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DavidR

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Re: 2016 sea ice area and extent data
« Reply #50 on: March 05, 2016, 09:54:06 PM »
<snippage>
893,046 km2 below 2000s average for this date.
418,373 km2 below 2010s average for this date.
371,306 km2 below 2015 value for this date.
544,880 km2 below 2012 value for this date.
1st lowest March to-date average.
1st lowest value for the date.
<more snippage>
This, more than the low extent, really, really worries me.

Last year at this stage only 6 days had been in the lowest 3 on record. This year it  is 54. That says an awful lot  about the state of the ice and the amount of open water that  must  be around to start receiving insolation.
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Andreas T

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Re: 2016 sea ice area and extent data
« Reply #51 on: March 05, 2016, 11:49:15 PM »
.....
In two weeks, areas at 80N will start getting 2 kilowatt hours per square meter a day of insolation.  That should be about the time energy input balances out the daily radiative loss.  By the time we get to April 1st, that available energy doubles.  By the time we get to May 1st, we're at 14KWH/Day/M2 of incident radiation hitting the sea surface.  It only gets worse.
.....
Are these values top of the atmosphere irradiances?
I found some measured surface values for 75 -80 deg north here:
http://onlinelibrary.wiley.com/doi/10.1029/2006JC003558/full
to get kWh from MJ divide by 3.6 i.e 30MJ is 8.3kWh/ day /m2 max in June

Andreas T

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Re: 2016 sea ice area and extent data
« Reply #52 on: March 06, 2016, 12:10:07 AM »
from the paper cited abovehttps://www.researchgate.net/profile/Marcel_Nicolaus/publication/234833783_Changes_in_Arctic_sea_ice_result_in_increasing_light_transmittance_and_absorption/links/0fcfd5112abcc37990000000.pdf (i.e. written in 2011) :
Quote
learly, short-wave radiative fluxes into the ocean will
increase in the future due to sea ice retreat, resulting in more
open water. Our results show that there will also be a signifi-
cant increase of fluxes through the (remaining) sea ice due to
the shift to more FYI. To the extent that the FYI measurements
described here are representative for todays summer condi-
tions, FYI transmits almost three times as much light as MYI,
which is expected to have less and less coverage in the future.
Averaging over the entire Arctic with a 50/50 distribution of
FYI and MYI in 2011 (Figure S5), todays transmittanceof
solar irradiance over the entire Arctic sea ice is 0.08. Assuming
similar fractions of pond coverage and transmittance ratios
of FYI and MYI in the future, solar heat input will increase by
about 50% when the point is reached where only small frac-
tions (e.g. 10%) of the Arctic are covered with MYI during
summer
Quote
However, a potential increase of
absolute fluxes through sea ice into the upper ocean also
depends on the evolution of solar surface irradiance, which is
strongly affected by clouds
Quote
For all further studies of season-
ality more (similar) large-scale observations are necessary to
allow the generation of a transmittance seasonality for dif-
ferent ice types [Nicolaus et al, 2010b; Perovich et al. 2011].
 Therefore, additional observations are suggested as
future work. This would be most beneficial between May and
July when fluxes are highly relevant for sea-ice mass balance
and primary productivity. At that time of year, the distribu-
tion of snow is particularly important in determining light
penetration and control its spatial variability

This is also interesting
Quote
In that
respect, strongly deformed FYI is also much more similar to
MYI than level FYI. Hence, changes in sea-ice dynamics
could also impact light transmittance of future sea ice beyond
the here presented aspects.
« Last Edit: March 06, 2016, 12:42:46 AM by Andreas T »

jdallen

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Re: 2016 sea ice area and extent data
« Reply #53 on: March 06, 2016, 01:50:20 AM »
.....
In two weeks, areas at 80N will start getting 2 kilowatt hours per square meter a day of insolation.  That should be about the time energy input balances out the daily radiative loss.  By the time we get to April 1st, that available energy doubles.  By the time we get to May 1st, we're at 14KWH/Day/M2 of incident radiation hitting the sea surface.  It only gets worse.
.....
Are these values top of the atmosphere irradiances?
I found some measured surface values for 75 -80 deg north here:
http://onlinelibrary.wiley.com/doi/10.1029/2006JC003558/full
to get kWh from MJ divide by 3.6 i.e 30MJ is 8.3kWh/ day /m2 max in June

Raw, it's about 1600W/M2 oblique at the top of the atmosphere.  By the time you get down to sea level, it's about 330.  You factor in the angle (about 43 degrees at 80N on Jun 21st at mid day) and I see that as around 12KWH/M2/Day.  Caveat: optical calculations are not my strong suit, so if anyone can show us better numbers, I'm fine with it.

Now, even if I'm off significantly, we can look at the factor for Albedo.  Ice with snow has an Albedo of about .85 - most of the energy is getting tossed back out.

Albedo of sea water at worst is going to be about 0.2.   So at worst, the areas exposed to sunlight can conservatively pick up 5 times the energy they would if they were still covered with sea ice.  That's a massive increase in energy input into the areas affected, and doesn't improve particularly if there's cloud cover.

I'm hard pressed to see how that could not have a significant effect conditioning the pack at the start of the melt season.
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Tor Bejnar

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Re: 2016 sea ice area and extent data
« Reply #54 on: March 06, 2016, 02:03:08 AM »
Thanks, jdallen and others for this discussion.
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jdallen

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Re: 2016 sea ice area and extent data
« Reply #55 on: March 06, 2016, 02:04:26 AM »
Let me make something else clear here.

Even with the massive inputs of energy, I'm not suggesting we will see sudden massive melting before the typical start of the melt season.

What I'm suggesting is, the extra energy will give the melt season a running start.  What I *think* that will translate into is, 1-2 weeks of additional melting on either end of the season. 

What the heat will be doing is boosting the net energy input into the system by something like 2-3%.  While that may not seem like a lot, it will add up quickly.

I think where that heat goes will be key to how the melt season plays out.
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Tealight

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Re: 2016 sea ice area and extent data
« Reply #56 on: March 06, 2016, 04:20:07 AM »
.....
In two weeks, areas at 80N will start getting 2 kilowatt hours per square meter a day of insolation.  That should be about the time energy input balances out the daily radiative loss.  By the time we get to April 1st, that available energy doubles.  By the time we get to May 1st, we're at 14KWH/Day/M2 of incident radiation hitting the sea surface.  It only gets worse.
.....
Are these values top of the atmosphere irradiances?
I found some measured surface values for 75 -80 deg north here:
http://onlinelibrary.wiley.com/doi/10.1029/2006JC003558/full
to get kWh from MJ divide by 3.6 i.e 30MJ is 8.3kWh/ day /m2 max in June

Raw, it's about 1600W/M2 oblique at the top of the atmosphere.  By the time you get down to sea level, it's about 330.  You factor in the angle (about 43 degrees at 80N on Jun 21st at mid day) and I see that as around 12KWH/M2/Day.  Caveat: optical calculations are not my strong suit, so if anyone can show us better numbers, I'm fine with it.

