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Wipneus

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Re: 2015 sea ice area and extent data
« Reply #650 on: July 15, 2015, 04:24:36 PM »
From today's NSIDC data update I calculate the following CT updates (the days in this list are the days of data released, three days behind ice dates):

Tue       6.037754
Wed -100.2  5.937507
Thu -69.2  5.868299
Fri -131.6  5.736748

The fat century (helped by lakes dropping -10k) was supported  by CAB (-62k4), ESS (-27k5), Baffin (-18k), Beaufort (-17k6) and the CAA (-11k). Increases in area are the Laptev (+21k) and Greenland Sea(+13k4).

Crazy region of the day is Laptev with an increase in extent of +83k .

In the attached NSIDC delta map, pixels with larger concentration changes than 7% or colored pinkish (down) or light blue (up). Solid red and blue are where the pixel concentration crosses the 15% limit (for extent).

seaicesailor

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Re: 2015 sea ice area and extent data
« Reply #651 on: July 15, 2015, 04:32:53 PM »
Just as much as yesterday's extent decrease in Laptev.

Bizarre

 8)

jdallen

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Re: 2015 sea ice area and extent data
« Reply #652 on: July 15, 2015, 05:58:47 PM »
Just as much as yesterday's extent decrease in Laptev.

Bizarre

 8)
Looking at the 7/13 Wordview closeup of the area, I see the ice in the whole area is extremely rotten, and has been getting rain. It's so dark it's almost charcoal.  It will likely disappear shortly, for real, giving the numbers another bump.
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Glenn Tamblyn

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Re: 2015 sea ice area and extent data
« Reply #653 on: July 16, 2015, 04:22:57 AM »
Although the main basin figures for 2012-15 (excluding the peripheral basins) still look similar, it is very much Chukchi  & ESS ahead counterbalanced by Beaufort behind with the Laptev catching up.

If the Chukchi/ESS continue on their current trend they will start to make inroads into the CAB sooner than previous years. The key seems to be the Beaufort. If the MYI there holds out, no chance of 2012. If it does melt out then even with little further penetration from the Beaufort into the CAB intrusion from the other basins should start to knock the CAB down.

Interestingly, CICE at DMI http://ocean.dmi.dk/anim/index.uk.php is showing a tongue of thinning ice from the Laptev all the way to the pole.


The Bight may not have appeared on the surface yet but it may be forming beneath.

JayW

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Re: 2015 sea ice area and extent data
« Reply #654 on: July 16, 2015, 11:30:04 AM »
Although the main basin figures for 2012-15 (excluding the peripheral basins) still look similar, it is very much Chukchi  & ESS ahead counterbalanced by Beaufort behind with the Laptev catching up.

If the Chukchi/ESS continue on their current trend they will start to make inroads into the CAB sooner than previous years. The key seems to be the Beaufort. If the MYI there holds out, no chance of 2012. If it does melt out then even with little further penetration from the Beaufort into the CAB intrusion from the other basins should start to knock the CAB down.

Interestingly, CICE at DMI http://ocean.dmi.dk/anim/index.uk.php is showing a tongue of thinning ice from the Laptev all the way to the pole.


The Bight may not have appeared on the surface yet but it may be forming beneath.

Wish I had seen this earlier, the June sea ice outlook from the national weather service in Anchorage. It was written June 25, I assume they will release a July outlook near the end of the month.   I'll just post a snippet to save space, for those interested in the whole outlook for the Chukchi and Beaufort, it's available here.
http://pafc.arh.noaa.gov/marfcst.php?fcst=FZAK30PAFC

Will be interesting to see how this area fares.

Quote
THE OFFSHORE REGION OF THE BEAUFORT SEA WILL CONTINUE TO BREAK UP
THROUGH SEPTEMBER. IT IS LIKELY THAT THE REGION FROM POINT BARROW TO
CAPE HALKETT NORTH TO 75N WILL NOT SEE ICE CONCENTRATIONS LESS THAN
3 TENTHS THIS SUMMER PERIOD
. THE OFFSHORE REGION FROM HARRISON BAY
TO FLAXMAN ISLAND NORTH TO 75N MAY SEE ICE CONCENTRATIONS DECREASE
TO 3 TENTHS BY THE END OF SEPTEMBER...AND THE OFFSHORE REGION FROM
FLAXMAN ISLAND TO DEMARCATION POINT NORTH TO 75N MAY SEE ICE
CONCENTRATIONS DECREASE TO 3 TENTHS BY THE END OF SEPTEMBER.
"To defy the laws of tradition, is a crusade only of the brave" - Les Claypool

Wipneus

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Re: 2015 sea ice area and extent data
« Reply #655 on: July 16, 2015, 04:13:15 PM »
From today's NSIDC data update I calculate the following CT updates (the days in this list are the days of data released, three days behind ice dates):

Wed       5.937680
Thu -69.2  5.868472
Fri -132.5  5.735944
Sat -119.7  5.616214

Saturdays century (despite +15k8 increase in lake "ice") has the support from the CAB (-42k8), ESS (-19k1), CAA (-17k) and Kara (-16k2).

In the attached NSIDC delta map, pixels with larger concentration changes than 7% or colored pinkish (down) or light blue (up). Solid red and blue are where the pixel concentration crosses the 15% limit (for extent).

OldLeatherneck

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Re: 2015 sea ice area and extent data
« Reply #656 on: July 16, 2015, 04:34:33 PM »


At first look, it would appear that 2015 has only a slight chance of competing with 2007 and 2011 and no realistic path to approaching 2012's minimum.  My projections, from the current date use the average losses (2004 - 2014), average + 10%, average - 10%, as well as record minimum  and maximum losses for each  semi-monthly period.  I've stopped the projections on September 15th, because after that there is too much noise in the data to be meaningful.

