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Philip Cohen

Much as I'm enjoying the race to a possible new max, I wonder how we know we haven't already reached it. JAXA SIE says it's now 13.76 square megameters, as compared to 13.94 on Feb 15, and you say the difference of .186 is 'quite significant'. But do we really know SIE to three significant figures? SIE is determined by 15% coverage, but is that 15% or 15.0% or 15.00%? In 'Mad max?' we're told that 'IARC-JAXA (IJIS) sea ice extent grew to 13,942,060 square kilometres', which is certainly impossible precision. Basically, I'm asking what the error bars are.

TenneyNaumer

The Arctic Oscillation Index is in negative territory right now so the extent may grow a little -- however, it is forecast to become positive again soon.

IMO, even if the extent increases above the old record, it won't matter much. The ice is already undergoing processes that normally accompany the breakup of the ice around the north of Greenland -- something that has been occurring in April, not March!

Neven
But do we really know SIE to three significant figures?

This is largely irrelevant. We're not interested in the 100% exact amount of extent or area. We want to compare to other years. So, if JAXA keeps doing what it does consistently every year, we can compare and have an idea of what's going on.

JAXA reports yet another drop of 35K, difference with the prelim max is now 221K. There have to be some serious upticks starting tomorrow, or else the max is a done deal.

Which means the melting season has started. Yay. :-)

Bill Fothergill

@ Philip

Precision and accuracy are two fundamentally different concepts in the wonderful world of mensuration*. (* I'll just check that I've spelled that word correctly!)

One can take measurements that are accurate, but lack precision, just as easily as one can have precise measurements which fall short in terms of accuracy.

As you rightly point out, spurious precision is basically a waste of time, and can simply detract from the more important overall accuracy.

Within the last year (somebody can correct me as to the exact date) the NSIDC dropped the last three digits from their daily measurements, and now only report down to thousands of sq kms.

NSIDC claim an accuracy figure of, if memory serves, +/- 50 thousand sq kms. Their provisional figure as of the 16th March is 14.427 million sq kms, which therefore translates to having a probability distribution centred on this value and having the +/-2 standard deviation points occurring at 14.477 and 14.377 million sq kms.

I hope that might help somewhat.

cheers bill f

Bill Fothergill

I could "probably" have done better on the last paragraph.

It might have been better if I had said NSIDC have 95% confidence that the true value lies within about 50 thousand sq kms either side of the reported value.

That was based on my unreliable memory of reading that they worked on 2SD confidence limits. If I've just imagined that, then I would expect the +/- 50 thousand sq kms to represent a 1 SD spread, and this would translate to 66% confidence that the actual number lies within +/- 50 thousand sq kms of the reported number.

Cesium62

There's some strong statements you make there, Neven: "will be settled in the coming week", "it will still break the previous record low maximum reached in 2011" I'm just going to have to take the contrary position. Not only will this be the latest max on record, but we just can't have the latest max and lowest max in the same year. ;-)

Al Rodger

Using the NSIDC data, the timing of the annual maximum in Arctic SIE, as discussed at the end of the Mad Max thread, can be shown to have a statistically significant trend by using 29-day rolling averages. Since the late 1980s the 29-day maximum has been getting later at a rate of 6 days/decade (+/-4 days to 2sd). But the early 1980s, when the NSIDC data is every other day not daily, perhaps shows an opposite trend.
The early 1980s timing of the maximum 28-day period averaged at 8th March. The late 1980s 29-day period averaged 3rd March while the central trend up to 2014 was at 17th March.

iceman

Can't say for certain that we'll have the final answer within a week, even though it's quite late in the season. Conditions look favorable for extent increases for a few days around the 25th. It's quite possible the number will be just below the 15th Feb peak and nosing up toward it - rather like a polar bear cruising beneath the ice, getting ready to pick off a hapless seal on the surface.

Colorado Bob

Divers will brave Arctic ice to unlock secret of Franklin’s doomed voyage

Navy divers and marine archaeologists are about to attempt a daring feat of polar exploration. In a few weeks they will drill beneath the thick ice in the remote Canadian Arctic and in freezing water explore the wreck of the Erebus, flagship of Sir John Franklin’s doomed expedition to discover the North-West Passage.

Link

Bill Fothergill

Interesting preliminary figure for 17th March on the NSIDC dailies.

"chickens, count, hatched"

Colorado Bob

Supply barge adrift in the Arctic for months

The company says it will try a recovery in July. A spokesman for the National Snow and Ice Data Center in Colorado suggests the barge could circle the Arctic if it gets caught in the trans-polar drift stream and come out on the Atlantic side, possibly through the Fram Strait between Spitzbergen and Greenland, depending on the weather

But as NSIDC Director Mark Serreze, says, they’ve been getting “crazy weather patterns in the Arctic as of late.”

The drifting barge has traveled somewhat erratically about 1,360 miles since it broke free, being pushed at times west, at times north, then further west by winds, ocean current, and the drifting icepack.

Fwmbrown

A couple of graphics I don't often see here but might be relevant to the discussion: http://ocean.dmi.dk/arctic/meant80n.uk.php and http://ocean.dmi.dk/anim/index.uk.php parameter ice convergence, are Arctic Ocean...

Jim Hunt

Cryosphere Today area has reported a 50 k drop today, much as predicted!

As Bill was hinting, the NSIDC daily extent fell by over 100 k also.

Are you willing to call it yet Neven?!

Neven

No, I don't call it, as a rule. :-B

wayne

"Mark Serreze, says, they’ve been getting “crazy weather patterns in the Arctic as of late.”"

What I have reported for months was lets say "crazy" because it was so stable. A stable heat engine on a planetary scale, with pistons the size of cyclones more than 1000 miles wide. I predicted this lesser ice extent for quite some time now.