On what Planet do you live?  ;D

On 21st June the max angle at 80N is only 33.4 degrees. The earth is tilted by 23.4 degrees and for 80N you just add another 10 degrees to that.
The solar constant on top of the atmosphere is on average 1365W/m2, but in June/July it is only 1321W/m2, because Earth is close to aphelion.

I think what most people don't realise is how much solar radiation thin clouds/haze or can filter out, when the sun is at a very low angle.
Most of us live in the temperate region 40-60N, where even in winter the solar angle can be higher than in the Arctic during summer.

I once created a chart which shows the distance a "light beam" has to travel through a cloud for various angles. The actual distance is of course even higher because the light gets constantly absorbed and re emitted.

For comparison at 50N on 21st June the max solar angle is 63.3 degrees.

« Last Edit: March 06, 2016, 04:34:24 AM by Tealight »

jdallen

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Re: 2016 sea ice area and extent data
« Reply #57 on: March 06, 2016, 08:32:08 AM »
.....
In two weeks, areas at 80N will start getting 2 kilowatt hours per square meter a day of insolation.  That should be about the time energy input balances out the daily radiative loss.  By the time we get to April 1st, that available energy doubles.  By the time we get to May 1st, we're at 14KWH/Day/M2 of incident radiation hitting the sea surface.  It only gets worse.
.....
Are these values top of the atmosphere irradiances?
I found some measured surface values for 75 -80 deg north here:
http://onlinelibrary.wiley.com/doi/10.1029/2006JC003558/full
to get kWh from MJ divide by 3.6 i.e 30MJ is 8.3kWh/ day /m2 max in June

Raw, it's about 1600W/M2 oblique at the top of the atmosphere.  By the time you get down to sea level, it's about 330.  You factor in the angle (about 43 degrees at 80N on Jun 21st at mid day) and I see that as around 12KWH/M2/Day.  Caveat: optical calculations are not my strong suit, so if anyone can show us better numbers, I'm fine with it.

On what Planet do you live?  ;D

On 21st June the max angle at 80N is only 33.4 degrees. The earth is tilted by 23.4 degrees and for 80N you just add another 10 degrees to that.
The solar constant on top of the atmosphere is on average 1365W/m2, but in June/July it is only 1321W/m2, because Earth is close to aphelion.
*Brain* F*rt* - *90* degrees from the pole to the equator.  *90*... Nine Zero, not one hundred...   :P

Thank you for the numbers.

I do understand that cloud cover would significantly reduce the total heat reaching the surface.

Back again to my key point - Albedo.  Regardless of how much is getting through, a much larger fraction is going to get captured by open water.  Multiply that fraction by 370,000 KM2, it adds up to a large amount of heat.
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Andreas T

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Re: 2016 sea ice area and extent data
« Reply #58 on: March 06, 2016, 09:21:29 AM »
.....

I once created a chart which shows the distance a "light beam" has to travel through a cloud for various angles. The actual distance is of course even higher because the light gets constantly absorbed and re emitted.
....
You seem to confuse scattering with absorption. Sunlight is "filtered" by the cloud droplets by scattering the incoming energy into all directions (some more than others) including downwards. That downwards scattered light is scattered again as it encounters more droplets depending on the thickness and density of the cloud.
Diffuse light from clouds is part of the energy input at the surface, but of course that is less than would be received by direct sunlight.

LRC1962

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Re: 2016 sea ice area and extent data
« Reply #59 on: March 06, 2016, 01:23:52 PM »
Personally IMO how much radiation from sunlight the Arctic will receive this year is totally ignoring the changes that seem to be happening. Look at this chart:


That is all the result of a lot of heat being pumped into the Arctic via storms. I think the main culprit is the cold Blob + superheated Golf Stream setting up dipoles that spin big storms into the heart of the Atlantic side of the Arctic. Since the experts are tending to believe that with the changes in the NA, they are going to be permanent fixtures, I do not think it is going out on a limb in saying that from now on, big storms spinning into the Arctic will become a year round occurrence. If that becomes the case those storms will be the biggest decider of melt and not the sun.
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Tealight

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Re: 2016 sea ice area and extent data
« Reply #60 on: March 06, 2016, 04:12:00 PM »
You seem to confuse scattering with absorption. Sunlight is "filtered" by the cloud droplets by scattering the incoming energy into all directions (some more than others) including downwards. That downwards scattered light is scattered again as it encounters more droplets depending on the thickness and density of the cloud.
Diffuse light from clouds is part of the energy input at the surface, but of course that is less than would be received by direct sunlight.

I know that most of the light is scattered and not absorbed, but it still makes a difference if it is scattered 100 or 200 times.

jdallen

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Re: 2016 sea ice area and extent data
« Reply #61 on: March 06, 2016, 10:55:29 PM »
Personally IMO how much radiation from sunlight the Arctic will receive this year is totally ignoring the changes that seem to be happening. Look at this chart:
<snippage>
That is all the result of a lot of heat being pumped into the Arctic via storms. I think the main culprit is the cold Blob + superheated Golf Stream setting up dipoles that spin big storms into the heart of the Atlantic side of the Arctic. Since the experts are tending to believe that with the changes in the NA, they are going to be permanent fixtures, I do not think it is going out on a limb in saying that from now on, big storms spinning into the Arctic will become a year round occurrence. If that becomes the case those storms will be the biggest decider of melt and not the sun.
Completely agree, LRC.  The point I've made doesn't have to do with how the Arctic was warm this winter.  Rather, I'm focusing in on how early, lower extent will increase the amount of energy captured early in the melt season coming up.  Compared to previous seasons, 2016 is...

2015    2.8% lower
2012    4.1% lower
2010s   3.1% lower

The extent this year, at this time is very similar to 2012, save for somewhat more extent being open in the Barents, and a *lot* more extent open in the Bering.

http://igloo.atmos.uiuc.edu/cgi-bin/test/print.sh?fm=03&fd=04&fy=2012&sm=03&sd=04&sy=2016

2016 has somewhat more extent in the Bering and considerably more in the Okhotsk than 2015, and significantly less on the Atlantic side.

http://igloo.atmos.uiuc.edu/cgi-bin/test/print.sh?fm=03&fd=05&fy=2015&sm=03&sd=04&sy=2016

The effect right now will be to dump more heat out of the water into the atmosphere - which will contribute to higher 80N temperatures and constrain ice thickening elsewhere.

The effect after the equinox will be to capture 80% more insolation over that area which in previous years would have been radiated into space, on the "wrong" side of the summer solstice. Add particularly, this heat is getting dumped into areas at high latitude which normally don't see that much heat until well into the melt season.

It's only 3% more relative to the total ice cover in the arctic, but it's like attaching a small weight to a spinning disk; it destabilizes the balance and sets off (mostly) unpredictable oscillations in the system.

