Wednesday, September 05, 2007

The Northwest Passage is open

and it looks like the Northeast Passage near Siberia will soon open. Has that EVER happened?

72 comments:

Anonymous said...

Actually Eli, if you look at the anomaly graph it looks like the ice might be past it's minimum and some refreezing is taking place.

The record low is still staggering at 3m km2 or thereabouts.

Fergus said...

Much more detail is visible here:
http://www.seaice.dk/iwicos/
You can even make your own picture up. Includes today's satellite runs.

Even the NH overview image (which enlarges nicely once it's loaded) shows that the NE passage is but days from opening. This would match the Kara/Laptev continuing decline documented on CT.

Enjoy the new toy.

Fergus said...

Has that ever happened? There is no record of it. It might have, along time ago...

Anonymous said...

Sigh...

Eli, Eli, Eli. Eli.

Don't you know the surface stations up there are sited next to polar bear dens, violating standards, and this means the record is contaminated and how can we be sure the ice is really melting anyway?

You know as soon as all the digital snaps of the polar bears are done the ice will refreeze and your alarmist buddies will have to find another chicken little cause to alarm us about.

Really now.

Best,

D

Anonymous said...

According to this article
"The minimum extent of sea ice usually occurs late in September each year, as the freezing Arctic winter begins to bite."

That's why they predict the north-east passage may yet open this year.

In a very real sense, the ice melting (in arctic and antarctic) is the critical factor with regard to climate change and all the talk about temperatures in the US lower 48 makes no difference whatsoever .

To ignore the ice melting/breakup and to concentrate on the .15C error that Hansen made is clueless and/or dishonest.

But that is who we are dealing with, clueless dishonest people.

Deech56 said...

Meanwhile, the CA folks are grubbing through the numbers doing, as one put it, "hero's work."

Munin said...

E pur si squaglia.

Anonymous said...

Yes, happened in 1904 and also 1942. Probably happens several times a century except during the little ice age. More often in MWP of course. Nothing special.

Adam said...

"Actually Eli, if you look at the anomaly graph it looks like the ice might be past it's minimum and some refreezing is taking place."

An up-turn in the anomaly graph does not necessarily show refreezing. It shows that the current rate of melting is now lower than the average rate of melting, but the total area may still be reducing. You need the actual extent graph to see if refreezing is occurring.

Anonymous said...

" Anonymous said...

Yes, happened in 1904 and also 1942. Probably happens several times a century except during the little ice age. More often in MWP of course. Nothing special."

What are the source(s) you used to make the above claim? Are we talking walking over ice, ice breakers or what?

Anonymous said...

Whether the NW passage has ever been open before is not the essential issue. That issue is that ice in the arctic is disappearing at an alarming rate and may be completely gone within 23 years!

I suspect Anon 3:59 knows that.

Anonymous said...

1904 was around about the time that Amundsen set off for his successful journey through the passage, it is noted that he took a few years to make the full journey and if you read the accounts of his trip then it becomes obvious that is by no means "open" during that time. Amundesn's journey speed was extremely slow owing the the laborious nature of finding a clear route through the ice. I've read that his ship could only travel in the small channel (few feet wide) of clear water that adjoins the islands and land in that region in the summer.

There were successful trips made through the passage in 1940 and 1944 but these used an ice fortified schooner, and there was much doubt as to whether this ship would survive being trapped in the ice. It really isn't clear from these accounts that their journey was easy - which might have been suggestive of it being "open".

In conclusion, I can't see the origins of the claim made by anon 1.59 am and I am left believing that the post is wishful thinking. Maybe a source of the claim would clear this up.

EliRabett said...

What was really interesting to me was the NorthEAST passage opening. I knew of Amundsen (everyone reads the Wiki right?) and that was one difficult trip, but going by Siberia???

Anonymous said...

navigation of the northeast passage is nothing new, but again, that's not the real issue.

Fergus said...

I thought you were asking if both had been open at the same time; don't think so. Someone contradict me. Next year, I'm going to sail my dinghy around the last iceberg in the Arctic. Do the team at the Pole have water-wings?
:)

Anonymous said...

Whether the NW passage has ever been open before is not the essential issue. That issue is that ice in the arctic is disappearing at an alarming rate and may be completely gone within 23 years!

Completely gone? Source?

Fergus said...

Eyes.

Anonymous said...

"completely gone" as in "completely ice free in summer".

here's the source that I listed above.

