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plinius

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Re: 2015 sea ice area and extent data
« Reply #1000 on: September 10, 2015, 01:22:57 PM »
well, Bruce, do me a favour first, please, and make a difference between Bering sea ice extent and Bering strait flow. That's two different pairs of shoes.
Apart from that - I am not aware of being insulting. Anecdotal evidence and cherry picking are words to describe the kind of evidence you produced, sorry if being frank hurts your feelings, but I won't mince words. And again, I cannot see that someone showed that PDV is related to early melt in the Chuckchi with a clean statistical analysis. Maybe you would like to point me to some literature or provide reliable statistics that have been properly detrended (very dangerous business here, since the PDV has a large autocorrelation and will in addition correlate with time due to the small number of phases --> you get an omitted variable bias in naively correlating PDV with sea ice indices).

Wipneus

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Re: 2015 sea ice area and extent data
« Reply #1001 on: September 10, 2015, 04:16:58 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):

day   chg  estimate  CT-value
Wed        3.110501  3.110124
Thu -15.9  3.094609  -
Fri  +8.0  3.102632  -
Sat +25.9  3.128514  -

Only "lake ice" changed significantly: +13k5.

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).

Bruce Steele

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Re: 2015 sea ice area and extent data
« Reply #1002 on: September 10, 2015, 04:59:46 PM »
Plinius, I don't think we have multiyear datasets to detrend . We are dealing with the new normal and as an amateur I think I can do a bit of speculating on what is happening to the ice. In my last post I said I thought low Bering Sea ice extent anomalies were contributing to " early " ice melt conditions for the Chukchi when weather conditions lined up to push that warm water through the straits.  I have been making the argument that positive PDO index years are contributing to low extent for the Bering and I don't have papers to quote for that conclusion as I came to that conclusion from what I saw in the data not from what someone else had said or written. Again without a longterm dataset to work from the 2004 Southern Bering ice extent started it's cliff decent on ~ about day 100 which is early in the 1979-2013 data.( see K.R. Wood et al / Progress in Oceanography)
 There is a reason why I think early inflow into the Northern Bering thru the Straits is important. Please see the below linked article
http://www.polarresearch.net/index.php/polar/article/viewFile/19552/pdf_

Starting the last paragraph on the first page the argument that increased easterlies , thinner sea ice and increased advection of fresh water from the Mackenzie combine to move the pack west to meet the warm inflow from the Bering strait.
 In my opinion the start of the Bering Strait inflow is important as it creates conditions favorable for insolation and the heating that the ice meets as it is pushed to the West.
 So there are multiple processes at work and low ice extent for the Southern Bering may be one of them. If we are moving back into a positive phase in the PDO cycle and we get 25-35 years with predominately positive index years maybe my thoughts on Bering Ice extent will be shown to be relevant but as I don't have letters in front of my name please take what I say with a grain of salt. If you would prefer to ignore me entirely that's fine too.   

For the dataset 1979-2015 every single year that had a negative sea ice anomaly for the Bering Sea also had a positive PDO index number except one year . Maybe I should have included the full data set in my first comment but I did supply both the PDO link and the Dosbat link I used to make my argument. So in my opinion I wasn't Cherrypicking.
« Last Edit: September 10, 2015, 06:39:04 PM by Bruce Steele »

Rick Aster

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Re: 2015 sea ice area and extent data
« Reply #1003 on: September 10, 2015, 05:54:28 PM »
Apart from that - I am not aware of being insulting. Anecdotal evidence and cherry picking are words to describe the kind of evidence you produced, sorry if being frank hurts your feelings, but I won't mince words.

Plinius, you do not come across as frank nor as scientific, but as dismissive. Merely referring to the strength of evidence when someone is engaged in formulating a hypothesis risks coming across as dismissive. Evidence comes in later in the scientific process when a hypothesis is tested, and when you want to skip over the scientific process of discovery and go directly to testing, you can not decently defend that as "frank."

plinius

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Re: 2015 sea ice area and extent data
« Reply #1004 on: September 10, 2015, 10:09:17 PM »
@Rick: I think you might wish to revisit the difference between hypotheses and claims. I didn't see Bruce lining out a hypothesis but making a claim instead. And yes, I have low regard for unbacked claims, as well as I suppose that some revision of scientific process might be beneficial for you.