Because there is still a significant amount of ice left in both the Hudson and Baffin bays, my projections are probably skewed somewhat high.  The general consensus is that these regions will be essentially ice-free by early September, if not sooner. Therefore, I'm not going to rule out having a minimum less that 2007 or 2011.

Setting a new record low SIE this year, will require maintaining near-record losses during the last half of July and first half of August, followed by new record losses in late August and/or early September.  Obviously, it will take ideal melt and transport conditions to prevail. 

If anyone finds this chart useful, I can post updates weekly, bi-weekly or never again.
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jdallen

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Re: 2015 sea ice area and extent data
« Reply #657 on: July 16, 2015, 06:12:03 PM »


At first look, it would appear that 2015 has only a slight chance of competing with 2007 and 2011 and no realistic path to approaching 2012's minimum.  My projections, from the current date use the average losses (2004 - 2014), average + 10%, average - 10%, as well as record minimum  and maximum losses for each  semi-monthly period.  I've stopped the projections on September 15th, because after that there is too much noise in the data to be meaningful.

Because there is still a significant amount of ice left in both the Hudson and Baffin bays, my projections are probably skewed somewhat high.  The general consensus is that these regions will be essentially ice-free by early September, if not sooner. Therefore, I'm not going to rule out having a minimum less that 2007 or 2011.

Setting a new record low SIE this year, will require maintaining near-record losses during the last half of July and first half of August, followed by new record losses in late August and/or early September.  Obviously, it will take ideal melt and transport conditions to prevail. 

If anyone finds this chart useful, I can post updates weekly, bi-weekly or never again.
would love to see more, OL.  Good to have you back.
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carmiac

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Re: 2015 sea ice area and extent data
« Reply #658 on: July 16, 2015, 07:40:04 PM »
This is a great chart! Please keep it updated!

OldLeatherneck

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Re: 2015 sea ice area and extent data
« Reply #659 on: July 17, 2015, 01:41:50 PM »
would love to see more, OL.  Good to have you back.

jdalllen,

Thanks.  I'll keep the chart updated and post it on a weekly basis, +/_ a few days.

Yesterdays IJIS SIE loss was 155K.  The average daily loss for the last 16 days of July is about 87K, while the record loss was over 99K. 

In following the comments and charts on the 2015 Melting Season topic, it would appear that we are in for a week to ten days of significant melting.  The  question remains, how much of that will be seen in SIE loss. 
« Last Edit: July 17, 2015, 04:15:40 PM by OldLeatherneck »
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JayW

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Re: 2015 sea ice area and extent data
« Reply #660 on: July 17, 2015, 03:35:56 PM »
Wasn't sure of the best place to post this.  Feel free to move to a more appropriate location.  :)

Quote
Technical Implementation Notice 15-36
National Weather Service Headquarters Washington DC
330 PM EDT Fri Jul 10 2015
 
To:       Subscribers:
          -Family of Services
          -NOAA Weather Wire Service
          -Emergency Managers Weather Information Network
          -NOAAPORT
          Other NWS Partners, Users and Employees
 
From:     Timothy McClung
          Chief Operating Officer
          NWS Office of Science and Technology Integration
 
Subject:  Upgrade to Global-Real Time Ocean Forecast System
          (RTOFS) Effective September 1st, 2015
 
Effective on or about September 1, 2015
, beginning with the 0000
Coordinated Universal Time (UTC) run, the National Centers for
Environmental Prediction (NCEP) will upgrade the Global-RTOFS.
 
The system changes include:
 
- An increase in the number of vertical layers from 32 to 41
hybrid layers with additional iso-level coordinate layers in the
upper ~200m.
- The coupling of the ocean component Hybrid Coordinate Ocean
Model (HYCOM) to Los Alamos National Laboratory’s Community Sea
Ice (CICE) model using v4.0 of Earth System Modeling Framework
(ESMF).

- Updated bathymetry, which improves representation of grid
points in shallow regions where minimum depth is set to 5m.
- An update of the climatology from the U.S. Navy's Generalized
Digital Environmental Model (GDEM) v3.0 to v4.2.
- An equation of state, which is updated from 9 terms to 17
terms.
 
Benefits of the system changes include:
 
- Fine vertical resolution in the oceanic mixed layer with 9
additional near surface layers.
- Anticipated improvement to air-sea boundary flux for future
coupled applications (including hurricanes).
- Improved vertical coastal ocean resolution for downstream
applications, such as the National Ocean Service Operational
Forecast System (NOS-OFS) and Eco forecasting.
- Planned addition of Sea Ice products.
 
http://www.nws.noaa.gov/os/notification/tin15-36global-rtofs.htm
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seaicesailor

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Re: 2015 sea ice area and extent data
« Reply #661 on: July 17, 2015, 04:25:17 PM »
Not very fast, bumpy. But all in all, in the last 20 days, NSIDC sea ice extent has averaged slightly more than 100K Km2 of decrease per day. And the prospects are not good.

Wipneus

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Re: 2015 sea ice area and extent data
« Reply #662 on: July 18, 2015, 08:24:04 AM »
From today's NSIDC data update I calculate the following CT updates (the days in this list are the days of data released, three days behind ice dates):

Wed       5.937680
Thu -69.2  5.868472
Fri -132.5  5.735944
Sat -119.9  5.616088
Sun -124.0  5.492084

Hudson and Baffin are the biggest contributors (-35k5 and -35k8) with  from the CAA (-24k3), Kara (-17k4). and "Lakes" (-15k5). The CAB shows a small increase (+12k3).

In the attached NSIDC delta map, pixels with larger concentration changes than 7% or colored pinkish (down) or light blue (up). Solid red and blue are where the pixel concentration crosses the 15% limit (for extent).

seaicesailor

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Re: 2015 sea ice area and extent data
« Reply #663 on: July 18, 2015, 12:55:08 PM »

The "piggy bank" Baffin&Hudson has decreased in size but still +400K-ish for extent and +300K-ish for area.


