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Jim Hunt

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Re: IJIS
« Reply #4350 on: June 13, 2017, 10:55:32 AM »
where are you finding that info. before Espen posts it?

See:

https://ads.nipr.ac.jp/vishop/#/extent

then hover your mouse pointer over the lines on the graph.
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gerontocrat

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Re: IJIS
« Reply #4351 on: June 13, 2017, 11:00:04 AM »
DavidR, are you saying that 2017 lost 112K of extent today, or that 2012 lost that amount on this date?  If 2017, where are you finding that info. before Espen posts it?  thanks
Jaxa data is dead easy to download and view, even on a mobile. 117 thousand km2 is yesterday.

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Bill Fothergill

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Re: IJIS
« Reply #4352 on: June 13, 2017, 11:33:54 AM »
... where are you finding that info. before Espen posts it?  thanks

Jim has already provided the appropriate link, and, as gerontocrat also says, it is easy to access.

That system is now running on Version 2, but, from time to time, I find it more convenient to go back to the earlier version, which is here...
https://ads.nipr.ac.jp/vishop.ver1/vishop-extent.html?N

If you are unfamiliar with the subtleties of the IJIS (now ADS) data, there is one point you should be aware of. The values appearing on the ADS site (and on their downloadable .csv files) are actually 2-day rolling averages. Hence, the nominal (i.e displayed) value for 12th June is, in fact, the arithmetic average of the measured values taken for the 11th and 12th.

Consequently, what appears to be the drop between the displayed values for the 11th and 12th is actually one half of the measured difference between the 10th and the 12th.

When you access the link to either Ver1 or Ver2, it is worth scrolling down in order to familiarise yourself with some of the background material provided.

pauldry600

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Re: IJIS
« Reply #4353 on: June 13, 2017, 11:48:01 AM »
I get 119,941 as yesterdays drop.

A lot of Hudson is burnt so maybe that.

Greenland has gained some ice to the West but everything looking torched at this stage


DavidR

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Re: IJIS
« Reply #4354 on: June 13, 2017, 12:26:34 PM »
I  get  the entire table of data from here. It  is typically available about 0430 UTC.

https://ads.nipr.ac.jp/vishop.ver1/data/graph/plot_extent_n_v2.csv

Very useful for checking the data when you  want to  and catching up  when you  have been away.

For those who are new the NSIDC arctic extent is available here. It  is typically available about 1330 UTC.
ftp://sidads.colorado.edu/DATASETS/NOAA/G02135/north/daily/data/

Jim Pettit

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Re: IJIS
« Reply #4355 on: June 13, 2017, 01:12:19 PM »
By this date in 2012, the first cliff of the melt season was nearly complete. That cliff saw a whopping 949k km2 disappear in just seven days, and 1.13M in nine days. However, the two weeks after that saw the frantic activity die down quite a bit to more moderate levels, so if 2017 maintains just a slightly above-average rate of decrease, 2012 will indeed fall behind (at least for a while), leaving 2017 at or near the front of the pack so far as years with record low minimums:




pauldry600

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Re: IJIS
« Reply #4356 on: June 13, 2017, 01:16:25 PM »
I suppose the next question I have is...............

Where do you access the wonderful graph Espen posts daily externally?

Sorry just looked at Jims link

This is more than adequate

Bookmarked

Peter Ellis

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Re: IJIS
« Reply #4357 on: June 13, 2017, 03:57:08 PM »

If you are unfamiliar with the subtleties of the IJIS (now ADS) data, there is one point you should be aware of. The values appearing on the ADS site (and on their downloadable .csv files) are actually 2-day rolling averages. Hence, the nominal (i.e displayed) value for 12th June is, in fact, the arithmetic average of the measured values taken for the 11th and 12th.

I don't think that's how it works. 

The AMSR-E orbital period is 99 minutes, and only part of the region is imaged on each pass. When they say they calculate extent based on 2 days' data, it means they calculate it by aggregating data from all the satellite passes in the preceding 48 hours. Within this time frame, some pixels will have been imaged many times, others only a few times.