Hank Roberts said...

> An up-turn in the anomaly graph
> does not necessarily show
> refreezing.

The definition of ice cover is more than 15 percent ice -- so an upturn could also be an area that used to be an expanse of mostly blue water plus one large sheet of ice, if the ice broke up and spread out.

Breakup of floating ice is a big problem for the instrument people.

Has anyone seen anything from the North Pole webcams since early August? Both had tipped somewhat (each views the other) back then and I have seen no new imagery since.

Hank Roberts said...

> North Pole webcams
Here's a different source page that has more current images:

http://www.arctic.noaa.gov/npole/gallery_np_selectall.php

Anonymous said...

Try looking it up in wikipedia and references. Its not particularly unusual at all. There have been quite a few times its been done.

Now, is there a problem, not with this, but with Artic ice in general?

I don't know. The argument started about the NW Passage, and the NW Passage is not an issue. Other things may or may not be.

Its like crying fire, and then when they point out there is none, you say, well, there's a flood.

Make up your mind what the problem is!

Dano said...

Its like crying fire, and then when they point out there is none, you say, well, there's a flood.

Anon, let us know when you, Galileo-like, travel up to the Arctic and prove the satellite pix wrong and publish a paper showing the world that those badbad scientists are crying fire (the old marginalization phrase of a few years ago was 'Chicken Littles', ahhhh, those were the good old days), your paper being complete with historical data showing previous passages and the ice thickness being no thinner than it is today and all that.

Best,

D

Steve Bloom said...

OT, Eli, but here's an opportunity for some snark directed at Ms. Byrnes. I haven't checked her site for amended views.

Anonymous said...

Anon 11:29"I don't know. The argument started about the NW Passage, and the NW Passage is not an issue. Other things may or may not be."

That's right, we won't have to worry about whether the NW or NE passages are free in the not too distant future -- because the whole damned arctic will be free of ice in the summer.

If you can't put 2 and 2 together in this case and see how the NW passage being free of ice might relate to a broader pattern of melting in the arctic, then I sure as hell can't help you (and i suspect that no one else will be able to either)

Anonymous said...

dano said (in part):

"complete with historical data showing previous passages"

well, here is the first guy to do it, in 1878-79. really, there is nothing terribly unusual about this. do your own research.

http://www.bartleby.com/65/no/NordnskNAE.html

Anonymous said...

By 2010 every single bit of ice will be gone in both winter and summer, forever. We must do something now!!!

Anonymous said...

Anon 4:34, put a sock puppet in it, why don't you.

Dano said...

Anon (er...Galileo) @ 4.12:

Write it up. Prove the alarmists wrong. Get back to us when you're rich and famous after Heritage feeds you on their Victory Tour.

Best,

D

Anonymous said...

My view is, this is evidence based stuff if its anything. Now, people cited the ability to go through the NW Passage as if it was something strange new and dramatic, and therefore a sign of catastrophic global warming. However, the NW Passage has been clear fairly frequently, there is nothing unusual about it, and so, while there may be something going on in the Artic, this is not germane to it one way or the other. Rather as if I say that theres a strong hurricane brewing this month. Yes, it happens. It does not mean much one way or the other. It would not have meant anything if the passage were closed, which it mostly is and has been.

Question: what about the ice generally? Well, we know there has been Arctic ice melting, and also Antarctic ice buildup. Is there anything more than a temporary regional phenomenon? I do not know. I don't think you guys do either. But I doubt it. I am sure the extent of Arctic ice in the medieval warm period was smaller than now, and in the little ice age bigger than now. Is it alarming? Not really.

It is normal for the Arctic ice to recede and grow. It would be very very strange if it were to stay exactly the way it was in 1955 or whatever the magic year is that you think is 'normal'. It would be even madder to engage in large scale global climate engineering to try to fix the climate in this magic year. Get used to the fact that climate changes. Focus your efforts on establishing bands for the change, over which you'll accept that something abnormal is happening.

At the moment you are behaving like a chap who weighs himself 10 times a day and worries about how to stabilize his weight so it stays constant through the day. Get used to it, as we eat and drink and sweat, its going to vary.

Fergus said...

Heads up; update..
http://fergusbrown.wordpress.com/2007/09/07/all-the-way-around-the-arctic/

EliRabett said...

