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13-09-2019, 15:27   #1
Kermit.de.frog
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Northern Hemisphere Ice and Snow Advance 2019/20

It's that time of year again...

In the last week the annual fall in sea ice has been plateauing and the ice will soon start it's advance again for this coming winter and will continue to do so right through until around the end March.









Let's keep tabs here.

Last edited by Kermit.de.frog; 13-09-2019 at 15:31.
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13-09-2019, 19:55   #2
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A little surprised that melt is easing off a little considering the unprecedented warmth (for the time of year) going on up the Arctic at the moment.
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14-09-2019, 11:22   #3
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It looks like this year's extent will bottom out about the same as 2007, the first year we heard the alarm bells being rung about ice-free Septembers within a decade or two. In actual fact, the trend in annual minima since then has been practically flat. That's 13 years (the latest one third) of the total satellite era with a flat trend. The annual MAXima, however, do show a decreasing trend.

Data from here. The 2019 minimum was taken as 4.238 million for now, which is probably the lowest it will get to, give or take.





Attached Images
File Type: jpg 2019 extent.JPG (59.7 KB, 4114 views)
File Type: png Arctic min extent 2007-19.png (23.4 KB, 4057 views)
File Type: png Arctic max extent 2007-19.png (28.0 KB, 4067 views)

Last edited by Gaoth Laidir; 14-09-2019 at 12:22.
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14-09-2019, 11:47   #4
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Just for completeness, here are the past four 10-year trends, starting at 1980. The greatest rate of decrease was 2000-09, but the most recent dedcade has actually shown a slight upward trend.







Attached Images
File Type: png Arctic min extent1980-89.png (20.5 KB, 4026 views)
File Type: png Arctic min extent 1990-99.png (22.4 KB, 4025 views)
File Type: png Arctic min extent 2000-09.png (25.7 KB, 4028 views)
File Type: png Arctic min extent 2010-19.png (19.8 KB, 4014 views)
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15-09-2019, 18:39   #5
Oneiric 3
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As I said, all this is surprising given that Arctic temps (North of the 60th) are at their warmest for this period in the Climate Reanalyser record at least. This chart shows the temperature anomaly in this region for the first half of September going back to 1979 up to the present:



I'll have a look at the DMI database later if I can be arsed to see how temperatures within the 80th are doing. Perhaps they are cooler within this smaller region when compared other years that is allowing ice melt to be relatively tame this time around.


Edit: NOAA reanalysis of September SST temp anomalies in the Arctic (C/O C.R) for between 1854 and 2018. September this year is already continuing this more recent trend.


Last edited by Oneiric 3; 15-09-2019 at 19:01.
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16-09-2019, 14:13   #6
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Had a quick look at the DMI daily Arctic temp (N of 80 Deg) set for this period of the year - 1st to 15th Sept, which I think tends to be when the ice melt has reached its peak, and while we are once again seeing very high temps up there for the period, they are not without precedent.

Top 5 warmest first half of Septembers up there since 1958. Anomaly figure are from the 1981-2010 average, and not the more nontraditional and to be frank, quite odd 1979-2000 bench which C.R/NOAA seems to favour.

Year Temp Anom
1991 -1.96 2.83
2012 -2.26 2.53
1984 -2.37 2.42
2019 -2.86 1.93
1972 -2.95 1.84

This year's actual mean temp for this period up there is standing at -2.86c, ranking it the 4th highest in this longer term data set. 1987 saw the coldest temps up there in this part of the year, with a mean temp of -8.02c.
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16-09-2019, 19:57   #7
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Quote:
Originally Posted by Oneiric 3 View Post
Had a quick look at the DMI daily Arctic temp (N of 80 Deg) set for this period of the year - 1st to 15th Sept, which I think tends to be when the ice melt has reached its peak, and while we are once again seeing very high temps up there for the period, they are not without precedent.

Top 5 warmest first half of Septembers up there since 1958. Anomaly figure are from the 1981-2010 average, and not the more nontraditional and to be frank, quite odd 1979-2000 bench which C.R/NOAA seems to favour.