It's not as simple as imaging everything once a day and then averaging two days together. It also means you CAN'T work backwards and try and reverse-derive daily values from the provided data set.

jplotinus

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Re: IJIS
« Reply #4358 on: June 13, 2017, 04:00:06 PM »
Espen

Are you ok? Is everything good with you?

🤔

Neven

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Re: IJIS
« Reply #4359 on: June 13, 2017, 04:32:08 PM »
Maybe the century break took him by surprise, and he went out for a beer.  ;)
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Lord M Vader

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Re: IJIS
« Reply #4360 on: June 13, 2017, 04:35:54 PM »
Well, quite a lot of beer then Neven! ;D

Do we want to think what happens if we are going to see a double century break? 8)

magnamentis

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Re: IJIS
« Reply #4361 on: June 13, 2017, 04:48:35 PM »
Again looking at it like a horse race, that was a spectacular day! 2017 retains its hold on 3rd place as the former 2nd and 4th switch positions. Also, even without what could be called a cliff, 2017 is now less than 350K out of the lead. It's made up nearly 100K in the past week.

2017 picks up the pace as 2012 rushes past, losing a solid 119K today. After tomorrow 2012  barely manages to keep pace with the two backmarkers for two solid weeks.  It certainly looks like the lightweight 2017 will catch and streak ahead of 2012 and close in on the front runner in that period. Its going to be a close call for the lead at the end of the month, but the smart money, (well my money),  is now on 2017 leading.

you more or less nailed it, here we go, just in time, further i share your point of view +1

only that short and mid/term prediction are prone to weather patterns, hence not reliable, in the long run it will be as you say, i'm extremely confident of that as well.

added the antarctic equivalent as well, another huge gap in the brick wall of global sea-ice and as you all know i look at things globally more than hemisphere wise, not even talking about regional, regional events are perhaps fun to watch but meaningless to a high degree IMO
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magnamentis

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Re: IJIS
« Reply #4362 on: June 13, 2017, 04:51:25 PM »
DavidR, are you saying that 2017 lost 112K of extent today, or that 2012 lost that amount on this date?  If 2017, where are you finding that info. before Espen posts it?  thanks

i think this is what you're asking for, data are available very early in the day for those who don't want to wait to see @espen his most useful regular and very much appreciated posts.

https://ads.nipr.ac.jp/vishop/#/extent
« Last Edit: June 14, 2017, 02:36:00 AM by magnamentis »
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pauldry600

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Re: IJIS
« Reply #4363 on: June 13, 2017, 05:56:35 PM »
I hope @espen doesnt live on a piece of sea ice that disappeared with that 119k

Pmt111500

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Re: IJIS
« Reply #4364 on: June 13, 2017, 06:08:34 PM »
The 2012 big early drop was largely for meltponding, how might this year fare looking at this. I won't check it but it might be interesting to compare.
« Last Edit: June 13, 2017, 06:24:58 PM by Pmt111500 »
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Espen

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Re: IJIS
« Reply #4365 on: June 13, 2017, 07:29:04 PM »
IJIS:

10,382,216 km2(June 12, 2017)down 119,941 km2 and 3rd lowest measured for the date.
Have a ice day!

Espen

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Re: IJIS
« Reply #4366 on: June 13, 2017, 07:31:31 PM »
Espen

Are you ok? Is everything good with you?

🤔


Im fine thanks IJIS/JAXA was a bit late today and I did not have the time to wait!
Have a ice day!

Bill Fothergill

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Re: IJIS
« Reply #4367 on: June 13, 2017, 07:40:03 PM »

If you are unfamiliar with the subtleties of the IJIS (now ADS) data, there is one point you should be aware of. The values appearing on the ADS site (and on their downloadable .csv files) are actually 2-day rolling averages. Hence, the nominal (i.e displayed) value for 12th June is, in fact, the arithmetic average of the measured values taken for the 11th and 12th.

I don't think that's how it works. 

The AMSR-E orbital period is 99 minutes, and only part of the region is imaged on each pass. When they say they calculate extent based on 2 days' data, it means they calculate it by aggregating data from all the satellite passes in the preceding 48 hours. Within this time frame, some pixels will have been imaged many times, others only a few times.

It's not as simple as imaging everything once a day and then averaging two days together. It also means you CAN'T work backwards and try and reverse-derive daily values from the provided data set.

