New Insights in Sea Ice Drift Based on Dirty Ice Samples Collected in 2005 by the HOTRAX Expedition

Several dirty sea ice samples collected over the rarely visited Alpha Ridge and from other central Arctic Ocean areas are compared to ice-drift back trajectories from International Arctic Buoy Programme. Both the back trajectories and Fe grain fingerprint sources suggest Russian sources near the Laptev Sea (New Siberian Islands), but the Fe grain sources also indicate other Russian sources such as the Kara Sea and even some sources were traced to the northern Arctic Canadian Archipelago. Drift patterns based on back trajectories show that a mix of Russian and N. American sources is possible because the location where the ice was sampled is close to the area where the Trans-Polar Drift carrying Russian ice joins that portion of the Beaufort Gyre moving toward Fram Strait and carrying N. American ice. The Fe grain sources also show that both Russian and N. American ice can occur juxtaposed within very short distances of tens of meters due to mixing of ice floes. This supports earlier findings in the Beaufort Gyre area where Russia floes co-mingled with N. American floes due to repeated separation and rejoining of ice floes. Two dirty ice samples north of Barrow, Alaska indicate a Bering Strait/Chukchi Sea source. The back trajectories in this area do not show any ice originating from any nearshore sources off Alaska nor northern Canada, but only a tight clockwise rotation over the past several years prior to 2005. Thus the Chukchi Sea source is entirely feasible in light of this back- trajectory data. If so this is the first direct evidence of ice in the Beaufort Gyre originating from the Chukchi Sea area.