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BornFromTheVoid

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Re: 2016 sea ice area and extent data
« Reply #62 on: March 07, 2016, 12:29:32 PM »
Update for the week to March 5th

The current 5 day mean is on 14,392,200km2 while the 1 day extent is at 14,381,000km2.

The daily anomaly (compared to 81-10) is at -1,107,010km2, a decrease from -1,148,070km2 last week. The anomaly compared to the 07, 11 and 12 average is at -423,070km2, an increase from -339,730km2 last week. We're currently lowest on record, the same as last week.



The average daily change over the last 7 days was +8.1k/day, compared to the long term average of +2.2k/day, and the 07, 11 and 12 average of +19.9k/day.
The average long term change over the next week is +0.8k/day, with the 07, 11, and 12 average being +4.3k/day.



The extent change so far this March is the 8th most negative on record. To achieve the smallest monthly gain, a loss of at least 23.7k/day is required, while the largest monthly gain requires an increase of at least 18.8k/day and an average gain requires a loss of 5.0k/day.



The extent increase in February was the 11th smallest on record, while the average extent was the smallest on record and first to average below 14.5 million km2




Jim Pettit

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Re: 2016 sea ice area and extent data
« Reply #63 on: March 08, 2016, 01:01:10 PM »
ADS-NIPR Extent:
13,858,745 km2 (07 March)
Up 61,752 km2 (0.45%) from previous day.
Down 83,762 km2  (-0.6%) over past seven days (daily average: -11,966 km2).
Down 83,762 km2  (-0.68%) for March (daily average: -11,966 km2).
811,603 km2 below 2000s average for this date.
357,852 km2 below 2010s average for this date.
199,329 km2 above 2015 value for this date.
850,341 km2 below 2012 value for this date.
2nd lowest March to-date average.
2nd lowest value for the date.
34 days this year (51.52% year-to-date) have recorded the lowest daily extent.
16 days (24.24%) have recorded the second lowest.
9 days (13.64%) have recorded the third lowest.
59 days in total (89.39%) have been among the lowest three on record.


CT Area:
12,724,465 km2 (06 March [Day 0.1753])
Down 21,882 km2 (-0.17%) from previous day.
Down 118,621 km2 (-0.93%) over past seven days (daily average: -16,946 km2).
Down 51,361 km2 (-0.46%) for March (daily average: -8,560 km2).
989,901 km2 below 2000s average for this date.
508,056 km2 below 2010s average for this date.
304,130 km2 below 2015 value for this date.
956,007 km2 below 2012 value for this date.
Lowest March to-date average.
Lowest value for the date.
35 days this year (53.85% year-to-date) have recorded the lowest daily area.
14 days (21.54%) have recorded the second lowest.
8 days (12.31%) have recorded the third lowest.
57 days in total (87.69%) have been among the lowest three on record.

Stat of the day: CT SIA is currently 956,007 km2 below the 2012 value for this date. That's a difference in area roughly the size of the US states of Texas and Oregon combined.




Jim Pettit

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Re: 2016 sea ice area and extent data
« Reply #64 on: March 09, 2016, 12:39:07 PM »
ADS-NIPR Extent:
13,921,066 km2 (08 March)
Up 62,321 km2 (.45%) from previous day.
Down 3,128 km2  (-.02%) over past seven days (daily average: -447 km2).
Down 21,441 km2  (-.18%) for March (daily average: -2,680 km2).
747,582 km2 below 2000s average for this date.
284,109 km2 below 2010s average for this date.
271,197 km2 above 2015 value for this date.
685,491 km2 below 2012 value for this date.
Lowest year-to-date (01 January - 08 March) average.
2nd lowest March to-date average.
2nd lowest value for the date.
34 days this year (50.75% year-to-date) have recorded the lowest daily extent.
17 days (25.37%) have recorded the second lowest.
9 days (13.43%) have recorded the third lowest.
60 days in total (89.55%) have been among the lowest three on record.


CT Area:
12,723,368 km2 (07 March [Day 0.1781])
Down 1,098 km2 (-0.01%) from previous day.
Down 52,459 km2 (-0.41%) over past seven days (daily average: -7,494 km2).
Down 52,459 km2 (-0.47%) for March (daily average: -7,494 km2).
995,370 km2 below 2000s average for this date.
541,114 km2 below 2010s average for this date.
284,673 km2 below 2015 value for this date.
941,751 km2 below 2012 value for this date.
Lowest year-to-date (Day 0.0000 - Day 0.1781) average.
Lowest March to-date average.
Lowest value for the date.
36 days this year (54.55% year-to-date) have recorded the lowest daily area.
14 days (21.21%) have recorded the second lowest.
8 days (12.12%) have recorded the third lowest.
58 days in total (87.88%) have been among the lowest three on record.

Jim Pettit

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Re: 2016 sea ice area and extent data
« Reply #65 on: March 11, 2016, 12:23:43 PM »
ADS-NIPR Extent:
13,855,406 km2 (10 March)
Down 43,077 km2 (-.31%) from previous day.
Up 30,949 km2  (.22%) over past seven days (daily average: 4,421 km2).
Down 87,101 km2  (-.71%) for March (daily average: -8,710 km2).
806,501 km2 below 2000s average for this date.
306,231 km2 below 2010s average for this date.
231,638 km2 above 2015 value for this date.
655,016 km2 below 2012 value for this date.
Lowest year-to-date (01 January - 10 March) average.
2nd lowest March to-date average.
2nd lowest value for the date.
34 days this year (49.28% year-to-date) have recorded the lowest daily extent.
19 days (27.54%) have recorded the second lowest.
9 days (13.04%) have recorded the third lowest.
62 days in total (89.86%) have been among the lowest three on record.


CT Area:
12,754,865 km2 (09 March [Day 0.1836])
Up 24,532 km2 (.19%) from previous day.
Down 10,852 km2 (-.09%) over past seven days (daily average: -1,550 km2).
Down 20,962 km2 (-.19%) for March (daily average: -2,329 km2).
958,378 km2 below 2000s average for this date.
506,414 km2 below 2010s average for this date.
213,137 km2 below 2015 value for this date.
854,555 km2 below 2012 value for this date.
Lowest year-to-date (Day 0.0000 - Day 0.1836) average.
Lowest March to-date average.
Lowest value for the date.
38 days this year (55.88% year-to-date) have recorded the lowest daily area.
14 days (20.59%) have recorded the second lowest.
8 days (11.76%) have recorded the third lowest.
60 days in total (88.24%) have been among the lowest three on record.


BornFromTheVoid

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Re: 2016 sea ice area and extent data
« Reply #66 on: March 14, 2016, 10:45:16 AM »
Update for the week to March 12th

The current 5 day mean is on 14,373,200km2 while the 1 day extent is at 14,388,000km2.

The daily anomaly (compared to 81-10) is at -1,132,060km2, an increase from -1,107,010km2 last week. The anomaly compared to the 07, 11 and 12 average is at -472,330km2, an increase from -423,070km2 last week. We're currently 2nd lowest on record, down from lowest last week.



