Guest post by Steven Goddard
NSIDC Arctic Ice Extent Just a few pixels from “average”.
May 1st is May Day . “Mayday” is a universally understood distress call signifying that an aircraft or other vessel is headed on a collision trajectory. 2009 Arctic ice extent is on a collision trajectory with normal, which could be disastrous for AGW alarmists. “May Day” is an international holiday celebrated on May 1. In the Soviet Union it celebrated the worker’s “liberation” from capitalism, though they hadn’t yet thought up “cap and trade” at that time.
I have more news to report about the ongoing mystery of why NSIDC shows Arctic ice extent much closer to the 1979-2000 average than NANSEN is to the 1979-2007 average. It should be the other way around.
Dr. Walt Meier at NSIDC has again graciously responded to further questions:
Dr. Meier:
It is possible that there could be inconsistency in the Nansen data. I’m not familiar with their processing. I am confident that our dataset is consistent. However, it may simply be due to the ice conditions. Most of the time, the differences between algorithm should be an offset – though this offset can vary over the course of the year (particularly summer vs. winter). However, there can inconsistencies in this depending on the character of the ice cover.
My suspicion is that much of this is due to the Bering. The ice in the Bering is very broken up and, basically, on its last legs. It could be that our algorithm is more sensitive in picking up the ice than the Nansen algorithm. Or it could be that our algorithm is overly sensitive and is not catching open water.
Remember that the threshold for ice extent is 15%. So if you have low concentration ice, even small differences in the algorithms can result in relatively large differences in extent. If Nansen consistently shows 5% less ice that NSIDC, when there is 90% ice, that makes no difference, but where there is ~15% ice, it can make a difference. From other imagery, it looks like there is a lot of area with concentrations in the ballbpark of 15%.
Me:
If it were due to Bering Strait ice, I would expect to see a convergence between the two data sets as the Bering ice melts. It looks to me like they are actually diverging over the last week or two though?
Any ideas from the readers?
UPDATE: Dr. Meier just responded, minutes after posting this article:
Dr. Meier:
It is the Bering Sea, not the Strait and as it begins to melt, with all the old, broken up, sparse ice, you see the divergence. As it melts out completely, I expect that we’ll see things go back to being more consistent.
Addendum from Anthony:
A question to Dr. Meier: When are we going to see a date/time stamp on the NSIDC imagery? NANSEN has one.
This NSIDC graphic above is one of the most widely displayed and quoted on the net today, yet it lacks this most basic feature found in many scientific images presented for public consumption.
I realize the curve itself is marked against the x axis, but it is not easy to determine an exact date. Science is exacting, it would seem prudent to add a date/time stamp. Otherwise, the appearance of exacting science presented to the public is one of sloppiness, IMHO.
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I do not understand the point you are making about current conditions vs. the average. The three typical ways to show this in a meaningful way are seasonally adjust the current number, compare 1 May to past May firsts, or show a long-term graph of the data.
This post does none of the three. With such strong seasonal swings, comparing May first vs. the average tells us little.
The NSIDC data shows the sequential March numbers in an declining trend since 1978, although they provide no statistics to support this visual (hence unrelaible) conclusion.
http://nsidc.org/arcticseaicenews/
Uh-oh.
The Antarctic sea ice extent is running away from the norm and heading towards record territory.
http://nsidc.org/data/seaice_index/images/daily_images/S_timeseries.png
“If it were due to Bering Strait ice, I would expect to see a convergence between the two data sets as the Bering ice melts. It looks to me like they are actually diverging over the last week or two though? ”
The Bering ice has held up well in the last week or two which could be the reason why you see the continued divergence. I think you really need to monitor ice throughout May to conclude one way or the other over the 15% explanation.
As to the 1st of May, is it any more significant that ice extent is likely to reach the average on the 1st of May than it being less than 2007 at the begining of Jan ?.
I think not, unless there is a reason why it is more significant that isn’t mentioned anywhere. Melting in April and May is all about synoptics, there is currently a warm plume in Northern Alaska and a colder Plume on the opposite side, but most important has been the longer than normal continuation of the Polar Jet preventing any real warmth from entering the Arctic Circle, When the Polar Jet does reduce we might see the real Arctic ice situation is like.
I have been keeping an eye on Arctic temps and jet stream patterns. The current conditions are quite cold in the Bering Strait and the prevailing winds are keeping the ice in the Arctic Circle, even compacting it. That includes the Greenland Sea Ice Area as seen in Cryosphere Today. I would believe the crashing into average graph, not the other one. The data supports cold-hard ice conditions, not melty mushy ones.
http://www.athropolis.com/map2.htm
http://squall.sfsu.edu/gif/jetstream_norhem_00.gif
Fabius,
Think about the absurdity of this statement.
“The Stock Market has been declining for 30 years, and is currently at the 30 year mean.”
I think it portends a cooler Arctic, probably because the currents have switched due to the PDO or/and the AMO. I also believe the eruption of Mt. Redoubt will be a contributing factor for the remaining year of 2009 and the Arctic ice will be even greater.
Any bets on how long before they “adjust”?
Please. The call for distress is not Mayday but M’Aide (with an acute accent of the e.
Mayday… Mayday… the rappers are into it now…
Hey Iceberg, you be talkin my language. Whisper more sweet things in my ear. I visit my jet stream favs every day. I have a bunch more that build a picture in my head of the interconnected status of daily weather-related data, as well as longer term possible weather pattern variation. I still occasionally visit cosmic ray and ozone stuff. Those sites have been replaced with daily visits to water vapor sites. I am also trying to find a good site for trade winds that are graphed instead of just tabled. I am also looking for atmospheric dust measurement sites. Got any leads?
