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oren

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Re: Sea Ice Extent around Antarctica
« Reply #1050 on: December 28, 2018, 03:21:40 AM »
The average remaining melt from this day to minimum would produce a minimum of 0.84 million km2,  1.31 million km2 less than the record low in 2016-17. A good proportion of the remaining ice is at low concentration compared with 2016 (see next post) adding to the chances of a record low extent. However, when that low concentration ice is gone the solid land fast ice on the coast will likely slow down further melt to a crawl. Nevertheless, a record low minimum, the first below 2 million km2, is my guess for the 2019 minimum, continuing the loss of Antarctic sea ice over the last three years.

All models have limitations. The first table attached shows that remaining melt in three of the previous years would result in an extent minimum of less than zero, an impossibility. Nevertheless, that is useful in that it shows how much extent this year is below that of the years to 2015.
First I want to thank you again for these daily updates.
I think the main limitation of the model is not separating the Antarctic sea ice into its constituent regions. This is true in the Arctic as well, but in the Arctic many of the various regions do interact with each other - once the Laptev or Beaufort are cleared the CAB is more easily attacked, once Chukchi is melted the ESS is next, etc., this applies both to melt progression and to export between regions.
In the Antarctic, due to having a continent in the middle, the interaction between the various regions in summer is minimal to nonexistent. So it pays off looking at the various regions as separate entities. Such an analysis (I am using AMSR2 area but I expect other metrics to behave similarly) reveals the fact that this year is leading mostly in the Ross Sea sector - the same one that went to almost zero in the past two winters (Feb 2018 and Feb 2017). The Ross Sea is what generates the negative result, as its normal losses are simply higher than the current extent. This is obviously not going to happen, and although an early and complete melt-out of the Ross Sea may have some serious implications, a record sea ice minimum is not necessarily one of them.
In the largest and most difficult to melt sector, the Weddel Sea, this year follows the previous two years to the letter and can reasonably be expected to bottom at the same low level by mid-Feb 2019.
All in all, I'm not sure if the expectation of a new record is justified, though it's certainly possible. At least one sector will have to break past limitations for that to happen.

gerontocrat

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Re: Sea Ice Extent around Antarctica
« Reply #1051 on: December 28, 2018, 09:44:11 AM »
JAXA ANTARCTIC Sea Ice Extent - 6,065,577 km2(December 27, 2018)

Extent loss of 194k , 18k less than average on this day. The first time below average for a long time. However, the loss is more than that on this day in 2016 and 2017, the years of record low minima.

Extent is 2nd lowest, at a reducing 77 k greater than 2016 on this day, and 1,068 million km2 below 2017. Extent loss from maximum is 1.352 million km2 (12.6%) greater than average so far, with on average 67.3% of extent loss for the season done and on average 54 days to minimum.

The average remaining melt from this day to minimum would produce a minimum of 0.86 million km2,  1.29 million km2 less than the record low in 2016-17. A good proportion of the remaining ice is at low concentration compared with 2016 (see next post) adding to the chances of a record low extent. However, when that low concentration ice is gone the solid land fast ice on the coast will likely slow down further melt to a crawl. Nevertheless, a record low minimum, the first below 2 million km2, is still my guess for the 2019 minimum, continuing the loss of Antarctic sea ice over the last three years.

All models have limitations. The first table attached shows that remaining melt in three of the previous years would result in an extent minimum of less than zero, an impossibility. Nevertheless, that is useful in that it shows how much extent this year is below that of the years to 2015.

Being in the Austral summer, low extent and area means with insolation high, albedo warming potential in the Antarctic is also high and well above average.

- see Tealight graphs at https://sites.google.com/site/cryospherecomputing/awp/antarctic-graphs
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gerontocrat

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Re: Sea Ice Extent around Antarctica
« Reply #1052 on: December 28, 2018, 09:57:11 AM »

I think the main limitation of the model is not separating the Antarctic sea ice into its constituent regions.

In the Antarctic, due to having a continent in the middle, the interaction between the various regions in summer is minimal to nonexistent. So it pays off looking at the various regions as separate entities. Such an analysis (I am using AMSR2 area but I expect other metrics to behave similarly) reveals the fact that this year is leading mostly in the Ross Sea sector - the same one that went to almost zero in the past two winters (Feb 2018 and Feb 2017). The Ross Sea is what generates the negative result, as its normal losses are simply higher than the current extent. This is obviously not going to happen, and although an early and complete melt-out of the Ross Sea may have some serious implications, a record sea ice minimum is not necessarily one of them.
In the largest and most difficult to melt sector, the Weddel Sea, this year follows the previous two years to the letter and can reasonably be expected to bottom at the same low level by mid-Feb 2019.
All in all, I'm not sure if the expectation of a new record is justified, though it's certainly possible. At least one sector will have to break past limitations for that to happen.

I wish that Antarctic Sea Ice extent and area was easily downloadable from somewhere as .csv or excel files as for the Arctic extent and area from JAXA and NSIDC. Is it?

You may well be right about the resistance of the Weddell Sea - as was also pointed out by Tealight. BUT - the attached image suggests that the Weddell Sea Ice is looking a bit more vulnerable than it did in 2016. So I am sticking with my guess at a likely minimum below 2 million km2, but nowhere near that produced by the spreadsheet. After all that only needs a minimum of 150 k less than in 2016-17.

There is one question for which I have not seen a good answer. Why has this sudden loss of Antarctic Sea ice over the last 3 years happened?
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Grygory

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Re: Sea Ice Extent around Antarctica
« Reply #1053 on: December 28, 2018, 12:56:10 PM »
"There is one question for which I have not seen a good answer. Why has this sudden loss of Antarctic Sea ice over the last 3 years happened?"

I think it's the wind's fault

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Re: Sea Ice Extent around Antarctica
« Reply #1054 on: December 28, 2018, 01:25:25 PM »
The 'flip flop' occurred in 2014 I think with the switch of a few of the major pacific natural drivers ( driven by the collapse of rates of dimming as China begins to clean up its act??) coupled with the reduction in ozone hole forcings on the Katabatic winds flowing off Antarctica and the circumpolar winds/current fell slack?

In the same way the growth in antarctic sea ice was driven by man and Nature I believe this 'flip flop' is also a collaboration?

As I see it there is upward of 30 years of warmth to now begin pushing into the continent?

The 10 HPa winds over the pole over the southern winter are now beginning to ape those of the polar night jet across the north pole also?

Full depth atmospheric mixing will bring some extreme weather to the temperate southern land masses?

The thing I am nor too sure in my mind on is cross hemisphere interactions in the upper/lower atmosphere?

