Long Range Transport Mechanism

Vertically distributes pollutants

Horizontally Spreads pollutants

Horizontally redistributes pollutants

Regional Scale Dispersion Processes

Day Time MixingRandom Mixing

Wind ShearAxial Mixing

Wind VeerAxial 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 mixingMonte 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 ComparisonHY-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