Such trips as there were through the NW passage were multiyear affairs with overwintering trapped in ice and lots of despair. Lots of ships got crushed and lots of people died. The NE passage was the same. This looks like a whole other glass of ice melt.

During the European Warm Period there were expeditions to the far north, and I don't think any of them ever got to Alaska or even close. The evidence is that the Arctic ice pack is collapsing.

Anonymous said...

However, the NW Passage has been clear fairly frequently, there is nothing unusual about it, and so, while there may be something going on in the Artic, this is not germane to it one way or the other.

This is bullsh*t. You don't know what you are talking about. You are full of sh*t. Balderdash.

Let's see your journal paper with your evidence. Let us know when the manuscript gets submitted so we can start a pool on how fast it gets rejected.

Best,

D

Anonymous said...

Anon 4:58: "Well, we know there has been Arctic ice melting, and also Antarctic ice buildup."

The part about Antarctica is just plain wrong. A recent gravity survey of Antarctica the GRACE satellite found a net ice mass LOSS from Antarctica

"The researchers found Antarctica's ice sheet decreased by 152 (plus or minus 80) cubic kilometers of ice annually between April 2002 and August 2005." -- from NASA press release linked to above

Anon 4:58 continues: "My view is, this is evidence based stuff if its anything"

It certainly appears that what you are claiming is purely "opinion based" -- and that you have no idea what you are talking about.

but don't let that get in the way of your posts in the future. I'm sure it has not so far, at any rate.

Anonymous said...

The Northwest Passage is open

umm that's good news innit?

Anonymous said...

"innit"?

Some of the comments here seem to have degenerated to the junior high writing -- and logic -- level.

Then again, I guess that is what is to be expected from junior high students.

Anonymous said...

anon 4:58 said:

"The part about Antarctica is just plain wrong. A recent gravity survey of Antarctica the GRACE satellite found a net ice mass LOSS from Antarctica"

the "recent gravity survey" you show is 2002-2005, with an uptick at the end. have you seen anything which shows 2006, and early 2007? i haven't, but regardless, a 4 year trend is not "climate change."

Anonymous said...

Anon 12:53

What a pathetic non-response.

Anonymous said...

the "recent gravity survey" you show is 2002-2005, with an uptick at the end. have you seen anything which shows 2006, and early 2007? i haven't, but regardless, a 4 year trend is not "climate change."

Nonetheless, it shows that claims about Antarctic ice BUILDUP are full of sh*t.

Best,

D

luminous beauty said...

"the "recent gravity survey" you show is 2002-2005, with an uptick at the end."

The up-tick is only in the thumbnail on the web-page. Click on the image to see the full graph and after some summer-winter '04-'05 mass accumulation it goes way down by late spring 05.

stevesadlov said...

Ask Wrong Way Flanagan about that East passage. Maybe go and ask him a couple of months from now, after he's been ice bound for 9 or so weeks.

stevesadlov said...

What was the nature of the adjustments made to either data or algorithms used by NSIDC/Cryosphere Today earlier this year? It's always been a tricky thing, trying to turn the outputs from passive microwave based satellite raw data into actual areal extent estimates. It's especially challenging during the late Spring through early Fall time frame. The biggest challenge is dealing with the range of spectral characteristics that the various types of ice, various surface types, etc result in. If there is snow cover over the ice, which melts as high summer approaches, that can also throw a wrench into the works. The image in this blog, is essentially a conservative minimum value. Another area where quality control is badly needed.

Anonymous said...

And of course Steve, this would make such a huge difference as to totally change the all significance of both the event and the trend. You're grasping a straws thinner than a Siberian river in late fall...

Steve Bloom said...

Sadlov, there's a good chance your fellow denialist (you didn't know that?) Flanagan will get through. It's dangerous for a small boat even when clear (since the ice can blow back in very quickly), and he says he can't afford to over-winter, both of which are good reasons for him to try to get the short lift through the worst patch so as to be completely out of the Arctic by the time the ice starts to re-form comprehensively. The irony to all of this is that if he had chosen the usually much more risky Northwest passage he'd already be on his way home, but since he had to make the route choice two years ago who can blame him for guessing wrong.

Regarding NSIDC, email them and ask. Be sure to mention that you've been calling them liars for the past few weeks all the while you've been insisting that the ice is starting to recover. But that's OK, like a stopped clock you'll eventually be right.

Anonymous said...

One continues to be amazed at the emotionality and anger and straightforward abuse that appears when there is any questioning of the doctrine of AGW.