Yesterday saw the break in 2 of Arctic fortress winter. by yet another cyclone over the Canadian Arctic.

There is such a thing as a path made by a cyclone which is usually followed by another, is like space time planetary physics, where a planet transforms space and time by its gravity, the planet
groves a space time valley.

But what was meteorologically "crazy" is that the cyclone path or valley was made in in December, grooving a piston chamber where the path was taken again and again by dozens of cyclones. Almost never interrupted by chance , such as caused by weather variations. For this to happen there must be a sable thermal dynamic heat engine infrastructure in place, which was/is warmer oceans and lesser sea ice, the cold and warm sources didnt move. but still some thick sea ice is needed in order to make the heat engine work. This is not the future of weather, this is what the weather looks like when sea ice thickness of old is almost all gone.

Will write soon of more sea ice news, this season is not at all like spring of 2014. Even though the details seems the same , there are dramatic differences. http://eh2r.blogspot.ca/

navegante

it is a mathematical certainty that the max can be the lowest and the latest in the same year

LRC

Neven has been burned a few years where all the numbers said the max had been reached and no way could anything happen to it. The Arctic then said SURPRISE!! And that include sudden upsurges in the last half of Mar.
That is why Neven has imposed that rule.

Neven

Neven has been burned a few years

Just one year, LRC! Just one year. Don't make it worse than it is. :-B

I do still call the minimums though. That's much easier.

LRC

Sorry! Thought someone mentioned A 2011,2012, But then maybe is was not you calling it but everyone else.

Bill Fothergill

Owing to the vagaries of wind, and tide, and cloud patterns, and ENSO, and so on, I don't tend to get worked up about records that pertain to a single day. (Well, not too much!)

The trend in monthly and annual figures is, I think, of more long term significance. (Although daily records can undoubtedly have persuasive political power.) To that end, I've been doing some projections to the end of this month.

The record low (on NSIDC) extent average for March is very much on the cards. Assuming I've set the spreadsheet up correctly, even if the 5-day rolling average goes up every day by about 20k sq kms for the rest of this month, 2015 should still just about edge out 2006.

If that daily increment went up to about 60k, 2015 would still end up displacing 2011 as the second lowest March average. Even an 80k per day rise would see 2007 pushed back to 4th lowest.

This, of course, doesn't necessarily imply a stunningly low September average this year, but it's only a matter of time until the Arctic fails to dodge the bullet.

Tensor11

Everyone, long time lurker here. Bill, I find it interesting that the two lowest years you have are 2006 and 2011 and what that possibly means for NEXT year.

Disclaimer, I've seen enough of "the arctic can and does surprise us", so I'm saying anything may happen, just finding it interesting.

VaughnA

One thing I am wondering about, considering the feeble response of the ice this year, is how much relative humidity affects freezing. I have asked this question before a few years ago but did not get very much response.
Consider that the heat of water vapor condensation(600 calories/gram + 80 calories/gram since the ice is going directly to vapor from ice) is about 8.5 times the heat of fusion alone(80 calories/gram).
Therefore when relative humidity is low subliming 1cm of ice from the surface will cause 8.5cm of ice to freeze on the bottom for a net gain of 7.5cm. provided that 100% of this heat comes from the ice and none from the air to change the ice to water.(I am NOT suggesting that the efficiency is anywhere near 100%.)

If the relative humidity is in the 90% range and there is no sublimation nor deposition then the ice thickness should not be affected by humidity but could still be thinner at similar temperatures in the past that had low humidity conditions.

Likewise, if the relative humidity is near 100%, then for every 1cm deposition of ice equivalent of frost should prevent 7.5 cm of ice from freezing if 100% of the heat goes into the ice.

Again, I am NOT suggesting the efficiency is near 100%. I do not know how much effect this has on freezing ice but I have watched ponds freeze under dry or humid conditions and the depth of the ice formed in the same number of days and similar temperatures is quite significant. I suspect this has been thoroughly researched but I have not seen any numbers published about the effects of humidity.

Based on numerous posts on this blog, it appears the the arctic has been considerably more humid this winter than in the past which could be contributing to how feebly the ice has responded. Any ideas about this or information would be most helpful.

Neven

JAXA reports yet another drop of 12K. I'd say that it's more than 90% certain that the prelim is not the prelim.

Bill Fothergill

Vaughn,

Calories? Grams? You, sirra, should be taken outside and given a good thrashing! What happened to SI units?

;)

(BTW Latent heat of vap for water is 540 cals/gram, not 600. Oops, I mean 2,270 kJ/kg)

You might want to check out a little article that NSIDC have on this topic...
http://nsidc.org/cryosphere/seaice/processes/thermodynamic_growth.html
They even have a metric called Freezing Degree Days (FDD).

cheers bill f

Bill Fothergill

Tensor11

The early month "vagaries" are astonishing. I'm sure you know that 2012 currently has the lowest September mean extent (and lowest annual average), but you may not be aware of its position in the other months...

Jan 6th; Feb 7th; Mar 12th; Apr 20th; May 13th.

So, nothing much to shout about there, I'm sure you'd agree. However, the next 7 months went...

2nd; 2nd; 1st; 1st; 2nd; 3rd; 2nd.

We've had much discussion about the lack of correlation between March/April/May and even June, with the eventual September minimum.


Welcome to the wild ride!


cheers bill f

Al Rodger

My brave call on Sunday of the maximum SIE being behind us - it is looking pretty solid today, just four days later.

The reason for this early timing of the SIE maximum (JAXA & NSIDC both) is perhaps worth discussion (although likely has no answer, this being the Arctic).
This will be the first time since the 1990s that February average SIE exceeded March average SIE, punctuating a strong trend in the opposite direction, abet a trend with a lot of noise on it.
So is this year's timing the result of a super icy February, a seriously melty March, or is it a combination of the two?