OldLeatherneck

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Re: 2015 sea ice area and extent data
« Reply #664 on: July 18, 2015, 01:07:57 PM »
IJIS SIE has lost 290K in just two days.  It will be interesting to see how many more century losses will occur before the end of July.

I know it's too early to get excited.......yet, this is exciting to watch.
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Wipneus

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Re: 2015 sea ice area and extent data
« Reply #665 on: July 18, 2015, 01:35:07 PM »
IJIS SIE has lost 290K in just two days.  It will be interesting to see how many more century losses will occur before the end of July.

I know it's too early to get excited.......yet, this is exciting to watch.

SIE, formerly known as IJIS, has a two day averaging. That means that yesterday's drop of 155053 km2 was actually a two-day drop of double that, or 310k. Can you already feel it in your stomach?

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Re: 2015 sea ice area and extent data
« Reply #666 on: July 18, 2015, 03:02:42 PM »
ADS-NIPR Extent:
7,920,694 km2 (17 July)
Down 6,021,366 km2 (43.19%) from 2015 maximum of 13,942,060 km2 on 15 February.
4,743,239 km2 above record minimum extent of 3,177,455 km2 (16 September 2012).
Down 134,225 km2 from previous day.
Down 740,125 km2 over past seven days (daily average: -105,732 km2).
Down 1,561,622 km2 for the month of July (daily average: -91,860 km2).
597,762 km2 below 2000s average for this date.
341,630 km2 above 2010s average for this date.
343,629 km2 above 2014 value for this date.
546,647 km2 above 2012 value for this date.
8th lowest July to-date average.
7th lowest value for the date.
64 days this year (32.32% year-to-date) have recorded the lowest daily extent.
32 days (16.16%) have recorded the second lowest.
32 days (16.16%) have recorded the third lowest.
128 days (64.65%) in total have been among the three lowest on record.


CT Area:
NOTE: due to the extended absence of official CT sea ice area data, I've instead used Wipneus' calculated area numbers for the period from Days 0.5343 through 0.5397. The official numbers will be inserted if/when available. In the meantime, thanks, Wipneus!
5,616,088 km2 (17 July [Day 0.5397])
Down 7,658,467 km2 (57.69%) from 2015 maximum of 13,274,555 km2 on 17 February [Day 0.1288].
3,382,079 km2 above record minimum area of 2,234,010 km2 (14 September 2012).
Down 119,856 km2 from previous day.
Down 753,754 km2 over past seven days (daily average: -107,679 km2).
Down 1,838,733 km2 for the month of July (daily average: -108,161 km2).
612,221 km2 below 2000s average for this date.
66,984 km2 above 2010s average for this date.
247,782 km2 below 2014 value for this date.
579,155 km2 above 2012 value for this date.
5th lowest July to-date average.
5th lowest value for the date.
7 days this year (3.54% year-to-date) have recorded the lowest daily area.
19 days (9.6%) have recorded the second lowest.
29 days (14.65%) have recorded the third lowest.
55 days in total (27.78%) have been among the lowest three on record.

Vergent

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Re: 2015 sea ice area and extent data
« Reply #667 on: July 18, 2015, 04:19:42 PM »
NSIDC Daily Extent:

2015,    07,  14,      8.746,     
2015,    07,  15,      8.615,   -131k   
2015,    07,  16,      8.403,   -212k
2015,    07,  17,      8.271,   -132k

Three day loss: -475k
Three day average: -158k

Well, pigs aren't flying, but NSIDC is migrating south.

Verg

Wipneus

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Re: 2015 sea ice area and extent data
« Reply #668 on: July 18, 2015, 04:31:14 PM »
From today's NSIDC data update I calculate the following CT updates (the days in this list are the days of data released, three days behind ice dates):

Wed       5.937680
Thu -69.2  5.868472
Fri -132.5  5.735944
Sat -119.9  5.616088
Sun -124.3  5.491835
Mon -93.7  5.398108

Hudson, Laptev and CAA are the biggest decliners (~-18k). ESS and "lake ice" dropped -10k.

Baffin is the funny region with zero (CT) area change and an increase in (NSIDC) extent of +27k5.

In the attached NSIDC delta map, pixels with larger concentration changes than 7% or colored pinkish (down) or light blue (up). Solid red and blue are where the pixel concentration crosses the 15% limit (for extent).

OldLeatherneck

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Re: 2015 sea ice area and extent data
« Reply #669 on: July 19, 2015, 12:30:55 PM »


Considering the losses of the past few days and the current forecasts for the next week, I am willing to say that 2015 will almost certainly end up below 2013 and 2014.  I now also think that 2007 and 2011 are vulnerable, although it will still take favorable melt conditions for the remainder of the season. As to 2012, it's probably safe for now.

The big question is this; how rotten, mushy and slushy will the remaining ice be when this current attack of heat ends?
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Jim Pettit

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Re: 2015 sea ice area and extent data
« Reply #670 on: July 19, 2015, 02:11:41 PM »
According to Wipneus's spot-on SIA numbers, 2015 area has now dropped below 1980's minimum of 5.5 million km2.  Next up: 1986.

If this year's SIA is going to make a serious run toward the bottom, now is the time. Beginning today, 2012 entered a 12-day run that saw just a single century drop, 2014 was a week away from the start of an overall one-week decrease of only 82k, and 2013 was less than a week away from kicking off a bizarre 10-day stretch which saw an overall increase of 21k.

Area will drop into 4th place tomorrow, leapfrogging over and ahead of 2010. This will be the first time 2015 SIA has been ranked higher than 5th place in over a month.

2015 is still 630k above 2012 for the date.

