Arctic Ice Discussion (the Refreeze)

[BornFromTheVoid]

Here's a question.. the NSIDC (I think) is above 13 mil and uses the area covered by 15% of sea ice as it's standard... CT is above 12 mil... so how much is CT (20% of area, 25%) and what is the standard that you use for the record-keeping?

The NSIDC graphs the sea ice extent, which is 15% coverage. On Cryosphere Today they use sea ice area, which is 30% coverage. Both measurements are widely used so I don't know if there is any particular single standard.

[Isolated Frost]

The NSIDC graphs the sea ice extent, which is 15% coverage. On Cryosphere Today they use sea ice area, which is 30% coverage. Both measurements are widely used so I don't know if there is any particular single standard.

Thanks.

So what is (was) the AMSR coverage? And does anyone know when AMSR will be back online? Also, which is more used, Cryosphere Today's ice data or NSIDC's?

Sorry, for the questions

[BornFromTheVoid]

Thanks.

So what is (was) the AMSR coverage? And does anyone know when AMSR will be back online? Also, which is more used, Cryosphere Today's ice data or NSIDC's?

Sorry, for the questions

That was a sensor aboard the AQUA satellite, Advanced Microwave Scanning Radiometer for EOS (AMSR-E). It malfunctioned so won't be coming back online.

I'd say the NSIDC provides a fairly large amount of info for free, so that would be used much more.

Don't worry about the questions, I need a distraction from my seismic survey assignment anyway!

[songster]

The NSIDC graphs the sea ice extent, which is 15% coverage. On Cryosphere Today they use sea ice area, which is 30% coverage. Both measurements are widely used so I don't know if there is any particular single standard.

Not quite. Sea extent uses a hard cutoff at 15% (for NSIDC) or 30% (for DMI) and then treats each pixel as either present or absent. Sea ice area (e.g. Cryosphere Today) applies the 15% cutoff and then weights each individual pixel by its concentration.

Let's pretend we have five "pixels", each of 10 km^2, with the following concentrations: 95%, 85%, 35%, 25%, 12%

DMI reports that as an extent of 30 km^2 (three pixels are over 30% concentration)

NSIDC reports that as an extent of 40 km^2 (four pixels are over 15% concentration)

CT reports that as an area of 24 km^2 (i.e. (0.95+0.85+0.35+0.25) x 10 km^2)

At this time of year, the vast majority of pixels are >90% concentrated, the loose pack being confined to a fringe around the edge. In fact, you can estimate the average concentration of the pack as a whole by calculating area / extent.

NSIDC has consistently used the SSM/I data. Cryosphere Today used that for earlier years, then AMSR-E data (higher resolution) while the satellite was functioning, but is now back to SSM/I. Note that different satellites will "see" different ice concentrations depending on the sensor characteristics, and also that the numbers you get depend on what algorithm you use to calculate the ice concentration from the raw microwave data (how you filter out cloud cover, account for storms altering the reflection from open water, different emission properties of first year and multi-year ice etc.)

Edited January 8, 2012 by songster

[Isolated Frost]

CT has us above the 12m km2 mark...

The anomaly shortens... but how long for?

Easterly overload according to the ECM's latest offering at +192... rampant easterlies for the basin. Over the next week I'd say the Alaska-E Siberia area should see some melt with uppers moving towards 0c, and HP in control, but that cold spills out as the pv breaks open and the floodgates are there for some slight ice expansion, with very cold air in much of northern canada for a week or more.

The strat graphs indicate the pv is going to take a gradual 'walloping' for a good few weeks now, and so things could be a bit more grim for arctic sea ice as we move into february, but if the anomalies can close into average before the strat warmth takes effect then at least we've put in a valiant attempt... of course this'll be reversed again in summer by a ever declining ice thickness rate... the arctic is in real trouble, and all we can do is analyse it's demise, slowly and painfully...

[Isolated Frost]

Another gain, however the anomaly is still a rather large -0.404. Respectable in terms of recent years, but when you look at the synoptics, it's no shock... high pressure to exert more influence over the next few days, but with little sunlight for most, only temperatures can prevent ice loss... thicknesses should slow or lower across the canada-alaska and rise across the basin and greenland/ne canada area imo.

[loafer]

I wonder what the anomaly would be if they updated the mean to include years 2009-2011?

[songster]

I wonder what the anomaly would be if they updated the mean to include years 2009-2011?

It would be lower. Meanwhile, the positive anomalies in the 70s and early 80s would be higher. The amount of ice lost over the last few decades (which is what actually matters) would be unaffected. So, what's the point?

[loafer]

Simply that there are many ways of comparing and including the longest and most up to date data would seem to be the most sensible.

