Wipneus Thanks for pointing out the issue with the average thickness plot. The average thickness should indeed be weighted by the area of the grid cells which our code for generating this particular graph didn't. It is now fixed. Thanks for pointing this out! Axel

If someone wants to take the time and figure out a (probabilistic) answer, 13-years of buoys placed at the North Pole are here. http://psc.apl.washington.edu/northpole/Buoys.html. The recirculating branch that Neven has in in his figure doesn't seem to be very likely if something is placed at the North Pole exactly. I've seen a figure once that computed average residence times for different zones in the Arctic but I can't find it right now, above should give enough of an answer. Cheers Axel