CMAQ Process Analysis

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

• Gail Tonnesen

2
Process Analysis Overview

• Process Analysis (PA) provides quantitative
  information on the effects of the chemical
  reactions and other atmospheric processes that
  are being simulated in CCTM.
• ? t
• O3t O30 ?t0 P(O3) ? L (O3)dt
  ? Xport ? Dep
• Useful for QA and diagnosing errors.
• PA is an explanatory tool (not a predictive
  tool).

3
Components of PA

• 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

4
Evolution of IRR analysis

• 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).

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
Running Process Analysis

• 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.

13
Practice Session