@Bruce: Hope you are aware that the paper you link a) does not even mention the PDV/PDO (for good reasons) and that it is chiefly about Mackenzie input? And concerning the statistics: You first state that you do not have the data to detrend (I would actually differ, you could attempt to estimate the systematic uncertainty connected to the short scale), then you end with citing your same data again as evidence. What now? I do think that your claim interesting, which is why I responded strongly, but at the same time I cannot see how one could construct a viable argument in theory to that, nor can I see that the data provide it. Also the cited passage would talk against the Bering inflow in this region as a positive factor, since the same winds pushing the Mackenzie waters out, would exert the same wind stress on the coastal current. Yet, again to stress - even if that current plays a dominant role for the ice variability here, I haven't seen any evidence that PDV is a significant factor in the Bering through-flow or the Alaskan coastal current.

sedziobs

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Re: 2015 sea ice area and extent data
« Reply #1005 on: September 10, 2015, 10:27:27 PM »
I think the conditions of the early Ice conditions in the Bering did influence the melt season this year. I believe the low ice extent in the Bering was very much influenced by the PDO however rather than the El Nino.

This is how Bruce opens his argument - not a definitive claim.  A strong rebuttal is constructive.  The arrogant and pedantic tone is not.

Bruce Steele

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Re: 2015 sea ice area and extent data
« Reply #1006 on: September 10, 2015, 11:06:16 PM »
Plinius, I tried by best to present what evidence I had that Sea ice extent for the Bering Sea and positive PDO index values  over the last 35 years lined up except one outlier year. That is my strongest argument and if battling it out makes any difference I am sticking with my claim. I assumed you chose to call that Cherrypicking but honestly I can't detrend the data. Maybe you could give it a shot for me?
 As to the anecdotal claim regarding Bering Strait inflow I am in a much weaker position. Weather plays a huge role in how much flow moves thru the Straits and insolation is a much larger driver of melt conditions for the Chukchi and northern Bering than Bering inflow anyhow and I have argued that point on this forum many times. So if we can step back from this a bit I'd be fine with that. I tried to stress "early" and as we go through the next few years the" early"part is what I will be looking for. The buoy data that was published by Woodward was dependent upon a buoy array no longer in place so again if you could inform this conversation with how I might get real time current flow data I'd be all ears.   

oren

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Re: 2015 sea ice area and extent data
« Reply #1007 on: September 10, 2015, 11:07:50 PM »
I think the conditions of the early Ice conditions in the Bering did influence the melt season this year. I believe the low ice extent in the Bering was very much influenced by the PDO however rather than the El Nino.

This is how Bruce opens his argument - not a definitive claim.  A strong rebuttal is constructive.  The arrogant and pedantic tone is not.

I agree.

But in any case guys, please move off-topic should the discussion desire to continue.

Bruce Steele

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Re: 2015 sea ice area and extent data
« Reply #1008 on: September 10, 2015, 11:23:39 PM »
Oren, Done

plinius

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Re: 2015 sea ice area and extent data
« Reply #1009 on: September 10, 2015, 11:28:53 PM »
Plinius, I tried by best to present what evidence I had that Sea ice extent for the Bering Sea and positive PDO index values  over the last 35 years lined up except one outlier year. That is my strongest argument and if battling it out makes any difference I am sticking with my claim. I assumed you chose to call that Cherrypicking but honestly I can't detrend the data. Maybe you could give it a shot for me?
 As to the anecdotal claim regarding Bering Strait inflow I am in a much weaker position. Weather plays a huge role in how much flow moves thru the Straits and insolation is a much larger driver of melt conditions for the Chukchi and northern Bering than Bering inflow anyhow and I have argued that point on this forum many times. So if we can step back from this a bit I'd be fine with that. I tried to stress "early" and as we go through the next few years the" early"part is what I will be looking for. The buoy data that was published by Woodward was dependent upon a buoy array no longer in place so again if you could inform this conversation with how I might get real time current flow data I'd be all ears.   

Yes, we should stop here. I am happy to give the detrending a try when I have a bit more time in a couple of weeks. Concerning the Bering flow data - I could not find a real-time dataset, but that does not mean anything. The point about dominant impact of insolation after breaking the ice up initially is btw. also nicely corroborated by your linked paper, though I am not sure if the Alaska current can do the same thing as easily, since it is saltier....

Wipneus

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Re: 2015 sea ice area and extent data
« Reply #1010 on: September 11, 2015, 04:49:55 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):

day   chg  estimate  CT-value
Thu        3.094609  3.093846
Fri  +8.0  3.102632  -
Sat +25.9  3.128514  -
Sun  +9.1  3.137634  -

What there is, is in the CAB: +11k8.[/s]

UPDATE: NSIDC changed the data. The updated post is below.

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).
« Last Edit: September 12, 2015, 08:21:20 AM by Wipneus »

Wipneus

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Re: 2015 sea ice area and extent data
« Reply #1011 on: September 12, 2015, 08:19:04 AM »
Update: NSIDC changed the data a second time at the same date with some significant changes. Here is the updated post, that replaces the one above.

