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ORH_wxman

Arctic Sea Ice Extent, Area, and Volume

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Fwiw ... and I'm sure others are aware of this - or should be... The mean nadir going back a decade doesn't typically occur until the 15th thru the 20th ... There are a few years as others have noted where the minimum is achieved at an earlier date.   

Anyway, I suspect that the momentum and back-ground do not really favor the earlier nadir scenario.  Whether that results in historic lows, notwithstanding.  I suspect whether we do see that or not, we're losing ice until the Equinox.  

It'll be interesting to see - 

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Odd late season behavior continues on NSIDC extent. Extent has increased 95k last 2 days. It was 4.238 million sq km on 9-4 and now 4.333 million sq km for the 6th.  The melt season featured a record low extent for July only to fall back to 4th place as of 9-6. Big slowdown after mid August followed by an acceleration of losses into early September. 

Currently in 4th place for NSIDC extent. 

3.387....2012-9-17

4.155....2007-9-18

4.165....2016-9-10

4.333....2019

4.344....2011-9-11

 4.433....2015-9-9

4.586....2008-9-19

 4.615....2010-9-21

 4.656....2018-9-23

 4.665....2017-9-13

Zack Labe notes the statistical tie for record Arctic warmth this summer with 2012.

https://mobile.twitter.com/ZLabe/status/1170022132216029185

Boreal summer 2-m temperatures were statistically tied (with 2012) for the warmest on record in the #Arctic [using JRA-55 data]
 
 
Line graph of summer temperature anomalies in the Arctic using JRA-55 data
 
 

 

 

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38 minutes ago, bluewave said:

Odd late season behavior continues on NSIDC extent. Extent has increased 95k last 2 days. It was 4.238 million sq km on 9-4 and now 4.333 million sq km for the 6th.  The melt season featured a record low extent for July only to fall back to 4th place as of 9-6. Big slowdown after mid August followed by an acceleration of losses into early September. 

Currently in 4th place for NSIDC extent. 

 

There is nothing "odd" about NSIDC sea ice extent, and sea ice does not exhibit "behavior".

If you remove 9.4 from the daily NSIDC area data set, 8.24 would have the lowest daily area value for the current melting season. The weather dispersed and then compacted sea ice these last two weeks. The freezing momentum was enough to get us within one day of having a record early sea ice area minimum. The current distribution and orientation of sea ice will not allow for much more compaction.

There is now more freezing than melting in the arctic. This is consistent with the significant 59,524 square kilometer increase in area, looking at the daily value for 9.5. The freezing season is here.

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33 minutes ago, Weatherdude88 said:

 

There is nothing "odd" about NSIDC sea ice extent, and sea ice does not exhibit "behavior".

If you remove 9.4 from the daily NSIDC area data set, 8.24 would have the lowest daily area value for the current melting season. The weather dispersed and then compacted sea ice these last two weeks. The freezing momentum was enough to get us within one day of having a record early sea ice area minimum. The current distribution and orientation of sea ice will not allow for much more compaction.

There is now more freezing than melting in the arctic. This is consistent with the significant 59,524 square kilometer increase in area, looking at the daily value for 9.5. The freezing season is here.

The term behavior is commonly used when referring to sea ice. Odd would be a mild term for describing the first time pressure extremes that this season has exhibited. Those extremes lead to the unusual pattern of sea ice loss this melt season.

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High resolution AMSR2 data showing area and extent gains in the Central Arctic Basin, Beaufort Sea, and now Canadian Archipelago. Note: The data for the attached graphs only has 8 years of data. 2019 will finish comfortably in fourth place, for NSIDC and JAXA sea ice extent values.

NdHh0cv.png

tMPOu0F.png

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The single daily NSIDC sea ice area value for 9.6 is 3,012,376 square kilometers (pole hole adjustment). 

This is significant gain of 52,449 square kilometers from the previous day. We are now 111,973 square kilometers above the 9.4 NSIDC sea ice area minimum value.

The 2019 NSIDC sea ice area melting season has concluded. We are now in the freezing season. Historically, we would need anomalous  and unprecedented sea ice area losses to extend the sea ice area melting season. The sea ice area melt rate in 9 out of the last 10 years would not get us to a new area minimum.

