Résumé
In the Arctic domain there is evidence for very long distance transport of pollen grains from boreal forests to tundra environments. However, the sampling protocol used in earlier studies did not allow the determination of the precise timing of the deposition of exotic grains. The ongoing "Epilobe" project monitors the deposition of exotic grains on both western and eastern coasts of Greenland utilizing wind filters, which are changed weekly throughout the entire year. A combination of the identification of tree pollen grains, the dates of deposition of the pollen on the filters, and the distribution map of the trees identified, allows the selection of modeled backward trajectories of air parcels responsible for the capture of the grains in the growing area of northeastern North America, and their long distance transport to Greenland. A survey of data obtained from four stations, analyzed during 2004 and 2005, indicates the occurrence of a general pattern, every spring, which follows the main cyclone tracks reaching this Arctic region