Hi Peter,

I was responding to a query by arctic-watcher at #4349 as to the provenance of the ADS (aka IJIS) data. As that was only the 5th posting by arctic-watcher, and following the old adage about "don't try to run before you can walk", I tried to answer at what I considered to be the most appropriate level.

I fully appreciate that orbital periods generally don't line up with any 24 hour period, and that the coverage swathe paths most certainly do not tessellate, but rather overlap in a seriously convoluted fashion.

However, please try the following thought experiment...

The data from (say) Hour 0 to Hour 48 gets aggregated and presented as the extent for (say) Day X. The following day, the data from Hour 24 to Hour 72 gets aggregated and is presented as the extent for Day (X+1). The data garnered during Hour 24 to Hour 48 is common to both days, and therefore has no impact on the delta between Day X and Day (X+1)

The only thing that differs between the two days is that the data from Hour 0 to Hour 24 has been replaced by the corresponding data from Hour 48 to Hour 72.


Surely this is analogous to what happens on the NSIDC rolling 5-day Charctic? The extent there on the 11th June was 11.297 million sq kms, and this dropped the following day to 11.219 million sq kms. Consequently, we have a delta of 78 thousand sq kms between the two days. The June 11 Charctic value is the arithmetic average of the single-day values obtained between June 7 and June 11, whereas the June 12 Charctic is the average of the June 8 to June 12 dailies. The daily values from June 8 to June 11 are common to both, and the difference is purely due to the replacement of the June 7 daily with the June 12 daily.

Moving to the NSIDC single day values, June 7th came in at 11.455 million sq kms, with the June 12th equivalent having dropped to 11.069 million sq kms. The delta is now 386 thousand sq kms, which, allowing for rounding error, is 5 times the difference between the June 11 and June 12 rolling 5-day averages.

Working backwards from the Charctic numbers, although it is not feasible to reverse-engineer the precise one day values (unless given a seed value to start with), it is a trivial exercise to calculate what the delta between (say) Day Z and Day (Z+5) must have been.

If the ADS data was presented in two formats - as a single day value and as an aggregated 2-day value - then the difference between Day X and Day (X+1) on the aggregated 2-day format would be one half of the difference between Day (X-1) and Day (X+1) on the single day format.

magnamentis

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Re: IJIS
« Reply #4368 on: June 14, 2017, 02:40:06 AM »
https://ads.nipr.ac.jp/vishop/#/extent

this is the link i forgkt to paste, sincere appologies for that little lapsus.😉😂😎🍺
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arctic-watcher

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Re: IJIS
« Reply #4369 on: June 14, 2017, 03:41:43 AM »
Thanks to everyone for all the IJIS extent info.  Bookmarks set. 

Espen

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Re: IJIS
« Reply #4370 on: June 14, 2017, 05:32:29 AM »
IJIS:

10,299,545 km2(June 13, 2017)down 82,671 km2 and 3rd lowest measured for the date.
Have a ice day!

mmghosh

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Re: IJIS
« Reply #4371 on: June 14, 2017, 10:38:23 AM »
Meltponding or not, the numbers are setting up nicely for a few big autumn cyclones...

Shared Humanity

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Re: IJIS
« Reply #4372 on: June 14, 2017, 03:47:44 PM »
Melt ponding does not have as big of an impact on SIE as it does SIA, IMHO. These drops in extent are due to compaction or melting, most likely both.

Espen

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Re: IJIS
« Reply #4373 on: June 15, 2017, 05:23:18 AM »
IJIS:

10,228,536 km2(June 14, 2017)down 71,009 km2 and 3rd lowest measured for the date.
« Last Edit: June 15, 2017, 03:53:41 PM by Espen »
Have a ice day!

Unmex Chingon

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Re: IJIS
« Reply #4374 on: June 15, 2017, 05:25:55 AM »
We really need several Century drops....  Got to get to Zero Ice..  We need to be happy we are right!

Juan C. García

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Re: IJIS
« Reply #4375 on: June 15, 2017, 06:06:37 AM »
We really need several Century drops....  Got to get to Zero Ice..  We need to be happy we are right!

