CMAQ Process Analysis

1. CMAQ Process Analysis Gail Tonnesen Gail Tonnesen, Zion Wang UCR Regional Modeling Center Training January 17, 2002

2. Process Analysis (PA) provides quantitative information on the effects of the chemical reactions and other atmospheric processes that are being simulated in CCTM.  t [O3]t = [O3]0 + t0[P(O3)  L (O3)]dt  Xport  Dep Useful for QA and diagnosing errors. PA is an explanatory tool (not a predictive tool). Process Analysis Overview

3. The two Process Analysis techniques available in the CMAQ system: integrated process rate (IPR) analysis provides a fundamental explanation of the reasons for a model's predictions and shows the relative importance of each process. useful in identifying potential sources of error in the model formulation or its inputs and in interpreting model outputs, integrated reaction rate analysis (IRR) used to determine important characteristics of different chemical mechanisms. particularly useful for investigating mechanistic differences under different chemical regimes Components of PA

4. Box model: Output all react reaction rates and use a post processing program. (1990) Grid Model: Post processing is too expensive so hard code the key IRR terms in the grid model. (1995). CMAQ: Develop a Process Analysis Control Program (PACP) to provide flexibility in selecting the IRR outputs (1998). Evolution of IRR analysis

5. CMAQ is preconfigured to provide many of the chemical process terms of interest:

6. IPR – examples

7. IPR – examples

8. IRR examples

9. IRR examples

10. IRR examples

11. IRR examples

12. Edit PA.input file to select the desired PA outputs. Build the PACP program using the bld.script Run the PACP program to create PA include files. PA_CTL.EXT PA_CMN.EXT PA_DAT.EXT PA.REPORT (docmentation file) Compile the CCTM program using the PA include files. IRR only works with GEAR and QSSA solver, cannot use with MEBI. Running Process Analysis

13. Practice Session