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Author Topic: IJIS  (Read 1180066 times)

Bill Fothergill

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Re: IJIS
« Reply #4150 on: April 15, 2017, 08:58:36 AM »
We read the Arctic Sea Ice Forum here on Pluto too, you know. Earth bigot!

P.S. Pluto is so a planet.

Clyde Tombaugh sends his regards. (Or would, were he still amongst us.)

DavidR

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Re: IJIS
« Reply #4151 on: April 15, 2017, 09:35:41 AM »
@Bill,

That chart of "lowest three" ice extents - does it measure the lowest three so far up to the year in question or does it consider future years too? ie if 2012 set a record for a given day which 2016 subsequently beat, would the day be ranked as a "lowest" or a "second lowest" for 2012?
The chart of lowest three extents is based on the  latest date. So for the next  5 days, 2007  which is third will become fourth and lose 5 days at third from its total.

Bill Fothergill

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Re: IJIS
« Reply #4152 on: April 15, 2017, 11:11:56 AM »
@Bill,

That chart of "lowest three" ice extents - does it measure the lowest three so far up to the year in question or does it consider future years too? ie if 2012 set a record for a given day which 2016 subsequently beat, would the day be ranked as a "lowest" or a "second lowest" for 2012?

Paddy,
As David correctly stated above, the stacked bar chart updates as each new data point for 2017 comes in. However, that's only the case for the chart on my computer; the one shown in yesterday's comment is merely a static GIF representation.

Since the data for Day 104 (April 14th) has been added, the number of "lowest" places for 2017 has risen from 55 to 56. However, this introduces a "shuffle effect", with 2016 losing a "lowest" but gaining a "2nd", 2004 losing a "2nd" but gaining a "3rd", and 2007 losing a "3rd".

My intention is to re-post an updated version of the stacked bar chart each time something significant happens. I suspect the next such instance will be when 2017 overtakes 2007 in terms of  total number of appearances in the lowest 3.

Espen

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Re: IJIS
« Reply #4153 on: April 15, 2017, 12:05:13 PM »
IJIS:

13,120,623 km2(April 14, 2017)down 34,702 km2 and lowest measured for the date.
Have a ice day!

Espen

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Re: IJIS
« Reply #4154 on: April 16, 2017, 08:37:28 AM »
IJIS:

13,119,114 km2(April 15, 2017)down 1,509 km2 and lowest measured for the date.
Have a ice day!

Espen

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Re: IJIS
« Reply #4155 on: April 17, 2017, 09:15:20 AM »
IJIS:

13,094,044 km2(April 16, 2017)down 25,070 km2 and lowest measured for the date.
Have a ice day!

Oyvind Johnsen

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Re: IJIS
« Reply #4156 on: April 17, 2017, 12:57:55 PM »
IJIS is really heading south now April 17, 2013:

13,174,375 km2

Now at 2000s average, but with this attitude go below that within days, easily.

This thread started with the Message above. But I can´t find a green line for 2013 at this point in the graph. And 2000s average? Can anyone explain this?

crandles

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Re: IJIS
« Reply #4157 on: April 17, 2017, 01:22:23 PM »
IJIS is really heading south now April 17, 2013:

13,174,375 km2

Now at 2000s average, but with this attitude go below that within days, easily.

This thread started with the Message above. But I can´t find a green line for 2013 at this point in the graph. And 2000s average? Can anyone explain this?

Sorry can't see the problem

oren

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Re: IJIS
« Reply #4158 on: April 17, 2017, 03:36:39 PM »
The problem if I understand correctly is that the 2013 line and the 2000s average are not at 13.174 but much higher  :o
Must have been some kind of revision from then to now?
« Last Edit: April 17, 2017, 03:42:18 PM by oren »

deinst

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Re: IJIS
« Reply #4159 on: April 17, 2017, 05:34:42 PM »
The problem if I understand correctly is that the 2013 line and the 2000s average are not at 13.174 but much higher  :o
Must have been some kind of revision from then to now?

Yes.  On 06 September 2013 there was a change in the data set -- see comment #406.  Unfortunately the descriptive link is broken.  I believe that the change had to do with the handling of the land masks, but Epsen or Wipneus would know much more than I do.