To be at the same level than 2012 on June 30th (9,039,911 km2), we need an average daily drop of 74,289 km2.
In a way, hoping to have an ice-free Arctic seems suicidal to me...   :(
Which is the best answer to Sep-2012 ASI lost (compared to 1979-2000)?
50% [NSIDC Extent] or
73% [PIOMAS Volume]

Volume is harder to measure than extent, but 3-dimensional space is real, 2D's hide ~50% thickness gone.
-> IPCC/NSIDC trends [based on extent] underestimate the real speed of ASI lost.

DavidR

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Re: IJIS
« Reply #4376 on: June 15, 2017, 06:28:00 AM »
We really need several Century drops....  Got to get to Zero Ice..  We need to be happy we are right!
2017 is on track to have one of the largest  June declines on record. It's currently  running second behind 2012.   We just need to be patient and see what  develops.  Zero Ice is a few years away yet.

budmantis

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Re: IJIS
« Reply #4377 on: June 15, 2017, 06:29:57 AM »
We really need several Century drops....  Got to get to Zero Ice..  We need to be happy we are right!
2017 is on track to have one of the largest  June declines on record. It's currently  running second behind 2012.   We just need to be patient and see what  develops.  Zero Ice is a few years away yet.

And no one on this blog will be happy to see it.

BudM

Darvince

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Re: IJIS
« Reply #4378 on: June 15, 2017, 03:31:39 PM »
Unless you're a sadist... ???

magnamentis

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Re: IJIS
« Reply #4379 on: June 15, 2017, 04:54:18 PM »
We really need several Century drops....  Got to get to Zero Ice..  We need to be happy we are right!

To be at the same level than 2012 on June 30th (9,039,911 km2), we need an average daily drop of 74,289 km2.
In a way, hoping to have an ice-free Arctic seems suicidal to me...   :(

not only that, it is very far fetched (not a realistic szenario, close to impossible IMO) but some folks obviously seek distraction and a kick through big events and big headlines more than to have the real goal of this forum in mind. certainly interesting times are exiting but being happy with a catastrophe is the syndrom we often see on highways when passers by reduce speed to stare and make photos.
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woodstea

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Re: IJIS
« Reply #4380 on: June 15, 2017, 09:01:04 PM »
I expect there will eventually come a time where the number of climate change deniers will dwindle to the point where they're essentially irrelevant, like the flat earthers. I would love to think that we could reach that point earlier rather than later, maybe because some event like an ice-free North Pole some year soon would convince certain prominent voices among them to change their minds.

It's a thin hope, but I think it's behind why some part of me roots for a record low extent each year.

StopTheApocalypse

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Re: IJIS
« Reply #4381 on: June 15, 2017, 09:03:08 PM »
I expect there will eventually come a time where the number of climate change deniers will dwindle to the point where they're essentially irrelevant, like the flat earthers. I would love to think that we could reach that point earlier rather than later, maybe because some event like an ice-free North Pole some year soon would convince certain prominent voices among them to change their minds.

It's a thin hope, but I think it's behind why some part of me roots for a record low extent each year.

If it makes you feel better, this is actually the case literally everywhere besides the US. Parties that deny the reality of climate change have been continually eviscerated; UKIP was the latest example. Insofar as that reflects the views of the electorate, it does seem to indicate that most people in the world accept that climate change is happening and caused by humans.

Edit: Sorry, realized this is probably too off topic. Won't respond any further.

pauldry600

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Re: IJIS
« Reply #4382 on: June 16, 2017, 10:56:48 AM »
Down another 71k

163,477 behind 2016

Espen

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Re: IJIS
« Reply #4383 on: June 16, 2017, 04:30:27 PM »
IJIS:

10,157,105 km2(June 15, 2017)down 71,431 km2 and 4th lowest measured for the date.
Have a ice day!

DavidR

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Re: IJIS
« Reply #4384 on: June 16, 2017, 05:06:40 PM »
After 15 days of June IJIS has the second biggest loss since 2002 with 1054282 km^2 gone.

On average, losses in the second half of June are more than 50% higher than the first  half.  If 2017 second half losses are 50% bigger than the first half, 2017 will have the biggest June decline in the record and be well out in front. 