Bill Fothergill

Al asked a question with 3 possible answers...

"is this year's timing the result of a super icy February, a seriously melty March, or is it a combination of the two?"

Given that the NSIDC had Feb 2015 average extent as 3rd lowest in their dataset, that pretty much eliminates a super icy Feb as the culprit.

cheers bill f

Neven

Cryosphere Today reports the 3rd century break of the season, bringing the difference with the prelim down to 433K, so very probably that the max has been reached there too. It would be second lowest, 13.27 million km2 vs 13.14 million km2 in 2011, and the earliest in the 2006-2015 record.

Sunkensheep

I'd have to put it down to stable stratospheric conditions and a cloudy winter. There has not been the 'clear skies' that result from a large stratospheric warming event. There has also been a lack of spreading events so far this 'spring'.

Speaking of stratospheric warming, here's NOAA's 50hpa temp anomaly animation showing one just getting underway in the NH. http://www.cpc.ncep.noaa.gov/products/intraseasonal/temp50anim.gif

Sunkensheep

If it was not clear, I was replying to Al Rodger "is this year's timing the result of a super icy February, a seriously melty March, or is it a combination of the two?"

Jim Hunt

"Speaking of stratospheric warming, here's NOAA's 50hpa temp anomaly animation showing one just getting underway in the NH."

Over the North Atlantic?! A UK Met Office video on SSWs

https://youtu.be/1MiUlTthSNA

plus “The Achilles heel of the North Atlantic"

http://unews.utah.edu/news_releases/stratosphere-targets-deep-sea-to-shape-climate/

Neven

I hear the NSIDC is going to call the maximum today. Finally! ;-)

Fwmbrown

Shouldn't really be on this thread, but I'm not a part of the forum AFAIK, so :http://www.polarresearch.net/index.php/polar/article/view/24603

Published a few days back, it looks at results from a GCM and an RCM our to the 2030s and then the 2080s.

The usual caveats apply, but one headline indicator was temperature increases up to +15K. Some interesting graphics on sea ice extents, too...

wayne

To be cloudy or not to be cloudy? That is the post earliest max ever question. If all that 1 million + dark water is hit by sun rays increasing in intensity every day, odds are 2012 would be toast.
But now the weather must change, the hemispheric wide heat engines have shrunk but are still in action. More data is needed
to figure out if clouds and cyclones will continue or if the sun would change the cloud scene to blue. El-Nino is said to come, but :

http://www.ospo.noaa.gov/data/sst/anomaly/2015/anomnight.3.19.2015.gif

The South equatorial Pacific is very La-Nina like. For the mean time , the North Pacific is still quite warm, The current circulation scheme should lag, but change is in the air. More sea ice news will be breaking very soon. Current signals are a bit complex, I await simpler ones to report.

Neven

NSIDC calls it (sort of ;-) ):


On February 25, 2015, Arctic sea ice extent appeared to have reached its annual maximum extent, marking the beginning of the sea ice melt season. This year’s maximum extent not only occurred early; it is also the lowest in the satellite record. However, a late season surge in ice growth is still possible. NSIDC will post a detailed analysis of the 2014 to 2015 winter sea ice conditions in early April.

Jim Hunt

NASA have a video out too, along with this associated article:

http://www.nasa.gov/content/goddard/2015-arctic-sea-ice-maximum-annual-extent-is-lowest-on-record/

Gergyl

The earliest maximum snow depth in the 60-year Australian record happened last year: http://gergs.net/2014/07/peak-timing/ (a similar game of "will it or won't it" was played through that season). There is a clear trend to earlier maximums: http://gergs.net/wp-content/uploads/2014/07/Spencers_Creek_peak_date.png

Are earlier extremes a general effect of AGW on the cryosphere?

VaughnA

Bill thanks, you are absolutely right about the 540 cal/ gram. I read the article from NSIDC. Yes, good information but it really didn't answer my questions so I will rephrase them:

If one cm of ice sublimes from the ice surface into the air, where does all the heat come from to sublime the ice and how much does it affect the freezing of the ice?

If one cm of ice equivalent condenses on the ice from the air where does all that released heat go and how much does it affect the freezing of the ice?

I am not sure about the effect but it must at least be something.

Kate

Now this is interesting

http://www.dmi.dk/fileadmin/SatelliteArctic/Lincoln/20150319TERR.jpg

Fwmbrown

The pattern you describe, of southward drift, is projected to continue at a pace by the DMI in the Barents and Greenland Seas. Drift is also showing southward in the Bering Sea. But AARI is showing the 'far' side of Novaya Zemlya as Nilas.

So in part, the next week's numbers may depend on how the various 'interpretations' read the drift - as thin pack, or lose drift ice. It looks like Hudson Bay has started to thaw, and this will also impact on the overall numbers. Note that Barents SSTs are above zero and wind and current are still pushing heat northwards.

Artful Dodger

Hi Folks,

Happy 1st day of Spring! (or Fall, depending on your declinations...)

Meanwhile for the Arctic, the NSIDC has called the Max: (provisionally, of course, as with most things Arctic ;^)

14.54 M km^2 on Feb 25, 2015.

Note that NSIDC uses a 5-day trailing average to report SIE. Significantly, that minimum occurred about 15 days earlier than average.

So then, will it be 'Cry Havoc, and let slip the sled-dogs of war' for Arctic Summer 2015?

El Nino effects? Wayne?

Cheers,
Lodger

Scott

Gergyl,
We have seen a similar change here in Minnesota. March has historically been our snowiest month. Now it's January. The theory is that January has warmed enough to now allow for bigger storms (warmer air holding more water vapor) while March has warmed so much that a lot of its snow is now falling as rain.