Everything after Sep 2013 seems comparable, stuff before has a different calibrationr

Espen

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Re: IJIS
« Reply #4160 on: April 18, 2017, 05:23:16 AM »
IJIS:

13,069,913 km2(April 17, 2017)down 24,131 km2 and lowest measured for the date.
Have a ice day!

Oyvind Johnsen

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Re: IJIS
« Reply #4161 on: April 18, 2017, 09:57:11 AM »
The problem if I understand correctly is that the 2013 line and the 2000s average are not at 13.174 but much higher  :o
Must have been some kind of revision from then to now?

Yes.  On 06 September 2013 there was a change in the data set -- see comment #406.  Unfortunately the descriptive link is broken.  I believe that the change had to do with the handling of the land masks, but Epsen or Wipneus would know much more than I do.

Everything after Sep 2013 seems comparable, stuff before has a different calibrationr

Thanks for the explanation! The thread is a little long to read through to see what happened, easier to ask.  :)

Neven

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Re: IJIS
« Reply #4162 on: April 18, 2017, 10:53:37 AM »
IJIS:

13,069,913 km2(April 17, 2017)down 24,131 km2 and lowest measured for the date.

Shouldn't that be second lowest? In my spreadsheet 2016 was at 13,059,136 on April 17th.
Il faut cultiver notre jardin

Tfisher

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Re: IJIS
« Reply #4163 on: April 18, 2017, 03:53:20 PM »
I think when Espen writes "lowest measured for the date" he really means "lowest measured for this day of the year."  The difference is that in a leap year like 2016, March 1 is day number 61 while in a non-leap-year like 2017, March 1 is day number 60. 

Siffy

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Re: IJIS
« Reply #4164 on: April 18, 2017, 04:20:24 PM »
IJIS:

13,069,913 km2(April 17, 2017)down 24,131 km2 and lowest measured for the date.

Shouldn't that be second lowest? In my spreadsheet 2016 was at 13,059,136 on April 17th.

Leap year date difference maybe?

Espen

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Re: IJIS
« Reply #4165 on: April 19, 2017, 05:26:04 AM »
IJIS:

13,044,495 km2(April 18, 2017)down 25,418 km2 and 2nd lowest measured for the date.
Have a ice day!

Espen

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Re: IJIS
« Reply #4166 on: April 20, 2017, 04:54:05 PM »
IJIS:

13,033,695 km2(April 19, 2017)down 18,800 km2 and 2nd lowest measured for the date.
Have a ice day!

Bill Fothergill

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Re: IJIS
« Reply #4167 on: April 20, 2017, 06:20:12 PM »
IJIS:

13,033,695 km2(April 19, 2017)down 18,800 km2 and 2nd lowest measured for the date.

That minor drop on the 19th takes the 2017 extent to just below that clocked up by April 23rd 2007. Unless the extent actually rises during the next four days, the number of appearances in the "lowest 3 for the date" category for 2017 will rise from 107 to 111 by the 23rd. Simultaneously, the number of appearances in the "lowest 3" for 2007 will drop from 113 to 110.

By that stage, only 2012 and 2016 will have more appearances in the "lowest 3" - with 171 and 312 respectively.

Espen

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Re: IJIS
« Reply #4168 on: April 21, 2017, 05:38:46 AM »
IJIS:

13,000,702 km2(April 20, 2017)down 32,993 km2 and 2nd lowest measured for the date.
Have a ice day!

Espen

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Re: IJIS
« Reply #4169 on: April 22, 2017, 10:06:42 AM »
IJIS:

12,933,184 km2(April 21, 2017)down 67,518 km2 and 2nd lowest measured for the date.
Have a ice day!

Shared Humanity

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Re: IJIS
« Reply #4170 on: April 22, 2017, 04:19:12 PM »
2017 will continue to separate itself from the 2000's average IMHO, much like 2016.

Jim Pettit

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Re: IJIS
« Reply #4171 on: April 23, 2017, 02:57:48 PM »
For those wondering, this was posted a few days back:


Espen

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Re: IJIS
« Reply #4172 on: April 25, 2017, 05:32:57 AM »
IJIS:

12,832,850 km2(April 24, 2017)and 2nd lowest measured for the date.
Have a ice day!

solartim27

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Re: IJIS
« Reply #4173 on: April 25, 2017, 08:14:05 AM »
: Espen link=topic=230.msg111111#msg111111 (April 24, 2017)and 2[sup
nd[/sup] lowest measured for the date.
A century, and the graph is flat?  Something seems wrong.
FNORD

oren

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Re: IJIS
« Reply #4174 on: April 25, 2017, 08:46:43 AM »
A century, and the graph is flat?  Something seems wrong.
It's covering 3 days, since IJIS was down.