We have seen the northern polar jet 'apparently' cross the pole and end up over S.Africa so could we see constructive/destructive interference now as the Southern hemisphere's atmosphere ( and lower strat?) become as 'tweaked' as we have seen our Northern hemisphere Atmosphere become since the turn of the century?
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Re: Sea Ice Extent around Antarctica
« Reply #1055 on: December 28, 2018, 02:39:31 PM »
I wish that Antarctic Sea Ice extent and area was easily downloadable from somewhere as .csv or excel files as for the Arctic extent and area from JAXA and NSIDC. Is it?
Haven't followed the discussions lately but I usually look at this one:
https://ads.nipr.ac.jp/vishop.ver1/data/graph/plot_extent_s_v2.csv
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Re: Sea Ice Extent around Antarctica
« Reply #1056 on: December 28, 2018, 02:46:04 PM »
I wish that Antarctic Sea Ice extent and area was easily downloadable from somewhere as .csv or excel files as for the Arctic extent and area from JAXA and NSIDC. Is it?
Haven't followed the discussions lately but I usually look at this one:
https://ads.nipr.ac.jp/vishop.ver1/data/graph/plot_extent_s_v2.csv

Sorry - wasn't specific enough. I am looking for and not finding daily Antarctic extent and area data by region in a nice simple format - e.g. .csv and .xls . It's so easy downloading the NSIDC and JAXA files but they don't do the regional data for the Antarctic
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magnamentis

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Re: Sea Ice Extent around Antarctica
« Reply #1057 on: December 28, 2018, 09:53:29 PM »
"There is one question for which I have not seen a good answer. Why has this sudden loss of Antarctic Sea ice over the last 3 years happened?"

I think it's the wind's fault

i don't thing that there is a single cause but that the system is buffering to a certain extent and once a tipping point is reached it rapidly caves in until the next level of resistance while the intervals and forces it takes will have to be higher on each new plateau that means further south/north and therefore insolation and number of melting days is reduced through orbital facts (earth orbit around the sun)
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oren

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Re: Sea Ice Extent around Antarctica
« Reply #1058 on: December 29, 2018, 12:00:55 AM »
I wish that Antarctic Sea Ice extent and area was easily downloadable from somewhere as .csv or excel files as for the Arctic extent and area from JAXA and NSIDC. Is it?
Haven't followed the discussions lately but I usually look at this one:
https://ads.nipr.ac.jp/vishop.ver1/data/graph/plot_extent_s_v2.csv
Sorry - wasn't specific enough. I am looking for and not finding daily Antarctic extent and area data by region in a nice simple format - e.g. .csv and .xls . It's so easy downloading the NSIDC and JAXA files but they don't do the regional data for the Antarctic
I am quite certain it's available on NSIDC file system somewhere, but expereince has taught me that almost any data one may be seeking is to be found on Wipneus' ArctischePinguin.
I usually browse the sea ice extent and area data section, at:
https://sites.google.com/site/arctischepinguin/home/sea-ice-extent-area/data

I think this is the file you are looking for.:
https://sites.google.com/site/arctischepinguin/home/sea-ice-extent-area/data/nsidc_ant_nt_detail.txt?attredirects=0&d=1
It's a text file, but pasting into Excel and then using "text to columns" command gives you what you want.

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Re: Sea Ice Extent around Antarctica
« Reply #1059 on: December 29, 2018, 04:49:45 AM »
"There is one question for which I have not seen a good answer. Why has this sudden loss of Antarctic Sea ice over the last 3 years happened?"

I think it's the wind's fault

Maybe ocean stored heat reaching the area via underwater currents, which have also attacked the glacial ice there.

steve s

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Re: Sea Ice Extent around Antarctica
« Reply #1060 on: December 29, 2018, 07:46:57 AM »
The drop in sea ice began with a pretty dramatic step function, downward, when sea ice should have been growing.

On 9/3/17 Tigertown posted a graph showing the drop:


A JAXA video of 8/1 to 9/17/16 (attached) shows the ice loss. Was there a time correlated weather event?


Pmt111500

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Re: Sea Ice Extent around Antarctica
« Reply #1061 on: December 29, 2018, 09:57:57 AM »
"There is one question for which I have not seen a good answer. Why has this sudden loss of Antarctic Sea ice over the last 3 years happened?"

I think it's the wind's fault

Maybe ocean stored heat reaching the area via underwater currents, which have also attacked the glacial ice there.
This is also my assumption, tried to tie this reduction in antarctic sea ice to the last el nino. The heat from this would have gone mostly southwards evidenced by abnormal heatwaves in Australia/New Zealand.
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oren

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Re: Sea Ice Extent around Antarctica
« Reply #1062 on: December 29, 2018, 10:01:01 AM »
The drop in sea ice began with a pretty dramatic step function, downward, when sea ice should have been growing.
...
A JAXA video of 8/1 to 9/17/16 (attached) shows the ice loss. Was there a time correlated weather event?
The thing is, most of the Antarctic sea ice is seasonal FYI, so the "memory" of the system is quite low, as opposed to the Arctic where MYI used to dominate and still has important buffering effects. Therefore a one-time crash should not have been felt two years after the event.
In addition, enhanced melting of the glaciers and ice shelves is expected to lead to freshening of the sea surface and growth in sea ice, as postulated by Hansen, so I don't think warming is to blame for the lack of sea ice. This is again very different from the Arctic due to having the continent in the middle, while Greenland melt runoff flows through Nares, Baffin and the Greenland Sea, all of which have strong southbound currents carrying the fresh water away from the main body of sea ice in the CAB.
I am also guessing the explanation has to do with wind patterns around Antarctica (or perhaps the monster El Nino of 2016) but this is far out of my league.

gerontocrat

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Re: Sea Ice Extent around Antarctica
« Reply #1063 on: December 29, 2018, 10:29:31 AM »
JAXA ANTARCTIC Sea Ice Extent - 5,908,432 km2(December 28, 2018)

Extent loss of 157k , 36k less than average on this day. The 2nd day of below extent loss average after a long period of above average extent loss. However, the loss is more than that on this day in 2016, the year of the record low minimum.

Extent is 2nd lowest, at a mere 17 k greater than 2016 on this day, and 1,045 million km2 below 2017. Extent loss from maximum is 1.352 million km2 (12.6%) greater than average so far, with on average 67.3% of extent loss for the season done and on average 54 days to minimum. Extent loss in the last 3 days of 2016 was very low - the chance of 2018 being at the record low for the day before 1 Jan 2019 is high.

The average remaining melt from this day to minimum would produce a minimum of 0.89 million km2,  1.26 million km2 less than the record low in 2016-17. A good but reducing proportion of the remaining ice is at low concentration compared with 2016 (see next post) adding to the chances of a record low extent. However, when that low concentration ice is gone the remaining solid ice close to the coast will likely slow down further melt to a crawl. Nevertheless, a record low minimum, the first below 2 million km2, is still my guess for the 2019 minimum, continuing the loss of Antarctic sea ice over the last three years.

All models have limitations. The first table attached shows that remaining melt in three of the previous years would result in an extent minimum of less than zero, an impossibility. Nevertheless, that is useful in that it shows how much extent this year is below that of the years to 2015.

Being in the Austral summer, low extent and area means with insolation high, albedo warming potential in the Antarctic is also high and well above average.

- see Tealight graphs at https://sites.google.com/site/cryospherecomputing/awp/antarctic-graphs
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gerontocrat

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Re: Sea Ice Extent around Antarctica
« Reply #1064 on: December 29, 2018, 12:09:34 PM »
Sorry - wasn't specific enough. I am looking for and not finding daily Antarctic extent and area data by region in a nice simple format - e.g. .csv and .xls . It's so easy downloading the NSIDC and JAXA files but they don't do the regional data for the Antarctic
I am quite certain it's available on NSIDC file system somewhere, but expereince has taught me that almost any data one may be seeking is to be found on Wipneus' ArctischePinguin.
I usually browse the sea ice extent and area data section, at:
https://sites.google.com/site/arctischepinguin/home/sea-ice-extent-area/data

I think this is the file you are looking for.:
https://sites.google.com/site/arctischepinguin/home/sea-ice-extent-area/data/nsidc_ant_nt_detail.txt?attredirects=0&d=1
It's a text file, but pasting into Excel and then using "text to columns" command gives you what you want.