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):

day   chg  estimate  CT-value
Fri        3.102632  3.102235
Sat +25.8  3.128477  -
Sun +36.4  3.164897  -

What there is, is in the CAB: +19k3.

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).

Jim Pettit

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Re: 2015 sea ice area and extent data
« Reply #1012 on: September 12, 2015, 02:31:24 PM »
ADS-NIPR Extent:
4,365,032 km2 (11 September)
Down 9,577,028 km2 (68.69%) from 2015 maximum of 13,942,060 km2 on 15 February.
1,187,577 km2 above record minimum extent of 3,177,455 km2 (16 September 2012).
Up 6,114 km2 (.14%) from previous day.
Down 3,917 km2  (-.09%) over past seven days (daily average: -560 km2).
Down 73,664 km2  (-1.66%) for September (daily average: -6,697 km2).
1,139,110 km2 below 2000s average for this date.
45,006 km2 below 2010s average for this date.
622,701 km2 below 2014 value for this date.
1,130,770 km2 above 2012 value for this date.
3rd lowest September to-date average.
4th lowest value for the date.
64 days this year (25.2% year-to-date) have recorded the lowest daily extent.
35 days (13.78%) have recorded the second lowest.
39 days (15.35%) have recorded the third lowest.
138 days in total (54.33%) have been among the lowest three on record.


CT Area:
NOTE: due to delayed updates of official CT sea ice area data, I'm using a combination of those official data and Wipneus' calculated area numbers. The official numbers will be inserted as they become available.
3,164,897 km2 (12 September [Day 0.6959])
Down 10,109,658 km2 (76.16%) from 2015 maximum of 13,274,555 km2 on 17 February [Day 0.1288].
930,888 km2 above record minimum area of 2,234,010 km2 (14 September 2012).
Up 36,420 km2 (1.16%) from previous day.
Up 38,326 km2 (1.23%) over past seven days (daily average: 5,475 km2).
Down 183,344 km2 (-5.48%) for September (daily average: -15,279 km2).
803,714 km2 below 2000s average for this date.
71,788 km2 above 2010s average for this date.
392,575 km2 below 2014 value for this date.
902,838 km2 above 2012 value for this date.
6th lowest September to-date average.
6th lowest value for the date.
7 days this year (2.75% year-to-date) have recorded the lowest daily area.
19 days (7.45%) have recorded the second lowest.
30 days (11.76%) have recorded the third lowest.
56 days in total (21.96%) have been among the lowest three on record.

Wipneus

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Re: 2015 sea ice area and extent data
« Reply #1013 on: September 12, 2015, 07:15:12 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):

day   chg  estimate  CT-value
Fri        3.102632  3.102235
Sat +25.8  3.128477  -
Sun +37.5  3.165998  -
Mon +39.9  3.205939  -

CAB increased +34k8, "lakes" by +17k.

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).

iceman

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Re: 2015 sea ice area and extent data
« Reply #1014 on: September 13, 2015, 03:39:21 PM »
To my eye, Climate Reanalyzer indicates some compaction effect on the main pack through the 17th.  A few days before then, though, the northern part of the Canadian Archipelago will start gaining ice cover fairly quickly.  Wild card is how much of the recently-frozen part of northern Greenland Sea will melt back next few days.
      As usual this time of year, lots of offsetting factors and regions.  I guessed the 15th for extent minimum, but the graph will probably stay flattish and bumpy for a while longer.

Wipneus

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Re: 2015 sea ice area and extent data
« Reply #1015 on: September 13, 2015, 04:18:16 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):

day   chg  estimate  CT-value
Sun        3.165998  3.167057
Mon +39.9  3.205856  -
Tue +60.9  3.266745  -

CAB increased by +55k9.

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).

Jim Pettit

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Re: 2015 sea ice area and extent data
« Reply #1016 on: September 14, 2015, 12:17:38 PM »
ADS-NIPR Extent:
4,268,045 km2 (13 September) (NOTE: 2015 minimum to-date)
Down 9,674,015 km2 (69.39%) from 2015 maximum of 13,942,060 km2 on 15 February.
1,090,590 km2 above record minimum extent of 3,177,455 km2 (16 September 2012).
Down 51,149 km2 (-1.18%) from previous day.
Down 81,386 km2  (-1.87%) over past seven days (daily average: -11,627 km2).
Down 170,651 km2  (-3.84%) for September (daily average: -13,127 km2).
1,216,074 km2 below 2000s average for this date.
116,995 km2 below 2010s average for this date.
634,646 km2 below 2014 value for this date.
1,067,415 km2 above 2012 value for this date.
3rd lowest September to-date average.
3rd lowest value for the date.
64 days this year (25.% year-to-date) have recorded the lowest daily extent.
35 days (13.67%) have recorded the second lowest.
40 days (15.63%) have recorded the third lowest.
139 days in total (54.3%) have been among the lowest three on record.


