Detection of a plume 400 km from the source

Abstract An unexpected SO 2 reading over the northern edge of Toronto, Canada, by means of a COSPEC remote sensor, and the posterior trajectory analysis of the air parcel over Toronto at the time of the measurement, indicate that the INCO Sudbury plume was observed at 400 km from its source. Some estimates of the mass flux in the plume and of its horizontal dimensions are presented.