Thanks Oren, I was just not looking in the right place.
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Pmt111500

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Re: Sea Ice Extent around Antarctica
« Reply #1065 on: December 29, 2018, 01:31:52 PM »
The drop in sea ice began with a pretty dramatic step function, downward, when sea ice should have been growing.
...
A JAXA video of 8/1 to 9/17/16 (attached) shows the ice loss. Was there a time correlated weather event?
The thing is, most of the Antarctic sea ice is seasonal FYI, so the "memory" of the system is quite low, as opposed to the Arctic where MYI used to dominate and still has important buffering effects. Therefore a one-time crash should not have been felt two years after the event.

<Cut>

Yep, and the El nino explanation won't suffice on it's own. Maybe it the winds, or some strengthening of a warm current somehow making its way near the ice. Not saying this could be related to AMOC slowdown though, that would be jumping to conclusions way too early. At least it should be first checked if the exchange between indian Ocean and Southern Atlantic has diminished... Or... Again everything moves and the causal relationships are not clear., The kind of stuff that overthinking it might drive a weaker scientist into hoodoo science. Glad I don't have to do the analyses on these.
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steve s

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Re: Sea Ice Extent around Antarctica
« Reply #1066 on: December 29, 2018, 01:57:12 PM »
The drop in sea ice began with a pretty dramatic step function, downward, when sea ice should have been growing.
...
A JAXA video of 8/1 to 9/17/16 (attached) shows the ice loss. Was there a time correlated weather event?
The thing is, most of the Antarctic sea ice is seasonal FYI, so the "memory" of the system is quite low, as opposed to the Arctic where MYI used to dominate and still has important buffering effects. Therefore a one-time crash should not have been felt two years after the event.
In addition, enhanced melting of the glaciers and ice shelves is expected to lead to freshening of the sea surface and growth in sea ice, as postulated by Hansen, so I don't think warming is to blame for the lack of sea ice. This is again very different from the Arctic due to having the continent in the middle, while Greenland melt runoff flows through Nares, Baffin and the Greenland Sea, all of which have strong southbound currents carrying the fresh water away from the main body of sea ice in the CAB.
I am also guessing the explanation has to do with wind patterns around Antarctica (or perhaps the monster El Nino of 2016) but this is far out of my league.

I quite agree. The step function has to reflect either a large scale change somewhere stabilized by a feedback from the Antarctic sea ice and waters; or another variable having changed elsewhere influencing condition massively. In either case, the cause is not local to Antarctica.

My main point is that we know when the shift occurred, although not why. And we also know that the shift took place in the middle of the Antarctic winter, a fact that seems to me likely to prove diagnostic.

gerontocrat

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Re: Sea Ice Extent around Antarctica
« Reply #1067 on: December 30, 2018, 07:37:29 AM »
JAXA ANTARCTIC Sea Ice Extent - 5,760,637 km2(December 29, 2018)

Extent loss of 148k , 62k less than average on this day. The 3rd day of below average extent loss after a long period of above average extent loss. However, the loss is more than that on this day in 2016, the year of the record low minimum.

Extent is lowest in the satellite record for this day, 52 k le4ss than 2016 on this day, and 1.019 million km2 below 2017. Extent loss from maximum is 1.259 million km2 (11.3%) greater than average so far, with on average 69.8% of extent loss for the season done and on average 52 days to minimum.

The average remaining melt from this day to minimum would produce a minimum of 0.96 million km2, 1.19 million km2 less than the record low in 2016-17. A reducing proportion of the remaining ice is at low concentration. When that low concentration ice is gone the remaining solid ice close to the coast will likely slow melt down further to a crawl. Nevertheless, a record low minimum, the first below 2 million km2, is still my guess for the 2019 minimum, continuing the loss of Antarctic sea ice over the last three years.

All models have limitations. The first table attached shows that remaining melt in three of the previous years would result in an extent minimum of less than zero, an impossibility. Nevertheless, that is useful in that it shows how much extent this year is below that of the years to 2015.

Being in the Austral summer, low extent and area means with insolation high, albedo warming potential in the Antarctic is also high and well above average. - see Tealight graphs at https://sites.google.com/site/cryospherecomputing/awp/antarctic-graphs

_____________________________________________________________________
It seems that the climate scientists have not come up with a generally accepted reason for this third year of much lower Antarctic sea ice extent.

The conventional wisdom (not just from Hansen by any means) is that as Antarctic ice sheet melt increases, additional fresh and cold water should encourage an increase in sea ice. The last 3 years data is in contradiction to that. When the GRACE mass data re-starts (from early 2019), perhaps this will tell us the extent to which the rate of Antarctic ice sheet mass loss has increased or decreased over the last 3 years.
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Re: Sea Ice Extent around Antarctica
« Reply #1068 on: December 30, 2018, 08:34:46 AM »
"There is one question for which I have not seen a good answer. Why has this sudden loss of Antarctic Sea ice over the last 3 years happened?"

I think it's the wind's fault

Maybe ocean stored heat reaching the area via underwater currents, which have also attacked the glacial ice there.
The change really started in 2015 as the El Nino  built. The attached graph shows the NSIDC daily rankings for extent since the beginning of 2014. As can be seen the daily ranking was only less than 26th on three occasions before the beginning of August 2105. The rankings then plummet  to well below 2014 until the end of the year.  Rankings jumped around between 5 and 25 for most of 2016 until they dropped quickly below 10 at the end of August  2016 and remained below 10 ever since.

In my view this is not because the ice has a 'memory' of earlier conditions. It is because global sea and Air temperatures have been at  record highs since 2014. As the ice expands during winter it is butting up against warmer waters in the Atlantic, Pacific and Indian oceans which limits growth and makes melt easier.

NASA has also observed that  the ozone hole is in decline. https://www.nasa.gov/feature/goddard/2018/nasa-study-first-direct-proof-of-ozone-hole-recovery-due-to-chemicals-ban The Ozone hole has previously  been implicated in distributing the ice and increasing extent.
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Re: Sea Ice Extent around Antarctica
« Reply #1069 on: December 30, 2018, 01:22:30 PM »
Said to a friend in early 2016 that the hot spot of warming might be moving to southern hemisphere for a while, as it looked like northernmost Atlantic started to lose highest temperature anomalies then. And the Antarctic ice went down. Expected it to reverse back by now but no. Some very large swing almost has to have happened during last 3 years. Possibly too complex for my brain right now. Won't try to figure it out. Enough to ponder otherwise too.
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Re: Sea Ice Extent around Antarctica
« Reply #1070 on: December 30, 2018, 02:25:46 PM »
Only one weak La Nina during the 60's, the last real one this decade was 10-11.
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Re: Sea Ice Extent around Antarctica
« Reply #1071 on: December 31, 2018, 11:15:51 AM »
JAXA ANTARCTIC Sea Ice Extent - 5,617,569 km2(December 30, 2018)

Extent loss of 143k , 82k less than average on this day. The 4th day of below average extent loss after a long period of above average extent loss. However, the loss is more than that on this day in 2016, the year of the record low minimum.