CT Area:
NOTE: due to delayed updates of official CT sea ice area data, I'm using a combination of those official data and Wipneus' calculated area numbers. The official numbers will be inserted as they become available.
3,266,745 km2 (14 September [Day 0.7014])
Down 10,007,810 km2 (75.39%) from 2015 maximum of 13,274,555 km2 on 17 February [Day 0.1288].
1,032,736 km2 above record minimum area of 2,234,010 km2 (14 September 2012).
Up 60,889 km2 (1.9%) from previous day.
Up 112,995 km2 (3.58%) over past seven days (daily average: 16,142 km2).
Down 81,496 km2 (-2.43%) for September (daily average: -5,821 km2).
715,296 km2 below 2000s average for this date.
138,703 km2 above 2010s average for this date.
291,705 km2 below 2014 value for this date.
1,032,736 km2 above 2012 value for this date.
6th lowest September to-date average.
6th lowest value for the date.
7 days this year (2.72% year-to-date) have recorded the lowest daily area.
19 days (7.39%) have recorded the second lowest.
30 days (11.67%) have recorded the third lowest.
56 days in total (21.79%) have been among the lowest three on record.

BornFromTheVoid

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Re: 2015 sea ice area and extent data
« Reply #1017 on: September 14, 2015, 12:40:26 PM »
(sorry for the delay, was away yesterday)
Update for the week to September 12th

The current 5 day mean is on 4,430,800km2 while the 1 day extent is at 4,469,000km2.
The daily anomaly (compared to 81-10) is at -1,848,930km2, a decrease from -1,908,690km2 last week. The anomaly compared to the 07, 11 and 12 average is at +411,133km2, an increase from +319,867km2 last week. We're currently 4th lowest on record, down from 3rd lowest last week.



The average daily change over the last 7 days was -7.5k/day, compared to the long term average of -16.1k/day, and the 07, 11 and 12 average of -20.6k/day.
The average long term change over the next week is +3.4k/day, with the 07, 11, and 12 average being +2.9k/day.



The change so far this September is the 17th least negative on record. To achieve the largest monthly drop, a daily loss of at least 7.5k/day is required, while the largest monthly growth requires an increase of at least 55.6k/day and an average change requires an increase of 23.6k/day.

I recently joined the twitter thing, where I post more analysis, pics and animations: @Icy_Samuel

OldLeatherneck

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Re: 2015 sea ice area and extent data
« Reply #1018 on: September 14, 2015, 03:22:27 PM »
 46,403 Km2 below 2011 and 132,417 Km2 above 2007.

1,154 Km2 BELOW  2011’s  annual minimum and 202,286 Km2 above 2007’s annual minimum.

A week ago I was dead certain that 2015 would go below 2011's annual minimum SIE. Two or three days ago I was almost as certain that 2015 had no chance of reaching a minimum lower that 2011.  This goes to show how difficult it is to make predictions in the middle of September, when we have simultaneous melting and re-freezing occurring.  It will be interesting to see if there will be anymore significant losses this year.


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Wipneus

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Re: 2015 sea ice area and extent data
« Reply #1019 on: September 14, 2015, 04:07:07 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):

day   chg  estimate  CT-value
Mon        3.205856  3.206003
Tue +61.1  3.266990  -
Wed +11.5  3.278448  -

CAB changed +35k1, "lake ice" dropped by -11k2.

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).

Wipneus

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Re: 2015 sea ice area and extent data
« Reply #1020 on: September 15, 2015, 04:57:02 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):

day   chg  estimate  CT-value
Tue        3.266990  3.267611
Wed +11.1  3.278100  -
Thu +28.0  3.306086  -

CAB changed +51k2, "lake ice" dropped by -14k.

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).

Wipneus

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Re: 2015 sea ice area and extent data
« Reply #1021 on: September 16, 2015, 04:21:02 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):

day   chg  estimate  CT-value
Tue        3.266990  3.267611
Wed +11.1  3.278100  -
Thu +27.8  3.305936  -
Fri +49.4  3.355328  -

CAB increased by +59k4, Greenland Sea by +14k5. Lake ice dropped -15k3.

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).

AmbiValent

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Re: 2015 sea ice area and extent data
« Reply #1022 on: September 16, 2015, 07:34:10 PM »
Does CT officially call an area minimum? If so, have they done so yet, or are they still waiting a week or two to be sure?
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Re: 2015 sea ice area and extent data
« Reply #1023 on: September 17, 2015, 12:20:41 AM »
Does CT officially call an area minimum? If so, have they done so yet, or are they still waiting a week or two to be sure?

Not sure.

