EXAMPLES of CALPUFF APPLICATIONS on the Northeast Domain

Preliminary studies done by the Planning Section

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Modeling with the CALPUFF system started in 1999 for a variety of purposes. During 2001 and 2002 the Planning Section began setting up CALPUFF to assist with evaluating impacts from new LARGE sources proposed to be constructed in the northeast. The primary focus for impacts was the Lye Brook Wilderness area in SW Vermont because, under the federal Clean Air Act, it is a Class I area (a pristine area requiring enhanced levels of protection against air quality deterioration).

The CALPUFF modeling system includes its own diagnostic wind-field model using input in the form of a network of surface measurements from the National Weather Service automated surface observation system (ASOS) and twice daily upper air measurements obtained from a limited number of balloon (radiosonde) release points across the U.S. The CALPUFF model also includes a treatment of the chemistry that occurs in the atmosphere that converts gaseous SO2 into particle phase sulfates (SO4) under the influence of moisture in the atmosphere (humidity) during transport over long distances. The model uses only a rudimentary approach to representing conversion in clouds which is known to be where significant conversion occurs. This means that the model is likely underpredicting the conversion of SO2 to SO4 over distances of hundreds of kilometers. The modeled depictions shown below should be viewed in the context of the limitations inherent in this type of model.

CALPUFF SO4 Concentration Field 3.3 MB AVI : Multiple PT & Area Sources Meteorology = Jun 26-Jul 2 1995 analysis from CALMET	CALPUFF SO4 Concentration Field 24.0 MB AVI : Multiple PT & Area Sources    Meteorology = Jun 26-Aug 5 1995  analysis from CALMET

The patterns shown represent 1-hr average predicted sulfate concentrations. These results are a preliminary test of the modeling system and should not be considered final results. The Division is refining the inputs for this modeling system and will be conducting a full set of actual analyses for a five year period covering 1990-1995.

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