Wipneus

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Re: 2015 sea ice area and extent data
« Reply #671 on: July 19, 2015, 04:13:09 PM »
From today's NSIDC data update I calculate the following CT updates (the days in this list are the days of data released, three days behind ice dates):

Wed       5.937680
Thu -69.2  5.868472
Fri -132.5  5.735944
Sat -119.9  5.616088
Sun -124.3  5.491835
Mon -93.7  5.398108
Tue -88.9  5.309186

With Tuesday's -89k the remarkable sequence of near one century drops is now numbered 11. This member came from Hudson (-22k8), Beaufort (-21k8) Laptev (-16k) and the ESS (-12k3). Baffin increased by +14k9.

In the attached NSIDC delta map, pixels with larger concentration changes than 7% or colored pinkish (down) or light blue (up). Solid red and blue are where the pixel concentration crosses the 15% limit (for extent).

BornFromTheVoid

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Re: 2015 sea ice area and extent data
« Reply #672 on: July 19, 2015, 04:45:41 PM »
Update for the week to July 18th

The current 5 day mean is on 8,431,000km2 while the 1 day extent is at 8,120,000km2.
The daily anomaly (compared to 81-10) is at -1,052,840km2, an increase from -854,100km2 last week. The anomaly compared to the 07, 11 and 12 average is at +754,867km2, a decrease from +799,267km2 last week. We're currently 7th lowest on record, up from 9th last week.



The average daily change over the last 7 days was -114.3k/day, compared to the long term average of -85.9k/day, and the 07, 11 and 12 average of -107.9k/day.
The average long term change over the next week is -89.0k/day, with the 07, 11, and 12 average being -80.2k/day.



The loss so far this July is the 11th largest on record. To achieve the largest monthly drop, a daily loss of at least 135.8k/day is required, while the smallest drop requires a loss of less than 20.0k/day and an average drop requires a loss of 70.4k/day.


Vergent

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Re: 2015 sea ice area and extent data
« Reply #673 on: July 19, 2015, 05:55:57 PM »
NSIDC Daily Extent:

2015,    07,  14,      8.746,     
2015,    07,  15,      8.615,   -131k   
2015,    07,  16,      8.403,   -212k
2015,    07,  17,      8.271,   -132k
2015,    07,  18,      8.120,   -151k

4 day loss 626k

Verg

Peter Ellis

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Re: 2015 sea ice area and extent data
« Reply #674 on: July 19, 2015, 06:39:26 PM »
From today's NSIDC data update I calculate the following CT updates (the days in this list are the days of data released, three days behind ice dates):

Wed       5.937680
Thu -69.2  5.868472
Fri -132.5  5.735944
Sat -119.9  5.616088
Sun -124.3  5.491835
Mon -93.7  5.398108
Tue -88.9  5.309186

With Tuesday's -89k the remarkable sequence of near one century drops is now numbered 11.

Uh, can you explain that?  Unless I'm misunderstanding, in order to get a sequence of 11 'near one century drops', you have to be including the -69.2 last Thursday.  If so, then this really is stretching the definition of 'near' to a ridiculous degree.

Notwithstanding all the excitable talk in this forum - as things stand, the July melt to date is somewhat lower than the average for the last decade.  June was the slowest melt month for many years.  In the absence of an unprecedented late July / early August collapse, this year will be another comparative squib, and end up no lower than 2010.
« Last Edit: July 19, 2015, 06:45:27 PM by Peter Ellis »

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Re: 2015 sea ice area and extent data
« Reply #675 on: July 19, 2015, 07:10:12 PM »

With Tuesday's -89k the remarkable sequence of near one century drops is now numbered 11.

Uh, can you explain that?  Unless I'm misunderstanding, in order to get a sequence of 11 'near one century drops', you have to be including the -69.2 last Thursday.  If so, then this really is stretching the definition of 'near' to a ridiculous degree.

Perhaps he's excluding the increase in "lake ice", which stretches the definition of "real" to a ridiculous degree.

Quote from: Wipneus
So a sub-century on Thursday, lake ice is a factor as it jumped +20k1 (or CT's decision to include it in its sea ice area calculation).

Notwithstanding all the excitable talk in this forum - as things stand, the July melt to date is somewhat lower than the average for the last decade.  June was the slowest melt month for many years.  In the absence of an unprecedented late July / early August collapse, this year will be another comparative squib, and end up no lower than 2010.

Yes, I for one will be shocked when this year Baffin and Hudson continue their unprecedented collapse a few weeks later than usual (about 600 km2 left to go) ... shocked!   ::)

https://sites.google.com/site/arcticseaicegraphs/regional

The Permian–Triassic extinction event, a.k.a. the Great Dying, occurred about 250 million years ago and is the most severe known extinction event. Up to 96% of all marine species and 70% of terrestrial vertebrate species became extinct; it is also the only known mass extinction of insects.

Wipneus

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Re: 2015 sea ice area and extent data
« Reply #676 on: July 19, 2015, 07:14:32 PM »


Uh, can you explain that?  Unless I'm misunderstanding, in order to get a sequence of 11 'near one century drops', you have to be including the -69.2 last Thursday.  If so, then this really is stretching the definition of 'near' to a ridiculous degree.

I do mean it. In a time series where the day-to-day changes them selves often change more than a century the 40k is still "close". Add to this that we know that in the -69k was included a +20k jump in "lake ice", something I'd rather ignored.

Attached the day-to-day changes since end May. I looked for it today but there is no such series as the last 11 days to be found in 2012, 2013 or 2014 Arctic summers.

Peter Ellis

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Re: 2015 sea ice area and extent data
« Reply #677 on: July 19, 2015, 08:44:59 PM »
I looked for it today but there is no such series as the last 11 days to be found in 2012, 2013 or 2014 Arctic summers.

Can you explain the methodology by which you looked for it?