Extent is lowest in the satellite record for this day, 70 k less than 2016 on this day, and 1.001 million km2 below 2017. Extent loss from maximum is 1.173 million km2 (10.4%) greater than average so far, with on average 71.2% of extent loss for the season done and on average 51 days to minimum.

The average remaining melt from this day to minimum would produce a minimum of 1.04 million km2, 1.11 million km2 less than the record low in 2016-17. A reducing proportion of the remaining ice is at low concentration. With that low concentration ice mostly gone the remaining solid ice close to the coast will likely slow melt down further to a crawl. Nevertheless, a record low minimum, the first below 2 million km2, is still my guess for the 2019 minimum, continuing the loss of Antarctic sea ice over the last three years.

All models have limitations. The first table attached shows that remaining melt in three of the previous years would result in an extent minimum of less than zero, an impossibility. Nevertheless, that is useful in that it shows how much extent this year is below that of the years to 2015.

Being in the Austral summer, low extent and area means with insolation high, albedo warming potential in the Antarctic is also high and well above average. - see Tealight graphs at https://sites.google.com/site/cryospherecomputing/awp/antarctic-graphs

_____________________________________________________________________
It seems that the climate scientists have not come up with a generally accepted reason for this third year of much lower Antarctic sea ice extent, though there has been much speculation about this in this thread

The conventional wisdom (not just from Hansen by any means) is that as Antarctic ice sheet melt increases, additional fresh and cold water should encourage an increase in sea ice. The last 3 years data is in contradiction to that. I can find no science paper on this contradiction at all. When the GRACE mass data re-starts (from early 2019), perhaps this will tell us the extent to which the rate of Antarctic ice sheet mass loss has increased or decreased over the last 3 years.
_______________________________________________________________________
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Sleepy

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Re: Sea Ice Extent around Antarctica
« Reply #1072 on: January 01, 2019, 06:36:02 AM »
_______________________________________________________________________
It seems that the climate scientists have not come up with a generally accepted reason for this third year of much lower Antarctic sea ice extent, though there has been much speculation about this in this thread

The conventional wisdom (not just from Hansen by any means) is that as Antarctic ice sheet melt increases, additional fresh and cold water should encourage an increase in sea ice. The last 3 years data is in contradiction to that. I can find no science paper on this contradiction at all. When the GRACE mass data re-starts (from early 2019), perhaps this will tell us the extent to which the rate of Antarctic ice sheet mass loss has increased or decreased over the last 3 years.
_______________________________________________________________________

Those still alive will see in another decade or two. Meanwhile, adding Hansen's latest mailing.
http://www.columbia.edu/~jeh1/mailings/2018/20181206_Nutshell.pdf
Quote
As yet the rate of freshwater injection onto the Southern Ocean may not have yet reached a level large enough to counter the loss of sea ice due to global warming, as judged from the large sea ice area reduction that has accompanied the warming of the past few years.

 Nevertheless, it is clear that amplifying feedbacks will produce increasingly rapid sea level rise if fossil fuel emissions and global temperatures continue to increase unabated. Even in the case of slowly changing paleoclimate forcings, ice sheet disintegration on a number of occasions achieved a rate that produced meter and multi-meter sea level rise in a century, confirming the existence and the potential large magnitude of amplifying feedbacks. Once the global warming effect on ice sheets is sufficient to strongly spur the amplifying feedbacks, we would expect the rate of mass loss by the ice sheets and the rate of sea level rise to grow nonlinearly, at a faster and faster rate.

 A capable means of assessing possible Greenland and Antarctic ice sheet mass loss became available with the first precise monitoring of Earth’s gravitational field from a satellite (Fig. 17). Early results from the gravity satellite showed shockingly rapid growth of the mass loss rates for both the Greenland and Antarctic ice sheets, for Greenland through 2012 and for Antarctica through 2015 (Fig. 17). Doubling times for mass loss rates were only of the order of a decade for both Greenland and Antarctica. However, in Greenland in 2013 and Antarctica in 2016 the rapid growth of mass loss was interrupted by a negative feedback: increased precipitation (snowfall).

 Decreased summer melt and increased snowfall over Greenland were associated with a change of summer weather patterns. The 2012 summer was characterized by sunny weather and a steady stream of warm air streaming from the south over Greenland, but subsequent summers have had a high proportion of cloudy days with moist marine air. Increased snowfall over Antarctica in the past two years was associated with reduced sea ice in the adjacent Southern Ocean, which coincided with rapid global warming during that period. The magnitude of the sea ice loss may have been related to the coincident strong El Niño. On the longer run, it has been predicted that increasing ice discharge from Antarctica, especially in the Western Hemisphere from the Ross to Weddell seas, will tend to cause an increase of sea ice cover, altering the precipitation feedback (see Fig. 16).
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gerontocrat

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Re: Sea Ice Extent around Antarctica
« Reply #1073 on: January 01, 2019, 03:24:12 PM »
Thanks Sleepy - I've saved that.
Two opposing forces
- increased cold fresh water from increased melt of the AIS and shelves,
- increased ocean warmth (e.g. Tealight's AWP graphs) and atmospheric warmth.
and
- Loads more energy and water vapour in the system.
- so increased mass from loads more snowfall, and loads more melt at the surface and below.

The sleeping giant of Antarctica awakes?

meanwhile.....

JAXA ANTARCTIC Sea Ice Extent - 5,423,435 km2(December 31, 2018)

Extent loss of 194k , 13 k more than the average for this day. The loss is again more than that on this day in 2016, the year of the record low minimum.

Extent is lowest in the satellite record for this day, 134 k less than 2016 on this day, and 1.065 million km2 below 2017. Extent loss from maximum is 1.108 million km2 (10.3%) greater than average so far, with on average 71.7% of extent loss for the season done and on average 50 days to minimum.

The average remaining melt from this day to minimum would produce a minimum of 0.89 million km2, 1.26 million km2 less than the record low in 2016-17.(Note that a minor correction to the spreadsheet made -change of year glitch).  A reducing proportion of the remaining ice is at low concentration. With that low concentration ice mostly gone the remaining solid ice close to the coast will likely slow melt down further to a crawl. Nevertheless, a record low minimum, the first below 2 million km2, is still my guess for the 2019 minimum, continuing the loss of Antarctic sea ice over the last three years.

All models have limitations. The first table attached shows that remaining melt in two of the previous years would result in an extent minimum of less than zero, an impossibility. Nevertheless, that is useful in that it shows how much extent this year is below that of the years to 2015.

Being in the Austral summer, low extent and area means with insolation high, albedo warming potential in the Antarctic is also high and well above average. - see Tealight graphs at https://sites.google.com/site/cryospherecomputing/awp/antarctic-graphs
 
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gerontocrat

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Re: Sea Ice Extent around Antarctica
« Reply #1074 on: January 02, 2019, 01:02:28 PM »
JAXA ANTARCTIC Sea Ice Extent - 5,263,487 km2(January 1, 2019)

Extent loss of 160k , 19 k less than the average for this day.

Extent is lowest in the satellite record for this day, 110 k less than 2016 on this day, and 1.088 million km2 below 2017. Extent loss from maximum is 1.163 million km2 (10.0%) greater than average so far, with on average 72.9% of extent loss for the season done and on average 49 days to minimum.

