PPT Slide

Day 1 12/23/89 Yellow

Day 2 11/04/89 Green

Day 3 2/04/89 Red

Sudbury

Noranda

HY-SPLIT / NGM Trajectories arriving

at 3 PM for Underhill, Vermont

Previous slide

Next slide

Back to first slide

View graphic version

Backward air trajectory calculations using the NOAA HY-SPLIT trajectory model and NGM meteorological data suggest flows arriving at Underhill, VT at 3 PM on days with highest Arsenic concentrations had passed over an area where large Canadian smelters at Noranda and Sudbury are presumed to emit relatively high levels of Arsenic (and SO2).

For these events, it appeared more likely that Noranda, rather than Sudbury, was the most important source. Although conceivably there may be other unconsidered Arsenic sources along this path. Also, the estimated uncertainty of the trajectory model (20 to 30 % of trajectory distance) may not allow a clear distinction between the large smelters at this distance and direction.