I was impressed by how well that method worked just from cell concentration with no knowledge of what nearby cells were doing.
Having said this 50 days is quite short term.
It seems quite possible that that 50 day period is within a predictability window but that the method might lose skill rapidly if you tried to increase the forecast lead time to 60, 70 or more days. From volume max to volume min it might not be a good technique. For a season ahead, volume is likely to be a better predictor. Still impressed with how well it worked.
Absolutely, crandles.
I think with this though I can explain how it is I'm not as certain of Dr. Slater's prediction.
I've been wondering about how much of a difference large areas of open water at high latitude make in energy capture, considering the large areas currently appearing all along the Northern Sea Route.
To that end, I've been entertaining myself with some thumb-nail calculation sketches to approximate and to some fashion quantify the net increase in energy being captured, in order to understand the potential effect on the pack.
So, rough factors I'm using are these.
Albedo (via NSIDC) - Ocean 0.05
- Bare Sea Ice 0.5
- Snow covered Ice 0.9
To be modestly generous, I'll assume most of the ice is snow covered, for an effective average albedo of 0.85
Currently, the total daily flux hitting the areas that have become exposed is running on the close order of 14KWH/Day/M2 - that converts out as approximately 50,000 KJoules/Day, assuming a latitude of about 75N.
(nice on-line insolation calculator I found here:
http://www.pveducation.org/pvcdrom/properties-of-sunlight/calculation-of-solar-insolation )
That is enough energy to melt about 0.15 cubic meters of ice. Distributed evenly over one square meter, that means about 15CM of ice.
Applying the Albedo values, heat captured by our estmated ice (average Albedo of about 0.85) is enough to melt 2CM of ice/snow a day. The loss to Albedo lowers the captured energy in sea water to about the equivalent of 15CM. These are of course idealized values, but still establish the contrast in effects I am trying to illustrate.
So obviously, the impact of having open water under sunlight in the region is huge, and the capture of energy it represents would be enough to entirely melt out 2M thick ice covering an area of equivalent size in approximately 14 days. Fortunately, we have the negative feedback of cloudiness to save the ice from such a direct exposure of heat. The change in albedo will still have profound impact regionally.
Evaluated regionally, roughly comparing the open water to the remaining coverage of ice in the ESS, Laptev and Kara, the open water and reduced concentration implies ~ 15% open water across them. That modest increase of 15% open water translates into a 60% regional increase in potential heat capture, regardless of weather.
Succinctly, my thumb-nail estimate leads me to conclude that relatively small amount of additional open water at a minimum doubles the potential for energy to enter those regions via sunlight.
Scale up as appropriate for increased open water, and higher latitude.
I think this by itself makes predictions much, much more vulnerable to the vagaries of weather. Open water this early has potential to be an exponential multiplier of later melt.
(Sidebar - my fiddling with albedo also puts Neven's comments regarding melt ponds into perspective as well. Much of my observations about open water apply similarly to melt ponds. Assuming slightly higher albedo, 20% melt pond coverage regionally could similarly translate into about a doubling of potential energy capture.)
