Process Analysis Application:The 2000 Houston Ozone Attainment

Simulations

5th Annual CMAS Conference Friday Center

Chapel Hill, NC

10/17/2006

Marianthi-Anna Kioumourtzoglou, William Vizuete,

Harvey Jeffries, Barron Henderson

vizuete@unc.edu

http://ftpozone.sph.unc.edu

Outline

• Introduction

• Ozone chemistry

• The need for a tool to quantify physical and chemical processes for better understanding of O3 formation (Process Analysis in Python)

• Application

• Region of Interest: Houston, TX, designated as Non-Attainment Region by EPA

• Model used: Comprehensive Air Quality Model with extensions (CAMx)

• The Emission Inventory used was developed by TCEQ for the 8hr SIP modeling scenario

• Post Processor: Process Analysis in Python

Introduction

Sensitivity Runs

• CO: favors propagation of OH

• Xylene and Toluene: internal sources of OH, lead to formation of HCHO that when photolyzed produces OH

• HCHO: direct source of OH

List of Sensitivity Runs Performed

• Base Case (no imputation)

• 0.25xCO

• 4xCO

• 2xXYL_TOL

• FL_FORM

• CO_FORM

VOC Addition: CO and Xylene+Toluene

• Two CO sensitivity runs– 0.25xCO: 1/4 times the gridded CO emissions – 4xCO: 4 times the gridded CO emissions– Full length run (08.22-09.06.2000) – Domain wide imputation (36km, 12km, and 4km)

• Xylene and Toluene sensitivity run– 2xXYL_TOL: 2 times the Xylene and Toluene gridded emissions

– Full length run– Domain wide imputation

VOC Addition: Formaldehyde

• Two Formaldehyde sensitivity runs– Flares (FL_FORM)

• We assumed that HCHO emitted was equal to 1% of total VOC flow rate.

• Full length run • Imputed 13 flare emissions

– Mobile sources (CO_FORM)• Recent data (SWRI, 2005*) on Heavy Duty Diesel show that HCHO is 23% of VOC. HCHO was 5% of CO.

• We added HCHO at 4% of gridded CO emissions.

• Full length run• 4km domain wide imputation

*Reference: Diesel Exhaust Standard-Phase II: CRC Project No. AVFL-10b SwRI Poject No. 03.10410 Fanick, Robert. 2005

•Process Analysis•CAMx/CMAQ quantifies the chemical and physical processes that lead to ozone formation for each grid cell•Process Analysis is a post processor suite of programs that extracts, aggregates and calculates several chemical parameters

•Chemical parameters•Total OH Balance•Total VOC Reacted•New NO•Total NO Reacted•Total NO2 Available•O3 Source Balance•O3 Balance•New O3 per new NO and VOC reacted

Process Analysis: Application

12 13

14 15

08/25Base

O3

HOUSTON

VOC sensitivity:C35C O3 Impact

SCENARIO Base 0.25xCO 4xCO 2xXYL_TOL FL_FORM CO_FORM

O3 CHEMICALLY PRODUCED

131.9 126.11 148.7 153.81 153.28 167.78

pyPA provides quantification of important physical and chemical parameters that help us understand and explain how O3 is formed.We have shown by this quantification the impacts of VOC sensitivity analyses to physical and chemical parameters of the O3 chemistry.

Conclusion

Acknowledgements

Funding• Eight Hour Ozone Coalition• HARC H60 “Regional Transport Modeling for East

Texas”– Jay Olaguer, Project Officer

Special thanks • Jim Smith, TCEQ for supplying CAMx ready files for

base1b 8-H SIP Case• UNC MAQ Lab