G man

I find it odd that NSDIC would say that this the lowest when DMI clearly shows 2011 to be lower and NANSEN clearly shows 2007 to be much lower.

http://arctic-roos.org/observations/satellite-data/sea-ice/observation_images/ssmi1_ice_area.png

http://ocean.dmi.dk/arctic/plots/icecover/icecover_current_new.png

Jim Hunt

G man - You're trying to compare apples with oranges.

Your first link is to a graph of area, not extent. Which is why the numbers are lower than those quoted by NSIDC.

Your second link is (despite the title!) to a graph of Northern Hemisphere ice extent, including the Great Lakes, which is why the numbers are higher than those quoted by NSIDC, for 2015 at least. Compare e.g.

http://osisaf.met.no/p/ice/nh/conc/imgs/OSI_HL_SAF_201503191200_pal.jpg

and

http://osisaf.met.no/p/ice/nh/conc/imgs/OSI_HL_SAF_201103191200_pal.jpg

Bill Fothergill

@ G man

As you rightly observe, neither Nansen nor DMI show 2015 in lowest place: in both cases it is languishing all the way up at second lowest.

Again, as you rightly mention, NSIDC does show current levels at their lowest ever recorded for this time of year: JAXA and CT also show current values at lowest ever levels.

So that's 5 reporting systems all showing 2015 with either the lowest or second lowest levels of Arctic Sea Ice ever seen at this time of year. To me, at least, that rather suggests two things: that these 5 systems are in reasonably good agreement, and that current levels just might be unusually low.

Perhaps you should spell out the point you are trying to make?

cheers bill f

G man

[Northern Hemisphere ice extent including the great lakes] Not sure what you're saying there Jim as both the DMI and NANSEN graphs are for the Arctic sea ice. Last time I looked the Great Lakes weren't in the Arctic. And area=extent so you're just parsing words with me. It seems as though and alarmist media/activists are yet again crying wolf with headlines like "bad news for ice seals" (btw what's an "ice" seal?) etc.... This looks like another case of the "2014 hottest year evah" well maybe.

Ghoti Of Lod

Wow! The uninformed making noise claiming the people who actually take the time and make the effort to read and understand the definitions of the various measurement systems are wrong.

Of course deniers never let the facts intrude on their statements of "truth"

wayne

Hi Artful D, very tough call for ENSO. There were some CCN streaks
in the stratosphere polar vortex, but none lately when a cyclone broke its wind pattern. None, absolutely clear twilight sky. Very rare event. A warmer stratosphere does not create PSC's. It rather implies La-Nina than El-Nino. The North Pacific warmer sst's
will eventually replace cloud seeding from the Equator in July. So in the interim it looks like a great chunk of the Arctic will be cloud free, especially where he thickest ice is.

Neven

It seems as though and alarmist media/activists are yet again crying wolf with headlines like "bad news for ice seals" (btw what's an "ice" seal?) etc....

Hmmmm, I've seen a dozen or so articles in the past two weeks that dealt with the possibility of a record low/early maximum. In each article it was stressed that a low maximum doesn't mean there will be a low minimum. I haven't seen any article mentioning seals or polar bears in relation to the maximum.

Differences between the datasets are caused by the following aspects:

1) Datasets don't all use the same satellite sensor, but I believe AMSR-2 on JAXA's GCOM-W1 spacecraft, launched May 18, 2012, is the most sophisticated.
2) The Arctic is divided into grids, and the size of these grids determine the resolution. The smaller the grid, the more precise (in theory). The University of Hamburg puts out experimental data that has a grid resolution of 3.25 (grid measures 3.25 x 3.25 km), that is used by commenter Wipneus to make graphs like the ones in this blog post. For comparison: Arctic Roos uses a 25 km resolution.
3) Different data sets use different land masks and define the total area differently (some include this sea/lake or that sea/lake, others don't).
4) And then there's algorithms. I don't understand any of that stuff, but I believe they're formulae that make sense of the satellite data to determine what is sea ice and what is not.
5) The difference between extent and area is explained here. Area is more accurate, but extent is more trustworthy during the high melt months.

Anything else I forgot? Maybe I should write a blog post about this. Someone on the Forum was also puzzled by the differences between data sets.

wayne

"2014 hottest year evah"

English aside , "the warmest year on record", as I predicted last year in April. And you thought a person would figure out :

hotter = less Arctic sea ice

But we can always try to teach .....

G man

Thanks Neven. Informative as always.

G man

You could easily see with elevated SST's in the N Pac last summer there could be a loss of sea ice in the Bering and Okhotsk. And that's where the majority of the loss was/is. The Arctic proper looks relatively normal and according to PIOMASS the ice is thicker. So while there may be less extent/area there is technically MORE sea ice.

Neven

Whether there's more or less ice depends, of course, on what you compare it against. But the sea ice near the coast of Greenland and the CAA seems to have thickened some more. I'm going to try and give an idea how this freezing season compares to those in previous years, probably somewhere in April.

wayne

And the "elevated SST's in the N Pac " contributed to the "2014 hottest year evah". The greater volume of sea ice is debatable , but not impossible since 2013 summer sea ice melted in place, no real movement, may have meant more ridging, not caused by cooling, however thicker ridged sea ice can cause more arctic cooling - by meteorological dynamics. 2014 warmest year on record was confirmed by 2014-2015 record low minima sea ice, which makes the world temperature record more robust and far less debatable. Following such events, 2005 and 2010, came the lowest sea ice records ever 2007 and 2012.

wayne

---by 2014-2015 record low maxima sea ice--

Jim Hunt

G man - At the risk of repeating myself, and as you can check for yourself by clicking the links I helpfully provided, whatever your views (or indeed mine) on the matter may be the OSISAF concentration data on which DMI base their numbers include the Great Lakes.