Steve B, as an example, the use of the term 'denialist' is counter productive. It implies that the person to whom it is applied must be in bad faith and simply wilfully denying incontrovertible facts. This is not what is going on, some of us are simply not convinced by the 'evidence' that has been supplied.

I would welcome a series of clear statements from someone on Arctic ice. Like roughly the following:

How much variation in Arctic ice do you think is normal measured over 1,000 years or so?

What do you think a level of normal, non alarming shrinkage would be?

What do you think a normal, non alarming growth would be?

What makes you think the current shrinkage has exceeded what is normal for such a period?

Where do you think the extent of the ice was during MWP? When the Vikings colonized Greenland?

The onus of proof is on people who think something catastrophic is happening. It is not going to be met by emotional abuse. What is going to happen is that we will all just turn off.

Remember, we have had one example already of a truly idiotic proposal also advocated with great emotion and vituperation. It was Kyoto - a series of proposals designed to cost a bomb and achieve, even in its own terms, almost nothing. And yet, anyone in the least sceptical of its merits met with wild abuse. You guys do not have a very good track record on soundness.

luminous beauty said...

Anonymous @ 1:13

What's amazing is the whininess of denialists at being called denialists.

Are you not convinced by the evidence that the extent of artic ice is apparently crashing in the present era?

What significance does historical advance and retreat of artic ice extent, for which there is no evidence of the kind of dramatic crashing we are presently seeing since the early Holocene, have in countering the direct observation that artic ice extent is crashing now? The magical hand-waving of 'MWP' just doesn't cut it. There is no (zero, zilch, none, nada) evidence that global temperatures in the MWP were as high as they are now. In fact, there is considerable evidence the MWP was not a global phenomenon, but a regional feature largely confined to western Eurasia and eastern North America. The similar hand-waving argument that current global warming can be explained by natural variation, also fails to provide a convincing physical mechanism to explain exactly what natural features may be causal.

If you cannot believe the evidence of direct observation, what kind of evidence would convince you? If you don't think the principles of physics are causative of worldly phenomena, what principles of causation do you propose?

Something is happening. The onus is to provide a scientific explanation for what it is that is happening, and to use our best understanding of that explanation to project, as best we can, what the future consequences of that something mostly likely will entail. Whether the ultimate consequences are catastrophic depends on how diligent we are in expanding our understanding and addressing that something. To say there is no cause for alarm, that the potential for damaging consequences to human civilization and the biotic well-being of the planet upon which human civilization depends do not and cannot exist, is a head-in-the-sand reaction which only ensures that something will never be properly addressed. Denialist is therefore an appropriate descriptor.

As you use the terms, 'Alarmist' and catastrophic' are strawmen. You are projecting your own emotional horror at the thought of climate change being the consequence of human activity on people who are trying to make an objective assessment of phenomena that are evidenced by both observation and scientific theory. You reject the evidence and the supporting scientific explanation because you don't want it to be true, not out of any objective concern for making certain that the science is right. You find the message too scary to contemplate, so you denounce the messenger. That is a head-in-the-sand reaction, and denialist is an appropriate descriptor.

Anonymous said...

Anon 1:13 "You guys do not have a very good track record on soundness."

You guys?

That's a pretty broad brush (roller?) you are using.

I would welcome a clear statement of precisely whom are you addressing.

Anonymous said...

This post would be aptly termed "The Northwest passage is now open for business".

Ironically, the business that it may facilitate (oil and gas transport from the acrtic) could actually accelerate the melting in the arctic.

As an article in the Guardian put it
"It has long been expected that Arctic sea routes including the North-West Passage and its north-east counterpart along the coast of Siberia will become more passable as the Earth's temperature climbs.

Both are considered strategic cargo routes because they are shortcuts between the northern parts of the Atlantic and Pacific oceans."

By the way, barely navigable over some time period is hardly equivalent to "open" -- as some have indicated above, questioning the meaning of the current condition of the passage.

This is the obvious (as in the "nose on your face" obvious) link between what is happening to ice in the Northwest Passage and what is happening to the arctic ice as a whole.

Horatio Algeranon said...

"The Northwest Passage is open
umm that's good news innit?"

That depends. There are passages and then there are passages.

Anonymous said...

Nice plot:
http://nsidc.org/news/press/2007_seaiceminimum/20070810_index.html

jon

stevesadlov said...