Only three of the 14 years in the record have a first half/second half ratio that would see 2017 out of lowest place.  However two of these are the years with the biggest early losses. 

With the thinness of the ice this year I can see no reason for IJIS not to keep powering down until the end of the month.

Espen

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Re: IJIS
« Reply #4385 on: June 17, 2017, 10:02:12 AM »
IJIS:

10,106,722 km2(June 16, 2017)down 50,383 km2 and 4th lowest measured for the date.
Have a ice day!

Feeltheburn

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Re: IJIS
« Reply #4386 on: June 17, 2017, 11:44:32 PM »
IJIS:

10,106,722 km2(June 16, 2017)down 50,383 km2 and 4th lowest measured for the date.

Based on temperatures leveling out and the fact that the ice around the edges was thinner than usual and has melted out fast, there is a good chance the rate of melting will begin to decrease somewhat and ice extent will maintain 4th place for a while and then climb perhaps to 6-8th place. Just a hunch. If I knew how to project the future I'd be rich trading stocks!
Feel The Burn!

Jim Pettit

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Re: IJIS
« Reply #4387 on: June 18, 2017, 12:06:31 AM »
Based on temperatures leveling out and the fact that the ice around the edges was thinner than usual and has melted out fast, there is a good chance the rate of melting will begin to decrease somewhat and ice extent will maintain 4th place for a while and then climb perhaps to 6-8th place. Just a hunch. If I knew how to project the future I'd be rich trading stocks!

For your "hunch" to come to fruition, the rate of extent decrease, which has been the second fastest on record for this time of year so far this month, would have to magically slow to by far the slowest on record.

Not. Going. To. Happen.

Friendly advice: stay away from the stock market. :)

oren

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Re: IJIS
« Reply #4388 on: June 18, 2017, 12:15:50 AM »
Based on temperatures leveling out and the fact that the ice around the edges was thinner than usual and has melted out fast, there is a good chance the rate of melting will begin to decrease somewhat
I should point out that if you check the regional charts on the PIOMAS thread, you will find that the ice in the core is thinner than usual, while the ice around the edges has typical thickness. So your fact is in fact not very factual.

magnamentis

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Re: IJIS
« Reply #4389 on: June 18, 2017, 02:23:19 AM »
Based on temperatures leveling out and the fact that the ice around the edges was thinner than usual and has melted out fast, there is a good chance the rate of melting will begin to decrease somewhat
I should point out that if you check the regional charts on the PIOMAS thread, you will find that the ice in the core is thinner than usual, while the ice around the edges has typical thickness. So your fact is in fact not very factual.

so glad you point it out, saves me further bashing LOL enjoy further
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Re: IJIS
« Reply #4390 on: June 18, 2017, 05:45:36 AM »
For your "hunch" to come to fruition, the rate of extent decrease, which has been the second fastest on record for this time of year so far this month, would have to magically slow to by far the slowest on record.

Not. Going. To. Happen.
And the 2016 May melt was going to lead to a record low minimum? ;) The system is far more complex than it appears. I wouldn't be surprised if we continued at the same pace or even slowed down slightly for the rest of June. (excepting a possible cliff in the Hudson Bay extent)

DISCLAIMER: I expect the sea ice minimum in September to be exceptional, no matter what extent number is reached. We had record high dispersion last year, with area nearly tying 2012 for how low it got (area by mid-August again represents actual sea ice area).

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Re: IJIS
« Reply #4391 on: June 18, 2017, 06:23:46 AM »
We are getting very very close to going out ahead of 2012 now, as 2017 and 2012 are only about 20k apart. It could happen any day now.

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Re: IJIS
« Reply #4392 on: June 18, 2017, 07:29:52 AM »
It could, but it's not like that's been a long time coming. 2012 only passed 2017 a week ago, and the maximum gap so far is something like 65K. When will 2017 pass 2016 though, and will that be soon enough to retake the number one position? (Probably not, but you never know.)

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Re: IJIS
« Reply #4393 on: June 18, 2017, 11:14:10 AM »
Today the drop was 58787 km2, a medium but steady decline in the first 17 days.