The average daily change over the last 7 days was -2.7k/day, compared to the long term average of +0.8k/day, and the 07, 11 and 12 average of +4.3k/day.
The average long term change over the next week is -9.8k/day, with the 07, 11, and 12 average being -5.5k/day.



The extent change so far this March is the 11th most negative on record. To achieve the largest monthly loss, a drop of at least 31.4k/day is required, while the largest monthly gain requires an increase of at least 26.8k/day and an average gain requires a loss of 5.8k/day.


Jim Pettit

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Re: 2016 sea ice area and extent data
« Reply #67 on: March 14, 2016, 11:35:57 AM »
ADS-NIPR Extent:
13,872,861 km2 (13 March)
Down 27,697 km2 (-.2%) from previous day.
Up 75,868 km2  (.55%) over past seven days (daily average: 10,838 km2).
Down 69,646 km2  (-.57%) for March (daily average: -5,357 km2).
744,787 km2 below 2000s average for this date.
337,592 km2 below 2010s average for this date.
186,445 km2 above 2015 value for this date.
705,035 km2 below 2012 value for this date.
Lowest year-to-date (01 January - 13 March) average.
2nd lowest March to-date average.
2nd lowest value for the date.
34 days this year (47.22% year-to-date) have recorded the lowest daily extent.
22 days (30.56%) have recorded the second lowest.
9 days (12.5%) have recorded the third lowest.
65 days in total (90.28%) have been among the lowest three on record.


CT Area:
12,851,209 km2 (13 March [Day 0.1946])
Up 11,456 km2 (.09%) from previous day.
Up 126,743 km2 (1.%) over past seven days (daily average: 18,106 km2).
Up 75,382 km2 (.68%) for March (daily average: 5,799 km2).
804,933 km2 below 2000s average for this date.
413,859 km2 below 2010s average for this date.
143,527 km2 below 2015 value for this date.
680,341 km2 below 2012 value for this date.
Lowest year-to-date (Day 0.0000 - Day 0.1946) average.
Lowest March to-date average.
Lowest value for the date.
42 days this year (58.33% year-to-date) have recorded the lowest daily area.
14 days (19.44%) have recorded the second lowest.
8 days (11.11%) have recorded the third lowest.
64 days in total (88.89%) have been among the lowest three on record.




« Last Edit: March 14, 2016, 01:34:41 PM by Jim Pettit »

Jim Pettit

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Re: 2016 sea ice area and extent data
« Reply #68 on: March 16, 2016, 12:24:37 PM »
ADS-NIPR Extent:
13,874,820 km2 (15 March)
Up 37,813 km2 (.27%) from previous day.
Down 46,246 km2  (-.33%) over past seven days (daily average: -6,607 km2).
Down 67,687 km2  (-.55%) for March (daily average: -4,512 km2).
696,999 km2 below 2000s average for this date.
373,271 km2 below 2010s average for this date.
150,382 km2 above 2015 value for this date.
791,491 km2 below 2012 value for this date.
Lowest year-to-date (01 January - 15 March) average.
2nd lowest March to-date average.
3rd lowest value for the date.
34 days this year (45.95% year-to-date) have recorded the lowest daily extent.
23 days (31.08%) have recorded the second lowest.
10 days (13.51%) have recorded the third lowest.
67 days in total (90.54%) have been among the lowest three on record.


CT Area:
12,859,657 km2 (14 March [Day 0.1973])
Up 8,449 km2 (.07%) from previous day.
Up 136,290 km2 (1.07%) over past seven days (daily average: 19,470 km2).
Up 83,831 km2 (.75%) for March (daily average: 5,988 km2).
781,672 km2 below 2000s average for this date.
420,571 km2 below 2010s average for this date.
116,133 km2 below 2015 value for this date.
660,407 km2 below 2012 value for this date.
Lowest year-to-date (Day 0.0000 - Day 0.1973) average.
Lowest March to-date average.
Lowest value for the date.
43 days this year (58.9% year-to-date) have recorded the lowest daily area.
14 days (19.18%) have recorded the second lowest.
8 days (10.96%) have recorded the third lowest.
65 days in total (89.04%) have been among the lowest three on record.

Wipneus

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Re: 2016 sea ice area and extent data
« Reply #69 on: March 16, 2016, 05:16:09 PM »
From today's NSIDC sea ice concentration data I calculate sea ice area, in the Cryosphere Today way. "day" is the day that CT normally publishes that data for the Northern Hemisphere, SH and global normally follow the next day. "CT-date" is approximately the date that CT uses.


day  CT-date       NH               SH                Global
Mon 2016.1945  +10.9 12.851103  +43.4  2.265887   +54.3 15.116990
Tue 2016.1973   +8.8 12.859880  +93.0  2.358840  +101.7 15.218720
Wed 2016.2000  +25.6 12.885500  +37.8  2.396603   +63.4 15.282103
Thu 2016.2027 -175.0 12.710511  +81.5  2.478095   -93.5 15.188606
Fri 2016.2055  +18.7 12.729209 +118.9  2.596975  +137.6 15.326184


As can be seen, CT-area (NH) will tomorrow drop an almost-near double century, possibly the start of the new melting season in the Arctic.

When NSIDC does not revise its concentration data (they do occasionally), my values are normally accurate withing a few k. Uncertainties are the exact algorithm for assumed concentration in the pole hole and some subtleties handling bad data.

In the attached graph the performance of my reverse-engineering for the past few weeks can be judged.

Wipneus

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Re: 2016 sea ice area and extent data
« Reply #70 on: March 16, 2016, 06:03:24 PM »
To answer a question on the blog, I attach here yesterday's delta map (corresponding to the big drop in CT area).

Lord M Vader

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Re: 2016 sea ice area and extent data
« Reply #71 on: March 16, 2016, 07:15:42 PM »
Quite impressive with a possible century break already. But I suppose that is due to the "fish ice" in Okhotsk and Saint Lawrence? The cold weather that have been persistent for weeks in the Okhotsk have given an impressive SIE number there. I doubt we'll see ay more ice growth there until melting starts.

According to Cryosphere Today, the only other year from 2005 and onwards that have had a higher SIA in Okhotsk is 2012. On a third place we find 2007.

Wipneus:

//LMV

DoomInTheUK

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Re: 2016 sea ice area and extent data
« Reply #72 on: March 17, 2016, 10:33:03 AM »
Wipneus, to be only a few K out is an incredible effort on your part, and I thank you. You're one of the brightest stars in Neven's firmament.

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Re: 2016 sea ice area and extent data
« Reply #73 on: March 17, 2016, 02:11:31 PM »
Quite impressive with a possible century break already.

Impressive indeed. Though for the record, Day 0.2028 has a history of largish area drops: seven of the 38 years on record have seen a loss of a century or more, including 1995, which experienced a similar drop of 174k, and 2007, which fell a whopping 240k.

Prior to today, CT SIA had increased on seven of the previous eight days, picking up +162k of ice. Today's drop clearly erases that, and then some. In fact, today's reading brings area roughly back to where it was a fortnight ago, Day 0.1671.