I took the complete data record from here:
http://arctic.atmos.uiuc.edu/cryosphere/timeseries.anom.1979-2008

Then appended the last 6 days as per your post here:
http://forum.arctic-sea-ice.net/index.php/topic,1112.msg57176.html#msg57176

i.e the following values, which were not in the main source file from CT
5.868472
5.735944
5.616088
5.491835
5.398108
5.309186


For this file, I then simply calculated the total drop for each 11-day window up to the present day.
The last line of the file is thus:
2015.548     /     5.309186     /     -1.1493721
(i.e. date / current value / total drop over the preceding 11 days)

In the file as a whole, there are 494 cases where the aggregate drop over 11 days exceeds the most recent 11-day run.  If I restrict it to only 2012 onwards, there are still 80 11-day periods with a greater drop.

I have no idea what criteria you are using to make the current rate of area decrease stand out as in any way exceptional.

Peter Ellis

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Re: 2015 sea ice area and extent data
« Reply #678 on: July 19, 2015, 08:55:55 PM »
Next check - count the number of century breaks in each 11-day window.

(i.e. date / current value / total drop over the preceding 11 days / daily drop / number of century breaks in 11 days)

Filtering only the ones since 2010 with 9 or more centuries in 11 days - nothing unusual here for recent years.

2010.4795     /     7.3327947     /     -1.598886     /     -0.1868057     /     9
2010.4822     /     7.1141281     /     -1.7062216     /     -0.2186666     /     9
2010.485     /     7.0036221     /     -1.6926097     /     -0.110506     /     9
2010.4877     /     6.8817024     /     -1.5509939     /     -0.1219197     /     9
2010.4904     /     6.7840648     /     -1.6320424     /     -0.0976376     /     9
2010.4932     /     6.7720647     /     -1.6078153     /     -0.0120001     /     9
2012.4548     /     8.0299053     /     -1.7262392     /     -0.1740399     /     9
2012.4575     /     7.9473367     /     -1.769813     /     -0.0825686     /     9
2012.4603     /     7.7897234     /     -1.8719988     /     -0.1576133     /     10
2012.463     /     7.8461437     /     -1.6677141     /     0.0564203     /     9
2013.5096     /     6.8665686     /     -1.3926468     /     -0.1600747     /     9
2013.5452     /     5.3513508     /     -1.4234743     /     -0.1603718     /     9
2015.5425     /     5.491835     /     -1.323424     /     -0.124253     /     9

« Last Edit: July 20, 2015, 12:18:53 AM by Peter Ellis »

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Re: 2015 sea ice area and extent data
« Reply #679 on: July 19, 2015, 09:05:08 PM »
Final check: dropping the threshold to -85k to allow for "near centuries".

(i.e. date / current value / total drop over the preceding 11 days / daily drop / number of <-85k breaks in 11 days)

Filtering only the ones since 2010 with 9 or more <-85k breaks in 11 days - nothing unusual here for recent years.

2010.474     /     7.7280726     /     -1.3769956     /     -0.1562052     /     9
2010.4767     /     7.5196004     /     -1.4989695     /     -0.2084722     /     9
2010.4795     /     7.3327947     /     -1.598886     /     -0.1868057     /     9
2010.4822     /     7.1141281     /     -1.7062216     /     -0.2186666     /     9
2010.485     /     7.0036221     /     -1.6926097     /     -0.110506     /     9
2010.4877     /     6.8817024     /     -1.5509939     /     -0.1219197     /     9
2010.4904     /     6.7840648     /     -1.6320424     /     -0.0976376     /     10
2010.4932     /     6.7720647     /     -1.6078153     /     -0.0120001     /     10
2010.4958     /     6.7475667     /     -1.4625087     /     -0.024498     /     9
2011.5535     /     4.8431249     /     -1.1880912     /     -0.0875363     /     9
2011.5562     /     4.7263017     /     -1.258482     /     -0.1168232     /     10
2011.559     /     4.6315165     /     -1.2373094     /     -0.0947852     /     10
2011.5616     /     4.5535083     /     -1.1761851     /     -0.0780082     /     9
2011.5643     /     4.4520302     /     -1.1919308     /     -0.1014781     /     9
2012.4548     /     8.0299053     /     -1.7262392     /     -0.1740399     /     9
2012.4575     /     7.9473367     /     -1.769813     /     -0.0825686     /     9
2012.4603     /     7.7897234     /     -1.8719988     /     -0.1576133     /     10
2012.463     /     7.8461437     /     -1.6677141     /     0.0564203     /     9
2013.5096     /     6.8665686     /     -1.3926468     /     -0.1600747     /     9
2013.5452     /     5.3513508     /     -1.4234743     /     -0.1603718     /     9
2015.526     /     6.1565456     /     -1.2632199     /     -0.1007295     /     9
2015.5288     /     6.0377536     /     -1.2449732     /     -0.118792     /     9
2015.5315     /     5.9376798     /     -1.1660933     /     -0.1000738     /     9
2015.5343     /     5.868472     /     -1.2231976     /     -0.0692078     /     9
2015.537     /     5.735944     /     -1.1424983     /     -0.132528     /     9
2015.5397     /     5.616088     /     -1.1596974     /     -0.119856     /     9
2015.5425     /     5.491835     /     -1.323424     /     -0.124253     /     10
2015.5452     /     5.398108     /     -1.2525439     /     -0.093727     /     10
2015.548     /     5.309186     /     -1.1493721     /     -0.088922     /     10


The recent run in 2015 does seem to have extended a couple of days longer than the ones in 2011, 2012 and 2013, and is similar length the the one in 2010.  However, 2010, 2012 and even 2013 were associated with far higher total losses over 11 days.

So I guess the strongest comment the data actually justifies is that we have just had an unusually consistent run of melt days all either just under or just over a century, but that the actual rate of melt is not particularly unusual for the time of year - exactly what BFTV's post shows and what I originally commented on.
« Last Edit: July 20, 2015, 12:17:27 AM by Peter Ellis »

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Re: 2015 sea ice area and extent data
« Reply #680 on: July 19, 2015, 10:03:38 PM »
Final check: dropping the threshold to -85k to allow for "near centuries".