Do you disagree?

Selective application of data ranges is certainly an area of substantial contention in climate science. For example, the flat temperatures for the last 10 years have been dismissed because the data range "isn't long enough".

[Geordiesnow]

I wonder what affect some might think the upcoming Arctic pressure pattern will have on the Sea ice, are these constant southerlies we appeared to have for most of the winter a good thing for the Arctic in general as it stops the thicker ice leaving the fram stright or is it bad news as it brings higher temperatures around the pole which may make the ice weaker for the summer season?

It looks like the Arctic will be warming up significantly soon as it appears to been below average so far this winter across most of the basin because of the PAO but I heard a NAO is actually a good thing for Arctic ice despite the warmer temperatures?

[Gray-Wolf]

http://www.wwfblogs.org/climate/content/arctic-temperatures-continue-rapid-rise-2011-breaks-record

Seems we had record temps across the arctic in 2011 (beating 2010's record)? Maybe that's why we were able to see so much insitu melt with such large amounts of extra 'energy' around to lend a helping hand?

What will the next Nino' year pump up there???

[jethro]

GW - thicko question here.....

The link that BFTV posted about the bubble of cold, fresh water - could that be making the surrounding waters artificially (for want of a better description) warm and pushing them further North into/under the ice?

[Gray-Wolf]

Neven's Blog had the above offering. It shows the journey that the water has taken to find itself 'corralled inside' the Beaufort Gyre. I do not think that this is having much of an impact though? If we think back to Catlin's last journey north he found sinking 'fresh' down at 200m (?) with warmer , Atlantic bottom waters, forced to the surface. Whilst it is at the surface things seem OK but were we to slow the Gyre and allow this water to spread into the west of the basin (and then our way via the trans polar drift) would we not find Catlin's findings repeated across the whole basin?

You know I have a thing about the loss of the 'old halocline', well here we have another process able to disrupt , over a large area, the stratification of the basin leading to warmer ,saltier waters at the surface. We can only imagine the impacts of this on re-freeze and spring melt dates?

EDIT: and the ice bridge across Nares has formed in the lower section again;

Edited January 25, 2012 by Gray-Wolf

[BornFromTheVoid]

According to Cryosphere Today, NH sea ice is back to being over 1,000,000km² below average. The main areas dragging the extent down (no overall increase since around January 10th) are...

Barents sea, ~350,000km² below average.

Kara sea, ~150,000km² below average.

Sea of Okhotsk, ~200,000km² below average.

The Bering sea ice is the only one keeping things somewhat respectable, being a little over 200,000km² above average.

I can only presume we'll see some kind of improvement in these figures soon, as there's never been an ice maximum in January on record.

The 06z GFS shows uppers remaining very cold around the Bering strait for the next 4 days, before the cold air gets shifted towards the sea of Okhotsk at day 5. Around then, slightly colder air appears over the Barents and Kara seas. Unfortunately it's short lived as strong southerly winds send up milder air and begin to squeeze the cold air south into eastern Siberia and Canada. By t168, we have uppers above 0C into the Beaufort sea and almost all the coldest air outside of the Arctic basin. The sea of Okhotsk is the only sea ice forming area that retains any significant cold.

[Geordiesnow]

I did ask earlier in this thread what affect would those frequent southerlies between Svalbard and the Kara seas will have on sea ice apart from keeping extent way below average around that area and unfortunately I got no answer.

Would the frequent southerlies stop the thicker ice heading out of the fram stright and if not, what is the ideal Arctic weather pattern. This winter has seen frequent southerly winds heading towards the poles whereas it would seem northerly winds from the poles to Svalbord tends to reduce the thicker ice in the Arctic basin so it would appear we are in a lose-lose situation.

Unless the pressure patterns change which looks unlikely in the foreseeable future, I imagine we will see no ice in the Kara sea by the end of March and the ice in the Laptev sea being quite vulnable to much earlier melt than usual.

The only year that looks similar to this year was 2006 but I don't think the southerlies have been as frequent during that winter as this one has been.

I'm sure the Svalbard isles and the Zemlya isles are having one of its most mildest winters on record and a record winter so far of very little in the way of Northerly direction winds!

[Gray-Wolf]

Agreed G.S. , the switch to AO-ve has now let the colder airs out of the basin and ,with the sun on the rise, means that the coldest part of winter is now over. Spring storms in Bering will mess the extra ice there and give early drops to the 'extent' figures. The upcoming Full moon may also disrupt ice across the basin , the one after will disrupt the ice (esp. the shore ice that is 'Floating').

