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Messages - cesium62

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Arctic sea ice / Re: The 2020 melting season
« on: September 13, 2020, 01:35:29 AM »
Reminder that if 2012 wasn't a thing we'd all be blown away by this melting year. We are so far ahead of #3 in terms of extent.

We shouldn't be blown away.  This extent was predictable and predicted. https://www.arcus.org/sipn/sea-ice-outlook/2020/august

The narrative is not "omg, so much ice melted this year! What a surprise!".  The narrative is "Ayup.  a lot of ice melted this year, and probably a lot of ice will melt again next year.  Of course, we might get a once in 30 year perfect storm and a helluva lot of ice will then melt..."

2
Arctic sea ice / Re: The 2020 melting season
« on: September 08, 2020, 12:39:39 AM »
In what region would you expect that rebound, gandul?
Check it out yourself above
Not his job to prove your point, please.

You made the assertion, your job to lay it out and describe your evidence for it.
Concur.  The amount of yellow+red in 2020 visually looks roughly the same as in 2019.  More to the point, the yellow and red for 2020 is closer to the CAA.  So the compaction and current flows over the next year is really going to thin out that band and stretch it through the Beaufort and Chukchi, where it will melt next year.  2021 is looking kinda scary on that front...



3
Arctic sea ice / Re: 2019 sea ice area and extent data
« on: August 20, 2019, 12:11:35 AM »
Our friendly star is remarkably stable but the slight variation in energy received from the sun across solar cycle can nudge annual average global surface temperature up and down by ca. 0.1C. 

Link to a peer reviewed paper, please.  I ran the regression between solar cycle and september minimum extent.  There is no correlation.

4
Arctic sea ice / Re: Land snow cover effect on sea ice
« on: July 08, 2018, 12:37:48 PM »
Rob: I think your model is fun and interesting, so I spent some time with it.

Assuming I've correctly re-produced your results...

The question above is, roughly:  what's the probability that the actual result is 0.7M km2 or more away from the predicted result?  This occurred in: 1980, 1982, 1983, 1986, 1988, 1991, 2001, and 2006.  That's 8 out of 39 years, or about a 20% chance.

Eyeballing the graph you published pretty much agrees that both 2001 and 2006 predictions are off by around 0.7M km2.


We can slightly simplify your approach by noting that you are predicting minimum extent as a linear combination of three variables: June snow area, June ice area, and June ice extent.  The multi-variable linear regression package that I'm using (XL miner in google sheets) notes that the 'extent' parameter isn't very useful in this prediction.  The software suggests there's a 6% probability that 'extent' should really be part of the equation.

Also, graphing the trend lines through the minimum and the predicted minimum, suggests that the prediction is diverging from actual (getting larger) as each year passes.  Since both snow cover and minimum extent trend downward year by year, it might be interesting to add 'year' as a parameter to better explore how well snow cover helps explain minimum extent.

Overfitting a model based on year, snow area, and ice area to all data from 1979 through 2017, we get the second attached picture.  And a forecast of 4.58 M km2 for the 2018 min extent.  (With a 360 K km2 geometric mean error.)  (Overfitting Dekker's model gives a forecast of 4.76 M km2 with a 435 K km2 geometric mean error.)  (If I train the year-based model on just 1992 through 2015, the forecast is 4.64 M km2 with a 386 K km2 geometric mean error.)

My simple physical explanation for the year-based model would be: heat is accumulating worldwide year by year due to greenhouse gases; the snow and ice area (or lack thereof) takes into account how much insolation is absorbed in the northern hemisphere in June.  Together, this suggests the amount of heat available for melting ice, subject to the vagaries of weather.




5
Arctic sea ice / Re: Land snow cover effect on sea ice
« on: July 08, 2018, 07:28:40 AM »
it is highly unlikely (less than 2.5% chance) that Sept 2018 will end up below 4.5 M km2.

You are saying that there is a <2.5% chance of this year's final outcome being about half a grid line below the prediction.  There are a couple of other years (2006, 2001, maybe 2010 and 2016) and  where the final outcome is about half a grid line away from the prediction.  It doesn't seem right that 10% of the years should display an event that should occur less than 2.5% of the time...

6
Arctic sea ice / Re: The 2018 melting season
« on: June 30, 2018, 01:47:36 AM »
I played around a bit with those SMOS images. 

Just for fun, Here's the correlation between Steven's hard earned numbers and NSIDC Min Extent.  The dot at x=4.5 on the line is the projection for 2018.

7
Arctic sea ice / Re: The 2018 melting season
« on: June 17, 2018, 08:55:04 PM »
Unless a massively anomalous ridge of high pressure blows up and parks over the CAB,CAA, and GIS for the next 5 weeks there is zero chance for record low extent or area this year.

Volume is already past any chance for record lows

Who are you? and what have you done with our Frivolous?

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