(i.e. date / current value / total drop over the preceding 11 days / daily drop / number of <-85k breaks in 11 days)

<snippage>

The recent run in 2015 does seem to have extended a couple of days longer than the ones in 2011, 2012 and 2013, and is similar length the the one in 2010.  However, 2010, 2012 and even 2013 were associated with far higher total losses over 11 days.

So I guess the strongest comment the data actually justifies is that we have just had an unusually consistent run of melt days all either just under or just over a century, but that the actual rate of melt is not particularly unusual for the time of year - exactly what BFTV's post shows and what I originally commented on.

Let's also consider the numbers in this context - the years in question.  2010, 2011, 2012, which are in our bottom 5.  2013 *would* have been in the same category save for it's astonishing August "stall".

Let's also consider conditions.  IIRC, 2010-2012 had much different weather, with much higher levels of export.

Let's also consider ice; 2010 - 2013 all had significantly lower volume than 2015.

So, if you look at just the loss numbers, you don't get the full story.  I think it makes 2015's losses - with slower export, different weather, thicker ice - more remarkable in context.

I will also point out, irrespective of that, 2015's run puts it into the same league as 3 out of the bottom 5 minimums.  This could be interpreted as a very strong signal indicating this year is heading into competition with them, and quite possibly will displace them.
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Re: 2015 sea ice area and extent data
« Reply #681 on: July 20, 2015, 12:19:24 AM »
Some number crunching using IJIS extent data.

I looked at how much melt took place for 2007-2013 from this date (July 19) through the year's annual minimum.

From that I derived rough Average and StdDev values for those values.

-2SDEV   2174266
-1SDEV   2686549
Average   3198831
+1SDEV   3711114
+2SDEV   4223396



Reducing the current IJIS extent (7767000) by those numbers, I get the following rough probabilities presuming melt conditions averaged over those years:

Prob  Extent
0.05   >5600000
0.11   5100000-5600000
0.34   4570000-5100000
0.34   4050000-4570000
0.11   3500000-4050000
0.05   < 3500000

So, given "average" behavior, reaching 2012 is a less than 5% probability.
Beating 2010 is above 50-50
Beating 2008 is about 50-50
Beating 2011 is above 1 chance in 6
Beating 2007 about 1 chance in 6

So,  I expect this year will make it into the top 5, probably the top 4, and still has very high probability of breaking into the top 3, especially when one considers the existing extra ice in the Hudson and Baffin, combined with the dipole forecast and continued high heat.  Those may actually persuade me to consider increasing my odds in favor of more melt by as much as 25%. 

The next week will tell me if my impressions of the weakness of ice in the eastern CAB and peripheral seas is correct, and persuades me to shift my expectations accordingly.

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Re: 2015 sea ice area and extent data
« Reply #682 on: July 20, 2015, 12:29:00 AM »
I will also point out, irrespective of that, 2015's run puts it into the same league as 3 out of the bottom 5 minimums.  This could be interpreted as a very strong signal indicating this year is heading into competition with them, and quite possibly will displace them.

Sorry I wasn't clear - when looking at century and near-century breaks, I only looked at 2010 onwards, since Wipneus said he'd looked at 2012, 2013 and 2014. I've edited my posts to clarify this.

If I extend the same comparison back further, you can find similar near-century runs in the summers of 2009, 2003,1999,1997,1995,1991,1986,1983, 1981 and 1979. Area and extent loss for this July to date are just not exceptional. Look at BFTV's post.  July losses are the 11th lowest on record (out of 36 years), and the 7th lowest in the last decade.  That is, only a little faster than the long-term average, and a little slower than most recent years.

I don't know how to put this more plainly.
« Last Edit: July 20, 2015, 12:44:17 AM by Peter Ellis »

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Re: 2015 sea ice area and extent data
« Reply #683 on: July 20, 2015, 01:22:06 AM »
Peter,

  How many 11 day sequences were there where all 11 days had a drop of at least 69.2k km2?

  That is what Wipneus actually found to be remarkable.

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Re: 2015 sea ice area and extent data
« Reply #684 on: July 20, 2015, 02:49:40 AM »
I will also point out, irrespective of that, 2015's run puts it into the same league as 3 out of the bottom 5 minimums.  This could be interpreted as a very strong signal indicating this year is heading into competition with them, and quite possibly will displace them.

Sorry I wasn't clear - when looking at century and near-century breaks, I only looked at 2010 onwards, since Wipneus said he'd looked at 2012, 2013 and 2014. I've edited my posts to clarify this.

If I extend the same comparison back further, you can find similar near-century runs in the summers of 2009, 2003,1999,1997,1995,1991,1986,1983, 1981 and 1979. Area and extent loss for this July to date are just not exceptional. Look at BFTV's post.  July losses are the 11th lowest on record (out of 36 years), and the 7th lowest in the last decade.  That is, only a little faster than the long-term average, and a little slower than most recent years.

I don't know how to put this more plainly.

I wasn't aware you'd stopped, but I'll trust your reporting on the numbers, so no, in that context it does not seem that unusual.

I think my follow up post pretty much summarizes my expectation for how things will go.  In it, I'm basing my extrapolation the heat budget, as exemplified by the melt numbers.
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Re: 2015 sea ice area and extent data
« Reply #685 on: July 20, 2015, 09:41:54 AM »
Peter,

  How many 11 day sequences were there where all 11 days had a drop of at least 69.2k km2?

  That is what Wipneus actually found to be remarkable.

1980, 1981, 1983, 1985, 1997, 2003, 2007, 2011, 2012, 2014 and 2015.