The average remaining melt from this day to minimum would produce a minimum of 0.91 million km2, 1.24 million km2 less than the record low in 2016-17.(Note that a minor correction to the spreadsheet was made -change of year glitch).  A reducing proportion of the remaining ice is at low concentration. With that low concentration ice mostly gone the remaining solid ice close to the coast will likely slow melt down further to a crawl. Nevertheless, a record low minimum, the first below 2 million km2, is still my guess for the 2019 minimum, continuing the loss of Antarctic sea ice over the last three years.

All models have limitations. The first table attached shows that remaining melt in two of the previous years would result in an extent minimum of less than zero, an impossibility. Nevertheless, that is useful in that it shows how much extent this year is below that of the years to 2015.

Being in the Austral summer, low extent and area means with insolation high, albedo warming potential in the Antarctic is also high and well above average. - see Tealight graphs at https://sites.google.com/site/cryospherecomputing/awp/antarctic-graphs
« Last Edit: January 02, 2019, 01:14:13 PM by gerontocrat »
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gerontocrat

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Re: Sea Ice Extent around Antarctica
« Reply #1075 on: January 03, 2019, 11:56:37 AM »
JAXA ANTARCTIC Sea Ice Extent - 5,115,518 km2(January 2, 2019)

Extent loss of 148k , 28 k less than the average for this day.

Extent is lowest in the satellite record for this day, 108 k less than 2016 on this day, and 1.075 million km2 below 2017. Extent loss from maximum is 1.138 million km2 (9.6%) greater than average so far, with on average 73.9% of extent loss for the season done and on average 48 days to minimum.

The average remaining melt from this day to minimum would produce a minimum of 0.94 million km2, 1.21 million km2 less than the record low in 2016-17.  A reducing proportion of the remaining ice is at low concentration. With that low concentration ice mostly gone the remaining solid ice close to the coast will likely slow melt down further to a crawl. Nevertheless, a record low minimum, the first below 2 million km2, is still my guess for the 2019 minimum, continuing the loss of Antarctic sea ice over the last three years.

All models have limitations. The first table attached shows that remaining melt in two of the previous years would result in an extent minimum of less than zero, an impossibility. Nevertheless, that is useful in that it shows how much extent this year is below that of the years to 2015.

Being in the Austral summer, low extent and area means with insolation high, albedo warming potential in the Antarctic is also high and well above average. - see Tealight graphs at https://sites.google.com/site/cryospherecomputing/awp/antarctic-graphs
"Para a Causa do Povo a Luta Continua!"
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gerontocrat

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Re: Sea Ice Extent around Antarctica
« Reply #1076 on: January 04, 2019, 10:09:09 AM »
JAXA ANTARCTIC Sea Ice Extent - 4,977,912 km2(January 3, 2019)

Extent loss of 138k , 22 k less than the average for this day.

Extent is lowest in the satellite record for this day, 171 k less than 2017 on this day, and 1.069 million km2 below 2018. Extent loss from maximum is 1.117 million km2 (9.3%) greater than the 10 year average so far, with on average 74.9% of extent loss for the season done and on average 47 days to minimum.

The average remaining melt from this day to minimum would produce a minimum of 0.96 million km2, 1.19 million km2 less than the record low in 2016-17.  A reducing proportion of the remaining ice is at low concentration. With that low concentration ice mostly gone the remaining solid ice close to the coast will likely slow melt down further to a crawl. Nevertheless, a record low minimum, the first below 2 million km2, is still my guess for the 2019 minimum, continuing the loss of Antarctic sea ice over the last three years (currently 4 million km2 less than the record high in 2014-15).

All models have limitations. The first table attached shows that remaining melt in one of the previous years would result in an extent minimum of less than zero, an impossibility. Nevertheless, that is useful in that it shows how much extent this year is below that of the years to 2015.

Being in the Austral summer, low extent and area means with insolation high, albedo warming potential in the Antarctic is also high and well above average. - see Tealight graphs at https://sites.google.com/site/cryospherecomputing/awp/antarctic-graphs
"Para a Causa do Povo a Luta Continua!"
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gerontocrat

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Re: Sea Ice Extent around Antarctica
« Reply #1077 on: January 04, 2019, 10:57:08 AM »
Here is a look at Sea Ice concentration in the record low year of 2017 and 2019 courtesy of University of Bremen.

As Tealight commented some time ago - the final minimum may well depend on the Weddell Sea - looking a bit more vulnerable this year.
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gerontocrat

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Re: Sea Ice Extent around Antarctica
« Reply #1078 on: January 05, 2019, 12:20:12 PM »
JAXA ANTARCTIC Sea Ice Extent - 4,864,032 km2(January 4, 2019)

Extent loss of 114k , 55 k less than the average for this day.

Extent is lowest in the satellite record for this day, 175 k less than 2017 on this day, and 1.007 million km2 below 2018. Extent loss from maximum is 1.117 million km2 (9.3%) greater than the 10 year average so far, with on average 74.9% of extent loss for the season done and on average 47 days to minimum.

The average remaining melt from this day to minimum would produce a minimum of 1.01 million km2, 1.13 million km2 less than the record low in 2016-17.  A reducing proportion of the remaining ice is at low concentration. With that low concentration ice mostly gone the remaining solid ice close to the coast will likely slow melt down further to a crawl. Nevertheless, a record low minimum, the first below 2 million km2, is still my guess for the 2019 minimum, continuing the loss of Antarctic sea ice over the last three years (currently 4 million km2 less than the record high in 2014-15).

All models have limitations. The first table attached shows that remaining melt in one of the previous years would result in an extent minimum of less than zero, an impossibility. Nevertheless, that is useful in that it shows how much extent this year is below that of the years to 2015.

Being in the Austral summer, low extent and area means with insolation high, albedo warming potential in the Antarctic is also high and well above average. - see Tealight graphs at https://sites.google.com/site/cryospherecomputing/awp/antarctic-graphs
[/quote]
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gerontocrat

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Re: Sea Ice Extent around Antarctica
« Reply #1079 on: January 06, 2019, 10:18:00 AM »
JAXA ANTARCTIC Sea Ice Extent - 4,743,537 km2(January 5, 2019)

Extent loss of 120k , 37 k less than the average for this day.

Extent is lowest in the satellite record for this day, 225 k less than 2017 on this day, and 946 k km2 below 2018. Extent loss from maximum is 1.021 million km2 (8.3%) greater than the 10 year average so far, with on average 77% of extent loss for the season done and on average 45 days to minimum.

The average remaining melt from this day to minimum would produce a minimum of 1.05 million km2, 1.10 million km2 less than the record low in 2016-17.  A reducing proportion of the remaining ice is at low concentration. With that low concentration ice mostly gone the remaining solid ice close to the coast will likely slow melt down further to a crawl. Nevertheless, a record low minimum, the first below 2 million km2, is still my guess for the 2019 minimum, continuing the loss of Antarctic sea ice over the last three years (currently 3.99 million km2 less than the record high in 2014-15).

All models have limitations. The first table attached shows that remaining melt in one of the previous years would result in an extent minimum of less than zero, an impossibility. Nevertheless, that is useful in that it shows how much extent this year is below that of the years to 2015.

