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Author Topic: Subdividing the Central Basin  (Read 1647 times)


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Subdividing the Central Basin
« on: July 23, 2019, 06:41:52 AM »
I'm exploring a market niche here. This is a straw man, not an attempt at a finished product.

In a sense, I see an underserved market here at ASIF. A disconnect between what NSIDC provides and the interests of ASIF users. If I'm wrong and the concept biggie. Most startups fail. If it takes hold, it won't be me making the finished product. The startups that succeed are usually swallowed by bigger fish.

One thing that is clear is that this community is interested in how low the ice is going to go. It's arguably the #1 topic of interest.

The data threads are understandably popular and you get daily breakdowns of area by region to help understand the picture. You get a semi-monthly picture of volume by region. It's good stuff.

The problem / opportunity I see is this. At the end of the year, maybe 75% of the area and 90% of the volume is in one region, the Central Basin. The NSIDC made their decision of how to partition the data based upon geography which is certainly logical and that's what we work with. But it also mean you get 14 buckets of data corresponding to regions of ice which have little bearing on the the thing which is apparently most interesting to you.

As we move into the future, the understanding of whether new minimum thresholds is more and more about what happens inside the CAB.

Since the NSIDC doesn't provide any breakdown inside the CAB, there isn't any language or convention that I see which people at ASIF to subdivide the CAB.

I'll propose here that you create your own language and use this thread as a place to share your ideas. I have a straw man of my own to propose, but I'll use a different post to explain it. Too much in one post is no good.


  • Guest
Re: Subdividing the Central Basin
« Reply #1 on: July 23, 2019, 06:56:12 AM »
My personal inclination to pursue this comes from my reaction to the daily area thread can that Gerontocrat produces.

I see the # that NSIDC shares for the Central Basin and I wonder.... where in the Central Basin are those numbers coming from? How can I reconcile the data from NSIDC with the weather and all of the other useful information available to me?

If I'm curious to know, I'm guessing I'm not the only one. What's clear is that someone(s) at NSIDC must have a much more granular understanding of the gridded data than is being shared on ASIF.

Unfortunately, my proposal doesn't address that. Maybe someone at NSIDC reads this and decides to offer more detailed data, but that's beyond the intent here.


  • Guest
Re: Subdividing the Central Basin
« Reply #2 on: July 23, 2019, 10:25:01 AM »
 I'm proposing subdividing the CAB like a clock. A 360 degree circle centered at the he N. Pole. 12 sections of 30 degrees each extending to 80 N.

I'm starting with this because it facilitates easy to understand math related to what ASIF regs like to do....guessing the minimum.

If you look at Aluminum's animations, you see that there are only 2 lines passing through 90N separating the hemispheres. Those are my clock lines.

At 12 o'clock on the you have the islands between the Laptev. At 3 o'clock, Fram Strait. At 6 o'clock the w. edge of Ellesmere and at 9 o'clock the boundary between Chuchki and ESS.

My math comes up with an area of ~ 3.875 M km2 N of 80N. With a little bit of rounding, that works out to about 320K km2 in each hour of the clock. Others have a different preference for subdividing, but I like it because anyone can understand it.

The ratio of area in the 80-85N portion of the clock is also a neat 3:1 ratio of the area in the 85-90N area. Simple back of the envelope math. No calculator necessary.

Let's try a forecast for 2019....


  • Guest
Re: Subdividing the Central Basin
« Reply #3 on: July 23, 2019, 11:35:53 AM »
According to Gerontocrat's charts, the current area in the CAB area is 2,677,000 km2. In order to approach a record, the CAB probably needs to go below 2M km2 for 2019 to even approach the 2012 Arctic wide record of 2.25M. I'm assuming at least a few hundred K remaining in Beaufort, CAA and Greenland Sea. Everything else is assumed to go to zero.

Is an additional 700-800K loss in the CAB realistic? Let's turn to the clock. 

1-O'Clock (Kara)

The Atlantic is showing the most progress to date through the Kara. >0C water is already out close to 81N and it has advanced to an average of 81.5N. Let's say it makes it to 85N by end of season. That's an additional 150K.

2-O'Clock (Barents)

Not as much Atlantic heat build-up as the Kara. Average progression is to 81N so far. Let's say it gets to ~ 84N.

Still good for another 125K.

3-O'Clock (Svalbard / Greenland Sea)

Not much progress inside 80N to date and part of this area gets continuing export traffic. Let's say average progress is to 82N.

Additional 90K.

4-O'Clock to 6-O'Clock
(Outbound Fram Strait to Ellesmere Island)

Not a promising area to have much ice free area at the minimum. Some disintegration showing off the Greenland coast.

I'll put a token amount of 30K for this entire region.

7-O'Clock (CAA border to McKenzie)

Also not a promising place to lose ice. The CAB / CAA crack is a function of the wind. Here today, gone tomorrow.

No loss projected.

8-O'Clock (Beaufort)

The portion closest to the CAA isn't likely to melt inside 80N. The portion adjacent to the Chuchki will.

Additional 50K.

9-O'Clock (Chuchki)

I think it's reasonable to project advance here to ~ 82N.

Additional 100K.

10-O'Clock (ESS)

Same here. 82N looks reasonable.

Additional 100K.

11-12 O'Clock

Already at the 80N line. Get's a little boost from the Atlantic side. Average progression to 83.5N. Subtract a little for progress already made and land inside 80N.

Additional 270K.

Add it all up and it gets to an additional 915K in losses. IMO, that's enough to squeeze into record territory.

I'm not at all tied to this as a prediction and don't care if it's close or not. I'm just trying to pain a picture of what the CAB might look like in a record setting scenario and promote intra-CAB awareness and discussion.

Nightvid Cole

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Re: Subdividing the Central Basin
« Reply #4 on: July 23, 2019, 11:53:40 AM »
I suppose we could invoke the so-called Sector Principle and use terminology like "Chukchi-CAB", "ESS-CAB", "Laptev-CAB", etc.


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Re: Subdividing the Central Basin
« Reply #5 on: July 23, 2019, 12:01:05 PM »
That works for me.

The only point about the clock reference is that the lingo implies that the sections are of equivalent size in terms of land area. It's implies the utility as a math tool that sector naming doesn't.


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Re: Subdividing the Central Basin
« Reply #6 on: July 23, 2019, 12:31:41 PM »
We --- or at least I --- have been using this since many years ago in a vague manner, like Beaufort-CAB or Laptev-CAB. It is a nice formalization of that in any case. So thank you for your initiative. :)


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Re: Subdividing the Central Basin
« Reply #7 on: July 23, 2019, 08:09:57 PM »
Big fan of the CAB “clock” division system. It makes sense given the shape of Earth and the fact that longitudinal lines converge at the poles.

Making any other system which arbitrarily tries to assign size, name and area to CAB (>80 deg) would therefore engender less information even in the naming. The clock idea is a solid plan. Perhaps use a fixed line as the 12:00 reference though, for simplicity’s sake. Don’t just start somewhere pointing towards Siberia, use the International Date Line, or Common Time Line perhaps as the reference starting point for 12:00.

Any newbies armed with that simple understanding, in theory, could look at the CAB and know what sector 7:00 refers to.