA) system! It assimilates information about the ice edge but not ice thickness, not least because the latter is rather more tricky to measure than the former.

werther · « **Reply #435 on:** April 29, 2014, 11:50:54 AM »

An ever changing array of aspects through subtle differences in physical processes…. That comes to my mind watching today’s MODIS tiles on the Chukchi/ESS side of the Central Arctic Basin.

It looks as yet another different melt season unfolding. Vast swaths of small floes (mean say 70 km2) become visible within an intricate mesh pattern of leads. I’ll give it a try later, comparing to earlier years. Right now, I’m getting more anxious by the day to find out what this season will bring.
It doesn’t look good. Once again. What I see relates to last winter. I see scattered small floes that survived last summer and froze in situ. The main part, where the leads have formed now, is FYI. Formed in the initial cold period October-November, it soon became snow-covered. More than usual. The snow cover and the low ‘winter power’ after November prohibited much thickening.

My guess is a mean 1.4 m for the FYI and 1.8 for the surviving floes. Not much more than the FYI; the difference is mainly structural. (Jim, is there an ice-tethered buoy in the ESS region?)

It seems most of the unusual thick snow cover is now gone. Not through melt, but I guess through wind-sweep and sublimation. This leaves the remaining ice vulnerable. It is highly mobile and lacks strength.
One indication will be given by PIOMAS soon. Expect volume to be near or under the lowest for the date. If so, what I see on MODIS could be the beginning of a spectacular season.

It doesn’t matter that the Barentsz Sea has quite some extent at the moment. The big story is ice quality over vast stretches of the Alaskan and Siberian side of the Basin.

Apocalypse4Real · « **Reply #436 on:** April 29, 2014, 12:54:38 PM »

In regard to Arctic Sea Ice conditions in MYI, it is fracturing as much as the FYI elsewhere in the AO. Below is the NOAA-19 AVHRR IR AO/NP Canadian Arctic view. The ice has fractured often across the Beaufort and Canadian Arctic through this winter as depicted here. (Click the image for the higher resolution).

Also below is the NP shot fromm IceBridge for April 27, 2014, taken by James K. Yungel. Note the fracturing, and also the refreezing leads.

An increased radiation on the ice will have an impact on melt through the summer.

werther · « **Reply #437 on:** April 29, 2014, 01:18:18 PM »

Thanks, A4R,

That AVHRR shows Beaufort-Central Pack. To the Sib side lie the regions that I commented on. There's subtle difference. On the parts shown on AVHRR, get a look on the MODIS tile over there (r04c03 FI). There's more snow cover left, the floes between the fractures look larger.
That belonged to last year's remaining 'coherent' MYI, about 1.8 Mkm2 in September.

Go on the same tile to the upper right corner (dir Siberia) and the pattern changes in the way I tried to describe...

Jim Hunt · « **Reply #438 on:** April 29, 2014, 01:54:36 PM »

Quote from: werther on April 29, 2014, 11:50:54 AM

My guess is a mean 1.4 m for the FYI and 1.8 for the surviving floes. Not much more than the FYI; the difference is mainly structural. (Jim, is there an ice-tethered buoy in the ESS region?)

There are no IMB's on the Eastern side of the Arctic, unless you count 2014E currently at 1.13E near the pole. There's one fully functional ITP (74), but that's north of Franz Josef Land. I assume this is the area under discussion, from the 26th?

gerrit · « **Reply #439 on:** April 29, 2014, 03:03:34 PM »

Quote from: Jim Hunt on April 28, 2014, 12:29:21 PM

...

Bottom melt doesn't get going until the whole floe is above -2ºC, which doesn't (usually!) take place until July.

This makes me think of Neven's post about the correlation between melt ponds in May and September extend. Whilst melt ponds are directly an indication of warmth experienced by a floe, it is also a mechanism that assures the whole floe's temperature is kept (regulated) at about 0C.

So if my science is correct, it would mean that:
If a melt pond is present and cold weather passes overhead, the melt pond will first have to refreeze before the floe's temp can drop, and all the while bottom melt is continuing, even as the melt pond is busy refreezing.
Melt ponds are thus an indication of bottom melt, irrespective of surface temp (excluding small range where temp is between -2 and 0 - when melt will be slow)

ChrisReynolds · « **Reply #440 on:** April 29, 2014, 07:37:07 PM »

Gerrit,

The major issue with melt ponds is that early formation allows them to absorb a lot more solar radiation over the melt season that would be the case without them. More melt ponds seem to be happening because in recent years the seasons are are starting with flatter first year ice, whereas in the past there was more ridged multi year ice.

Bottom melt happens, but the sun dominates the ice and changes in the amount of sunlight trapped (not reflected back to space) are very important because of the sun's leading role.