Being in the Austral summer, low extent and area means with insolation high, albedo warming potential in the Antarctic is also high and well above average. - see Tealight graphs at https://sites.google.com/site/cryospherecomputing/awp/antarctic-graphs
"Para a Causa do Povo a Luta Continua!"
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Darvince

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Re: Sea Ice Extent around Antarctica
« Reply #1080 on: January 09, 2019, 04:56:31 AM »
The value for Antarctic sea ice extent given on VISHOP today (2019-01-08) (4.34 M km^2) is already lower than the lowest seen during both January 2014 and 2015.

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Re: Sea Ice Extent around Antarctica
« Reply #1081 on: January 09, 2019, 06:15:28 AM »
[ADS NIPR VISHOP (JAXA)] Antarctica Sea Ice Extent.

January 8th, 2019:
     4,341,764 km2, a drop of -141,319 km2.
     2019 is the lowest on record.
Which is the best answer to Sep-2012 ASI lost (compared to 1979-2000)?
50% [NSIDC Extent] or
73% [PIOMAS Volume]

Volume is harder to measure than extent, but 3-dimensional space is real, 2D's hide ~50% thickness gone.
-> IPCC/NSIDC trends [based on extent] underestimate the real speed of ASI lost.

Juan C. García

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Re: Sea Ice Extent around Antarctica
« Reply #1082 on: January 10, 2019, 05:22:48 AM »
[ADS NIPR VISHOP (JAXA)] Antarctic Sea Ice Extent.

January 9th, 2019:
     4,242,472 km2, a drop of -99,292 km2.
     2019 is the lowest on record.
Which is the best answer to Sep-2012 ASI lost (compared to 1979-2000)?
50% [NSIDC Extent] or
73% [PIOMAS Volume]

Volume is harder to measure than extent, but 3-dimensional space is real, 2D's hide ~50% thickness gone.
-> IPCC/NSIDC trends [based on extent] underestimate the real speed of ASI lost.

gerontocrat

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Re: Sea Ice Extent around Antarctica
« Reply #1083 on: January 10, 2019, 05:53:25 AM »
JAXA ANTARCTIC Sea Ice Extent : 4,242,472 km2(January 9, 2019)

Extent loss of 99k , 60 k less than the average for this day.

Extent is lowest in the satellite record for this day, 372 k less than 2017 on this day, and 763 k km2 below 2018. Extent loss from maximum is 915k km2 (7.1%) greater than the 10 year average so far, with on average 81% of extent loss for the season done and on average 41 days to minimum.

The average remaining melt from this day to minimum would produce a minimum of 1.15 million km2, 1 million km2 less than the record low in 2016-17.  A reducing proportion of the remaining ice is at low concentration. With that low concentration ice mostly gone the remaining solid ice close to the coast will likely continue to slow melt down further to a crawl. Nevertheless, a record low minimum, the first below 2 million km2, is still my guess for the 2019 minimum, continuing the loss of Antarctic sea ice over the last three years (currently 3.99 million km2 less than the record high in 2014-15).

All models have limitations. The first table attached shows that remaining melt in one of the previous years would result in an extent minimum of less than zero, an impossibility. Nevertheless, that is useful in that it shows how much extent this year is below that of the years to 2015.

Being in the Austral summer, low extent and area means with insolation high, albedo warming potential in the Antarctic is also high and well above average.  - see Tealight graphs at https://sites.google.com/site/cryospherecomputing/awp/antarctic-graphs
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Juan C. García

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Re: Sea Ice Extent around Antarctica
« Reply #1084 on: January 11, 2019, 05:19:31 AM »
[ADS NIPR VISHOP (JAXA)] Antarctic Sea Ice Extent.

January 10th, 2019:
     4,140,351 km2, a drop of -102,121 km2.
     2019 is the lowest on record.
Which is the best answer to Sep-2012 ASI lost (compared to 1979-2000)?
50% [NSIDC Extent] or
73% [PIOMAS Volume]

Volume is harder to measure than extent, but 3-dimensional space is real, 2D's hide ~50% thickness gone.
-> IPCC/NSIDC trends [based on extent] underestimate the real speed of ASI lost.

gerontocrat

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Re: Sea Ice Extent around Antarctica
« Reply #1085 on: January 11, 2019, 08:46:28 AM »
JAXA ANTARCTIC Sea Ice Extent : 4,140,351 km2(January 10, 2019)

Extent loss of 102k , 37 k less than the average for this day.

Extent is lowest in the satellite record for this day, 377 k less than 2017 on this day, and 674 k km2 below 2018. Extent loss from maximum is 877k km2 (6.7%) greater than the 10 year average so far, with on average 81.6% of extent loss for the season done and on average 40 days to minimum.

The average remaining melt from this day to minimum would produce a minimum of 1.19 million km2,  960k km2 less than the record low in 2016-17.  Most of the remaining ice is at high concentration. With low concentration ice mostly gone the remaining solid ice close to the coast will likely continue to slow melt down further to a crawl. Nevertheless, a record low minimum, the first below 2 million km2, is still my guess for the 2019 minimum, continuing the loss of Antarctic sea ice over the last three years (currently 3.8 million km2 less than the record high in 2014-15).

All models have limitations. The first table attached shows that remaining melt in one of the previous years would result in an extent minimum of less than zero, an impossibility. Nevertheless, that is useful in that it shows how much extent this year is below that of the years to 2015.

Being in the Austral summer, low extent and area means with insolation high, albedo warming potential in the Antarctic is also high and well above average.  This effect is on the decline as 40 days of the highest insolation have now passed.

- see Tealight graphs at https://sites.google.com/site/cryospherecomputing/awp/antarctic-graphs
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gerontocrat

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Re: Sea Ice Extent around Antarctica
« Reply #1086 on: January 12, 2019, 10:15:36 AM »
JAXA ANTARCTIC Sea Ice Extent : 4,028,842 km2(January 11, 2019)

Extent loss of 112k , 52 k less than the average for this day.

Extent is lowest in the satellite record for this day, 238 k less than 2017 on this day, and 615 k km2 below 2018. Extent loss from maximum is 822k km2 (6.2%) greater than the 10 year average so far, with on average 82.6% of extent loss for the season done and on average 39 days to minimum.

The average remaining melt from this day to minimum would produce a minimum of 1.24 million km2,  900k km2 less than the record low in 2016-17.  Most of the remaining ice is at high concentration. With low concentration ice mostly gone the remaining solid ice close to the coast will likely continue to slow melt down further to a crawl. Nevertheless, a record low minimum, the first below 2 million km2, is still my guess for the 2019 minimum, continuing the loss of Antarctic sea ice over the last three years (currently 3.8 million km2 less than the record high in 2014-15).

All models have limitations. The first table attached shows that remaining melt in one of the previous years would result in an extent minimum of less than zero, an impossibility. Nevertheless, that is useful in that it shows how much extent this year is below that of the years to 2015.

Being in the Austral summer, low extent and area means with insolation high, albedo warming potential in the Antarctic is also high and well above average.  This effect is on the decline as 42 days of the highest insolation have now passed.

- see Tealight graphs at https://sites.google.com/site/cryospherecomputing/awp/antarctic-graphs
"Para a Causa do Povo a Luta Continua!"
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Tealight

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Re: Sea Ice Extent around Antarctica
« Reply #1087 on: January 12, 2019, 03:21:14 PM »
Being in the Austral summer, low extent and area means with insolation high, albedo warming potential in the Antarctic is also high and well above average.  This effect is on the decline as 42 days of the highest insolation have now passed.
- see Tealight graphs at https://sites.google.com/site/cryospherecomputing/awp/antarctic-graphs

Peak insulation was on the 21st of December. In my calender it's just 22 days and we still have about 95% of the peak solar radiation. It doesn't drop significantly until February.