I terms of JAXA sea ice extent average decline/km2 per day, for the first 17 days of June i see:

2012   -88367
2001   -72053
2011   -70487
1999   -68609
2017   -68146
2010   -63830
1998   -62804
2008   -55807
2005   -55678
1994   -54603
2013   -53997
2014   -53987
2006   -50753
2007   -48371
1991   -47301
1990   -46456
2003   -46339
2009   -46181
2015   -44246
1988   -43146
1993   -42585
2000   -39443
2002   -39338
1997   -38236
1992   -37966
2004   -37923
1995   -37315
2016   -33398
1989   -27500
1996   -27277

The same but for the percentage of the JAXA sea ice extent decline/km2 for 17th June compared to 1st June is:
2012   12.4%
2011   10.2%
2017   9.8%
2001   9.6%
2010   9.2%
1999   8.8%
1998   8.3%
2005   7.8%
2008   7.7%
2014   7.6%
2013   7.4%
2006   7.2%
1994   7.1%
2007   6.8%
2015   6.5%
2009   6.4%
2003   6.3%
1990   6.3%
1991   6.1%
1993   5.7%
1988   5.6%
2002   5.4%
2000   5.3%
2004   5.3%
2016   5.1%
1995   5.1%
1997   5.1%
1992   5.0%
1996   3.6%
1989   3.6%

Cato

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Re: IJIS
« Reply #4394 on: June 18, 2017, 11:25:21 AM »
I like contrarian strategies on the stock market therefore I agree with feeltheburn :) synoptic configuration has changed significantly and current conditions are much more favourable to ice preservation. Melting ponds evolution is quite encouraging as well.

Record lows remain the most crowded trading by far, but real big money is made on unpopular tradings :) :)

Espen

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Re: IJIS
« Reply #4395 on: June 18, 2017, 12:08:18 PM »
IJIS:

10,047,935 km2(June 17, 2017)down 58,787 km2 and 4th lowest measured for the date.
« Last Edit: June 18, 2017, 12:21:05 PM by Espen »
Have a ice day!

Jim Pettit

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Re: IJIS
« Reply #4396 on: June 18, 2017, 01:44:55 PM »
Synoptic configuration has changed significantly and current conditions are much more favourable to ice preservation.

"Much more favorable to ice preservation" is one thing. "Ice decrease suddenly screeching to a halt and dropping down to a late-June, early-July rate of decrease never before seen in the record" is something else entirely.

But, as always, we'll see...

Cato

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Re: IJIS
« Reply #4397 on: June 18, 2017, 10:56:01 PM »
Jim, it's the difference between being contrarian on the stock exchange and dilapidating your savings at the casinò I guess ;D

Espen

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Re: IJIS
« Reply #4398 on: June 19, 2017, 05:30:36 AM »
IJIS:

9,982,791 km2(June 18, 2017)down 65,144 km2 and 4th lowest measured for the date.
Have a ice day!

Ned W

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Re: IJIS
« Reply #4399 on: June 19, 2017, 07:27:12 PM »
Based on temperatures leveling out and the fact that the ice around the edges was thinner than usual and has melted out fast, there is a good chance the rate of melting will begin to decrease somewhat and ice extent will maintain 4th place for a while and then climb perhaps to 6-8th place. Just a hunch. If I knew how to project the future I'd be rich trading stocks!

For your "hunch" to come to fruition, the rate of extent decrease, which has been the second fastest on record for this time of year so far this month, would have to magically slow to by far the slowest on record.

Not. Going. To. Happen.

Friendly advice: stay away from the stock market. :)
I'm trying to understand this and, apparently, failing.

The most recent 2017 value for IJIS is 9982791.  FTB didn't specify an exact time frame, so let's say this is over the next two weeks:

* If the ice follows the pattern of 2003, 2005, 2008, 2009, 2011 or 2016 it would climb to 6th place.

* If the ice follows the pattern of 2015 it would reach 8th place

* If the ice follows the pattern of 2004 it would reach 9th place

So melt rates from 8 of the past 14 years would bring FTB's "hunch" to fruition. 

Maybe I've badly miscalculated something, or maybe I misunderstood the claim.  But Jim Pettit's comment makes no sense to me.