The high Arctic pollen sites, studied by the Polar Continental Shelf Project (Reference Bourgeois, Koerner and AltBourgeois and others 1985), lie in the region dominated by the cold-core westerly circumpolar vortex which is a unique feature of high Arctic atmospheric circulation. The characteristic slow-moving, or quasi-stationary, cold lows of a non-frontal nature, which extend from the surface to the upper atmosphere, produce moisture and aerosol transport conditions which differ considerably from those to the south over southern Baffin Island and the mainland. The geographical position of the transition zone separating these two distinct circulation regimes is now under investigation but it appears to pass between Penny Ice Cap and Bylot Island under present-day summer conditions.