You can always count on political activists like Bloom to go into smear mode. It's their comfort zone. I digress .... I've called no one a liar.

I am questioning methods, not people. Does it matter? I don't know. If passive microwave has a 1% problem, in summer, then no. If it's a 10% problem, it's interesting but not critical. If it's a 30% problem? Big problem. No one knows. We should know. Data. Quality. And dare I say ... Sigma.

Dano said...

I am questioning methods, not people. Does it matter? I don't know.

So what. It doesn't matter that an ideologue has questions.

Decision-makers are briefed by the people doing the work, or by their staffers who have done their homework by reading the people who do the work.

Staffers or decision-makers don't read blog comments to look for ideologues who have many quibbling questions but few explanations of their own, nor do they look to ideologies that have nothing more than quibbling questions and no hypotheses, models, papers, equations, data, thoughts, scribblings on napkins.

Any decision-maker worth their salt doesn't fall for such transparent tactics. Puh-leez.

Best,

D

Hans Erren said...

EG how much do aerosols cool?

stevesadlov said...

NSIDC uses a criterion of 15% concentration to depict ice versus open water. Cryosphere Today is somewhere in that range as well. The methology is to look at the pixels of remote sensing data (using passive microwave sensing) and all neighboring pixels to each given pixel. Integrals are performed and concentration approximated. So here is a question. NOAA, using a different paradigm (I believe, but may be mistaken, it's a combination of MODIS and other IR data) show 70 to 90% concentration ice making contact with the NE shores of the Svalbard group. And yet, in the image shown in this blog (Cryosphere Today) some 100 or more Km of open water (e.g. which would mean, if accurate, l.t. 15% concentraion) is shown there. How can this be?

Anonymous said...

Steve Sadlov said: "The methology is to look at the pixels of remote sensing data..."

Methology?

"Integrals are performed and concentration approximated."

Boy, that's some pretty fancy terminology you're throwing about.

"NOAA, using a different paradigm (I believe, but may be mistaken...

Steve, may I suggest that you go look for a clue and come back after you have located one?

stevesadlov said...

Anon 7:19PM, please answer the question. How can this be? How can one depiction show 70 - 90% concentration up to the NE shores of the Svalbard Group, while another shows over 100KM of open water?

Anonymous said...

It's "methodology", Stevieboy -- and it's obvious you have no clue what that is.

Dano said...

Sadlov,

Instead of trying to sow doubt by asking fancy-sounding questions, why don't you e-m the authors and get back to us with their answer.

I've given the general format before over at CA.

Let us know how you do.

Best,

D

stevesadlov said...

RE: Anon 5:18 AM - So, you therefore admit that methodology differences can result in differences in the depicted areal extent. Oh, and shoot me about my typos. According to you, typo rate is inversely proportional to IQ. "Interesting" theory. I'll leave it at that.

Dano - this seems to be sort of a sensitive topic. Otherwise, you'd not have taken the time to comment / disparage / smear.

Anonymous said...

"According to you, typo rate is inversely proportional to IQ.'

I see.

Stevie boy said above:
"NOAA, using a different paradigm (I believe, but may be mistaken, it's a combination of MODIS and other IR data)"

In other words, you have no clue what their "methodology" is.

I'll leave it at that.

stevesadlov said...

http://nsidc.org/data/docs/daac/nsidc0051_gsfc_seaice/TM104647.html

"The algorithm to obtain sea ice concentration employs three of the ten channels of the SMMR instrument: vertically and horizontally polarized radiances at 18 GHz and vertically polarized radiances at 37 GHz. Before computing sea ice concentrations, isolated missing brightness temperature pixels on the daily brightness temperature maps were filled by spatial interpolation. Larger areas of missing data were filled later by temporal interpolation of the sea ice concentrations."

"Gloersen et al. also describe the corrections used for a long-term drift in the SMMR data and for errors related to ecliptic-angle that were observed in the 8.8 year data set. These and other errors had been accommodated in the sea ice concentration data set used in the Gloersen et al. monthly averages without also correcting the gridded radiances. Since the publication of Gloersen et al., some additional errors have been identified in the gridded brightness temperature data set."

