UPDATE: Dr. Walt Meier of NSIDC writes in with some information, seethe end of the article.
I’m getting weary of answering this question in comments, so here it is front page. Note the little bump right about June 1st.
Rick W asks:
Can anyone explain the upward bump in the sea ice extent that seems to occur each June? Apologies if previously covered.
Answer:
This is a seasonal adjustment to compensate for meltwater on top of the ice, which would ordinarily be viewed as “open water”. Right about now, the Arctic sea ice gets melt pools forming on the surface. If these are not compensated for, sea ice extent will read artificially low.
That being said, I wonder why we don’t see the same adjustment at NSIDC:
I don’t know the answer, but it could be in the difference between SSMI and AMSR-E satellite sensors (NSIDC uses SSMI, JAXA uses AMSR-E).
We also don’t see an adjustment at Cryosphere Today, and they also use SSMI:
Nor does NANSEN:
Click for larger images
If anyone knows why JAXA does the adjustment but the others do not, I’m all ears. My theory is that it is sensor related, but we should find out for sure. I’m swamped today, so I’ll leave this puzzle for WUWT readers to solve.
UPDATE
Dr. Walt Meir writes in with this:
Since you mentioned it on your blog, I can fill in at least some info:
You are correct. When the melt season kicks in the surface water changes
the contrast between ice and water. To more accurately measure the
area/extent, you should adjust coefficients to account for this.
This is done for SSM/I. However, because the SSM/I algorithm is
different from the AMSR-E algorithm (and other differences between the
sensors) the adjustment is different. In SSM/I, the adjustment is
smoother and thus there isn’t that “bump”.
You have to remember that AMSR-E is a research sensor and the algorithms
are still being refined. That is one reason we don’t use AMSR-E for the
long-term timeseries (though the more important reason is the
inconsistency between the two sensors and algorithms).
– Walt
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the UK Hadley centre predicts that by 2080, London will be experiencing temps of 120 degrees F., and East Anglia will be an arid desert….this from an organisation that cannot accurately predict weather 14 days ahead.
AndyW35, I am certainly interested why this self-declared science blog, is so silent on the fast ice extent melt-off from late April until today. The ice extent has gone from average to low levels ( one source,NSDIC, shows the ice extent even lower than 2007 for this date). Clearly the daily loss of ice extent over the last 40 days, could be the highest ever recorded for this time period?
Why isn’t Mr. Watts and Mr. Goddard publishing a headline stating “Daily ice loss for May and June (so far) shows highest rate on record!” ??? I guess the self declared independent analysis and conclusions published on this site, aren’t so independent, aren’t really into analysis, and their conclusions seem to be censored pretty heavily…
Check out how many times these ‘self-esteemed ‘ gentlemen have declared Arctic ice is recovering on this site. Now it seems that these statements smell a lot like distractions, over-simplifications, and [snip]
REPLY: It is really quite simple, I’m waiting for Mark Serreze, now director of NSIDC, to declare an “ice free north pole” or some other alarming event in a press release. The time is about right for such silly news stories, they did so last year when we saw a similar situation where the 2008/2007 lines converged. BTW his prediction last year failed, miserably. We’ll see if they’ve learned anything from their mistake this year. – Anthony
It would seem that you have not been keeping up. This blog has been all over ice extent since April–including the severe problems with the satellites. I suggest you review past activity.
I would also be more circumspect regarding accusations of lying.
Also note that in any pro-AGW blog, skeptical posts that offensive would be entirely deleted in a trice. But we try to allow as much freedom of expression as we realistically can.
Aron,
I don’t see any numbers in the reindeer article. Of course, there is also no methodology – the downfall of many Global Warming Wizards of Oz!!
paulK (12:19:37) :
Taking the tape graph from cryosphere I overlaid the 2009 ice season (in red) on top of the seasons of 2006, 2007, and 2008. It thus shows quite an interesting tale…
http://s247.photobucket.com/albums/gg136/BigLee57/?action=view¤t=IceSea1.jpg
There is not ice on planet earth…we are in the hockey stick phase of AGW. Obama has hidden this information from us to keep the panic down. Temps will soar in the future after the next mini ice age is over 30 years from now.
This is where I found that link.
At Sea Ice 2009 comment 395.
http://www.climateaudit.org/?p=5614#comment-337310
Sorry.. that link in my last post may not work for you… this one should.
http://i247.photobucket.com/albums/gg136/BigLee57/IceSea1.jpg
Jim asked Andy: Even the low extent represented in the latest chart is within 2 SD of the baseline data. How much are we to make of this?
Jim linked to the June 2nd data from NSIDC. If he used the June 10th data showing less than 12 M sq km of ice extent, he would see the current ice extent is less than the two standard deviation band, which places the current data BELOW the 95% confidence band. If the datapoints continue below the 2D band for 7-9 days or so, that is a very STRONG statisitical signal.
So yes, the data is sending a strong statistical signal, and we can make “much of this”.
Andy,
Please explain when Real Climate will post about the current 7 year cooling trend? When will they put up the MSU graph showing this clear trend? When will they stop denying the recent global cooling? The chart in this post speaks for itself. At least they do not hide the data here and pretend it does not exist. You will NEVER see any charts or posts on Real Climate that go against the AGW agenda. Asking Anthony to highlight something like this, when you will never see anything similar ever on your favorite site is just dumb. Head back over there for the pro warming agenda.
paulK (12:19:37),
Evan is right, just go through the past few months’ archives and you will see numerous posts on sea ice.
And you may not be aware of it, but the Arctic is only in the Northern Hemisphere. It’s true! I’ll bet you’re surprised that the Antarctic has ice, too — and that it’s expanding substantially more than the Arctic ice is contracting.