If you remove 9.4 from the daily NSIDC area data set, 8.24 would have been the lowest area value for the 2019 melting season.

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Most of the maps you find from DMI and others show 1952 was the minimum extent of the sea ice in the prior warm AMO period, and then there was a flat period and something of a recovery until the recent downturn. Researchers think there could be a 60-year pattern to the melting which is consistent with 2012 being so hard to beat, just like 1952 was in it its era. Not suggesting we aren't seeing more warming or melting, just that the warming doesn't really change the established cyclical patterns...it just warms them up. These guys looked at fish migration patterns and tree data as well as weather data.

 https://researchonline.jcu.edu.au/38582/4/Parker222015JGEESI16694.pdf

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Assuming the remaining 4 monthly means are close to the averages of the last 5 years then 2019 might be expected to finish 3rd or 2nd for the annual mean.

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There were 2 new monthly record low average NSIDC extents in 2019. The records occurred in April and July. There have been 9 new monthly records since 2016. ASO are the only 3 months without a new monthly record low average extent since 2016.

https://mobile.twitter.com/ZLabe/status/1157122835409596416

NSIDC monthly record lowest average sea ice extents 

Jan...2018

Feb.. 2018

Mar...2017

Apr....2019

May...2016

Jun....2016

Jul.....2019

Aug...2012

Sep...2012

Oct...2012

Nov...2016

Dec...2016

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On 7/1/2019 at 10:02 AM, ORH_wxman said:

Final June NSIDC-adjusted area numbers are in, and we're currently 2nd lowest on record behind 2012 though 2007 and 2010 were very close to 2019 as well. What this means is that this year has an excellent chance to finish in the top 3 lowest extent/areas on record.

Here are the top 5 lowest:

2012 (6.53 million sq km)

2019 (6.76 million)

2010 (6.77 million)

2007 (6.81 million)

2016 (6.94 million)

 

Does this year have enough of a good start to set a new record? Most likely not. The numbers do not support it. That doesn't mean 0 chance though like more recent years. But we will have to set a new record for area loss between now and the minimum to get there...however, we don't have to set it by much....only about 40k. If we melt 40k more area than 2016 from here on out, we'll set a new minimum area record.

The average 2007-2018 loss from July 1st onward was 4.13 million sq km. That would leave 2019 at 2.63 million sq km of ice at the minimum for area. The 2012 record sits at 2.22 million sq km of ice which means in order to set a new recrod, we need to lose 4.56 million sq km of ice area. 2016 is the current record of ice area loss from this point forward losing 4.52 million sq km. So as stated above, we will need to beat this by about 40k or more to pass 2012 at the minimum. That is going to be about 2 standard deviations or even a little more for losses. So I'd put the chances of setting a new record at about 5%. Again, this is for area only. Not extent.

Extent is a little tougher since things like compaction can occur that affect extent a lot more than it affects area. Still, it will be hard to set the extent record as well. We might have a slightly greater than 5% chance at setting the extent record since 2012 wasn't extremely compacted.

 

 

Getting back to area, below is a histogram of what would happen to 2019 if we followed all area losses from previous years....so for example, if we followed 2018 area losses from this point forward, we would finish with an area minimum of just over 2.50 million sqkm:

 

2019_min_prediction.png.76798fb41b0c7c0de844a4bf1bfe089c.png

 

 

 

 

So given the information above, I am going to predict a minimum area of 2.60 million sq km +/- 200k (2.4-2.8 for a range). I will set a minimum NSIDC extent of 3.8 million sq km +/- 200k (3.6-4.0 as a range). Neither of these ranges include the 2012 record...I don't believe we will quite make it. But this year at least has an outside shot unlike previous recent years, so at least there is a reason to track closely.

 

 

Time to verify this prediction based on the data at the end of June.

 

Assuming we have reached the minimums for both area and extent on 9/4 (looking more and more likely), then both of these fell outside my range, albeit not by much. The final minimum area was 2.87 million sq km and the final minimum extent was 4.23 million sq km. These are both NSIDC numbers. The predictions were looking excellent through mid-August until we had an unprecedented slowdown in late August that has leaked into early September. So I ended up making predictions that were slightly too low compared to reality.