"The next step in preparing the data sets was the correction for land-to-ocean spillover (often referred to as "land contamination") and residual weather-related effects. Land-to-ocean spillover refers to the problem of blurring sharp contrasts in brightness temperature, such as exist between land and ocean, by the relatively coarse width of the sensor antenna pattern (Figure 1a). This problem is of concern here because it results in false sea ice signals along coastlines. (Land and ice both have much higher brightness temperatures than ocean.) The method used to reduce the spillover is an extension of the method employed for the single-channel Nimbus 5 Electrically Scanning Microwave Radiometer (ESMR) data in Parkinson et al. (1987). The rationale behind the approach is that a minimum observed (generally in late summer) sea ice concentration in the vicinity of coastlines where no ice remains offshore is probably the result of land spillover and is thus subtracted from the image. To reduce the error of subtracting ice in areas of ice cover, the technique searches for and requires the presence of open water in the vicinity of the image pixel to be corrected."

http://ieeexplore.ieee.org/iel5/9010/28604/01294432.pdf

[Ref - entire paper. Sadlov.]

http://www.giss.nasa.gov/meetings/seaice1999/session5.html

"Amongst the highlighted concerns were the huge scarcity of data for the pre-satellite period, especially in the southern hemisphere, and the difficulties of merging data sets from different sources (including different satellite instruments, even when of the same type)."

"For instance, for the satellite era, the wintertime ice charts of the National Ice Center are being adjusted to match more closely the passive-microwave ice concentrations, and the summertime apparent "meltpond bias" in the passive-microwave data is being adjusted for through comparisons with the National Ice Center charts. The preliminary homogenized blend in the Southern Hemisphere now yields no trend in sea ice coverage, in contrast to the earlier downward trend suggested before the homogenization."

"He also explained differences between the ice concentrations of the National Ice Center and those of Nomura/Grumbine and the difficulty, in view of the lack of validation data, of knowing which values are closer to being correct. Problems appear to be particularly large in summer, highlighting the need to get an improved handle on meltponding and on understanding how the meltponds impact the satellite sea ice signatures."

"She illustrated how well the passive-microwave data can reveal the large-scale location of the ice edge but discussed also the greater uncertainties in deriving ice concentrations and the difficulties arising from such phenomena as "land contamination," produced because data for coastal ocean areas are contaminated by radiation from the adjacent land, resulting in a miscalculation of ice along the coasts. The problems with land contamination become especially apparent in time series spanning different satellite instruments and hence must be adjusted for in order to create consistent, merged data sets."

"Kim Partington mentioned that in comparing the National Ice Center ice charts with ice concentrations derived from satellite passive-microwave data, he has found that in some regions the passive-microwave data appear to underestimate ice concentrations by as much as 50%, perhaps because of interpreting meltponds as open water. Don Cavalieri agreed that the passive-microwave data have errors introduced by meltponds but expressed greater concern with the National Ice Center's policy of sometimes inserting assumed ice values in preference to calculated values with high error bars. Peter Stone questioned Parkinson about the satellite-derived ice extent trends, and she reiterated the importance of having done the trend calculations with different definitions of the ice edge, showing that the trend values at least are robust with respect to whether the ice extent is defined based on a 15%, 20%, or 30% ice-concentration cutoff."

[Just a note - no doubt, some progress has been made vis a vis dealing the the melt ponding (e.g. ponds on top of the ice) issue. But there is no perfect solution to it. As for the land contamination problem, there is a danger that actual ice near land is being arbitrarily excised. Sadlov.]

http://www.tos.org/oceanography/issues/issue_archive/issue_pdfs/6_1/6.1_barry_et_al.pdf

[Is black body the correct assumption? Or should it be grey body? What is the maximum error bar due to emissivity variation of bare ice? Of snow covered ice? It is commonly assumed that sea ice is snow covered. How valid is that assumption? Side note - there is some excellent general info from the oceanographic / cryological perspective in this paper. The comments about differences in open water within the pack are fascinating, especially in light of the apparent characteristics of this summer's remaining ice pack. Sadlov.]

http://www.ghrsst-pp.org/GHRSST-PP-Sea-ICe-Technical-Advisory-Group-(SI-TAG).html

"However, the ice-mask requirement for SST does not require the retrieval of ice properties, but merely identification of the presence of ice in particular infrared pixels. Increasingly strict timeliness constraints apply with increasing resolution. Ice drift velocities may well exceed 0.1 ms-1, which implies that the ice may move in excess of 2 km (pixels) within one six hourly update period, Figure 1 shows an example. The most likely solution to the ice masking problem for the high resolution infrared sensors is therefore to mask based on contemporaneous information with a suitable resolution available within the data stream of the satellite platform. Currently, this is restricted to visible bands."