Based on past years movements:

Only two years manage sufficient falls (261k) after date of last data which if these movements happened this year would result in a new minimum.

1984 which looks like an erroneous upswing allowing a similarly rapid fall, and
1995 which fell 420k from day 261 to day 273.

Some low pressure near the weak parts so I would suggest it is still difficult to call it with 97.5% or more confidence.

So probably callable at the 95% confidence level but may take a few more days to get to 97.5%, 99%, and baring asteroid strike levels.

Neven

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Re: 2015 sea ice area and extent data
« Reply #1024 on: September 17, 2015, 01:10:46 AM »
Does CT officially call an area minimum? If so, have they done so yet, or are they still waiting a week or two to be sure?

No, they don't.
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Jim Pettit

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Re: 2015 sea ice area and extent data
« Reply #1025 on: September 17, 2015, 12:58:26 PM »
Does CT officially call an area minimum? If so, have they done so yet, or are they still waiting a week or two to be sure?

Crandles explain it very well, so I'll just add that CT SIA has increased each of the past 8 days, growing an average of 32.7k per day during that period; while a sudden decrease of greater than half-a-million square kilometers is, one supposes, possible after the September mid-point has been reached, I'd place the odds of it happening this year at well under 1%. (And if I were a betting man, I'd wager my entire stack of chips that the 2015 area minimum of 3.094M km2 on Day 0.6876 will stand.)

Wipneus

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Re: 2015 sea ice area and extent data
« Reply #1026 on: September 17, 2015, 04:19:50 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):

day   chg  estimate  CT-value
Thu        3.305936  3.305741
Fri +49.6  3.355513  -
Sat  -8.8  3.346749  -

Tiny decline, all regions very quit (area wise).

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).

Wipneus

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Re: 2015 sea ice area and extent data
« Reply #1027 on: September 18, 2015, 04:07:55 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):

day   chg  estimate  CT-value
Fri        3.355513  3.355191
Sat  -8.8  3.346749  -
Sun +45.4  3.392147  -

Contributing are CAB (+27k), Greenland Sea (+17k2) and "lakes" (+11k4)

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 #1028 on: September 19, 2015, 04:19:06 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):

day   chg  estimate  CT-value
Sat        3.346749  3.346038
Sun +45.8  3.392520  -
Mon +57.2  3.449757  -

Only the CAB deserves a mention: +38k4

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).

Wipneus

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Re: 2015 sea ice area and extent data
« Reply #1029 on: September 20, 2015, 04:09:11 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):

day   chg  estimate  CT-value
Sat        3.346749  3.346038
Sun +45.8  3.392520  -
Mon +57.2  3.449739  -
Tue +67.0  3.516733  -

CAB increased +52k, lake ice increased by +21k9.

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).

Jim Pettit

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Re: 2015 sea ice area and extent data
« Reply #1030 on: September 20, 2015, 05:35:02 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):

day   chg  estimate  CT-value
Sat        3.346749  3.346038
Sun +45.8  3.392520  -
Mon +57.2  3.449739  -
Tue +67.0  3.516733  -


Interesting how 2015 SIA continues to regrow at a rate faster than that seen in any other season in nearly 20 years. In fact, over the past two weeks, CT area has increased by a rate more than four-and-a-half times faster than the 10-year average for the same two-week period, including a whopping 27 times faster than that recorded just last year (which saw just 13k of growth vs. this year's 363k). My guess--and it's only that--is that the normal October/November time of fastest growth won't be quite so dramatic this year as it has been in years past.

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Re: 2015 sea ice area and extent data
« Reply #1031 on: September 20, 2015, 06:54:52 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):

day   chg  estimate  CT-value
Sat        3.346749  3.346038
Sun +45.8  3.392520  -
Mon +57.2  3.449739  -
Tue +67.0  3.516733  -


Interesting how 2015 SIA continues to regrow at a rate faster than that seen in any other season in nearly 20 years. In fact, over the past two weeks, CT area has increased by a rate more than four-and-a-half times faster than the 10-year average for the same two-week period, including a whopping 27 times faster than that recorded just last year (which saw just 13k of growth vs. this year's 363k). My guess--and it's only that--is that the normal October/November time of fastest growth won't be quite so dramatic this year as it has been in years past.

Surface refreezing within the broken ice has been very fast given more than 1 week of sustained winds from the North. The area of broken ice is huge. And I guess open water surrounded 360° by ice is very susceptible to freezing. I still expect Beaufort and Chukchi to completely refreeze anomalously late.

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Re: 2015 sea ice area and extent data
« Reply #1032 on: September 20, 2015, 07:06:36 PM »
Now that the northern CAA has filled with ice again, do you have information whether that new CAA ice is old thick ice from the CAB (as usually happens when ice melts in the CAA) or whether it is young, freshly frozen ice?
Bright ice, how can you crack and fail? How can the ice that seemed so mighty suddenly seem so frail?