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Re: 2015 sea ice area and extent data
« Reply #686 on: July 20, 2015, 10:33:41 AM »
Most of the other similar drops have been a bit earlier in the year.  Shifting of it into July this year represents the slow June we had, and thus the ongoing contribution of Hudson Bay to the daily numbers.

Yes, it's true that having ~300k still "in the bank" in Hudson means that there's more pain stored up for later in this season.  However, the flip side of that is that if Hudson had melted out earlier, as expected, then the current daily values would be that much less impressive, with few recent centuries. 

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Re: 2015 sea ice area and extent data
« Reply #687 on: July 20, 2015, 11:52:22 AM »
Most of the other similar drops have been a bit earlier in the year.  Shifting of it into July this year represents the slow June we had, and thus the ongoing contribution of Hudson Bay to the daily numbers.

Yes, it's true that having ~300k still "in the bank" in Hudson means that there's more pain stored up for later in this season.  However, the flip side of that is that if Hudson had melted out earlier, as expected, then the current daily values would be that much less impressive, with few recent centuries.
The Baffin/Hudson bank has only declined by a couple of hundred K km^2 in the last 10 days because the decline is normally  pretty high at this time.  So the extent decline over the past 10  days would still be near 1 M km^2.

This is still very much a tale of two areas the Canadian side of the Arctic is slow but starting to catch up. The Siberian side is well ahead of 2012 and shows no signs of slowing down. This is the areas where warmer waters will have the most  impact on the CAB.

The Beaufort now appears to be moving into a faster melting phase and the ice is very  broken up right up to the 80th parallel in that area. Melting in the Queen Elizabeth Islands also seems to be well ahead of the past couple of years, there is no snow on the islands themselves and the fracture in the ice north of the islands is more pronounced than in previous years.

In short the whole Arctic appears to  be primed for a lot  of melt throughout the next two months.  Although a record seems highly unlikely a minimum below 2007 remains a distinct possibility. 


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Re: 2015 sea ice area and extent data
« Reply #688 on: July 20, 2015, 03:25:56 PM »

Can you explain the methodology by which you looked for it?


A  methodology to look at a graph ? Come on, you are looking for more than there is into this.


Quote
I have no idea what criteria you are using to make the current rate of area decrease stand out as in any way exceptional.

So in English the words remarkable and exceptional are synonymous? Perhaps it is my simple English but that is not what is meant.

I did choose the word "remarkable" with some care. I did not want to imply anything about significance. Instead I am in the process of trying to understand the day-to-day changes, using the different sources of information that are available each day. The CT-area path is mostly a rocky road, the eleven day smooth pause is noticeable (is that a better word?) enough.

So that is the second point where you missed my intended meaning: it is not the current rate but the constancy of it.

All in all, I always like to word things better when it causes misunderstandings and did so in the past. I am not sure how to have done it here, but am open to suggestions.

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Re: 2015 sea ice area and extent data
« Reply #689 on: July 20, 2015, 03:46:18 PM »

Can you explain the methodology by which you looked for it?


A  methodology to look at a graph ? Come on, you are looking for more than there is into this.
Quote
I have no idea what criteria you are using to make the current rate of area decrease stand out as in any way exceptional.

So in English the words remarkable and exceptional are synonymous? Perhaps it is my simple English but that is not what is meant.

I did choose the word "remarkable" with some care. I did not want to imply anything about significance. Instead I am in the process of trying to understand the day-to-day changes, using the different sources of information that are available each day. The CT-area path is mostly a rocky road, the eleven day smooth pause is noticeable (is that a better word?) enough.

So that is the second point where you missed my intended meaning: it is not the current rate but the constancy of it.

All in all, I always like to word things better when it causes misunderstandings and did so in the past. I am not sure how to have done it here, but am open to suggestions.
Wipneus,
I think the word you want is 'noteworthy' it has the meaning  of being worth commenting on without necessarily being exceptional.

 I  had the same problem once when someone confused 'regularly' with 'frequently' the one implying  a pattern of behaviour while the other implied the number of times it occurred.  ???

Another whopping decline in NSIDC extent yesterday 188K km^2.   In the last 4 days that's 80 K per day closer to the lowest to date.
« Last Edit: July 20, 2015, 03:58:49 PM by DavidR »
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Re: 2015 sea ice area and extent data
« Reply #690 on: July 20, 2015, 03:52:46 PM »
Veering from data analysis toward numerology! :o

All statistical data gathering processes have quirks and flaws and we can read too much into the fine grains of any data stream that is subject to uncertainty, especially a daily one converting relatively crude sensor readings of a remote and inaccessible area of the planet from space!  It all evens out...

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Re: 2015 sea ice area and extent data
« Reply #691 on: July 20, 2015, 03:57:15 PM »

So in English the words remarkable and exceptional are synonymous? Perhaps it is my simple English but that is not what is meant.

One should strive to be a 'charitable reader' - especially in dialogue where not all are native English speakers.  My initial reaction to the post was probably similar to Peter's, but I thought a little more and a 'charitable' reading of the post was that Wipneus chose to remark upon the numbers. That in itself made the numbers remarkable.  It's a tautology. 

As Wipneus points out 'remarkable' does not equal 'exceptional.'

DavidR - 'remarkable' comes from the French remarquer -- 'take note of'  :)



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Re: 2015 sea ice area and extent data
« Reply #692 on: July 20, 2015, 04:05:57 PM »
937k dropped in the last week on the daily NSIDC data.
If we drop just 186k over the next 2 days, we'll have yet another mega melt week (>1,000,000km2), the 5th year in a row to do so. This is especially impressive consider they occurred for just 2 years prior to 2007.

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Re: 2015 sea ice area and extent data
« Reply #693 on: July 20, 2015, 04:28:44 PM »
Wipneus,

Quote
Note: snow cover data not updating ... we hope to have a new data source by July, 2015.