I don't know that 2016 reached its peak with yesterday's 12.885 million km2--we're beyond the statistically average day of maximum, though still within a standard deviation of the norm--but it seems almost certain that this year will be the first that NH SIA fails to cross 13 million.


Wipneus

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Re: 2016 sea ice area and extent data
« Reply #74 on: March 17, 2016, 03:38:02 PM »
From today's NSIDC sea ice concentration data I calculate sea ice area, in the Cryosphere Today way. Here "day" is the day that CT normally publishes that data for the Northern Hemisphere, SH and global normally follow the next day. "CT-date" is approximately the date that CT uses.
When NSIDC does not revise its concentration data (they do occasionally), my values are normally accurate withing a few k. Uncertainties are the exact algorithm for assumed concentration in the pole hole and some subtleties handling bad data.


day  CT-date       NH               SH                Global
Thu 2016.2027 -175.0 12.710511  +81.5  2.478095   -93.5 15.188606
Fri 2016.2055  +18.8 12.729338 +118.9  2.596975  +137.7 15.326313
Sat 2016.2082  -18.7 12.710662 +117.9  2.714847   +99.2 15.425509


In attached dleta map, bright red (blue) indicates the concentration goes below (above) the 15% mark. Pinkish (blueish) colors when the concentration increases (decreases) by more than 7%.

Jim Pettit

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Re: 2016 sea ice area and extent data
« Reply #75 on: March 19, 2016, 01:33:53 PM »
ADS-NIPR Extent:
13,902,527 km2 (18 March)
Up 61,022 km2 (.44%) from previous day.
Up 31,471 km2  (.23%) over past seven days (daily average: 4,496 km2).
Down 39,980 km2  (-.33%) for March (daily average: -2,221 km2).
627,429 km2 below 2000s average for this date.
353,406 km2 below 2010s average for this date.
194,522 km2 above 2015 value for this date.
777,449 km2 below 2012 value for this date.
Lowest year-to-date (01 January - 18 March) average.
2nd lowest March to-date average.
3rd lowest value for the date.
34 days this year (44.16% year-to-date) have recorded the lowest daily extent.
23 days (29.87%) have recorded the second lowest.
13 days (16.88%) have recorded the third lowest.
70 days in total (90.91%) have been among the lowest three on record.


CT Area:
12,710,984 km2 (18 March [Day 0.2083])
Down 18,456 km2 (-.14%) from previous day.
Down 141,578 km2 (-1.1%) over past seven days (daily average: -20,225 km2).
Down 64,842 km2 (-.58%) for March (daily average: -3,602 km2).
917,629 km2 below 2000s average for this date.
557,005 km2 below 2010s average for this date.
130,950 km2 below 2015 value for this date.
918,461 km2 below 2012 value for this date.
Lowest year-to-date (Day 0.0000 - Day 0.2083) average.
Lowest March to-date average.
Lowest value for the date.
47 days this year (61.04% year-to-date) have recorded the lowest daily area.
14 days (18.18%) have recorded the second lowest.
8 days (10.39%) have recorded the third lowest.
69 days in total (89.61%) have been among the lowest three on record.




BornFromTheVoid

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Re: 2016 sea ice area and extent data
« Reply #76 on: March 19, 2016, 04:25:19 PM »
Update for the week to March 19th

The current 5 day mean is on 14,481,80km2 while the 1 day extent is at 14,482,000km2.

The daily anomaly (compared to 81-10) is at -954,710km2, a decrease from -1,132,060km2 last week. The anomaly compared to the 07, 11 and 12 average is at -324,730km2, a decrease from -472,330km2 last week. We're currently 3rd lowest on record, down from 2nd lowest last week.



The average daily change over the last 7 days was +15.6k/day, compared to the long term average of -9.8k/day, and the 07, 11 and 12 average of -5.5k/day.
The average long term change over the next week is -11.2k/day, with the 07, 11, and 12 average being -18.0k/day.



The extent change so far this March is the 12th most positive on record. To achieve the largest monthly loss, a drop of at least 58.8k/day is required, while the largest monthly gain requires an increase of at least 33.1k/day and an average gain requires a loss of -18.3k/day.



EDIT: Updated with data to the 19th. Though I'd be away from computer for a few days (turned out not to be the case), hence yesterdays update.
« Last Edit: March 20, 2016, 04:18:03 PM by BornFromTheVoid »

Jim Pettit

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Re: 2016 sea ice area and extent data
« Reply #77 on: March 21, 2016, 01:33:19 PM »
ADS-NIPR Extent:
13,910,563 km2 (20 March)
Up 16,484 km2 (.12%) from previous day.
Up 37,702 km2  (.27%) over past seven days (daily average: 5,386 km2).
Down 31,944 km2  (-.26%) for March (daily average: -1,597 km2).
579,413 km2 below 2000s average for this date.
307,768 km2 below 2010s average for this date.
204,564 km2 above 2015 value for this date.
750,047 km2 below 2012 value for this date.
Lowest year-to-date (01 January - 20 March) average.
2nd lowest March to-date average.
6th lowest value for the date.
34 days this year (43.04% year-to-date) have recorded the lowest daily extent.
23 days (29.11%) have recorded the second lowest.
13 days (16.46%) have recorded the third lowest.
70 days in total (88.61%) have been among the lowest three on record.


CT Area:
12,665,262 km2 (20 March [Day 0.2137])
Down 20,380 km2 (-.16%) from previous day.
Down 185,947 km2 (-1.45%) over past seven days (daily average: -26,564 km2).
Down 110,564 km2 (-.99%) for March (daily average: -5,528 km2).
966,433 km2 below 2000s average for this date.
591,538 km2 below 2010s average for this date.
161,749 km2 below 2015 value for this date.
1,035,412 km2 below 2012 value for this date.
Lowest year-to-date (Day 0.0000 - Day 0.2137) average.
Lowest March to-date average.
Lowest value for the date.
49 days this year (62.03% year-to-date) have recorded the lowest daily area.
14 days (17.72%) have recorded the second lowest.
8 days (10.13%) have recorded the third lowest.
71 days in total (89.87%) have been among the lowest three on record.


Xulonn

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Re: 2016 sea ice area and extent data
« Reply #78 on: March 21, 2016, 02:59:07 PM »
I am curious about the relationship between area and extent as the seasonal melting begins.  Currently, sea ice area is at a record low, and extent is not. 

When solid sheets of ice are broken up, it is intuitively obvious that the pieces would move about, open water would separate them, and extent would increase, as would the melting rate due to the increases in the total area of ice exposed to sea water.  (I am aware that the most common ice concentration cut-off point is 15%, meaning an "area" of "extent" might contain up to 85% open water.) 

Therefore if a 100km2 piece of contiguous ice fractured into small bits, and 40% of it melted, a theoretical maximum extent of 400km2 could replace 100km2 of area.  Would this mean that area would have decreased by100km2 and net extent could have increased by theoretical maximum of 300km2? (400km2 of new extent minus 100km2 reduction in area, which is included in extent.)