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Re: 2015 sea ice area and extent data
« Reply #1033 on: September 20, 2015, 07:23:55 PM »
In case you were asking to me, no idea, I have not been following that closely.

seaicesailor

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Re: 2015 sea ice area and extent data
« Reply #1034 on: September 20, 2015, 07:27:12 PM »
Now that the northern CAA has filled with ice again, do you have information whether that new CAA ice is old thick ice from the CAB (as usually happens when ice melts in the CAA) or whether it is young, freshly frozen ice?

I quote this from passage thread, seems MYI from CAB

McClure strait, september 18:



http://www.polarview.aq/images/106_S1jpgsmall/S1A_EW_GRDM_1SDH_20150918T151049_8612_N_1.jpg

anthropocene

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Re: 2015 sea ice area and extent data
« Reply #1035 on: September 20, 2015, 08:50:19 PM »
Since it seems another minimum has been passed I'd like to take this opportunity to thank you Wipneus on all the work you've done in providing these 'home brew' figures. Getting a break down of the figures to the regional level is invaluable in assessing the impact on the ice of various types of weather. 

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Re: 2015 sea ice area and extent data
« Reply #1036 on: September 21, 2015, 01:10:13 PM »
Since it seems another minimum has been passed I'd like to take this opportunity to thank you Wipneus on all the work you've done in providing these 'home brew' figures. Getting a break down of the figures to the regional level is invaluable in assessing the impact on the ice of various types of weather.

SECOND

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Re: 2015 sea ice area and extent data
« Reply #1037 on: September 21, 2015, 04:09:33 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):

day   chg  estimate  CT-value
Mon        3.449739  3.450049
Tue +67.0  3.516703  -
Wed +28.0  3.544729  -

Only the CAB changed significantly: +40k7.

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).

Wipneus

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Re: 2015 sea ice area and extent data
« Reply #1038 on: September 22, 2015, 05:40:23 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):

day   chg  estimate  CT-value
Tue        3.516703  3.517475
Wed +27.7  3.544371  -
Thu +31.8  3.576143  -

Only the CAB changed significantly: +21k4.

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 #1039 on: September 23, 2015, 12:42:27 PM »
(away due to family issues the last while, normal service should be resumed next sunday)

Update for the week to September 19th

The current 5 day mean is on 4,507,400km2 while the 1 day extent is at 4,566,000km2.
The daily anomaly (compared to 81-10) is at -1,795,880km2, a decrease from -1,848,930km2 last week. The anomaly compared to the 07, 11 and 12 average is at +457,333km2, an increase from +411,133km2 last week. We're currently 3rd lowest on record, up from 4th lowest last week.



The average daily change over the last 7 days was +10.9k/day, compared to the long term average of +3.4k/day, and the 07, 11 and 12 average of +2.9k/day.
The average long term change over the next week is +29.4k/day, with the 07, 11, and 12 average being +22.6k/day.



The change so far this September is the 15th least negative on record. To achieve the largest monthly drop, a daily loss of at least 13.9k/day is required, while the largest monthly growth requires an increase of at least 83.9k/day and an average change requires an increase of 31.6k/day.

I recently joined the twitter thing, where I post more analysis, pics and animations: @Icy_Samuel

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Re: 2015 sea ice area and extent data
« Reply #1040 on: September 24, 2015, 04:24:26 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):

day   chg  estimate  CT-value
Thu        3.576090  3.575569
Fri +23.0  3.599122  -
Sat +40.0  3.639130  -

The growth is shared by many regions, only Greenland Sea deserves a mention +13k4

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).

Wipneus

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Re: 2015 sea ice area and extent data
« Reply #1041 on: September 25, 2015, 06:51:31 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):

day   chg  estimate  CT-value
Fri        3.599122  3.597634
Sat +40.0  3.639130  -
Sun -21.3  3.617812  -

CAB dropped -30k8, Hudson -10k7.

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 #1042 on: September 26, 2015, 02:40:17 PM »
ADS-NIPR Extent:
4,758,781 km2 (25 September)
Down 9,183,279 km2 (65.87%) from 2015 maximum of 13,942,060 km2 on 15 February.
1,581,326 km2 above record minimum extent of 3,177,455 km2 (16 September 2012).
Up 3,498 km2 (.07%) from previous day.
Up 256,605 km2  (5.7%) over past seven days (daily average: 36,658 km2).
Up 320,085 km2  (7.21%) for September (daily average: 12,803 km2).
965,279 km2 below 2000s average for this date.
51,741 km2 above 2010s average for this date.
415,068 km2 below 2014 value for this date.
1,218,812 km2 above 2012 value for this date.
4th lowest September to-date average.
5th lowest value for the date.
64 days this year (23.88% year-to-date) have recorded the lowest daily extent.
35 days (13.06%) have recorded the second lowest.
44 days (16.42%) have recorded the third lowest.
143 days in total (53.36%) have been among the lowest three on record.


