A version of the Air Resources Laboratories Atmospheric Transport and Dispersion Model was tested to determine how well it could identify probable pathways and source regions of airborne pollens from non-local sources which were deposited in precipitation at Albany, New York. The model calculates either forward or backward trajectories from any selected location starting every 6-h during a chosen time period. Each trajectory is calculated using transport winds averaged over a selected vertical layer and is based on past upper air observations stored in the computer.

At Albany, New York, airborne pollens were sampled during both wet and dry weather. Samples were examined under a microscope and pollen grains identified and counted. In this study, only obviously fresh pollens of non-local origin are considered. These were obtained primarily in the winter and early spring months before local pollens of the same or similar species were released and include species whose ranges do not reach the north-eastern states. These cases document atmospheric transport from distant source regions and subsequent wet deposition.

Probable source regions were determined from ranges and flowering dates of the taxa collected. Backward trajectories from Albany were computed for nine precipitation events. In all cases, the trajectories passed through or very near previously identified source regions located to the south or south-west. Travel times ranged from 10 to over 50 h but were mostly from 18 to 42 h. Results demonstrate the utility of the model and the feasibility of locating source regions of materials transported over long distances.