 

I was correct in identifying the very strong chance of a top 3 finish (and also being skeptical of challenging the top spot), but I really needed to bump my middle numbers in the range up about 100-200k. Overall, I think this was a decent prediction compared to what we see on the Arctic Sea Ice outlook that gets published by NSIDC....but I am still disappointed I could not get it within my range. It might be that 200k error bars are just too small to consistently hit on predictions when it comes to sea ice. Using 400k error bars would have this method hit every year I've done it with the exception of 2016. But I will probably try to continue to use 200k error bars....and maybe see where the method can be improved.

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NSIDC extent continues to bounce up and down with the rapidly changing dipole conditions.

9-4......4.238 million sq km......lowest of season so far

9-9......4.342......  a 5 day increase of +104k

9-11.....4.280........a 2 day decline of -62k 

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9 hours ago, bluewave said:

NSIDC extent continues to bounce up and down with the rapidly changing dipole conditions.

9-4......4.238 million sq km......lowest of season so far

9-9......4.342......  a 5 day increase of +104k

9-11.....4.280........a 2 day decline of -62k 

Typical behavior of a sensitive system at the nadir - it's responding to everything

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On 9/7/2019 at 7:37 AM, Weatherdude88 said:

High resolution AMSR2 data showing area and extent gains in the Central Arctic Basin, Beaufort Sea, and now Canadian Archipelago. Note: The data for the attached graphs only has 8 years of data. 2019 will finish comfortably in fourth place, for NSIDC and JAXA sea ice extent values.

JAXA is now in third place. You going to disappear like you usually do when things aren't going your way?

PS, I would love to see you post your verification report on the ASIF where you claimed in July that top 3 SIE/SIA was not happening and top 5 was unlikely.

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Large 71k NSIDC daily extent decline for so late in the season. The 9-13 extent  drops below the previous minimum recorded back on 9-4. This puts 2019 in 4th place not far behind 2007 and 2016.

ftp://sidads.colorado.edu/DATASETS/NOAA/G02135/seaice_analysis/Sea_Ice_Index_Daily_Extent_G02135_v3.0.xlsx

Currently in 4th place for NSIDC extent. 

3.387....2012-9-17

4.155....2007-9-18

4.165....2016-9-10

4.209....2019

4.344....2011-9-11

4.433....2015-9-9

4.586....2008-9-19

4.615....2010-9-21

4.656....2018-9-23

4.665....2017-9-13

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On 9/7/2019 at 11:32 AM, Weatherdude88 said:

The single daily NSIDC sea ice area value for 9.6 is 3,012,376 square kilometers (pole hole adjustment). 

This is significant gain of 52,449 square kilometers from the previous day. We are now 111,973 square kilometers above the 9.4 NSIDC sea ice area minimum value.

The 2019 NSIDC sea ice area melting season has concluded. We are now in the freezing season. Historically, we would need anomalous  and unprecedented sea ice area losses to extend the sea ice area melting season. The sea ice area melt rate in 9 out of the last 10 years would not get us to a new area minimum.

If you remove 9.4 from the daily NSIDC area data set, 8.24 would have been the lowest area value for the 2019 melting season.

Wrong again or should we remove the past couple days from the data set too. 

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After another decline, Arctic sea ice extent (JAXA) has now decreased to 4.026 million square kilometers. That is approximately 40,000 square kilometers below the 2012 minimum extent figure (4th lowest) and just under 9,000 square kilometers above the 2016 figure (2nd lowest).

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Arctic sea ice pulling closer to 2007 and 2016. Now at 4.171 million sq km for 9-14 with a 38k NSIDC daily decline.

ftp://sidads.colorado.edu/DATASETS/NOAA/G02135/seaice_analysis/Sea_Ice_Index_Daily_Extent_G02135_v3.0.xlsx

Currently in 4th place for NSIDC extent. 

3.387....2012-9-17

4.155....2007-9-18

4.165....2016-9-10

4.171....2019

4.344....2011-9-11

4.433....2015-9-9

4.586....2008-9-19

4.615....2010-9-21

4.656....2018-9-23

4.665....2017-9-13

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The late season acceleration of sea ice losses is in response to the return of the strong Arctic dipole anomaly.  This was the dominant pattern from May through August 20th. A new Arctic high pressure record was set for this period. Now high pressure has returned to near record levels for this time of year.

