Appendix 8-1. CALGRID Zero-Out Modeling 

Mohammed A. Majeed, Ph.D. and P.E. 

Air Quality Management Section 

Delaware Department of natural Resources and Environmental Control 

Dover, DE 

May 2007

The NHDEP performed CALGRID zero-out modeling for a number of states 

including DE, PA, NJ, MD, and NY. The intent of the modeling is to assess what each 

state contributes to the ozone monitors that the attainment test does not demonstrate 

attainment of the 8-hour NAAQS. With this zero-out modeling we estimated Delaware’s 

contribution to the monitors in the PA-NJ-DE-MD non-attainment area. Figures 7-7, 7-8, 

7-9, 7-10 and 7-11 show the result of CALGRID zero-out modeling for Delaware, 

Maryland, New Jersey, New York, and Pennsylvania, respectively. Figure 7-12 shows 

the individual contribution from each of the states to Colliers Mills, Ocean County, NJ 

monitor - with the total contribution being 23 ppb. Note that Delaware’s contribution to 

Colliers Mills is only 9% of the total contribution from these five states. Modeling with 

CALGRID for model performance and future case runs indicated that CALGRID over 

predicts ozone at these monitors. Therefore, Delaware’s 9% contribution to Colliers Mills

monitor is a conservative number. 

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Episode Maximum 8-Hour Ozone Difference Concentrations

2009 Base minus 2009 Base w/Zero DE Emissions

July 31 - August 16, 2002

Ozone

Concentrations

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NHDES 12/4/06

CALGRID 2.45

Modeling Domain

Figure 7-7. CALGRID Zero-Out Modeling for Delaware

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Episode Maximum 8-Hour Ozone Difference Concentrations

2009 Base minus 2009 Base Case - Zero Out Maryland

July 30 - August 16, 2002

Ozone

Concentrations

(PPB)

NHDES 11/29/06

CALGRID 2.45 

Modeling Domain

Figure 7-8. CALGRID Zero-Out Modeling for Maryland

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Episode Maximum 8-Hour Ozone Difference Concentrations

2009 Base minus 2009 Base w/Zero NJ Emissions

July 31 - August 16, 2002

Ozone

Concentrations

(PPB)

NHDES 12/13/06

CALGRID 2.45

Modeling Domain

Figure 7-9. CALGRID Zero-Out Modeling for New Jersey 

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Episode Maximum 8-Hour Ozone Difference Concentrations

2009 Base minus 2009 Base w/Zero NY Emissions

July 31 - August 16, 2002

Ozone

Concentrations

(PPB)

NHDES 12/5/06

CALGRID 2.45

Modeling Domain

Figure 7-10. CALGRID Zero-Out Modeling for New York

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Episode Maximum 8-Hour Ozone Difference Concentrations

2009 Base minus 2009 Base w/Zero PA Emissions

July 31 - August 16, 2002

Ozone

Concentrations

(PPB)

NHDES 12/18/06

CALGRID 2.45

Modeling Domain

Figure 7-11. CALGRID Zero-Out Modeling for Pennsylvania 

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Figure 7-12. Individual State Contributions to Colliers Mill Monitor, 

Ocean County, New Jersey 

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