The NSIDC concentration data, on the other hand, do not:

ftp://sidads.colorado.edu/pub/DATASETS/nsidc0081_nrt_nasateam_seaice/browse/north/nt_20150319_f17_nrt_n.png

Hopefully you have learned by now that even at NERSC area != extent? just in case:

http://arctic-roos.org/observations/satellite-data/sea-ice/observation_images/ssmi1_ice_ext.png

Can you provide any photographic evidence, photoshopped or otherwise, of wolves eating ice seals?

G man

Well Jim I've followed links from DMI to OSISAF and they do not mention anything about including Great Lakes ice in their product for the Arctic. They do have multiple products including global ice which indeed may include Great Lakes ice. I've emailed them and will let you know what they say. The reference about the "Bad News for Ice Seals: Arctic Winter Sea Ice Hits Record-Breaking Low" was from a Yahoo link from takepart.com.

http://www.osi-saf.org/index.php

Jim Hunt

I could have saved you going to all that trouble G man, since I asked DMI that very question quite some time ago. Please do let me know if you receive a different answer to the one they gave me.

In the meantime I feel sure you must have many happy hours ahead of you reading the relevant manual:

http://www.osi-saf.org/biblio/docs/ss2_pmseaice_3_11.pdf

If you'd like to start crunching the numbers yourself there's even some instructions on how to go about doing so over on the forum:

http://forum.arctic-sea-ice.net/index.php/topic,782.0.html

Please do not hesitate to ask if there's anything there you do not understand.

Al Rodger

g man.
A picture tells a thousand words.

Al Rodger

usually.

Bhudson

Neve, I can't help but notice that your map has an arrow labeled "Saint Lawrence" pointed at the Strait of Belle Isle. I'm assuming that arrow is supposed to point at the Gulf of Saint Lawrence instead?

An aside: the arrow points where the Vikings are known to have (very briefly) settled at l'Anse aux Meadows, at the tip of Newfoundland. Wikipedia says it's a grassy area; I recall tundra from my visit 25 years ago.

Philip

Cryosphere today SIA is now about 30 days ahead of last year. Going to be an interesting season is it not?

Cincinnatus

... not.

Neven

Always interesting, Philip, not always spectacular. In the short term, that is.

Neve, I can't help but notice that your map has an arrow labeled "Saint Lawrence" pointed at the Strait of Belle Isle. I'm assuming that arrow is supposed to point at the Gulf of Saint Lawrence instead?

Yes, I pointed in the general direction, not knowing where the Gulf of St. Lawrence is, and too lazy to look it up. But I looked it up now (remorse is a great motivator):

Bill Fothergill

It's about 2 and a half hours till the latest NSIDC numbers are posted. Given that JAXA puts out a 2-day running mean, and given the ongoing reasonably good correlation between their figures, it's on the cards that the NSIDC daily extent value for March 20 is going to tumble somewhat.

cheers bill f

Neven

JAXA has reported an uptick of 100K in the past two days. The difference is now 137K. But Baffin and St. Lawrence have started to drop, so let's see how far the Arctic can crawl. ;-)

iceman

There's a lot of ice cover close to the 15% cutoff in Baffin and St. Lawrence, and increasingly in Bering. All three regions show a recent divergence between JAXA and UH AMSR2 in Wipneus' charts. The former appears to be counting extent near the fringe in places where the latter is not. This has occurred in prior years, probably owing to differences in grid cell size.

Bill Fothergill

@ Nev
Yep, in addition to JAXA, CT has gone up ~140k in three days, and Bremen, DMI and Nansen have also been moving upwards.

The NSIDC daily prelim for 22nd March seems to have finally joined the party, such that their record for the average monthly extent (currently with 2006) could still easily go either way.

However, even if the rise continues at a rate somewhat in excess of 80K/day for the rest of the month, 2015 would still supplant 2011 as the second lowest March in the NSIDC database. (After having already clocked up 3rd lowest place in both Jan and Feb.)

It will be interesting to see if Iceman's point about coverage in many places being close to the 15% boundary bears out.

cheers bill f

G man

@ Jim Hunt, Just received an email from DMI and no they do not use any Great Lakes data in their Arctic package. The sensors they use for global sea ice mapping are to coarse.

cheers

Martin Gisser

Just out, news on Gulf Stream (AMOC) weakening and the role of Greenland melt:

Rahmstorf, S., Box, J., Feulner, G., Mann, M., Robinson, A., Rutherford, S., Schaffernicht, E. (2015): Exceptional twentieth-Century slowdown in Atlantic Ocean overturning circulation. Nature Climate Change

http://www.realclimate.org/index.php/archives/2015/03/whats-going-on-in-the-north-atlantic/#more-18156

Video interviews: http://climatecrocks.com/2015/03/23/a-nasty-surprise-in-the-greenhouse-new-paper-new-video/

Cincinnatus

[Snipped some BS, sorry; N.]

In regard to Martin's specific topic, the notion that the Earth's surface temperature trends from 1900-now can be uniformly presented is laughable. I like how they cut out the Antarctic (musn't extrapolate those adjacent cool zones) but leave in central Africa and the Gobi Desert. Their "cool zone" in central North Atlantic is pure comedy. Probably they needed a place to put some inconvenient cold temperatures.

So was the central North Atlantic really warmer 100 years ago? Tell it to the Titanic, which went down there, struck by an iceberg. Now tell us how many icebergs are there today. Cheez.

Jim Hunt

G man - What was the question you asked DMI, what was their precise answer, and who provided it?

Have you bothered to read this yet?

http://forum.arctic-sea-ice.net/index.php/topic,782.msg22214.html#msg22214

I take it that you are aware that there is more than one DMI "Arctic package"?