Of course, such a theoretical maximum would never be seen, because the ice would not all magically spread out and stop at 15% concentration.  Which is why I asked if anyone has graphed the actual relationship between area and extent.   

And a bonus question - how is the difference between "slush" and solid ice determined?  Is slush included in extent but not area?


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Re: 2016 sea ice area and extent data
« Reply #79 on: March 21, 2016, 03:21:16 PM »
Can't find a recent Capie graph (Cryosphere area per IJIS extent).

Perhaps this from long term graph page helps?


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Re: 2016 sea ice area and extent data
« Reply #80 on: March 21, 2016, 03:40:58 PM »
Dice a piece of ice 2m*2m*2m into pieces 10cm*10cm*10cm that is 8000 pieces which covers 20 times the area ie 4m^2 area changes to 80m^2 area before dealing with 15% concentration effect for extent measure.

So I think your 3 times "theoretical maximum" increase is a potentially a bit low. Don't really expect the above to happen and is likely accompanied by some melting as you indicate.
« Last Edit: March 21, 2016, 03:46:38 PM by crandles »

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Re: 2016 sea ice area and extent data
« Reply #81 on: March 21, 2016, 03:58:53 PM »
And a bonus question - how is the difference between "slush" and solid ice determined?  Is slush included in extent but not area?

If slush is wet enough it may appear to satellite sensors as water. Storms have been known to cause 'flash melting' suddenly a lot of ice disappears but some of this can return over next 2 or 3 days as ocean gets calmer and the ice dry enough to be detected again.

If the ice is detectable it is included in area according to percent coverage estimated and included in extent if over the 15% threshold.

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Re: 2016 sea ice area and extent data
« Reply #82 on: March 21, 2016, 04:41:25 PM »
I am curious about the relationship between area and extent as the seasonal melting begins.  Currently, sea ice area is at a record low, and extent is not. 

When solid sheets of ice are broken up, it is intuitively obvious that the pieces would move about, open water would separate them, and extent would increase, as would the melting rate due to the increases in the total area of ice exposed to sea water.  (I am aware that the most common ice concentration cut-off point is 15%, meaning an "area" of "extent" might contain up to 85% open water.) 

Therefore if a 100km2 piece of contiguous ice fractured into small bits, and 40% of it melted, a theoretical maximum extent of 400km2 could replace 100km2 of area.  Would this mean that area would have decreased by100km2 and net extent could have increased by theoretical maximum of 300km2? (400km2 of new extent minus 100km2 reduction in area, which is included in extent.)
In this example the remaining ice would still be considered 'area' so area would decrease by 40 km2 and extent could  increase as you say by 300km2. However a more likely scenario is that the average coverage for the extent would be near 60% and with your assumed 40% melt there would be virtually no  change in extent.

Its also worth noting that there would be virtually  no increase in exposure to water as the ice would typically be only 0 - 2 metres thick, which in a 1 km2 bit would add less than 1% to the total area exposed to  water. 
Toto, I've a feeling we're not in Kansas anymore

Wipneus

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Re: 2016 sea ice area and extent data
« Reply #83 on: March 22, 2016, 03:28:08 PM »
By Thursday, the Arctic maximum is again very close.

From today's NSIDC sea ice concentration data I calculate sea ice area, in the Cryosphere Today way. Here "day" is the day that CT normally publishes that data for the Northern Hemisphere, SH and global normally follow the next day. "CT-date" is approximately the date that CT uses.
When NSIDC does not revise its concentration data (they do occasionally), my values are normally accurate withing a few k. Uncertainties are the exact algorithm for assumed concentration in the pole hole and some subtleties handling bad data.


day  CT-date       NH               SH                Global
Tue 2016.2164  +12.2 12.677734  +37.2  2.930337   +49.4 15.608071
Wed 2016.2192  +48.3 12.726083  +40.5  2.970887   +88.9 15.696970
Thu 2016.2219  +82.5 12.808631 +121.1  3.091945  +203.6 15.900576


In attached delta map, bright red (blue) indicates the concentration goes below (above) the 15% mark. Pinkish (blueish) colors when the concentration indecreases (deincreases) by more than 7%.

[UPDATE: in my description of the meaning of pink and blueish, I got them wrong. Corrected, and thanks Tor, for pointing this out.]

A large increase is in the St.Lawrence region, that may evaporate (so to speak) again on Friday.
« Last Edit: March 22, 2016, 05:15:04 PM by Wipneus »

Wipneus

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Re: 2016 sea ice area and extent data
« Reply #84 on: March 23, 2016, 03:30:31 PM »
Small increase, still below current maximum.

From today's NSIDC sea ice concentration data I calculate sea ice area, in the Cryosphere Today way. Here "day" is the day that CT normally publishes that data for the Northern Hemisphere, SH and global normally follow the next day. "CT-date" is approximately the date that CT uses.
When NSIDC does not revise its concentration data (they do occasionally), my values are normally accurate withing a few k. Uncertainties are the exact algorithm for assumed concentration in the pole hole and some subtleties handling bad data.


day  CT-date       NH               SH                Global
Wed 2016.2192  +48.3 12.726083  +40.5  2.970887   +88.9 15.696970
Thu 2016.2219  +82.6 12.808706 +121.1  3.091945  +203.7 15.900651
Fri 2016.2247  +17.7 12.826397 +188.5  3.280477  +206.2 16.106874


In attached delta map, bright red (blue) indicates the concentration goes below (above) the 15% mark. Pinkish (blueish) colors when the concentration decreases (increases) by more than 7%.

Increases in many places (st.Lawrence, Baffin, Barents, Bering) is almost completely offset by a crash in Okhotsk.

Jim Pettit

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Re: 2016 sea ice area and extent data
« Reply #85 on: March 24, 2016, 01:17:02 PM »
ADS-NIPR Extent:
13,899,979 km2 (23 March)
Down 26,173 km2 (-.19%) from previous day.
Up 18,110 km2  (.13%) over past seven days (daily average: 2,587 km2).
Down 42,528 km2  (-.35%) for March (daily average: -1,849 km2).
553,337 km2 below 2000s average for this date.
260,021 km2 below 2010s average for this date.
65,094 km2 above 2015 value for this date.
670,420 km2 below 2012 value for this date.
Lowest year-to-date (01 January - 23 March) average.
2nd lowest March to-date average.
5th lowest value for the date.
34 days this year (41.46% year-to-date) have recorded the lowest daily extent.
23 days (28.05%) have recorded the second lowest.
13 days (15.85%) have recorded the third lowest.
70 days in total (85.37%) have been among the lowest three on record.