CT Area:
NOTE: due to delayed updates of official CT sea ice area data, I'm using a combination of those official data and Wipneus' calculated area numbers. The official numbers will be inserted as they become available.
3,617,812 km2 (26 September [Day 0.7343])
Down 9,656,743 km2 (72.75%) from 2015 maximum of 13,274,555 km2 on 17 February [Day 0.1288].
1,383,803 km2 above record minimum area of 2,234,010 km2 (14 September 2012).
Down 21,318 km2 (-.59%) from previous day.
Up 224,711 km2 (6.62%) over past seven days (daily average: 32,102 km2).
Up 269,571 km2 (8.05%) for September (daily average: 10,368 km2).
577,497 km2 below 2000s average for this date.
127,292 km2 above 2010s average for this date.
219,140 km2 below 2014 value for this date.
1,014,578 km2 above 2012 value for this date.
6th lowest September to-date average.
6th lowest value for the date.
7 days this year (2.6% year-to-date) have recorded the lowest daily area.
19 days (7.06%) have recorded the second lowest.
30 days (11.15%) have recorded the third lowest.
56 days in total (20.82%) have been among the lowest three on record.

Wipneus

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Re: 2015 sea ice area and extent data
« Reply #1043 on: September 26, 2015, 04:33:59 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):

day   chg  estimate  CT-value
Fri        3.599122  3.597634
Sat +40.0  3.639130  -
Sun -21.4  3.617777  -
Mon +37.8  3.655563  -

CAB increased by +20k6, Greenland Sea by +12k5

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 #1044 on: September 27, 2015, 04:03:48 PM »
Update for the week to September 26th

The current 5 day mean is on 4,783,600km2 while the 1 day extent is at 4,872,000km2.
The daily anomaly (compared to 81-10) is at -1,725,640km2, a decrease from -1,795,880km2 last week. The anomaly compared to the 07, 11 and 12 average is at +585,400km2, an increase from +457,333km2 last week. We're currently 4th lowest on record, down from 3rd lowest last week.



The average daily change over the last 7 days was +39.5k/day, compared to the long term average of +29.4k/day, and the 07, 11 and 12 average of +22.6k/day.
The average long term change over the next week is +65.5k/day, with the 07, 11, and 12 average being +52.8k/day.



The change so far this September is the 9th most positive on record. To achieve the largest monthly drop, a daily loss of at least 107.0k/day is required, while the largest monthly growth requires an increase of at least 161.7k/day and an average change requires an increase of 17.9k/day.

I recently joined the twitter thing, where I post more analysis, pics and animations: @Icy_Samuel

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Re: 2015 sea ice area and extent data
« Reply #1045 on: September 27, 2015, 05:28:42 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):

day   chg  estimate  CT-value
Sat        3.639130  3.638174
Sun -21.4  3.617777  -
Mon +37.8  3.655548  -
Tue +60.9  3.716452  -

CAB increased +29k4, CAA +15k8

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 #1046 on: October 01, 2015, 10:12:22 AM »
We'll probably get stats soon from NSIDC on their September monthly minimum... from eyeballing the data, Sept 2015 extent looks practically identical to Sept 2011 extent, which means it has to come in close proximity to the 2011 figure of 4.63. Unless I'm missing something?

Jim Pettit

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Re: 2015 sea ice area and extent data
« Reply #1047 on: October 01, 2015, 01:21:16 PM »
ADS-NIPR Extent:
5,033,109 km2 (30 September)
Up 64,880 km2 (1.31%) from previous day.
Up 328,748 km2  (6.99%) over past seven days (daily average: 46,964 km2).
Up 594,413 km2  (13.39%) for September (daily average: 19,814 km2).
980,307 km2 below 2000s average for this date.
47,637 km2 above 2010s average for this date.
292,927 km2 below 2014 value for this date.
1,232,050 km2 above 2012 value for this date.
4th lowest September average.
4th lowest value for the date.
64 days this year (23.44% year-to-date) have recorded the lowest daily extent.
35 days (12.82%) have recorded the second lowest.
44 days (16.12%) have recorded the third lowest.
143 days in total (52.38%) have been among the lowest three on record.