Bill Fothergill

@ G man
Way back on the 20th, you were having some banter with Jim Hunt and wrote the following...

Last time I looked the Great Lakes weren't in the Arctic

Now, given that the Earth currently has an obliquity value of about 23.4 degrees, it is certainly reasonable to define the Arctic as anything lying above the 66.6*N line of latitude. (*As the integer between 5 and 7 occurs three times in a row there, would everyone please avoid the temptation to make reference to the Book of Revelation**.){** Dammit, just mentioned it myself!}

Using the Arctic Circle as the standard, we should certainly consider the Great Lakes as being outside the Arctic. However, why stop there?

By the same token we can ignore the following...

The Bering Sea
The Sea of Okhotsk
Hudson Bay
The Gulf of St Lawrence
The White Sea
The Baltic Sea
Most of the Labrador Sea
Large chunks of the Greenland Sea
Large chunks of the Norwegian Sea
A tiny bit of the Barents Sea

So, perhaps the Arctic Circle is not the best litmus test to apply here?

Other commonly used definitions for "the Arctic" include...

The 10 degree C July isotherm, which pretty well maps onto the most northerly extent of the tree line

UAH satellite products refer to the 60N-85N region as "North Pole"

Gistemp use 64N-90N as their "Arctic"

DMI refer to Arctic as anything lying above 60N
See ... http://ocean.dmi.dk/arctic/weather/arcticweather.uk.php

A few hours ago, you continued the good-natured banter by informing Jim that DMI had confirmed that they did not use Great Lakes data in their products. Now, I find that slightly confusing. (Well, to be honest, at my age I find most things to be confusing.)

However, take a look at the animation on this DMI page.

http://ocean.dmi.dk/arctic/index.uk.php

Now, if one runs the animation and looks at the Great Lakes, what does one see?

I'm not saying whether or not DMI use Great Lakes data now, but it certainly appears that they used to use it.

In any case, when considered in the great scheme of things, does it matter whether or not one (or more) of the teams elect to include 5 bodies of water that add up to a tad less than a quarter of a million sq kms?

I'll repeat the question I asked three days ago, but still haven't had a reply...

So that's 5 reporting systems all showing 2015 with either the lowest or second lowest levels of Arctic Sea Ice ever seen at this time of year. To me, at least, that rather suggests two things: that these 5 systems are in reasonably good agreement, and that current levels just might be unusually low.

Perhaps you should spell out the point you are trying to make?

I should have said 6 systems, but I forgot to include Bremen - sorry.

cheers bill f

G man

Ok Jim without naming names here is the exact question/answer I got.question={Hello, A question for you. Do you include Greats Lakes ice in your Arctic sea ice data?}reply=[No, we do not include the Great Lakes ice extent/area in the Arctic package. The resolution of the sensors that we use for global sea ice mapping is too coarse.] Which would seem to dovetail with your link [the old product there were not many ice or open water pixels left in the Great Lakes.] If push comes to shove I would forward the email to Neven for veracity but not for public view.

Jim Hunt

G man - Perhaps you could point your contact at DMI at the answer I received from my contact at DMI last year around this time, and ask for further clarification?

Whilst you're at it perhaps you might remind them that their web site (the bits I'm looking at at least) explicitly refers to "Total sea ice extent on the northern hemisphere" everywhere except in the title of their "new" graph?

http://ocean.dmi.dk/arctic/icecover.uk.php

G man

Jim I'm just having trouble understanding just what is your going on about. As I noted your link appears to agree with the answer I received from DMI. And your link in the latest reply is the same one I've been referencing. Sure it says N Hemi but it says "sea ice". I'm sorry but the G Lakes are not sea ice.

Al Rodger

g man.
(1) DMI use O&SISAF data.
(2) O&SISAF do not document on-line why they include lake ice but their code includes it and their graphics of "sea ice" show the Great Lakes and Lagoda with winter ice concentrations. It also shows a far coarser coverage at ocean shorelines.
(3) Smaller lakes are not shown to be included, probably because the mapping resolution is too coarse.

Jim Hunt

G man - For the umpteenth time, the answer I received said "The Great Lakes are included in both the old and the new version of the OSISAF data".

The verbiage accompanying the "new" version of DMI extent says:

"The plot above replaces an earlier sea ice extent plot, that was based on data with the coastal zones masked out."

If most of the Great Lakes were masked out in the "old version", it doesn't imply they are also mostly masked out in the "new" version. Quite the reverse in fact.

Susan Anderson

Ah Jim, give it up. He's made up his mind and is not interested in the obvious facts which you have repeatedly pointed out. It seems to serve his ideas better to stick with the top layer misinterpretation he prefers. The rest of us can see who has taken a good look and checked the information in more detail and been generous with your sources. Unfortunately, a lot of these shallow thinkers are now in charge in our Congress and prefer their biases (and unfortunately the big money it brings to their "side", never mind the apres moi le deluge selfishness of it all).

G man

Wow that's quite a leap there Susan. Jim you made a reference to DMI using G Lakes ice in their Arctic extent/area graph I inquired directly with DMI and they said they didn't. Who should I believe? Should I believe some guy on the internet or a Project Manager at DMI?

Bill Fothergill

G man

1) Go to http://ocean.dmi.dk/arctic/index.uk.php

2) Click on the graphic in order to step through the years

3) Watch what happens at the Great Lakes

4) Come back and tell us what you see


cheers bill f
PS Still waiting for a response to my questions timed at...
March 20 17:25
March 23 22:10

G man

Bill I see tiny little pixels crop up here and there on the GL's which when compared to other comparably sized areas in the graphic where the colors change uniformly from gray to blue such as S. Hudson Bay. This would leave me to conclude (because we know the G Lakes avg 52.35% http://www.glerl.noaa.gov/data/ice/imgs/IceCoverAvg1973_2014.jpg ice cover)they don't focus on the G Lakes. In 2003 there was 74.6% ice cover and just less than that in 2009. And the graphic does not show anything close to that.