"The microwave ice retrieval has difficulties distinguishing sea ice in conditions that include high cloud and/or rain."

"Techniques that combine the information from microwave and infrared data should be explored. In that respect one should be very aware of the shortcomings of microwave observations, the most relevant of which are the reduced sensitivity to thin ice types and land contamination."

"Figure 3 shows an example of the thin ice problem in the Davis Strait region, where the OSISAF ice edge product fails to detect a considerable amount of sea ice. The ice concentration product clearly does better and retrieves some, but not all, of the sea ice that follows the coast in the Southwesterly direction. This region was shown by Agnew and Howell (2003) to show particularly large discrepancies between ice charts and passive Microwave products. The Sea of Okhotsk is another prominent area affected by large concentrations of thin ice (Cavalieri, 1994). Andersen et al. (2006) shows that the atmospheric correction of the microwave radiances may improve the detection of thin ice."

[In the case of the Sea of Okhotsk, this is indeed an issue. Some of the "thin ice" in question is sufficiently robust to allow fur seals to safely rest on and traverse the ice. I personally witnessed this on the north shores of Hokkaido during the Spring of 1995. Sadlov.]

http://nsidc.org/data/seaice/pm.html

[This one is just FYI. Sadlov.]

http://www.osi-saf.org/biblio/docs/ss2_pmseaice_3_5.pdf

[Actual examples of calcs for one particular method are here. I wonder how many organizations are now using Toudal's PC analysis and when did they begin to use it? Note page 12 - ref. "NSIDC climatological maximum sea ice edge." Fascinating. Some interesting quality control practices, I must wonder if all orgs use them or only OSISAF? Note page 32, this is very interesting. Sadlov.]

Anonymous said...

Dano - this seems to be sort of a sensitive topic. Otherwise, you'd not have taken the time to comment / disparage / smear.

You poor dear. Having your FUD pointed out to you.

Are you going to e-mail them with your questions, or spread FUD?

Let us know which path you choose.

Best,

D

stevesadlov said...

We've got GISS affiliated folks here. They know how to read.

Dano said...

So you're not really interested in the answers to your qweshins.

We knew that, but thanks for being so blatant about it.

Best,

d

Anonymous said...

Long ago, I decided to not believe software-generated images of anything (movies, sea ice maps.)

Fortunately, there are REAL-TIME satellite images from the MODIS Terra and Aqua polar orbiting satellites which produces images in the Visible spectrum and you can see what the ice is really doing with your own two eyes.

The MODIS satellites take pictures every 5 to 15 minutes in their 2 hour polar orbits and allow you to zoom into 4 km to 250M resolution and various false color images to pick out sea ice from cloud cover for example.

You can link to it here if you want to believe your own eyes versus some chart from the NSIDC or the Cryosphere Today.

http://rapidfire.sci.gsfc.nasa.gov/

Then save it to your favorites and click on "Real-Time" each day (Explorer will get locked into a specific date rather than each day's new images if you don't do it this way or edit your favorites afterward to

http://rapidfire.sci.gsfc.nasa.gov/realtime/ )

Here is a good image from today of the NorthWest Passage (in the lowest resolution - zoom in with the links on the left if you want a closer look.)

http://rapidfire.sci.gsfc.nasa.gov/realtime/single.php?2007256/crefl1_143.A2007256204001-2007256204500.4km.jpg

I don't think there is way through today without an icebreaker (yesterday was good, last week wasn't, the two weeks before that were open, on August 15 you were stuck in the ice, it looks like it will close off until August 25, 2008 now.)

The Passage opens up every now and again, but the window is only days to a few weeks at most. Take your chances if you want. It is safer today with satellite phones but a few decades ago, you had to hope to run into a friendly Eskimo settlement for the winter.

Ohh, and the MODIS satellites are only going to work for the Arctic (in the Visible spectrum) for the next week or so because the Arctic goes into 6 months of darkness with no sunlight for 6 months on September 22 and it will get very cold in the Arctic if it isn't today.)

Anonymous said...

Steve sadlov said; "Some of the "thin ice" in question is sufficiently robust to allow fur seals to safely rest on and traverse the ice. I personally witnessed this on the north shores of Hokkaido... "

I see (icee, get it?) math is not your strong point -- and cut and paste is.