The main reason for the AWP anomaly drop are the below average sea ice area losses.

gerontocrat

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Re: Sea Ice Extent around Antarctica
« Reply #1088 on: January 12, 2019, 08:53:50 PM »
Being in the Austral summer, low extent and area means with insolation high, albedo warming potential in the Antarctic is also high and well above average.  This effect is on the decline as 42 days of the highest insolation have now passed.
- see Tealight graphs at https://sites.google.com/site/cryospherecomputing/awp/antarctic-graphs

Peak insulation was on the 21st of December. In my calender it's just 22 days and we still have about 95% of the peak solar radiation. It doesn't drop significantly until February.

The main reason for the AWP anomaly drop are the below average sea ice area losses.
It is certainly true that 'tis February when the sine curve of daylight hours hits the downward arm in the South and the upward arm in the North. As a SAD sufferer I can't wait (too many years in the tropics).

It is also true that it is 22 days (12th of Jan) after the solstice. One has to add to that the 22 days before the solstice plus the solstice day itself for the total number of days when daylight hours have been longer (South) or shorter (North), i.e. 43  45 days.

See attached an illustration of daylight hours I've not seen before from....
http://www.antarctica.gov.au/about-antarctica/environment/weather/sunlight-hours
« Last Edit: January 13, 2019, 08:08:33 AM by gerontocrat »
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gerontocrat

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Re: Sea Ice Extent around Antarctica
« Reply #1089 on: January 13, 2019, 08:17:21 AM »
JAXA ANTARCTIC Sea Ice Extent : 3,924,066 km2(January 12, 2019)

Extent loss of 105k , 35 k less than the average for this day.

Extent is lowest in the satellite record for this day, 176 k less than 2017 on this day, and 539 k km2 below 2018. Extent loss from maximum is 794k km2 (5.9%) greater than the 10 year average so far, with on average 83.5% of extent loss for the season done and on average 38 days to minimum.

The average remaining melt from this day to minimum would produce a minimum of 1.28 million km2,  870k km2 less than the record low in 2016-17.  Most of the remaining ice is at high concentration. With low concentration ice mostly gone the remaining solid ice close to the coast will likely continue to slow melt down further to a crawl. Nevertheless, a record low minimum, the first below 2 million km2, is still my guess for the 2019 minimum, continuing the loss of Antarctic sea ice over the last three years (currently 3.8 million km2 less than the record high in 2014-15).

All models have limitations. The first table attached shows that remaining melt in one of the previous years would result in an extent minimum of less than zero, an impossibility. Nevertheless, that is useful in that it shows how much extent this year is below that of the years to 2015.

Being in the Austral summer, low extent and area means with insolation high, albedo warming potential in the Antarctic is also high and well above average.  This effect is gradually declining as 45 days of the highest insolation have now passed, and will quickly decline come February.

- see Tealight graphs at https://sites.google.com/site/cryospherecomputing/awp/antarctic-graphs
"Para a Causa do Povo a Luta Continua!"
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Juan C. García

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Re: Sea Ice Extent around Antarctica
« Reply #1090 on: January 14, 2019, 07:50:55 AM »
[ADS NIPR VISHOP (JAXA)] Antarctic Sea Ice Extent.

January 13th, 2019:
     3,840,057 km2, a drop of -84,009 km2.
     2019 is the lowest on record.

Note: The 1979-1988 years that are without daily value, were not included in this analysis (It is usual to have a missing value on those years).
Which is the best answer to Sep-2012 ASI lost (compared to 1979-2000)?
50% [NSIDC Extent] or
73% [PIOMAS Volume]

Volume is harder to measure than extent, but 3-dimensional space is real, 2D's hide ~50% thickness gone.
-> IPCC/NSIDC trends [based on extent] underestimate the real speed of ASI lost.

gerontocrat

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Re: Sea Ice Extent around Antarctica
« Reply #1091 on: January 14, 2019, 11:46:39 AM »
JAXA ANTARCTIC Sea Ice Extent : 3,840,057 km2(January 13, 2019)

Extent loss of 84k , 58 k less than the average for this day.

Extent is lowest in the satellite record for this day, 110 k less than 2017 on this day, and 539 k km2 below 2018. Extent loss from maximum is 732k km2 (5.4%) greater than the 10 year average so far, with on average 84.4% of extent loss for the season done and on average 37 days to minimum.

The average remaining melt from this day to minimum would produce a minimum of 1.34 million km2,  810k km2 less than the record low in 2016-17.  Most of the remaining ice is at high concentration. With low concentration ice mostly gone the remaining solid ice close to the coast will likely continue to slow melt down further to a crawl.

Nevertheless, a record low minimum, the first below 2 million km2, is still my guess for the 2019 minimum, continuing the loss of Antarctic sea ice over the last three years (currently 3.8 million km2 less than the record high in 2014-15). However, the drop in daily extent losses has reduced confidence in that prediction.

All models have limitations. The first table attached shows that remaining melt in one of the previous years would result in an extent minimum of less than zero, an impossibility. Nevertheless, that is useful in that it shows how much extent this year is below that of the years to 2015.

Being still in the Austral summer, low extent and area means with insolation high, albedo warming potential in the Antarctic is also high and well above average.  This effect is gradually declining as 47 days of the highest insolation have now passed, and will quickly decline come February.

- see Tealight graphs at https://sites.google.com/site/cryospherecomputing/awp/antarctic-graphs
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Shared Humanity

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Re: Sea Ice Extent around Antarctica
« Reply #1092 on: January 14, 2019, 08:56:02 PM »
Given the current trajectory, I would not be surprised if SIE ends up being 3rd lowest.

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Re: Sea Ice Extent around Antarctica
« Reply #1093 on: January 15, 2019, 05:19:51 AM »
Jan 13th sea ice  concentration from 2016-2019
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Re: Sea Ice Extent around Antarctica
« Reply #1094 on: January 15, 2019, 05:57:56 AM »
[ADS NIPR VISHOP (JAXA)] Antarctic Sea Ice Extent.

January 14th, 2019:
     3,762,336 km2, a drop of -77,721 km2.
     2019 is the lowest on record.

Note: The 1979-1988 years that are without daily value, were not included in this analysis (It is usual to have a missing value on those years).
Which is the best answer to Sep-2012 ASI lost (compared to 1979-2000)?
50% [NSIDC Extent] or
73% [PIOMAS Volume]

Volume is harder to measure than extent, but 3-dimensional space is real, 2D's hide ~50% thickness gone.
-> IPCC/NSIDC trends [based on extent] underestimate the real speed of ASI lost.

gerontocrat

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Re: Sea Ice Extent around Antarctica
« Reply #1095 on: January 15, 2019, 09:45:19 AM »
JAXA ANTARCTIC Sea Ice Extent : 3,762,336 km2(January 14, 2019)

Extent loss of 78k , 69 k less than the average for this day.