CT Area:
3,709,512 km2 (30 September [Day 0.7452])
Down 5,523 km2 (-.15%) from previous day.
Up 133,943 km2 (3.75%) over past seven days (daily average: 19,135 km2).
Up 361,271 km2 (10.79%) for September (daily average: 12,042 km2).
661,094 km2 below 2000s average for this date.
41,672 km2 above 2010s average for this date.
306,135 km2 below 2014 value for this date.
946,280 km2 above 2012 value for this date.
6th lowest September average.
5th lowest value for the date.
7 days this year (2.56% year-to-date) have recorded the lowest daily area.
19 days (6.96%) have recorded the second lowest.
30 days (10.99%) have recorded the third lowest.
56 days in total (20.51%) have been among the lowest three on record.

Wipneus

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Re: 2015 sea ice area and extent data
« Reply #1048 on: October 03, 2015, 11:02:40 AM »
The latest NSIDC figures showed a big "first of the month" effect. Ice appearing in Bering, Okhotsk and Gulf of Alaska.

The ice - which is almost all false ice - is of low concentration, so area (including CT area) is not affected that much.

Here are the details ( calculated following the NSIDC way) :

Regional Arctic Sea Ice Extent and Area calculated from NSIDC NASA Team concentration data
Date: 2015-10-01 12:00  Values in 1000 km^2  Anomalies are from the 1981-2010 mean values

Extent (value, one day change, anomaly):
   Central Arctic Basin       East Siberian Sea              Laptev Sea
  4090.7   +0.6  -207.0    173.9   +3.7  -343.3    112.2   +3.3  -257.2
               Kara Sea             Barents Sea           Greenland Sea
    63.7   -0.1  -205.0     18.8  +14.9   -55.2    270.9  +28.9   -46.9
Baffin/Newfoundland Bay            St. Lawrence              Hudson Bay
    94.6  +28.5    +9.5      0.0   +0.0    +0.0     22.6  +11.0    -8.8
   Canadian Archipelago            Beaufort Sea             Chukchi Sea
   350.1  +47.5  -152.2     31.9   +1.3  -256.2     24.1  +11.3  -129.4
             Bering Sea          Sea of Okhotsk                   Lakes
    36.5  +36.5   +26.0     68.7  +68.7   +45.2    245.5   +8.1  +114.3
          Other regions       Total (ex. lakes)
    14.9  +13.0   +14.9   5373.6 +269.0 -1565.6

Area (value, one day change, anomaly):
   Central Arctic Basin       East Siberian Sea              Laptev Sea
  3267.2  -61.8  -436.1     71.4   -2.0  -291.2     58.8   -2.4  -185.4
               Kara Sea             Barents Sea           Greenland Sea
    27.9   +0.3  -137.2      8.3   +7.0   -27.3    151.2  +23.6   -53.3
Baffin/Newfoundland Bay            St. Lawrence              Hudson Bay
    47.1   +8.6    -0.4      0.0   +0.0    +0.0      7.4   +2.2    -3.1
   Canadian Archipelago            Beaufort Sea             Chukchi Sea
   186.5   +4.6  -151.9     10.1   +0.9  -190.8      7.4   +3.8   -94.6
             Bering Sea          Sea of Okhotsk                   Lakes
     9.1   +9.1    +6.3     24.5  +24.5   +16.7    101.6   -1.7   +45.5
          Other regions       Total (ex. lakes)
     6.4   +5.7    +6.4   3883.4  +24.2 -1542.1


And here are the area data , calculated like CT does, for the next few days:


day   chg  estimate  CT-value
Fri        3.788203  3.787954
Sat +63.7  3.851949  -
Sun +58.7  3.910651  -

 

BornFromTheVoid

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Re: 2015 sea ice area and extent data
« Reply #1049 on: October 04, 2015, 05:35:04 PM »
Update for the week to October 3rd

The current 5 day mean is on 5,230,600km2 while the 1 day extent is at 5,280,000km2.
The daily anomaly (compared to 81-10) is at -1,737,420km2, an increase from -1,725,640km2 last week. The anomaly compared to the 07, 11 and 12 average is at +662,733km2, an increase from +585,400km2 last week. We're currently 5th lowest on record, down from 4th lowest last week.



The average daily change over the last 7 days was +63.9k/day, compared to the long term average of +65.5k/day, and the 07, 11 and 12 average of +52.8k/day.
The average long term change over the next week is +91.4k/day, with the 07, 11, and 12 average being +69.7k/day.



The increase so far this October is the 15th largest on record. To achieve the smallest monthly gain, a daily increase of less than 60.7k/day is required, while the largest monthly gain requires an increase of at least 141.2k/day and an average gain requires an increase of 89.0k/day.



The extent change in September was the 15th most positive on record, while the average extent was the 4th smallest on record.



I recently joined the twitter thing, where I post more analysis, pics and animations: @Icy_Samuel