Year Temp Anom
1991 -1.96 2.83
2012 -2.26 2.53
1984 -2.37 2.42
2019 -2.86 1.93
1972 -2.95 1.84

This year's actual mean temp for this period up there is standing at -2.86c, ranking it the 4th highest in this longer term data set. 1987 saw the coldest temps up there in this part of the year, with a mean temp of -8.02c.
It could be down to the actual regions that are above average and how large an ice pack they enclose. A small ice area being very warm will affect the average temperature but not so much the overall total ice.

For example, the latest anomalies for the second half of August below shows the main warm anomalies over land. September may have continued on this pattern.

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File Type: png Figure 2.png (197.0 KB, 3701 views)

Last edited by Gaoth Laidir; 16-09-2019 at 20:01.
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17-09-2019, 20:58   #8
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Quote:
Originally Posted by Oneiric 3 View Post
Had a quick look at the DMI daily Arctic temp (N of 80 Deg) set for this period of the year - 1st to 15th Sept, which I think tends to be when the ice melt has reached its peak, and while we are once again seeing very high temps up there for the period, they are not without precedent.

Top 5 warmest first half of Septembers up there since 1958. Anomaly figure are from the 1981-2010 average, and not the more nontraditional and to be frank, quite odd 1979-2000 bench which C.R/NOAA seems to favour.

Year Temp Anom
1991 -1.96 2.83
2012 -2.26 2.53
1984 -2.37 2.42
2019 -2.86 1.93
1972 -2.95 1.84

This year's actual mean temp for this period up there is standing at -2.86c, ranking it the 4th highest in this longer term data set. 1987 saw the coldest temps up there in this part of the year, with a mean temp of -8.02c.
Interesting. 1984 was the second lowest of the 1980s for ice extent with 6.74 million square kilometres. 1985 was the lowest with 6.71m

1991 meanwhile equaled 1998 with 6.43m whilst 1990 (6.07m); 1993 (6.20m); 1995 (6.06m) and 1999 (5.84m) were all lower. Source: JAXA.

I don't think there is a strong link between ice and temperature anomaly.
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17-09-2019, 21:22   #9
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My second favourite thread of the year !
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22-09-2019, 23:13   #10
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CR/NOAA Arctic anomaly for Sept (1st-22nd) now down to 2nd place (behind 2016) in its records since 1979 but could rise back into 1st place again this week as temps likely remain in and around 2.0c above the average for a good while yet.
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27-09-2019, 06:56   #11
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Sea ice formation and snow cover will be taking off witnin the next week across Siberia.


Last edited by Kermit.de.frog; 27-09-2019 at 16:30.
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27-09-2019, 21:09   #12
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The minimum extent bottomed out at 4.15 million on September 18th, the 2nd lowest in the satellite era. With that figure now in the graph for the past 10 years the trend is practically flat, if not slightly rising at 0.08 per decade.



September's monthly volume is not in yet, but taking the August figures the past decade, the trend is slightly downward at 0.16 per decade, 34 times less than the 2000-09 trend of 5.66 per decade.

At the risk of getting more abuse, I think it's safe to say that for now at least, the runaway loss has leveled off.



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File Type: png Min ice 2010-19.png (19.4 KB, 3443 views)
File Type: png Volume.png (23.7 KB, 2671 views)
File Type: png Volume 2000-09.png (27.8 KB, 2679 views)
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27-09-2019, 23:56   #13
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5-yr running means



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File Type: png Volume 5-yr mean.png (15.2 KB, 2193 views)
File Type: png Minima 5-yr mean.png (17.7 KB, 2954 views)
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28-09-2019, 17:48   #14
Oneiric 3
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Is it possible to get hold of that data? Might be interesting to compare and contrast with the actual running temperatures up there to see if there is a strong correlation (or not) between both.
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28-09-2019, 18:26   #15
Gaoth Laidir
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Quote:
Originally Posted by Oneiric 3 View Post
Is it possible to get hold of that data? Might be interesting to compare and contrast with the actual running temperatures up there to see if there is a strong correlation (or not) between both.
All data are in Excel files here

https://nsidc.org/arcticseaicenews/sea-ice-tools/
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