Long Range Transport Mechanism

Vertically distributes pollutants Horizontally Spreads pollutants Horizontally redistributes pollutants Regional Scale Dispersion Processes Day Time Mixing Random Mixing Wind Shear Axial Mixing Wind Veer Axial Mixing The three transport processes that shape regional dispersion are wind shear, veer, and eddy motion or random mixing. Homogeneous hazy airmasses are create through shear and veer at night followed by vigorous vertical mixing during the day.

Regional Scale Dispersion The degree of of the airmass spreading after a day of transport is independent of the horizontal eddy diffusivity coefficient

HY-SPLIT: NGM wind fields, no mixing Monte Carlo Model:NGM wind fields, mixing At times individual Airmass histories compared very well At times individual Airmass histories compared very poorly Airmass History Model Comparison HY-SPLIT Vs. CAPITA Monte Carlo Model

Local Flows Current regional scale models poorly capture local flows –Complex Terrain –Land Water Boundaries –Near source impact Concentration are due to local and regional contributions Blumenthal et al., 1997

Monte Carlo Transport Animations