What do you think of that?
Jim, look how two articles on the same day which mention Canada are in conflict with each other
http://news.bbc.co.uk/earth/hi/earth_news/newsid_8094000/8094036.stm
http://www.reuters.com/article/wtUSInvestingNews/idUSTRE55851U20090609
Comedy gold
They are from the university of Bremen.
http://www.iup.uni-bremen.de:8084/amsr/arctic_AMSRE_nic.png
Hi Anthony:
How are things? Wanted to make you aware of this new video the European Union posted on YouTube. It’s called “Electrical Derby” and it uses the sport of roller derby to teach kids about science.
Here’s the link: http://www.youtube.com/watch?v=sQ9G2OL9ERo
I thought you and your readers might get a charge out of it (no pun intended).
Thanks for your attention! Love your blog!
Re:paulK (12:19:37) :
Here’s a real ‘over-simplification’ for you. Based on Arctic ice extent records that have been ‘accurate’ for only 30 years for an area of the planet that’s been frozen for millenia (except when it wasn’t but nobody knew cause Leif Erikson was fresh out of satellites), some people are predicting an ice-free North Pole by 20__ (fill in your own SWAG).
The AMSR-E imager used by JAXA has higher resolution because of the higher frequency microwaves used (89 GHz) than the SSMI used by NSIDC and Nansen(19.35, 22.235, 37.0, and 85.5 GHz). The different frequencies have different interactions with ice, clouds and water and so have different optimized algorithms for monitoring sea-ice. In the case of the AMSR-E it’s necessary to switch between algorithms to account for the effect of melt ponds in the summer months, the switch is done on June 1st and back on Oct 15th.
The SSMI uses the lower frequencies to detect surface emissivity of the ocean surface. Sea-ice has a higher emissivity than water, and therefore the two can be separated. Precautions are taken to avoid false signatures caused by dense clouds and precipitation. One of the frequencies used is the 22 GHz channel which was the one knocked out by the interference from the Navy device mounted on F15. The different polarizations have different signatures also and can be used for filtering the different signals.
More detail can be found at http://iup.physik.uni-bremen.de:8084/amsr/spreen05.pdf
UNI BREMEN archives are here.
http://www.iup.uni-bremen.de:8084/amsredata/asi_daygrid_swath/l1a/n6250/2008/jun/
Our dear UN says Cuba is a bastion of human rights activity and reaffirms the myth that Cuba has excellent education and health systems.
http://www.unhchr.ch/huricane/huricane.nsf/view01/0F3CC20F613CA7E9C12575D20029E1D7?opendocument
“Cuba had withstood many tests, and continued to uphold the principles of objectivity, impartiality and independence in pursuance of the realisation of human rights. Cuba was and remained a good example of the respect for human rights, including economic, social and cultural rights. The Universal Periodic Review of Cuba clearly reflected the progress made by Cuba and the Cuban people in the protection and promotion of human rights, and showed the constructive and responsive answer of Cuba to the situation of human rights.”
It also congratulates Saudi Arabia for making tremendous strides on human rights and tolerance. The land where an openly gay or atheist person can be killed and a person with a Bible can have their hands cut off.
That’s the UN for you. Now just put some “faith” in the gods of the UN-IPCC.
paulk – So now that we have an excursion past 2 SD, what predictions for the future do you base upon it? That is, what is the touted “much of this?”
OT, but check out the latest blog post at Accuweather AGW blog.
Some big AGW promoters have now shown that CO2 is no longer logarithmic in its impact,and that climate is now linear in its responses to CO2.
And this is being trumpeted as definitive *proof* of AGW.
June bump ?
Pregnant Polar bears ??
paulK (12:49:32) :
Jim asked Andy: Even the low extent represented in the latest chart is within 2 SD of the baseline data. How much are we to make of this?
Jim linked to the June 2nd data from NSIDC. If he used the June 10th data showing less than 12 M sq km of ice extent, he would see the current ice extent is less than the two standard deviation band, which places the current data BELOW the 95% confidence band. If the datapoints continue below the 2D band for 7-9 days or so, that is a very STRONG statisitical signal.
So yes, the data is sending a strong statistical signal, and we can make “much of this”.
-2sd relative to a population of 30 would be borderline for rejection as an outlier by Chauvenet’s criterion so data falling outside that band is indicative of being outside the ‘normal’ range.
My impression is that NANSEN have “coped on” and “are on the ball” and constantly adjusting upwards due to SMII downwards drift unlike CT who don’t, and really don’t care if it goes down,, as long as AGW can be shown… but its bleeding obvious from a direct visual look that NH ice extent is significantly greater now than in 2007 and 2008. That’s why NANSEN has seen the light .. LOL. I think you will soon see a big upwards adjustment by NSIDC as well.
Smokey (12:51:04) :
paulK (12:19:37),
Evan is right, just go through the past few months’ archives and you will see numerous posts on sea ice.
And you may not be aware of it, but the Arctic is only in the Northern Hemisphere. It’s true! I’ll bet you’re surprised that the Antarctic has ice, too — and that it’s expanding substantially more than the Arctic ice is contracting.
What do you think of that?
Basically that it’s not true, this time of year is when the decline in NH ice starts to exceed the growth of SH ice. At present global sea ice is about its seasonal maximum and a normal season would see a slight drop over the next couple of months, a similar season to the last two years would lead to a drop of about 2Mm^2 over the next few months.
Seems to me the volcanic ash would reduce sea ice by at least 10% over a normal season. Why is there not a discussion of that?