Thicker ice melt slower
Fabius,
The chart is doing what you asked. The blue is approaching the grey 1979-2000 average.
You wanted “compare 1 May to past May firsts, or show a long-term graph of the data.”
Your right! They should compare this May 1 to the… wait isn’t that the what is being done? The blue (this May 1) is approaching the grey 1979-2000 average of for May 1. Uhh, I don’t see the problem?
From the previous post on this matter:
http://wattsupwiththat.com/2009/04/29/what-is-normal-arctic-ice-extent/
I’d made a comment that “Dr. Meier makes a good point when he says, ‘The important thing to remember is that there is a good consistent record from the passive microwave data as long as you consistently use the same algorithm and the same processing.’”
The thought has since come to mind that perhaps what NANSEN did was to make an adjustment to their algorithm which was not applied to their archived, older data. If they had done so then the 1979-2007 average would now be lower and closer (if not touching) this year’s mark, much like it is with NSIDC. In making the change last year, it might have been agenda driven or just plain lazy sloppiness. Giving them the benefit of the doubt, I suspect the latter.
Remember, back in December when NANSEN explained how they had made their correction on 22 October, yet changes were obvious from 11 September. Perhaps they did just that; implemented a change to their algorithm on 22 October, then massaged it back to 11 September, then succumbed to laziness and didn’t massage older data. It’s a thought.
(For readers interested in the details of that mess, see: http://wattsupwiththat.com/2008/12/13/something-is-rotten-in-norway-500000-sq-km-of-sea-ice-disappears-overnight/ )
I concur. I don’t see a problem with this graph at all, it is precisely comparing every date within the year to the average for that same day through the time series. Where is the issue here? Granted, I would rather see a time series through the current year (ie: 1979-2008), but, otherwise, its all there!
http://en.wikipedia.org/wiki/Mayday_(distress_signal)
It looks like there are three reasons why the melt is heading towards Mayday: The bowl is plugged with hard ice, the winds are in the wrong direction and lack energy, and the temperatures are witch-tit COLD. The Okhotsk Sea near Russia just outside of the Bering Strait is not getting flushed out of ice and is thus melting very slowly in colder than average water. This is also true of the Barents Sea between Russia and Greenland. Opposite ends of the Arctic and both are under the same conditions. All other areas are near to just above average. These last two areas are rapidly moving towards average due to slow melt.
http://arctic.atmos.uiuc.edu/cryosphere/IMAGES/recent365.anom.region.14.html
http://arctic.atmos.uiuc.edu/cryosphere/IMAGES/recent365.anom.region.6.html
http://polar.ncep.noaa.gov/sst/ophi/color_anomaly_NPS_ophi0.png
I forgot to add the Arctic land temp map to my above post so that you could visit these sites and determine the cause for yourself.
http://www.athropolis.com/map2.htm
Have you seen this chart looks like a baloon being inflated? Perhaps by CO2 🙂
We could be witnessing the decadal (and more?) ups and downs of weather pattern variation here. The Arctic climate will always be the Arctic climate due to seasonal solar angle. That won’t change. But the weather pattern will, particularly during melt and summer season, and by quite a lot. It is understood that lack of summer melt, or slowing summer melt, can (but not always) lead to a mini or major ice age, depending on how long the weather pattern variation stays around, gets worse, or becomes locked with similar weather pattern variation indexes that bring changes South of the Arctic circle.
Cool stuff. Or rather “cold” stuff.
Quote of the week?
Steven Goddard (09:04:06) :
“The Stock Market has been declining for 30 years, and is currently at the 30 year mean.”
And Pamela, at the risk of being less than politically correct, or even snipped, might I compliment your feminine attributes in your many fine contributions.
Or something like that?
Off Topic, but Jim Cripwell, if you are going to correct people, then correct them.
It’s M’aidez!
No fo pah should go un attended.
Anthony, there are very strange things in this world, apart from the fact that no return on the accounts of Arctic ice …
You know that I follow the cheerful vicissitudes of Sidc , and even in April, the Belgian center is manifested always more dependent of the Catania observatory in counting sunspots!
Those who dont’t like that the north pole is in recovery, are probably the same which don’t love thefact that the sun continues to sleep so deeply!
no observatory in the world had seen the sunspots of solar April 6, except the usual … Catania and Sidc it counted …
Please read here, Simon:
http://72.14.221.132/translate_c?hl=it&sl=it&tl=en&u=http://daltonsminima.wordpress.com/2009/05/01/incredibile-il-sidc-ad-aprile-conta-2-giorni-con-macchie-piu-del-noaa-ed-eguaglia-lssn-con-12/&prev=hp&usg=ALkJrhiW4Y_91ycsdwEv0R5igius7XkJ2w
What about the Baltic?
I have long wondered why the separate pieces of the University of Illinois ice charts at Cryosphere Today fail to add up. Their main tally is “Northern Hemisphere Ice” – of which the Baltic is a part.
I would place the Bering Sea in 3rd place.
After the Baltic and the Sea of Okhotsk.
Throughout the winter – most of the ice anomaly was due to the later areas/
I wonder, if algorithm differences can make such significant variations… concerning the data going back to 1979, and considering the extraordinary developments in computing in the intervening thirty years, are the data consistent in terms of algorithmic interpretation? Are the same algorithms now used to interpret that data? Is it done retrospectively? Or are we relying on data interpreted by divergent algorithms as they themselves have become more sophisticated?
A clarification from Dr. Meier or anyone else would be appreciated.
Pamela Gray (09:03:55) :
Excellent point.
From your watching of the jet stream would you say that the general trend over the last few years has been towards the eqautor?
Do you have/know of any time lapse graphics that would show the trend?