Something is telling me this year will be an interesting one with the prospects of the same level of 'in-situ' melt and the possibility of 'normal' rates of export via Fram. Should this prove true we will be looking at a new record low come Sept.

Any move toward a 'perfect storm' synoptic would mean a low , IMHO, between 1 and 2 million sq km.

[songster]

Hum, I wouldn't be so certain. Yes, the southerlies have kept the pack low on the Kara/Barents side. However, they've also compressed (and thickened?) the central pack and shifted the distribution of thicker ice over into the Beaufort and Chukchi seas. To an untrained eye, it also looks as though there's also been less export through the Fram Strait than usual, aside from a couple of weeks near the start of the freeze when it was absolutely booking it out of there. If you're not careful, there's a danger of falling into the trap of seeing every possible wind direction as catastrophic. Winds blowing towards the Pole? Then the heat transport will be keeping the ice thin. Winds blowing away from the Pole? That's the old ice being flushed out to melt in warmer waters. Winds blowing round in circles? That's churning up the ice and proving it's in poor condition.

All told, there's been a lot of very cold air bottled up north of Canada for much of the winter, more than the last few seasons. I suspect therefore that melt in the Beaufort and Chukchi seas will be slower in 2012 than in 07-11. However, I agree that if losses in these seas are <i>not</i> substantially reduced this year, then yes, we're probably looking at a record or very near. That's simply a logical consequence of how low it it on the Atlantic side of things.

Edited February 3, 2012 by songster

[BornFromTheVoid]

Whatever the winds are up to this year songster, things are looking very poor across Kara and Barents with no favourable conditions for the next week.

CT has the Kara sea ice extent back to mid-November levels, while the conditions that have piled up a +ve 300,000km2 anomaly over the Bering sea is set to end in the coming days.

Current NH anomaly on CT is just below 1.1million km2.

[BornFromTheVoid]

A great new interactive ice area chart from Cryosphere Today

http://arctic.atmos.uiuc.edu/cryosphere/arctic.sea.ice.interactive.html

2012 currently lowest on record.

[Gray-Wolf]

I think we can blame Kara and Barentsz for that and thank Bering that we are not a lot lower on the plot!! According to the folk over on Neven's Blog March 10th sees the sun high enough to melt the ice again there (15 degree rule?) so it's has not long to freeze and let the temps get down to there normal -30c and not the current 'above -1.8c'. It does look as though melt has already arrived there with ice levels dropping back over recent weeks (compaction?)

If this area remains as is then be prepared for a low start to the season with that 'supporting ice' over in the Bering sea disappearing quite fast leaving us with the absent ice from Barentsz/Kara and normal melt over on the Bering side?

I've heard folk saying that the ice (what there is of it) is thicker this year? anyone got any data?

EDIT: I'd ask again , is there anywhere else on the planet where an anom of 28c goes un-noticed by the media/masses???

Edited February 7, 2012 by Gray-Wolf

[BornFromTheVoid]

Things not looking great in the Arctic at the moment. The anomaly on CT is nearly at 1.3million km2, lowest on record.

On the northern hemisphere charts the cold air has left the Bering sea and the +ve anomaly it had built up is now falling away. Uppers of over 5C now over the Beaufort sea and surface temps around Kara and Barents above 0C in places.

Not a whole lot of change then until about t120, when colder air manages to reach the Kara and Barents seas.

Will be interesting to see how the NH area fares over the coming 4 or 5 days...

[knocker]

I don't know whether this is of interest. The midday plots for the Arctic Ocean, Beaufort Sea, Barents Sea, Greenland Sea, Kara Sea,Laptev Sea Chuchi Sea.

Edited February 10, 2012 by weather ship

[Devonian]

I don't know whether this is of interest. The midday plots for the Arctic Ocean, Beaufort Sea, Barents Sea, Greenland Sea, Kara Sea,Laptev Sea Chuchi Sea.

Those are interesting. I took a double take until I realised it's Farenheit? Even then some of the temperatures are as extraordinarily warm as the cold across parts of Europe have been - indeed given Svalbard has been 13C above normal for the last 30 days (and, I see, had a hugely anomalously warm last 12 months) rather more extraordinary perhaps. Anyway, are those plots available on the net or are they done via synops and a program?

[knocker]

Anyway, are those plots available on the net or are they done via synops and a program?

The latter.

[BornFromTheVoid]

Just looking through CT, and spotted on the global sea ice graph that last year was the lowest maximum in the series, and the first not to reach 21,000,000km2.

Here's the CT graph with the 21 million line changed to solid black to make comparisons a little easier.

Original image here http://arctic.atmos.uiuc.edu/cryosphere/IMAGES/global.daily.ice.area.withtrend.jpg