3EA9292D-3847-4083-B525-C146AFC988C8.thumb.png.2c17373f59374032d5fc0e86b4e6c6aa.png

0745A35A-F53B-4A51-996D-AB8550C56D9F.thumb.png.fa611ad3eb6e3188e1305fda74199084.png

75FABCBB-886A-41DA-BD61-390E9273C054.png.e4c349f8c38a6e1659ab2bb761d93c33.png

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1 hour ago, bluewave said:

The late season acceleration of sea ice losses is in response to the return of the strong Arctic dipole anomaly.  This was the dominant pattern from May through August 20th. A new Arctic high pressure record was set for this period. Now high pressure has returned to near record levels for this time of year.

3EA9292D-3847-4083-B525-C146AFC988C8.thumb.png.2c17373f59374032d5fc0e86b4e6c6aa.png

0745A35A-F53B-4A51-996D-AB8550C56D9F.thumb.png.fa611ad3eb6e3188e1305fda74199084.png

75FABCBB-886A-41DA-BD61-390E9273C054.png.e4c349f8c38a6e1659ab2bb761d93c33.png

No argument ...

Firstly, as a primer, the arctic is very sensitive when nearing melt states; input therms mean much more to threshold periods than they do during deeply descended seasonality.

This year the arctic domain space has been near, or at that threshold ( as has that also been a predicament becoming more common over the last decade, plausibly longer), where in lock step the Arctic Oscillation teleconnector become a reasonably well correlated/indicator for melt rates.  

-AO is a warm signal above the 60th parallel; where the N. Hemisphere has yet to begin its seasonal cascade, that becomes problematic ( newly so..) at onset of this new/re-asserting -AO mode.  

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On September 15, Arctic sea ice extent had declined further to 4.006 million square kilometers on JAXA. As a result, 2019 now has the second lowest minimum extent figure on record. The previous second lowest figure was 4.017 million square kilometers, which was recorded in 2016.

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10k daily NSIDC extent decline moves 2019 into 3rd place place on 9-15. Only 6k behind the 2nd place 2007.

Currently in 3rd place for NSIDC extent. 

3.387....2012-9-17

4.155....2007-9-18

4.161....2019

4.165....2016-9-10

4.344....2011-9-11

4.433....2015-9-9

4.586....2008-9-19

4.615....2010-9-21

4.656....2018-9-23

4.665....2017-9-13

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7 hours ago, bluewave said:

10k daily NSIDC extent decline moves 2019 into 3rd place place on 9-15. Only 6k behind the 2nd place 2007.

Currently in 3rd place for NSIDC extent. 

3.387....2012-9-17

4.155....2007-9-18

4.161....2019

4.165....2016-9-10

4.344....2011-9-11

4.433....2015-9-9

4.586....2008-9-19

4.615....2010-9-21

4.656....2018-9-23

4.665....2017-9-13

What's the margin of error for these measurements? Is there any significant difference between the 2007, 2016, and 2019 extents or is it a statistical tie?

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4 hours ago, lookingnorth said:

What's the margin of error for these measurements? Is there any significant difference between the 2007, 2016, and 2019 extents or is it a statistical tie?

The near-real time products are not quality controlled. The final data is.

From the NSIDC site:

The daily and monthly images that we show in Arctic Sea Ice News & Analysis are near-real-time data. Near-real-time data do not receive the rigorous quality control that final sea ice products enjoy, but it allows us to monitor ice conditions as they develop.

https://nsidc.org/arcticseaicenews/faq/#average-vs-daily

It should be noted that the JAXA data set shows Arctic sea ice extent as second lowest and NSIDC shows it as 3rd lowest. One can probably have a reasonable degree of confidence that Arctic sea ice extent has fallen to at least the 3rd lowest figure on record at least somewhat below that of 2007. Corroboration across data sets adds confidence.

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On September 16, Arctic sea ice extent fell to 3.991 million square kilometers on JAXA. That is only the second time on record that Arctic sea ice extent will have a minimum figure below 4 million square kilometers.

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