CT Area:
12,808,733 km2 (23 March [Day 0.2219])
Up 82,634 km2 (.65%) from previous day.
Up 98,375 km2 (.77%) over past seven days (daily average: 14,054 km2).
Up 32,906 km2 (.3%) for March (daily average: 1,431 km2).
738,403 km2 below 2000s average for this date.
408,377 km2 below 2010s average for this date.
90,013 km2 below 2015 value for this date.
732,717 km2 below 2012 value for this date.
Lowest year-to-date (Day 0.0000 - Day 0.2219) average.
Lowest March to-date average.
2nd lowest value for the date.
51 days this year (62.2% year-to-date) have recorded the lowest daily area.
15 days (18.29%) have recorded the second lowest.
8 days (9.76%) have recorded the third lowest.
74 days in total (90.24%) have been among the lowest three on record.


Wipneus

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Re: 2016 sea ice area and extent data
« Reply #86 on: March 24, 2016, 03:42:15 PM »
Very small increase, still below current maximum.

From today's NSIDC sea ice concentration data I calculate sea ice area, in the Cryosphere Today way. Here "day" is the day that CT normally publishes that data for the Northern Hemisphere, SH and global normally follow the next day. "CT-date" is approximately the date that CT uses.
When NSIDC does not revise its concentration data (they do occasionally), my values are normally accurate withing a few k. Uncertainties are the exact algorithm for assumed concentration in the pole hole and some subtleties handling bad data.

day  CT-date       NH               SH                Global
Thu 2016.2219  +82.6 12.808706 +121.1  3.091945  +203.7 15.900651
Fri 2016.2247  +17.8 12.826516 +188.5  3.280477  +206.3 16.106993
Sat 2016.2274   +4.4 12.830869  +53.6  3.334093   +58.0 16.164962


In attached delta map, bright red (blue) indicates the concentration goes below (above) the 15% mark. Pinkish (blueish) colors when the concentration decreases (increases) by more than 7%.

In the St.Lawrence and the Baffin region area dropped big way (-83k), other regions area increased with smaller amounts.



Wipneus

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Re: 2016 sea ice area and extent data
« Reply #87 on: March 25, 2016, 03:23:28 PM »
Well, the +55k is exactly what is required to equal the maximum (12.88502)  :o
Too close to be certain that Sunday will set a new max. But judging by the deviation of my results during the last few weeks, it is likely.

From today's NSIDC sea ice concentration data I calculate sea ice area, in the Cryosphere Today way. Here "day" is the day that CT normally publishes that data for the Northern Hemisphere, SH and global normally follow the next day. "CT-date" is approximately the date that CT uses.
When NSIDC does not revise its concentration data (they do occasionally), my values are normally accurate withing a few k. Uncertainties are the exact algorithm for assumed concentration in the pole hole and some subtleties handling bad data.


day  CT-date       NH               SH                Global
Fri 2016.2247  +17.8 12.826516 +188.5  3.280477  +206.3 16.106993
Sat 2016.2274   +4.3 12.830855  +53.6  3.334093   +58.0 16.164948
Sun 2016.2301  +55.0 12.885890  +42.4  3.376455   +97.4 16.262345


In attached delta map, bright red (blue) indicates the concentration goes below (above) the 15% mark. Pinkish (blueish) colors when the concentration decreases (increases) by more than 7%.

Jim Pettit

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Re: 2016 sea ice area and extent data
« Reply #88 on: March 26, 2016, 01:19:29 PM »
ADS-NIPR Extent:
13,823,186 km2 (25 March)
Down 38,851 km2 (-.28%) from previous day.
Down 79,341 km2  (-.57%) over past seven days (daily average: -11,334 km2).
Down 119,321 km2  (-.98%) for March (daily average: -4,773 km2).
621,170 km2 below 2000s average for this date.
328,574 km2 below 2010s average for this date.
31,193 km2 below 2015 value for this date.
728,181 km2 below 2012 value for this date.
Lowest year-to-date (01 January - 25 March) average.
2nd lowest March to-date average.
2nd lowest value for the date.
34 days this year (40.48% year-to-date) have recorded the lowest daily extent.
24 days (28.57%) have recorded the second lowest.
13 days (15.48%) have recorded the third lowest.
71 days in total (84.52%) have been among the lowest three on record.


CT Area:
12,830,809 km2 (25 March [Day 0.2274])
Up 4,214 km2 (.03%) from previous day.
Up 119,824 km2 (.94%) over past seven days (daily average: 17,118 km2).
Up 54,982 km2 (.49%) for March (daily average: 2,199 km2).
660,695 km2 below 2000s average for this date.
383,866 km2 below 2010s average for this date.
200,314 km2 below 2015 value for this date.
714,911 km2 below 2012 value for this date.
Lowest year-to-date (Day 0.0000 - Day 0.2274) average.
Lowest March to-date average.
3rd lowest value for the date.
51 days this year (60.71% year-to-date) have recorded the lowest daily area.
15 days (17.86%) have recorded the second lowest.
10 days (11.9%) have recorded the third lowest.
76 days in total (90.48%) have been among the lowest three on record.

Wipneus

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Re: 2016 sea ice area and extent data
« Reply #89 on: March 26, 2016, 03:24:53 PM »
The situation is a bit clearer now. Tomorrow will very likely a new max, which will be followed by a (quite certain) new max on Monday. The margins are small, but big enough to predict what CT will record.

From today's NSIDC sea ice concentration data I calculate sea ice area, in the Cryosphere Today way. Here "day" is the day that CT normally publishes that data for the Northern Hemisphere, SH and global normally follow the next day. "CT-date" is approximately the date that CT uses.
When NSIDC does not revise its concentration data (they do occasionally), my values are normally accurate withing a few k. Uncertainties are the exact algorithm for assumed concentration in the pole hole and some subtleties handling bad data.

day  CT-date       NH               SH                Global
Sat 2016.2274   +4.3 12.830855  +53.6  3.334093   +58.0 16.164948
Sun 2016.2301  +55.3 12.886181  +42.4  3.376455   +97.7 16.262636
Mon 2016.2329   +4.8 12.891012 +113.5  3.489908  +118.3 16.380920

In attached delta map, bright red (blue) indicates the concentration goes below (above) the 15% mark. Pinkish (blueish) colors when the concentration decreases (increases) by more than 7%.

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Re: 2016 sea ice area and extent data
« Reply #90 on: March 26, 2016, 07:58:22 PM »
The situation is a bit clearer now. Tomorrow will very likely a new max, which will be followed by a (quite certain) new max on Monday. The margins are small, but big enough to predict what CT will record.

From today's NSIDC sea ice concentration data I calculate sea ice area, in the Cryosphere Today way. Here "day" is the day that CT normally publishes that data for the Northern Hemisphere, SH and global normally follow the next day. "CT-date" is approximately the date that CT uses.
When NSIDC does not revise its concentration data (they do occasionally), my values are normally accurate withing a few k. Uncertainties are the exact algorithm for assumed concentration in the pole hole and some subtleties handling bad data.

day  CT-date       NH               SH                Global
Sat 2016.2274   +4.3 12.830855  +53.6  3.334093   +58.0 16.164948
Sun 2016.2301  +55.3 12.886181  +42.4  3.376455   +97.7 16.262636
Mon 2016.2329   +4.8 12.891012 +113.5  3.489908  +118.3 16.380920

In attached delta map, bright red (blue) indicates the concentration goes below (above) the 15% mark. Pinkish (blueish) colors when the concentration decreases (increases) by more than 7%.

