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Author Topic: "Smart" and "Stupid" Questions - Feel Free To Ask  (Read 678451 times)

gerontocrat

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #3550 on: August 25, 2020, 06:38:56 PM »
Walrus claimed low Sept ice (we say volume) means high March ice (volume). You chart (and common sense) says the opposite Gero. So how is Walrus right?
I am tired - I re-read the post by Walrus, said bad words,  and edited my post above.

Nevertheless the correlation looks good - but counter-intuitive. I for one, accepted that one might expect a rebound in sea ice after a low minimum, as open water releases ocean heat much more quickly.   

And now the correlation says the reverse.

I suppose I had better do the same exercise using JAXA extent data.
« Last Edit: August 25, 2020, 08:30:23 PM by gerontocrat »
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gerontocrat

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #3551 on: August 25, 2020, 07:39:08 PM »
which I have done, using JAXA extent monthly averages, September & the following March deviations from the linear trend.

The result - zilch. No correlation.
The X-Y graph has similar numbers of data points in all 4 quadrants.
"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)

The Walrus

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #3552 on: August 25, 2020, 09:32:30 PM »
Gerontocrat,

Plotting by year makes the trend harder to see or measure.  Try plotting the minima on the x axis and the ensuing maxima on the y.  Using all years, the trend is small.  However, starting with the years with low minima (2002), the data points are not clustered equally throughout the four quadrants.  Compared to the trend, 7 years exhibited a lower minima and higher ensuing maxima, 5 showed a higher minima and lower maxima, 4 showed both a lower minima and maxima, and 2 both higher minima and maxima.  Twice as many data points appeared in the quadrants with opposite signs as those with similar signs.  Additionally, of the 9 years with a higher maxima, the 7 highest maxima where all preceded by lower minima.  The lower the minimum, the more likely that the ensuing maximum is higher.


binntho

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #3553 on: August 26, 2020, 12:04:58 PM »
I've been playing around with the numbers, but not sure if I'm doing it right.

I've taken the monthly JAXA extent averages for September and the following March, detrended them and plotted against each other, with Sept values on the x axis and March on y.

Below are two very ugly graphs, there seems to be a correlation and it is stronger since the turn of the century. So does this mean that there is a slightly bigger change of a larger maximum following a low minimum?

EDIT: it seems the odobenidae are leading by a whisker
« Last Edit: August 26, 2020, 01:18:54 PM by binntho »
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The Walrus

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #3554 on: August 26, 2020, 01:54:04 PM »
Binntho,
That is similar to what I have gotten.  My answer is that there is a slightly bigger chance of a larger maximum following a low minimum.  I like your wording, so I am going with it.

This was the question that Colding asked originally, and many responses did not address the question.  I agree with those posters that higher minima have no reflection on the following maxima, but that was not the question posed.  The scientific evidence points to open water losing more heat that ice-covered, but is it enough to overcome the extra heat added?  The data is inconclusive (or ugly), but does point in that direction.  If next March, the maximum is slightly higher again, then we have one more data point in support.  If not, then the opposite.

Thank you for your comment, but I admit that I had to consult my dictionary.

binntho

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #3555 on: August 26, 2020, 02:29:38 PM »
...  but I admit that I had to consult my dictionary.
"walking by their teeth" is the literal meaning, referring to the way they use the tusks to help them crawl forward on ice or dry land.
because a thing is eloquently expressed it should not be taken to be as necessarily true
St. Augustine, Confessions V, 6

Glen Koehler

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #3556 on: August 26, 2020, 04:42:04 PM »
<snip>I've taken the monthly JAXA extent averages for September and the following March, detrended them and plotted against each other, with Sept values on the x axis and March on y.

Below are two very ugly graphs, there seems to be a correlation and it is stronger since the turn of the century. So does this mean that there is a slightly bigger change of a larger maximum following a low minimum?
     Walrus was correct that I addressed the wrong issue in my previous post.  Perhaps a saving grace in my misdirected response is that regardless of the Sept. minimum's influence on the following March maximum, it really does not matter in the big picture because that March max has essentially no correlation with the NEXT Sept minimum.  But whether Sept affects the following March is of interest for understanding ice dynamics even if there is no long term effect, so pointing out the lack of long-term effect is really just to make me feel a bit less useless.

     Face-saving aside, I feel compelled to point out that with an R2 of 7% from a small number of data points the conclusion that there is a trend to discuss is a Hail Mary pass (if binntho can use an obscure scientific term, I can use one from American football) based on statistical noise.  In other words, that slope is almost certainly very far short of statistical signficance.  (binntho your graphing software probably either gave you a direct measure of significance or the variance needed to calculate it.  Sharing it would be informative.)
   