Bill Fothergill

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Re: IJIS
« Reply #4175 on: April 25, 2017, 09:30:28 AM »
A century, and the graph is flat?  Something seems wrong.
It's covering 3 days, since IJIS was down.
As Oren stated, we had a hiatus/pause from April 21 to April 24. The "missing" values can be found on the .csv file

April 22: 12875995
April 23: 12827488
April 24: 12832850

Feeltheburn

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Re: IJIS
« Reply #4176 on: April 25, 2017, 02:59:01 PM »
A century, and the graph is flat?  Something seems wrong.

It is consistent with NSIDC which shows melting hiatus the past few days.
Feel The Burn!

seaicesailor

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Re: IJIS
« Reply #4177 on: April 25, 2017, 08:33:43 PM »
Last year the Beaufort sea gap kept opening steadily until well entered may 2016, which contributed in part to anomalously low extent. The north of Svalbard was clear-cut clean by mid may while this year is covered by MYI that will be clearing gradually. The timing is different this year too, would be surprised if the curve follows 2016.
To add that Greenland Sea and Barentz have seen import of much thicker ice this year... "good" for extent now, bad for the prospects of ice
Surprisingly even with higher extent Tealight's accumulated albedo potential anomaly is running highest, although very small numbers, still very early in the season
https://sites.google.com/site/cryospherecomputing/warming-potential/graphs
« Last Edit: April 25, 2017, 08:48:25 PM by seaicesailor »

Deeenngee

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Re: IJIS
« Reply #4178 on: April 25, 2017, 09:47:31 PM »
An update of my chart showing cumulative days in the bottom 3 for each date. Also a grid view showing the numbers.

2017 has now overtaken 2006, 2007, 2011 and 2015. Unless there are a couple of extended plateaux, I'd be surprised if 2017 spends much time outside the bottom 3 to the end of May.

Finally, an update of my 2017 vs 1990-16 daily range chart, now shifted to April & May.

Ice Shieldz

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Re: IJIS
« Reply #4179 on: April 25, 2017, 09:51:39 PM »
Seaicesailor - Graphics down on the home page of Tealight's site.  From his site, I pulled the following graph (albedo derived from NSIDC concentration data) Is this the most relevant graph?

Deeenngee

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Re: IJIS
« Reply #4180 on: April 25, 2017, 10:51:12 PM »
One more - this time, 10 year averages.

Deeenngee

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Re: IJIS
« Reply #4181 on: April 25, 2017, 10:51:51 PM »
(this time with graph!)

oren

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Re: IJIS
« Reply #4182 on: April 25, 2017, 11:05:24 PM »
Seaicesailor - Graphics down on the home page of Tealight's site.  From his site, I pulled the following graph (albedo derived from NSIDC concentration data) Is this the most relevant graph?
Yes. The cumulative FDD graph is the most relevant for winter, and the one you posted is the most relevant over the melting season

seaicesailor

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Re: IJIS
« Reply #4183 on: April 26, 2017, 12:08:47 AM »
Seaicesailor - Graphics down on the home page of Tealight's site.  From his site, I pulled the following graph (albedo derived from NSIDC concentration data) Is this the most relevant graph?
Yes. The cumulative FDD graph is the most relevant for winter, and the one you posted is the most relevant over the melting season
I think so too. Worth keeping an eye during the season!

Espen

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Re: IJIS
« Reply #4184 on: April 26, 2017, 05:25:45 AM »
IJIS:

12,826,358 km2(April 25, 2017)down 6,492 km2 and 2nd lowest measured for the date.
Have a ice day!

Espen

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Re: IJIS
« Reply #4185 on: April 27, 2017, 05:25:30 AM »
IJIS:

12,810,275 km2(April 26, 2017)down 16,083 km2 and 2nd lowest measured for the date.
Have a ice day!

Espen

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Re: IJIS
« Reply #4186 on: Today at 05:28:37 AM »
IJIS:

12,800,339 km2(April 27, 2017)down 9,936 km2 and 2nd lowest measured for the date.
Have a ice day!