CT is going through a planned data source change. It may effect NSIDC as well. That may be the reason for the remarkable stability. You can see that the change effects concentration as well as snow by looking at the animation:

http://arctic.atmos.uiuc.edu/CT/animate.arctic.color.0.html

Verg

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Re: 2015 sea ice area and extent data
« Reply #694 on: July 20, 2015, 04:39:54 PM »
Charctic SIE loss today is 1.63 million Km^2
2012 loss for the same day was 1.004 million Km^2

http://nsidc.org/arcticseaicenews/charctic-interactive-sea-ice-graph/
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Re: 2015 sea ice area and extent data
« Reply #695 on: July 20, 2015, 04:41:25 PM »
Wipneus,

Quote
Note: snow cover data not updating ... we hope to have a new data source by July, 2015.

CT is going through a planned data source change. It may effect NSIDC as well. That may be the reason for the remarkable stability. You can see that the change effects concentration as well as snow by looking at the animation:

http://arctic.atmos.uiuc.edu/CT/animate.arctic.color.0.html

Verg

Could this be simply due to the 2-3 day lag "dropping out"?

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Re: 2015 sea ice area and extent data
« Reply #696 on: July 20, 2015, 04:52:53 PM »
From today's NSIDC data update I calculate the following CT updates (the days in this list are the days of data released, three days behind ice dates):

Sun       5.491770
Mon -93.7  5.398043
Tue -88.8  5.309246
Wed -115.6  5.193609

On Wednesday the discussed series will be twelve. Big decline in the Hudson (-40k8) followed by ESS (-20k9), Laptev (-18k4), CAB (-18k4) and CAA (-11k9).

Hudson did not just have a big drop in area, by extent (calculated the NSIDC way) the drop is -105k5.

In the attached NSIDC delta map, pixels with larger concentration changes than 7% or colored pinkish (down) or light blue (up). Solid red and blue are where the pixel concentration crosses the 15% limit (for extent).

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Re: 2015 sea ice area and extent data
« Reply #697 on: July 20, 2015, 04:54:28 PM »

Can you explain the methodology by which you looked for it?


A  methodology to look at a graph ? Come on, you are looking for more than there is into this.


Quote
I have no idea what criteria you are using to make the current rate of area decrease stand out as in any way exceptional.

So in English the words remarkable and exceptional are synonymous? Perhaps it is my simple English but that is not what is meant.

I did choose the word "remarkable" with some care. I did not want to imply anything about significance. Instead I am in the process of trying to understand the day-to-day changes, using the different sources of information that are available each day. The CT-area path is mostly a rocky road, the eleven day smooth pause is noticeable (is that a better word?) enough.

So that is the second point where you missed my intended meaning: it is not the current rate but the constancy of it.

All in all, I always like to word things better when it causes misunderstandings and did so in the past. I am not sure how to have done it here, but am open to suggestions.

We are beginning to get obsessed with semantics.  What may be "exceptional" or "remarkable" to one person may be mundane to someone else.  We should remember that for many members of this Forum, English is a second or third language.  Even among native English speakers there are significant semantic differences between countries and regions within a given country.  I found  this to be true when I had the opportunities to work with the British and Australian navies.

I have the utmost respect for the massive efforts Wipneus has made to both the Forum and the Blog.  His charts, graphs and animations have been "Exceptionally" valuable learning tools for each of us.  His choice of adjectives and adverbs is entirely up to him.

This thread is not about "Scientific Technical Writing 101"
"Share Your Knowledge.  It's a Way to Achieve Immortality."  ......the Dalai Lama

Nightvid Cole

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Re: 2015 sea ice area and extent data
« Reply #698 on: July 20, 2015, 05:00:18 PM »
Charctic SIE loss today is 1.63 million Km^2
2012 loss for the same day was 1.004 million Km^2

http://nsidc.org/arcticseaicenews/charctic-interactive-sea-ice-graph/

I think you need to move the decimal point one spot to the left...

Vergent

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Re: 2015 sea ice area and extent data
« Reply #699 on: July 20, 2015, 05:15:52 PM »
NSIDC Daily Extent:

2015,    07,  14,      8.746,
2015,    07,  15,      8.615,   -131k   
2015,    07,  16,      8.403,   -212k
2015,    07,  17,      8.271,   -132k
2015,    07,  18,      8.120,   -151k
2015,    07,  19,      7.932,   -188k

5 day loss: 814K, averaging -162/day. Climatology ('79 to 2010) for 7/14-7/19 is -461k

For reference 2012:

2012,    07,  14,      7.868..............2015,    07,  14,      8.746, ...................+878k   
2012,    07,  15,      7.705,  -163k....2015,    07,  15,      8.615,   -131k
2012,    07,  16,      7.606,   -99k.....2015,    07,  16,      8.403,   -212k
2012,    07,  17,      7.481,  -125k....2015,    07,  17,      8.271,   -132k
2012,    07,  18,      7.420,   -61k.....2015,    07,  18,      8.120,   -151k
2012,    07,  19,      7.350,   -70k.....2015,    07,  19,      7.932,   -188k..........+582
2012,    07,  20,      7.340,   -10k
2012,    07,  21,      7.297,  -113k
2012,    07,  22,      7.184,  -113k
2012,    07,  23,      7.118,   -66k
2012,    07,  24,      7.035,   -83k
2012,    07,  25,      6.931,  -104k
2012,    07,  26,      6.809,  -122k
2012,    07,  27,      6.677,  -132k
2012,    07,  28,      6.600,   -77k
2012,    07,  29,      6.478,  -122k
2012,    07,  30,      6.400,   -78k
2012,    07,  31,      6.368,   -32k

The 2012 lead is evaporating, er, melting. 2015 caught up by 296k in 5 days.

Verg

Edit: Tomorrow,....I see some low hanging fruit.
« Last Edit: July 20, 2015, 05:39:54 PM by Vergent »