500,000 km2 Discrepancy Between NSIDC and NORSEX

Yeah I know, but what else they gonna call em? ‘hide the lack of decline’ functions?

In relation to this comment:

This is a question I have never once seen brought up before. For many many years, I have seen the question about the June blip on the ice chart. And I have seen it patiently explained many many times. Since the june blip is explained by a change in algorythm each year on that date, that implies to me that they change the algorythm back on some other day. My question is…why is there not two blips per year?

If you are referring ot the IJIS Website extent linked on this website on the side panel, there is both an explanation and has been pointed out that there are two blips:

The current version of data processing produces an erroneous blip of sea-ice extent on June 1 and October 15, which is seen in the graph of sea-ice extent as a small peak on these dates. The apparent blip arises due to switching of some parameters in the processing on those dates. The parameter switching is needed because the surface of the Arctic sea ice becomes wet in summer due to the melting of ice, drastically changing the satellite-observed signatures of sea ice. We will soon improve the processing to make the graph much smoother.

The second blip is there, however while the first one is a slight bump making it stand out, the second is a slight leveling off and is harder to see unless you know exactly the date to look for.

I’ve seen animations on this website showing the transport of ice out of the Fram Strait. Given that the AO index has been strongly reversed this year I was wondering if anybody knows whether ice transport is affected.
I ask because using Cryosphere Todays comparative tool it looks like ice concentration in the central part of teh Arctic Ocean is quite high and seems fairly stable through this winter.
I’d also be interested in knowing whats going on with regerd winds and storms given the change in the AO index.
Just some things i’ve been thinking about recently, any help would be appreciated.

HR,
The -AO does help hold the ice in as opposed to the +AO conditions. This is one reason I think we’re likely to see a rebound again on the minimum extent. The AO rose back to around neutral for a good chunk of March and early April, but then fell back negative for the latter half of April. But more importantly, the winter time AO was massively negative and that seems to have a larger correlation with year to year minimums than the temperatures. There’s still other factors that could prevent a rebound such as an extremely anomalous wind pattern that brings both warmth and accelerates ice through the Fram Straight which is what likely helped the 2007 minimum get as low as it did in addition to that 2006-2007 hugely +AO in the winter leading up to that fateful summer.
People are tracking each fluctuation this spring in the ice extent, but it doesn’t mean much as there is a bottleneck in ice extent for all years in late May and early June. Unless we see an obvious outlier from that bottleneck this year, then the real tracking will not begin until late June or July. The extreme -AO this past cold season has kept more multi-year ice in the Beaufort Sea and adjacent Arctic basin than any of the past few years which is why I (and some others who may have mentioned this) are arguing for a decent chance at another increase. A lot of ice was caught up in the Beaufort Gyre this past winter.
But as mentioned before, there’s always other factors to consider, and if they conspire enough against the more dominant -AO factor, then we could see it negated and a drop this year from 2009.

Haven’t see Rush Limbaugh speaking to the fact that the arctic sea ice is now below last year’s level, yet he was so quick to report on the March “bump up” and touted the sea ice was still growing in early April when the winter maximum had been reached on the last day of March. What gives? Could he be biased? 🙂
REPLY: I dunno, could you be?

Phil,
I’d need to see good evidence of your claim before taking it to heart. You might be right, but I have a hard time believing that one month of neutral AO conditions negated a record -AO winter which was 3 months. The report from the NSIDC said that the flow of ice out of the Fram Straight increased in March compared to February…but that is not saying much since February had such little flow out of the Fram Straight…so of course there was an increase. But overall, I didn’t see anything like the flushing that occurred in 2007, 2008, or even 2009 (which was definitely less than the 2 prior years….coincidence that the ice extent increased again?).
You’ll have to provide me a good source of multi year ice that shows that March brought us all the way back down to levels seen in 2008 before I take your claims seriously. This is not a knock on you, but just simple quality check on data claims. Its almost impossible impossible for multi year ice that got caught up in the Beaufort Gyre in February to be flushed out of the Fram Straight by now…it doesn’t work that fast which is likely why the hugely -AO winters have produced higher extent minimums like 2001 and 1996. There are other factors too, but assuming those are fairly “normal” this summer, then we’ll expect a bump back up in extent.
The beauty of this debate is we do not need to wait a decade to see the results, we just need to wait a couple months to see the wind patterns and the ice extent numbers to see what it happening. And no, I don’t think that volume graph from UWAS is very reliable since its a model and not an observation. But regardless, we’ll find out soon enough…I think roughly 3 months time we’ll know about the state of this year’s ice.

There are several problems associated with the current satellite sea ice measures, apart from sensor degradation. The raw data from the sensor is processed multiple times before the final graph is produced and each process step involves assumptions about what the the expected result should be. Particular problems exist at the fractal sea/land boundary, and during the annual melt season, when liquid water on the surface of the ice distorts the results.
As in many thing related to climate metrics, none of the production sea ice area and extent graphs are absolute metrics, rather they are best estimates of what is happening in a highly chaotic, multi-variant system at a moment in time. No surprise, perhaps, when differences to the various estimates disagree.

NORSEX baseline is 1979-2006…NSIDC uses 1979-2000.

I ain’t no genius but having worked as a Test Engineer in high end technology I will postulate that a single sensor reading with multiple corrections will pick up an error tolerance (in ALL circumstances) of at least 3%. I believe ice data is ‘measured’ by pixel count? Best guess at such a ropey technique 5%. So you are studying noise. Fascinating how it goes up and down and down and up and up and up and down.
Suggest you stick the alarmists in a canoe and tell them to paddle the Northwest Passage this summer. Should have a very pleasant and quiet winter without them.

“”” Bruce of Newcastle says:
May 4, 2010 at 10:57 pm
@george E. Smith “well I guess uranium is only 18.95 ; so i guess it would just float like a feather for ages, in the atmosphere”
Yep. Half life for ordinary dust is about 1 year at 20 km altitude. Depends how high up it goes and how small the particle size it is. Likewise it depends on what the U is in – if in iron ore particulates, or in dirt (we also had a few big dust storms late last year), then the specific gravity of the particles is a lot lower, so they’d stay up longer. “””
I believe the post said that “lots of depleted Uranium” had been blown up into the atmosphere. Would you explain how it is that depleted Uranium becomes entangled with iron particles ?

So we have conflicting data. This does not surprise me. Techniques for measurement of climate change are inadequate. Sure, the climate will change; it always has, especially through this last ice age. But if we don’t have hard data, predictions are futile. Combine that with our lack of knowledge of how the climate is driven and our predictions are little better than guesswork. Given the past record of climate, all we can say with some reasonable confidence that the next Ice Age is heading towards us. Will it be in this century or in the next 500 years or maybe not for a couple of thousand years? We don’t know but my bet is that it is coming. What happens in the immediate future will have no real impact – we can adapt to a slightly warmer world. Adapting to an Ice Age will be a serious problem.