As to your previous ?'s I believe I spelled out my thoughts clearly as to my point.
And sorry your 2nd post is way too long for me as Susan noted I'm pretty shallow :-)

Check this DMI 30yr record of ice concentration http://ocean.dmi.dk/arctic/climatology/nhiceconc.uk.php and tell me what you see in the G Lakes. It would appear obvious that DMI takes the aforementioned oas-sif data and deletes the GL's as the images are fairly close to what Jim and Al Rodger linked to at oas-saf. http://osisaf.met.no/p/ice/nh/conc/imgs/OSI_HL_SAF_201503191200_pal.jpg


Jim Hunt

G man - So should I believe some guy on the internet who talks about things that "appear obvious" or someone from DMI who writes academic papers about sea ice concentration algorithms for a living?

Aren't you even slightly curious about the apparent difference of opinion at DMI?

The climo map you link to says it's "for the Arctic ocean" but nonetheless shows some pretty colours in the Baltic. It's also circular instead of rectangular. Weird, huh?

Bill Fothergill

@ G man

So, that's a DMI produced graphic, running on the DMI website showing varying levels of ice coverage on the Great Lakes - despite the fact that DMI don't use Great Lakes ice data?

Thanks for the link to the other DMI page - it is one I am very familiar with.

However, in case your depth is insufficient to remember your original point ;-)

"I find it odd that NSDIC would say that this the lowest when DMI clearly shows 2011 to be lower and NANSEN clearly shows 2007 to be much lower."[sic]

Jim, Neven and myself have each attempted to provide reasons why this should be entirely unremarkable. For whatever reason, you have decided to ignore everything else, and focus entirely on the Great Lakes.

This is getting like a dog with a bone.

cheers bill f

Bill Fothergill

"So was the central North Atlantic really warmer 100 years ago? Tell it to the Titanic, which went down there, struck by an iceberg. Now tell us how many icebergs are there today. Cheez."

The RMS Titanic was lost on the 15th April 1912, in waters that were long known to be potentially dangerous.

The region to the east of Newfoundland is known in the trade as "Iceberg Alley". During 1912, the total number of bergs recorded in the alley was approximately 1050. (I'm afraid I'm working from a graphic contained in an annual report, and don't have the exact numbers.)

The number recorded in 2014 was, from the same graphic, approximately 1550. That is an increase of close to 50%

The number of bergs recorded for April 1912 was 395. The number recorded as at the 1st May 2014 was 604. Once again, this represents a jump of around 50%.

The maximum number of bergs recorded in Iceberg Alley in any April occurred in 1984, with a jaw dropping 953.

There are many reasons why more ships don't go the way of the Titanic. However, for the purposes of this discussion, we can restrict this to just two...

1) Telemetry from satellites and aircraft is used to create near-real-time maps showing the locations of identified bergs. This gets constantly updated, and is sent to ship's navigators. Armed with this data, the crews of any ships navigating those waters know which particular grid areas it would be prudent to avoid.

2) Despite the best efforts of Harland & Wolff to fit out the Titanic, and her two sister ships, with all the available mod cons - including the new-fangled wireless telegraph from Marconi - radar had not yet been invented.

G man

Bill [So, that's a DMI produced graphic, running on the DMI website showing varying levels of ice coverage on the Great Lakes - despite the fact that DMI don't use Great Lakes ice data?] So Bill you think those "tiny" little pixels in 2003 represent 76% ice coverage? Really? If that's the case then we've nothing further to discuss.

Jim, It's apparent you don't like differing opinions or facts. I'll offer the email up again to Neven. Otherwise adieu.

Cincinnatus

Just to let you know that I did read your interesting and informative posting, Bill F. More good stuff in there than in all of Rahmstorf's comedic paper, cheers.

Bill Fothergill

@ G man

"So Bill you think those "tiny" little pixels in 2003 represent 76% ice coverage? Really? If that's the case then we've nothing further to discuss."

Nope, I absolutely do not think those "tiny" pixels in 2003 represent 76% coverage.

As Jim Hunt has said before, it is important not to compare apples with oranges. Or, if one is doing so, to at least be aware of the fact.

The DMI graphic clearly states it is showing mid February conditions. If one goes onto the Great Lakes Environmental Research Laboratory website, one can access their historic ice charts. Here is their ice chart for Feb 13th 2003...
http://www.glerl.noaa.gov/data/ice/atlas/glice//jpgs/2003/20030213.jpg
(Sorry, that's the closest I could get to mid February.)

You are possibly getting mixed up with GL maximums, which can be seen here...
http://www.glerl.noaa.gov/data/ice/imgs/IceCoverAvg1973_2014.jpg

The maximum coverage attained in 2003 was 74.6%, which sounds remarkably close to the figure of 76% that you have stated.

cheers bill f

G man

Bill you didn't even follow any of my links did you? And it appears you didn't even read my post. I posted the exact link you have just now posted (GL max's) and in the early post had the correct 74.6% cheeeesh man.

Jim Hunt

G man - We're obviously wasting our time here. Bill posted the exact same link that you originally posted in an endeavour to point out to you that you're trying to compare apples with oranges once again. It seems you didn't get the message.

You also seem convinced that "lake ice" has no bearing on your original question about differences between the DMI and NSIDC extent metrics. Having now done your due diligence, what's your explanation for those differences?

Bill Fothergill

Bill you didn't even follow any of my links did you? And it appears you didn't even read my post. I posted the exact link you have just now posted (GL max's) and in the early post had the correct 74.6% cheeeesh man.


