When we split the cost function across the four wind directions,
we identified that the proportion of the cost calculated for each
wind quadrant varies by monitor. The prominent wind quadrant
was southwest, which occurred in the region during 41% of the
period. When we examined station 29154, 66% of its total cost was
calculated during southwest winds. That result is contrasted by
monitor 29567, which is located southwest of the industrial sources
and during southwest winds only 31% of its total cost occurred. This
difference in the proportion of the total cost between the two
monitors demonstrates that the index can account for wind direction
effects that occur because of variable source locations, wind
directions, and monitor locations. In regions where the main wind
direction is expected to change the index could account for these
changes by weighing the cost values across wind directions.