     Moreover, the visually imagined "trend" is highly leveraged by two data points on the extreme ends of the X axis.  Take either one of those points out and there is almost nothing trendy left (not that there is much in the complete set of data points anyway).  Take both out and what's left is the a classic example of random distribution.  There are procedures to identify and justify removal of overly leveraged data points.  I doubt either of those two points is egregious enough to meet those criteria, so this comment is reverse cherry picking.  But it's not nit picking.  Just because a trend line from a small set of data points has a slope does not mean that it indicates anything real.  Noise is more real than signal in such cases.  At least until one shows a numerical test of significance.  The human eye is really great at seeing things that are not there (e.g. the face on Mars etc.) 

      As for the orginal question, I think that for now we can conclude that we don't know, and won't know until we have 20 mores year of data.  At which point the Arctic will be so different that we will have to throw out the first 20 years of data and start over.
« Last Edit: August 27, 2020, 04:40:09 PM by Glen Koehler »

binntho

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #3557 on: August 26, 2020, 05:16:29 PM »
Glen, my statistical expertise is not signifcant although it has been trending upwards in the last few years.

I downloaded the JAXA CSV file, ran a program on them to get a two colum CSV with september average in the first column, following march average in the second column. This I then pasted into Excel.

Following this I detrended by the simplest method - taking the difference from one value to the next. Lastly I made a scattergraph and asked Excel to show the trendline, the equation and the R2 value.

To be honest, I have absolutely no idea how reliable, or even how real, this result is. But tentatively I suggested that perhaps it indicated that there was a slight change of a higher maximum following a lower minimum.
because a thing is eloquently expressed it should not be taken to be as necessarily true
St. Augustine, Confessions V, 6

The Walrus

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #3558 on: August 26, 2020, 05:45:15 PM »
Glen,

I think we may have exhausted this topic for the time being.  We seem to be agreeing that there is a slight trend, but that it may not be real.  Any correlation may be small compared to other, longer term effects.  By the way, using the same data starting with the then-record low of 2002, the R2 was 24%.  Still nothing to write home about, but the Hail Mary can be thrown from a few yards closer.  Thanks for your posts.

karl dubhe2

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #3559 on: November 03, 2020, 03:24:15 PM »
Finally found this thread again.  :)  I've a question, that might be both.   Although I'm a bit hesitant to ask, as it might infringe on the chemtrail nuttery.   

I was wondering what effect the lower number of trans-Arctic flights has had on the ice this last year?   Fewer aircraft flying over the pole would result in a bit less water vapour and CO2 up there, right?   Or that's what I'd suspect anyhow. 

Phil.

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #3560 on: November 03, 2020, 05:07:29 PM »

oren

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #3561 on: November 04, 2020, 03:22:55 AM »
There was a thread earlier this year that attempted to discuss this issue. It did infringe on the chemtrail nuttery though. Still you might find some useful stuff there, and perhaps add your own thoughts.

https://forum.arctic-sea-ice.net/index.php/topic,3181.0.html

Tom_Mazanec

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #3562 on: November 05, 2020, 11:17:33 PM »
Here are a couple:
1) Is arctic sea ice frozen salt water and icebergs frozen fresh water?
2) How do we measure sea ice extent/area from space through clouds? I thought radar, but then remembered radar storm pictures, so I guess radar doesn't go through clouds?
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oren

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #3563 on: November 06, 2020, 03:32:44 AM »
Arctic sea ice is frozen seawater with some of the salt excluded during the freezing process, and more of it excluded as time goes by. Icebergs are made of snow compressed under its own weight into freshwater ice.

Ice remote sensing is done via a passive microwave radiometer, meaning the satellite scans several frequencies for the typical emissions of ice.

http://www.remss.com/missions/amsr/

Quote
The Advanced Microwave Scanning Radiometer...

We have processed data from all these instruments to provide the typical RSS microwave radiometer ocean measurement product suite consisting of: Sea Surface Temperature(SST), Surface Wind Speeds (low and medium frequency), Atmospheric Water Vapor, Cloud Liquid Water, and Rain Rate.

A key feature of these AMSR instruments is the ability to see through clouds, thereby providing an uninterrupted view of ocean measurements.

The AMSR instruments are dual-polarized, conical scanning, passive microwave radiometers.  Each is placed in a near-polar orbit which allows for up to twice daily sampling of a given Earth location.  The eight instrument channels are summarized in the following tables.

We use an on-orbit calibration method developed by RSS to convert counts to brightness temperatures.