Let's calculate how thick sea ice has to be to support an adult fur seal lying on its belly, shall we?

This table gives the sea ice thickness to support one person (at rest) 13cm.

Assuming that person is about 150lb and that their feet have a total cross sectional area of about 70 sq inches, that means sea ice 13cm thick will support roughly 2 lb per square inch.

Northern fur seal adults are about 600lb and 6 feet long. Assuming about half that length is touching the ice while they are lying on their belly and that the width of their belly is about a foot yields about 400 square inches touching the ice.

600 lb exerted over 400 sq inches is about 1.5 lb per square inch -- which is less than the 2 lb per square inch exerted by a person standing on the ice.

In other words, the 13cm of ice needed to safely support a person is almost certainly sufficient to support a 600lb fur seal.

Lest you try to weasel out by saying "that's for a person who is not moving", let me direct you to the very next entry in the table which is for a safe load of .4 ton (800lb) moving slowly across the ice -- which would almost certainly encompass a 600 lb seal moving across the ice. For that, only 18cm of sea-ice thickness is required. In other words, still not much.


So, 18 cm of ice would safely support a 600 lb seal moving across the sea-ice.

See the problem with your assumptions -- and your math?

In relative terms, 18 cm of sea ice is nothing -- or about as close to nothing as you can get without actually having no ice in the arctic.

Q: What's the difference between an arctic ocean covered by 18cm of sea ice and an open arctic ocean?

A: A few days above freezing temperatures.

stevesadlov said...

The following:

http://www.natice.noaa.gov/pub/East_Arctic/Barents_Sea/Barents_Sea_North/2007/Northwest/currentcolor.pdf

.... versus over 100Km of open water. Which will you choose to believe?

Anonymous said...

Not so good at the mathy things, are ya, Steve?

Cheers.

Bye bye.

stevesadlov said...

http://www.natice.noaa.gov/pub/East_Arctic/

Click down from here to the NW Barents Sea.

Anonymous said...

I know you can cut and paste, Steve.

If your posts above are any indication, you appear to have mastered that skill quite well. :)

But what I was challenging was your math and assumptions about ice thickness based on your comment about the seals.

I didn't really think you would understand the math but I thought I might lay it out nonetheless.

Garrett Piersa said...

I must correct this by saying that this has been even worse in the past because...Um...Greenland was once green you know!

Anonymous said...

Earth has been completely free of ice and completely covered in ice several times over. The coldest ice age had an average global temperature hovering around -50 celsius. Read a book or two.

AGW is flat earth scince. Period.

Klas said...

Anon 10:04:
If anyone questions whteher the climate has ever changed (from ice ages to really warm period) those persons would be real denialists !

The question about AGW is whether we (humans) accelerate and/or induce warming, so much that we'll change climate faster or as fast as in some natural distaters earlier in history, and thus creating if not annhiliation of humans, so at least a lot worse conditions than present, and we are doing this very fast.

Personally i do think that our pollutions affect the environment - or actually that one is a given, just go to a industrial area in a non western, or even some western countries and llok att the "nature" there !

However i do not think that co2 is the bad guy. At least not to the extend that political corectness today gives. We cannot see any definitiev proof to global warming yet (ices come and go, and we would need at least a decade or even longer of ever declining ice sheets in both the arctic and antarctic to se a trend i think). Actually we see the opposite right now (global temperatures are leveling out and even declining in the last couple of years) - although that doesnt yet proof anything either.

What we must focus on is better energy sources (the oil is going to run out, or at least become very hard to dig out) and better recycling as well as a global sense of environmental concern ! Not focusing so much on co2 that we forget the "rest", that is as dangerous as any scenario of co2 emissions that has been simulated !!

About "local variations" as someone above tried to explain the viking colonization of greenland with: Yes - but today the "global" temperatures show "local variations "as well Actually temperatures in the north hemisphere is higher than the south. And in Antarcitd they are even lower than "normal" in most places (satellite measurements http://vortex.nsstc.uah.edu/public/msu/t2lt/tltglhmam_5.2)

Actually it seems that temperature is higher where more people lives and we have more technology - is this a coincidence or maybe future research can show a connection here ? I am a bit curious how much our "emissions" of heat actually affects the climate - just think about all powerplants, activity, vehicles etc that innefectivly converts different forms of energy, and in the process emits a lot of heat - maybe all of this is just a fart in space globally - but as I said I am a bit curious of this..

/K