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As for slow wing & Richard Rathbone, I agree that prevailing currents go from the North Pacific to the North Atlantic. ...
Cheers, Frankendoodle. For my post above, I had read that the prevailing winds were more important than the currents, but maybe that has changed?
The ice drift map I posted was from a while back - data from 1978-2003. It shows the ice direction at the pole back then averaged 1-2 cm/s and the direction was from around 130E. But perhaps that has changed? Or there is a lot of year-to-year or seasonal variation?
This reconstruction of the past 365 days gives a good indication of ice movement towards the pole in the last melt season...
It can be seen that the ice region that ends up at the Pole in September 2012 starts at around (185W,82.5N) at this time of year last year - the beginning of April 2012. It is the ice at about half way in between two convenient markers: the red dash of thicker ice that starts at (183W,80N) and the point of a green strip that starts at (183W,85N) at the beginning of April 2012.
So the ice last year that travelled over the Pole in September came from almost the direction of Bering Strait, as you said. And it came from around 7.5 degrees South = 7.5*10,000/90 ~ 800 km away from the Pole at the beginning of April 2012.
The strange thing is that the red dash marker then completely changes direction after September, then heading roughly downwards in the direction ~110W. It does jerk around a bit too.
So the upshot is that I no longer believe that the September ice over the Pole in September will necessarily have come from the Russian side - that old pattern didn't apply last year.
IF the ice transport this year will turn out to be the same as last year then the ice currently at (185W,82.5N) will end up over the Pole in September. This is seen to be thicker ice, currently more than 3m thick:
...and so less likely to melt out than the thinner ice on the Eastern side. In that case, we probably won't get open ocean over the Pole this year.
Also, I note that the ice now even on the Russian side is thicker than it was at the same time last year. (Someone just posted that pictorial comparison on one of the other threads - thanks.)
Given the new uncertainties, I can no longer sustain a 70% probability of an ice free North Pole this year. I'm going to drop it to a 50% probability. (And that is even factoring in the recent fracturing that could favour quicker transport than last year.)
In order that I might better understand things, some general questions for those more knowledgeable than I:
1) does average ice drift direction depend on the season? For example, is the average Summer drift direction the same as in the Winter?
2) has the average ice drift direction changed over the years?
3) how much stochastic variability is in the ice drift direction? For example, how accurately can it be predicted where the region of ice is now that will be over the North Pole this September?
If you know the answer to any of these questions, what is the physics behind the answer?
Thanks,
slow wing