Definitely looks like a new 2016 maximum on Day 0.2301, then another on 0.2329, though still well within record low max territory (2011's 13.144 million km2 is safe), and, if 0.2329 is the end of it, still three days earlier than 2012's max on 0.2411 (and still 818k below that record year's maximum).

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Re: 2016 sea ice area and extent data
« Reply #91 on: March 26, 2016, 09:37:32 PM »
If the max does occur after 2012's date will it be the latest on record?
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Re: 2016 sea ice area and extent data
« Reply #92 on: March 27, 2016, 02:54:08 PM »
If the max does occur after 2012's date will it be the latest on record?

That would be correct. In descending order:

2012 -- 0.2439
2016* -- 0.2301
1985 -- 0.2246
1999 & 2003 -- 0.2219
1984 & 2014 -- 0.2192

* To-date

Of course, there doesn't appear to be any correlation between the date of maximum and the area that remains at minimum, mostly because a few days of anomalous weather in March and an overnight difference of a few thousand square miles of ice can cause a much earlier or much later than average maximum to occur. 2012's max, the latest ever, didn't seem to affect that year's recordbreaking minimum, while last year's earliest-ever maximum lead to only the sixth-lowest minimum. IOW, max dates are probably of no true scientific value. Which, of course, makes me ask myself why I bother tracking them. ;)

Anyway:


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Re: 2016 sea ice area and extent data
« Reply #93 on: March 27, 2016, 03:29:20 PM »
Thanks, Jim.
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Re: 2016 sea ice area and extent data
« Reply #94 on: March 27, 2016, 04:10:25 PM »
Another small uptick expected on CT's update on Tues day. So a higher and a later maximum.

From today's NSIDC sea ice concentration data I calculate sea ice area, in the Cryosphere Today way. Here "day" is the day that CT normally publishes that data for the Northern Hemisphere, SH and global normally follow the next day. "CT-date" is approximately the date that CT uses.
When NSIDC does not revise its concentration data (they do occasionally), my values are normally accurate withing a few k. Uncertainties are the exact algorithm for assumed concentration in the pole hole and some subtleties handling bad data.

day  CT-date       NH               SH                Global
Sun 2016.2301  +55.3 12.886181  +53.6  3.334093  +108.9 16.220274
Mon 2016.2329   +4.7 12.890922  +42.4  3.376455   +47.1 16.267377
Tue 2016.2356   +7.9 12.898859 +113.5  3.489908  +121.4 16.388767

In attached delta map, bright red (blue) indicates the concentration goes below (above) the 15% mark. Pinkish (blueish) colors when the concentration decreases (increases) by more than 7%.

A big drop in the Barents section (-55k) is compensated by many smaller increases elsewhere.

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Re: 2016 sea ice area and extent data
« Reply #95 on: March 27, 2016, 08:12:00 PM »
Update for the week to March 26th

The current 5 day mean is on 14,482,200km2 while the 1 day extent is at 14,380,000km2.

The daily anomaly (compared to 81-10) is at -875,990km2, a decrease from -954,710km2 last week. The anomaly compared to the 07, 11 and 12 average is at -198,530km2, a decrease from -324,730km2 last week. We're currently 6th lowest on record, down from 3rd lowest last week.



The average daily change over the last 7 days was +0.1k/day, compared to the long term average of -11.2k/day, and the 07, 11 and 12 average of -18.0k/day.
The average long term change over the next week is -14.5k/day, with the 07, 11, and 12 average being -4.9k/day.



The extent change so far this March is the 10th most positive on record. To achieve the largest monthly loss, a drop of at least 141.0k/day is required, while the largest monthly gain requires an increase of at least 79.5k/day and an average gain requires a loss of -44.0k/day.


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Re: 2016 sea ice area and extent data
« Reply #96 on: March 28, 2016, 04:40:15 PM »
Another uptick expected on CT's update on Wednesday. So a higher and a later maximum.

From today's NSIDC sea ice concentration data I calculate sea ice area, in the Cryosphere Today way. Here "day" is the day that CT normally publishes that data for the Northern Hemisphere, SH and global normally follow the next day. "CT-date" is approximately the date that CT uses.
When NSIDC does not revise its concentration data (they do occasionally), my values are normally accurate withing a few k. Uncertainties are the exact algorithm for assumed concentration in the pole hole and some subtleties handling bad data.

day  CT-date       NH               SH                Global
Mon 2016.2329   +4.7 12.890922 +113.5  3.489908  +118.2 16.380830
Tue 2016.2356   +8.2 12.899085 +111.1  3.600973  +119.2 16.500058
Wed 2016.2384  +22.0 12.921042 +120.3  3.721245  +142.2 16.642287

In attached delta map, bright red (blue) indicates the concentration goes below (above) the 15% mark. Pinkish (blueish) colors when the concentration decreases (increases) by more than 7%.

Small regional changes only, for a change.

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Re: 2016 sea ice area and extent data
« Reply #97 on: March 29, 2016, 04:21:44 PM »
A big century drop almost certainly ends the march to the top, and starts the race to the bottom.

From today's NSIDC sea ice concentration data I calculate sea ice area, in the Cryosphere Today way. Here "day" is the day that CT normally publishes that data for the Northern Hemisphere, SH and global normally follow the next day. "CT-date" is approximately the date that CT uses.
When NSIDC does not revise its concentration data (they do occasionally), my values are normally accurate withing a few k. Uncertainties are the exact algorithm for assumed concentration in the pole hole and some subtleties handling bad data.

day  CT-date       NH               SH                Global
Tue 2016.2356   +8.2 12.899085 +111.1  3.600973  +119.2 16.500058
Wed 2016.2384  +22.1 12.921232 +120.3  3.721245  +142.4 16.642477
Thu 2016.2411 -124.4 12.796836 +104.9  3.826190   -19.5 16.623026

In attached delta map, bright red (blue) indicates the concentration goes below (above) the 15% mark. Pinkish (blueish) colors when the concentration decreases (increases) by more than 7%.

Big drops in the Barents section and Okhotsk region.

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Re: 2016 sea ice area and extent data
« Reply #98 on: March 29, 2016, 04:23:08 PM »
A big century drop almost certainly ends the march to the top, and starts the race to the bottom.

Not latest on record...  :'(  ;)
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Re: 2016 sea ice area and extent data
« Reply #99 on: March 29, 2016, 04:30:29 PM »
A big century drop almost certainly ends the march to the top, and starts the race to the bottom.

Not latest on record...  :'(  ;)

True...but only by a day. And still pretty far outside the norm:



It's interesting to note that, despite occurring a full 40 days after last year's maximum, 2016 nevertheless has roughly 200,000 square kilometers less area today than on the same day last year.