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Old 20-03-2018, 12:56   #226
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Re: Northwest Passage - 2018

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I'm just basing my statement on the numbers from dmi of sea ice volums
Which is within standard deviations
DMI shows the ice extent at about 4 SD below the mean. That is nowhere near normal. 99.9% of the records are higher than that.
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Old 20-03-2018, 13:17   #227
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Re: Northwest Passage - 2018

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Old 20-03-2018, 15:26   #228
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Re: Northwest Passage - 2018

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That graphic covers land only. It has no information about The Arctic Ocean.
you are correct it does not cover the arctic ocean it just shows northern hemisphere snow cover and was posted as reference to your albedo comment. Snow is extremely reflective
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Old 20-03-2018, 15:28   #229
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Re: Northwest Passage - 2018

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Originally Posted by jackdale View Post
DMI shows the ice extent at about 4 SD below the mean. That is nowhere near normal. 99.9% of the records are higher than that.
not to be picky jack but I said volumes as in km3 now extent km2 and we shall see how it looks in september
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Old 20-03-2018, 16:11   #230
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Re: Northwest Passage - 2018

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you are correct it does not cover the arctic ocean it just shows northern hemisphere snow cover and was posted as reference to your albedo comment. Snow is extremely reflective
My albedo comment was referenced to the NSIDC site

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Sea ice has a much higher albedo compared to other earth surfaces, such as the surrounding ocean. A typical ocean albedo is approximately 0.06, while bare sea ice varies from approximately 0.5 to 0.7. This means that the ocean reflects only 6 percent of the incoming solar radiation and absorbs the rest, while sea ice reflects 50 to 70 percent of the incoming energy. The sea ice absorbs less solar energy and keeps the surface cooler.

Snow has an even higher albedo than sea ice, and so thick sea ice covered with snow reflects as much as 90 percent of the incoming solar radiation. This serves to insulate the sea ice, maintaining cold temperatures and delaying ice melt in the summer. After the snow does begin to melt, and because shallow melt ponds have an albedo of approximately 0.2 to 0.4, the surface albedo drops to about 0.75. As melt ponds grow and deepen, the surface albedo can drop to 0.15. As a result, melt ponds are associated with higher energy absorption and a more rapid ice melt.
As the extent of sea is lessened the albedo effect is lessened, meaning that the ocean absorbs more heat. Albedo is a function of surface area, not volume.
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Old 20-03-2018, 16:13   #231
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Re: Northwest Passage - 2018

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Originally Posted by newhaul View Post
not to be picky jack but I said volumes as in km3 now extent km2 and we shall see how it looks in september
We know that both volume and extent are well lower that the mean. With spring upon us we can expect that both volume and extent will stay well be the mean. There is no need to wait until September.
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Old 20-03-2018, 16:37   #232
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Re: Northwest Passage - 2018

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Originally Posted by jackdale View Post
My albedo comment was referenced to the NSIDC site



As the extent of sea is lessened the albedo effect is lessened, meaning that the ocean absorbs more heat. Albedo is a function of surface area, not volume.
Aren't you talking about current conditions wrt snow and ice albedo?
Isn't it still dark up there, so neither are relevant.

What is relevant is that less sea ice area means more sea surface to give off ocean heat content to the below zero atmosphere. Hence the warmer air termperatures in the arctic. And that warmer air rises ultimately radiating that heat to space. IOW - a negative feedback causing global cooling.
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Old 20-03-2018, 17:17   #233
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Re: Northwest Passage - 2018

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interesting the chart I have seems to say the same as to area however it seems to be a lot closer to the deviations than yours.
The mean for jackdale's chart is 1981-2000, while the mean for newhaul's chart is 1981-2010.
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Old 20-03-2018, 17:39   #234
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Re: Northwest Passage - 2018

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The mean for jackdale's chart is 1981-2000, while the mean for newhaul's chart is 1981-2010.
heck I didn't even notice that part thank you for catching it.
So unless I'm incorrect here that gives us an additional 10 data points to get a better average outlook on average conditions .
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Old 20-03-2018, 17:48   #235
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Re: Northwest Passage - 2018

It is not an average condition if you keep moving the mean bandwidth during a steady decline. All lines of all years are always at the bottom end of the mean or even below it. To change the graph by moving the mean over and over again is just fooling yourself.
Unfortunately the sea ice extent was already declining when they started measuring, so it is not really possible anymore to actually get the proper average numbers.

And by the way, the graph assumes anything with more than 15% ice as 'Covered' the areas where there is more open water than ice (considered covered!!) are increasing every year. If you now want to walk to the north pole from Greenland or Canada, you have to swim at least 10% of the distance around this time of year. That is absolutely absurd. It used to be solid ice with almost never a lead or a crack.

What I'm trying to say here is that the ice is actually disappearing faster than the graphs suggest, regardless of their source.
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Old 20-03-2018, 18:16   #236
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Re: Northwest Passage - 2018

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It is not an average condition if you keep moving the mean bandwidth during a steady decline. All lines of all years are always at the bottom end of the mean or even below it. To change the graph by moving the mean over and over again is just fooling yourself.
Unfortunately the sea ice extent was already declining when they started measuring, so it is not really possible anymore to actually get the proper average numbers.

And by the way, the graph assumes anything with more than 15% ice as 'Covered' the areas where there is more open water than ice (considered covered!!) are increasing every year. If you now want to walk to the north pole from Greenland or Canada, you have to swim at least 10% of the distance around this time of year. That is absolutely absurd. It used to be solid ice with almost never a lead or a crack.

What I'm trying to say here is that the ice is actually disappearing faster than the graphs suggest, regardless of their source.
all I'm saying is it will come back just like it has been melting and recovering in a cyclic manner for thousands of years just look at the ice cores.
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Old 20-03-2018, 18:21   #237
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Re: Northwest Passage - 2018

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And that warmer air rises ultimately radiating that heat to space. IOW - a negative feedback causing global cooling.
Are you really denying the GHE? Why is the stratosphere cooling?



While the troposphere is warming.



RSS / MSU and AMSU Data / Time Series Trend Browser
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Old 20-03-2018, 18:38   #238
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Re: Northwest Passage - 2018

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all I'm saying is it will come back just like it has been melting and recovering in a cyclic manner for thousands of years just look at the ice cores.
Here is the ice core data.



What the heck happened?
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Old 20-03-2018, 19:10   #239
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Re: Northwest Passage - 2018

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all I'm saying is it will come back just like it has been melting and recovering in a cyclic manner for thousands of years just look at the ice cores.
It has never happened this fast at such an alarming rate. I have looked at the ice cores, I was there when we retrieved over 200 of them off the Greenlandic ice cap.

This is not a normal cycle.
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Old 20-03-2018, 20:15   #240
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Re: Northwest Passage - 2018

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heck I didn't even notice that part thank you for catching it.
So unless I'm incorrect here that gives us an additional 10 data points to get a better average outlook on average conditions .
It would be more accurate to say that Jackdale's chart is deficient in that it uses 10 fewer data points than are required to derive climatological normals according to the accepted WMI standard.

The "climatological normal" that should be in use when reporting current data is 1981-2010.
The "climatological standard normal" that should be in use when reporting current data is the period 1961-1990, this will change in 2021 to 1991-2020.

(Pity we don't have accurate data from 1961 onwards, it would be interestng to see what things looked like under that scenario )
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