ChrisReynolds · « **Reply #441 on:** April 29, 2014, 07:39:36 PM »

Not long before we have PIOMAS April data - showing ice thickness at the start of the melt season. With luck Dr Zhang will post gridded data.

Then we need to wait to see the size of the CT Area June Cliff, which gives us a rough guide as to melt pond formation (I suspect).

ChrisReynolds · « **Reply #442 on:** April 29, 2014, 08:13:13 PM »

Spamming the thread with a third comment...

Using NCEP/NCAR - Jan Feb March north of 80degN (to be in line with the DMI temperature plots) was the warmest JFM since 1948. April so far has remained warm.

April so far (1st to 27th) in 2013 was above average temperature wise, this year has been much warmer!

See images below.

werther · « **Reply #443 on:** April 29, 2014, 08:34:49 PM »

Well done Chris,
I've been contemplating posting on this, since you illustrated it well, I can hold back my own spamming with NCEP/NCAR images for april '12/'14. Those are exemplaric too, but not as spectacular as your 1/1 to 27/4 image!
Meanwhile, DMI is about 4dC above normal for the date, 6dC above '12, so what about the headstart?
Not hard to see why MODIS shows 'subtle' differences with earlier years.

BornFromTheVoid · « **Reply #444 on:** April 29, 2014, 09:19:37 PM »

Some of this was touched on briefly in the Global Surface Air Temperatures thread, but it was also the warmest first 3 months of the year for north of 70N

And the 2nd warmest first 3 months for the northern polar (60N-85N) region according to UAH.

jdallen · « **Reply #445 on:** April 29, 2014, 09:29:55 PM »

Quote from: gerrit on April 29, 2014, 03:03:34 PM

Quote from: Jim Hunt on April 28, 2014, 12:29:21 PM

...

Bottom melt doesn't get going until the whole floe is above -2ºC, which doesn't (usually!) take place until July.

This makes me think of Neven's post about the correlation between melt ponds in May and September extend. Whilst melt ponds are directly an indication of warmth experienced by a floe, it is also a mechanism that assures the whole floe's temperature is kept (regulated) at about 0C.

So if my science is correct, it would mean that:
If a melt pond is present and cold weather passes overhead, the melt pond will first have to refreeze before the floe's temp can drop, and all the while bottom melt is continuing, even as the melt pond is busy refreezing.
Melt ponds are thus an indication of bottom melt, irrespective of surface temp (excluding small range where temp is between -2 and 0 - when melt will be slow)

I think that yes, where you have melt ponds, it mostly follows there is bottom melt.

Some caveats. First, MYI has a higher melting point, as de-brining will reduce salt content. In that case, bottom melt depends on higher water temperatures, and to a lesser degree, the action of salt on the relatively salt free ice. You can have melt ponds, and relatively no bottom melt.

Second, it's about rate of heat transfer and available heat. There is more than enough heat in tha arctic to melt *everything* there. It is sequestered mostly at depth, which is why in part storms and their related Ekman pumping are so destructive to ice.

Third, phase change, more than temperature, buffers the melt, both ways. Combined with the slower heat transfer through ice, it means top and bottom melt can frequently operate independent of one another. The thicker the ice, the more likely they are independent.

ChrisReynolds · « **Reply #446 on:** April 29, 2014, 09:56:20 PM »

BFTV,

Yep, I've been busy so may have missed this being stated on this thread or elsewhere.

Werther,

I can't wait to get April's time series graph, I can only plot time series for fully completed months.

Hubert · « **Reply #447 on:** April 29, 2014, 10:58:02 PM »

Cryosphere Today - freezing.
Date Area Change area
20.04: 12 160 368   11 030
21.04: 12 179 074   18 706
22.04: 12 196 437   17 363
23.04: 12 177 609   18 828
24.04: 12 199 998   22 389
25.04: 12 279 904   79 906
26.04: 12 311 213   31 309
27.04: 12 294 369   16 844

Why is this happening?

LarsBoelen · « **Reply #448 on:** April 29, 2014, 11:14:02 PM »

Hubert,

first of all get rid of at least 5 digits, they're not significant. (Clouds, fog, Reflections all influence the measurements)
Second : the arctic ice sheet is not a sheet, but more a collection of floats, being pushed around by the wind and currents
Third patches refreeze with thin ice due to low temperatures and melt out due to sun
Fourth melt pools form that hide underlying ice

Add them all up me you get a highly dynamic "area" affected by weatherm currents, clouds and what have you. So looking at daily updates is only indicative, no exact science.

Hope this helps

Hubert · « **Reply #449 on:** April 30, 2014, 11:59:22 AM »

Recently in the Arctic is quite warm, and sunny in most areas. So the conditions for melting. According to the NSIDC and JAXA ice extent decreases. That is erroneous reading of measurement data satellite CT.

And what are the the forecasts for the summer melting?

News:

Author Topic: The 2014 Melting Season (Read 1704842 times)