Extent is 2nd lowest in the satellite record for this day, (and about to become 2nd after 2017). Extent is 22 k less than 2017 on this day, and 391 k km2 below 2018. Extent loss from maximum is 664k km2 (4.9%) greater than the 10 year average so far, with on average 85.3% of extent loss for the season done and on average 36 days to minimum.

The average remaining melt from this day to minimum would produce a minimum of 1.41 million km2,  740k km2 less than the record low in 2016-17.  Most of the remaining ice is at high concentration. With low concentration ice mostly gone the remaining solid ice close to the coast will likely continue to slow melt down further to a crawl.

Nevertheless, a record low minimum, the first below 2 million km2, is still my guess for the 2019 minimum, continuing the loss of Antarctic sea ice over the last three years (currently 3.8 million km2 less than the record high in 2014-15). However, the drop in daily extent losses has reduced confidence in that prediction.

Being still in the Austral summer, low extent and area means with insolation high, albedo warming potential in the Antarctic is also high and well above average.  This effect is gradually declining as 49 days of the highest insolation have now passed, and will quickly decline come February.

- see Tealight graphs at https://sites.google.com/site/cryospherecomputing/awp/antarctic-graphs
[/quote]
« Last Edit: January 16, 2019, 01:41:37 PM by gerontocrat »
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gerontocrat

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Re: Sea Ice Extent around Antarctica
« Reply #1096 on: January 16, 2019, 01:35:09 PM »
JAXA ANTARCTIC Sea Ice Extent : 3,684,642 km2(January 15, 2019)

Extent loss of 78k , 59 k less than the average for this day.

Extent is lowest in the satellite record for this day, (and about to become 2nd after 2017). Extent is 45 k less than 2017 on this day, and 379 k km2 below 2018. Extent loss from maximum is 608k km2 (4.4%) greater than the 10 year average so far, with on average 86.2% of extent loss for the season done and on average 36 days to minimum.

The average remaining melt from this day to minimum would produce a minimum of 1.46 million km2,  680k km2 less than the record low in 2017.  Most of the remaining ice is at high concentration. With low concentration ice mostly gone the remaining solid ice close to the coast will likely continue to slow melt down further to a crawl.

Nevertheless, a record low minimum, the first below 2 million km2, is still my guess for the 2019 minimum, continuing the loss of Antarctic sea ice over the last three years (currently 3.8 million km2 less than the record high in 2014-15). However, the drop in daily extent losses has reduced confidence in that prediction.

Being still in the Austral summer, low extent and area means with insolation high, albedo warming potential in the Antarctic is also high and well above average.  This effect is gradually declining as 51 days of the highest insolation have now passed, and will quickly decline come February.

- see Tealight graphs at https://sites.google.com/site/cryospherecomputing/awp/antarctic-graphs
"Para a Causa do Povo a Luta Continua!"
"And that's all I'm going to say about that". Forrest Gump
"Damn, I wanted to see what happened next" (Epitaph)

gerontocrat

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Re: Sea Ice Extent around Antarctica
« Reply #1097 on: January 19, 2019, 11:44:59 AM »
JAXA ANTARCTIC Sea Ice Extent : 3,513,853 km2(January 18, 2019)

Extent loss of 63k , 76 k less than the average for this day.

Extent is 2nd lowest in the satellite record for this day.
Extent loss from maximum is 386k km2 (2.7%) greater than the 10 year average so far, with on average 88.6% of extent loss for the season done and on average 32 days to minimum.

The average remaining melt from this day to minimum would produce a minimum of 1.69 million km2,  460k km2 less than the record low in 2017.  Most of the remaining ice is at high concentration. With low concentration ice mostly gone the remaining solid ice close to the coast will likely continue to slow melt down further to a crawl.

Nevertheless, a record low minimum, the first below 2 million km2, is still my guess for the 2019 minimum, continuing the loss of Antarctic sea ice over the last three years (currently 3.1 million km2 less than the record high in 2014-15). However, the drop in daily extent losses has considerably reduced confidence in that prediction.

Being still in the Austral summer, low extent and area means with insolation high, albedo warming potential (AWP) in the Antarctic is also high and well above average. This effect is now quickly declining as 57 days of the highest insolation have now passed and daily area loss is so far below average. The cumulative AWP will certainly end up as 2nd lowest , behind the 2016-17 season.

- see Tealight graphs at https://sites.google.com/site/cryospherecomputing/awp/antarctic-graphs
[/quote]
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Steven

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Re: Sea Ice Extent around Antarctica
« Reply #1098 on: January 19, 2019, 10:49:37 PM »
Interesting new paper about the role that atmosphere and ocean have played in the reduction of Antarctic sea ice since 2016:

Meehl et al., 
"Sustained ocean changes contributed to sudden Antarctic sea ice retreat in late 2016"

https://www.nature.com/articles/s41467-018-07865-9

Abstract:
Quote
After nearly three decades of observed increasing trends of Antarctic sea ice extent, in September-October-November 2016, there was a dramatic decrease. Here we document factors that contributed to that decrease. An atmosphere-only model with a specified positive convective heating anomaly in the eastern Indian/western Pacific Ocean, representing the record positive precipitation anomalies there in September-October-November 2016, produces an anomalous atmospheric Rossby wave response with mid- and high latitude surface wind anomalies that contribute to the decrease of Antarctic sea ice extent. The sustained decreases of Antarctic sea ice extent after late 2016 are associated with a warmer upper Southern Ocean. This is the culmination of a negative decadal trend of wind stress curl with positive Southern Annular Mode and negative Interdecadal Pacific Oscillation, Ekman suction that results in warmer water being moved upward in the column closer to the surface, a transition to positive Interdecadal Pacific Oscillation around 2014–2016, and negative Southern Annular Mode in late 2016.

Evolution of subsurface temperature anomalies in the Southern Ocean between 2004 and 2017:


gerontocrat

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Re: Sea Ice Extent around Antarctica
« Reply #1099 on: January 20, 2019, 03:08:30 PM »
JAXA ANTARCTIC Sea Ice Extent : 3,438,574 km2(January 19, 2019)

Extent loss of 75k , 52 k less than the average for this day.

Extent is 2nd lowest in the satellite record for this day.
Extent loss from maximum is 327k km2 (2.3%) greater than the 10 year average so far, with on average 88.6% of extent loss for the season done and on average 31 days to minimum.

The average remaining melt from this day to minimum would produce a minimum of 1.74 million km2,  410k km2 less than the record low in 2017.  Most of the remaining ice is at high concentration. With low concentration ice mostly gone the remaining solid ice close to the coast will likely continue to slow melt down further to a crawl.

Nevertheless, a record low minimum, the first below 2 million km2, is still my guess for the 2019 minimum, continuing the loss of Antarctic sea ice over the last three years (currently 3.1 million km2 less than the record high in 2014-15). However, the drop in daily extent losses has considerably reduced confidence in that prediction.

Being still in the Austral summer, low extent and area means with insolation high, albedo warming potential (AWP) in the Antarctic is also high and well above average. This effect is now quickly declining as 59 days of the highest insolation have now passed and daily area loss is so far below average. The cumulative AWP will certainly end up as 2nd lowest , behind the 2016-17 season.

- see Tealight graphs at https://sites.google.com/site/cryospherecomputing/awp/antarctic-graphs
"Para a Causa do Povo a Luta Continua!"
"And that's all I'm going to say about that". Forrest Gump
"Damn, I wanted to see what happened next" (Epitaph)