1) Oops, sorry. I didn't realise it was my responsibility to check your postings for typing errors.


2) I don't know how many times this needs to be repeated, but the GLERL graphic to which you linked (and I deliberately re-linked) relates to GL maximum values. The DMI graphic relates to mid February.

They....are....not....the....same....thing

In order to do a comparison with the DMI mid February graphic, the equivalent GLERL graphic you should be looking at was the one I posted for 13th Feb, 2003. Here it is again...

http://www.glerl.noaa.gov/data/ice/atlas/glice//jpgs/2003/20030213.jpg


3) Let's re-examine your original post on this thread, shall we?...

"I find it odd that NSDIC would say that this the lowest when DMI clearly shows 2011 to be lower and NANSEN clearly shows 2007 to be much lower."[sic]

If you are now seeing differences between DMI and GLERL, then perhaps this may be an appropriate moment to reflect upon that opening gambit?


4) On the subject of consistency between datasets - and the reporting thereof - you will have hopefully noted that NSIDC, DMI, Nansen, CT, JAXA and Bremen have all shown upward movement, in both extent and area, over the last few days.


5) Staying with your opening comment, you have been presented with a whole list of reasons why various reporting systems would be expected to display minor differences. This has had roughly the same effect as pissing in the wind, as you have subsequently fixated totally upon the Great Lakes, and completely ignored the big picture.


6) You have just complained that ...

And it appears you didn't even read my post.

That is truly rich coming from somebody who opted out of answering a direct question earlier in this thread by saying...

And sorry your 2nd post is way too long for me...

Ah, good old hypocrisy. The words "pot", "kettle" and "black" seem to be swimming in front of my eyes. (Although that could have more to do with the beer last night.)


7) In your second comment on this thread, you flat out accused Jim of sophistry, when it was pointed out to you that graphs could relate to either "extent" or "area", and that these were not the same thing. Instead of taking the time to check for understanding when Jim tried to explain that these were not synonyms, your ill-considered response was...

And area=extent so you're just parsing words with me.

Now, there is absolutely nothing wrong with being unaware of the way terminology can have very specific meanings. As I'm sure happened to many people before me, I initially used to think that "area" and "extent" could be used interchangeably. In the continuing struggle to climb out of my pit of total ignorance regarding the Arctic, at least I'm trying to gradually learn from my mistakes.

Given the appropriate contexts, it is even possible for such meanings to be reversed. Consider the relevance of the words "first" and "second" in each of the following pairs of phrases...

1st degree murder and 2nd degree murder
1st degree burns and 2nd degree burns

Wow! You can take a horse to water, but you can't make it drink.


8) Sticking with your second post, it continued...

It seems as though and alarmist media/activists are yet again crying wolf with headlines like "bad news for ice seals" (btw what's an "ice" seal?) etc.... This looks like another case of the "2014 hottest year evah" well maybe.[sic]

I let the blatant sloganeering go sailing by at the time, because I simply can't be arsed rising to the bait every time it get's offered ("Fish", "barrel", "shooting", if you catch my drift.)

However, I'm starting to have fun here.

btw what's an "ice" seal?

Well, the word "seal", when used as a noun, can have many completely different meanings. However, given the context in which it was employed in the original article, it is perfectly obvious that it was being used to refer to the semi-aquatic marine mammal.

http://www.takepart.com/article/2015/03/19/arctic-winter-sea-ice-2015-record-low-extent-global-warming

Perhaps your confusion stems from the way the word "ice" has been deployed immediately in front of "seal"? In this context, it is clearly being used, not as a simple noun, but as an adjectival noun (or noun adjunct). Therefore, the phrase "ice seal" could be used, quite properly, to refer to that subset of the set of all seals (we're still talking about the semi-aquatic mammal here) that spend much of their time in the vicinity of sea ice.

Alternatively, your confusion could arise from a mistaken belief that all seals live in the vicinity of ice. If that is the case, might I suggest that you look up the term "pinniped", and also that you check out their diverse habitats.

Whilst reduced sea ice levels could indeed be bad news for ice seals, it could also be the case that some cetaceans, such as narwhal and beluga, would actually quite welcome the idea. After all, it would reduce the time they have to spend flaffing about chasing leads (check the context) that actually go somewhere.


9) In case it's slipped your mind, the title of this thread is "Early record, late record". Just how deep a hole are you trying to dig for yourself?


Apologies to Neven and everyone else for the distracting side show. I can't be bothered hitting my head off the wall any longer.


cheers bill f

G man

Loquacious or pedantic much Bill?
cheers

Carex

Mr. Fothergill, I find the loquacity in your post of 3/26/2015 15:39 to informative, lighthearted and enjoyable. An opposed to pedantically being mired in, fascinated with, and blinded by its details, I find that it uses facts and detail to expand the argument and achieve a broader understanding.

VaughnA

Bill, I thoroughly enjoyed your post. I got a couple chuckles here and there but I do have a couple questions/observations...

"btw what's an "ice" seal?"

I was thinking maybe of a generic type of a seal type animal carved out of ice...hmmm....
Or maybe when a waterpipe freezes and it is sealed full of ice. I would consider that to be an "ice seal."

Or even a film of frozen water over the top of soft snow. Now that would be a real "ice seal."

How about an ice arch? Now that could be could be considered to be an "ice seal" now couldn't it?

This is the first I have heard about "ice seals" so I was rather scratching around for an answer and I do like your analysis of "ice seals" as well.

Btw, I like your sign off handle, 'cheers bill f," however I do feel annoyed when someone else plagiarizes it. I mean, really, are sign off handles that limited?

Kevin McKinney

"Loquacious or pedantic much Bill?"

Translation:

"It's only a flesh wound!"

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