Process Analysis Diagnostics

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Process Analysis Diagnostics

Overview - What is Process Analysis?

Process-based Analysis examines the change in each species due to each process and reaction. Models predict atmospheric state, which in a time-series can be used to create net-change of each species. What this cannot tell us, is which processes led to that change. To supplement state (or concentration, GEOS-Chem has long archived emissions and employed advanced diagnostics to predict gross chemical production or loss. Process Analysis goes a step further archiving grid-cell budgets for each species, and decomposing gross production/loss into individual reaction contributions. Process Analysis extensions are currently available in CAMx, [WRF-Chem], [CMAQ], and now GEOS-Chem.

Details - No really, what is it?

The budget is built from process contributions and reaction throughput. Process contributions are referred to as Integrated Process Rates (IPR) and can be calculated because of operator splitting. Each process is distinctly called, and state before and after the call can be differenced to see the process contribution.

Reaction contributions are more complex to calculate than IPR. Reaction contributions are constructed from integrated reaction rates (IRR). IRR are calculated according to equation 1. The rate coefficient (<math>k</math>) is evaluated by calcrate.f and then SMVGEAR or KPP solve over short timesteps (<math>t_s</math>). To calculate the IRR, we must add code to SMVGEAR or KPP that finds successful steps and archives equation 1.

  1. IRRrxn = Δ ts· krxn · ∏rct[Crct]
  2. ΔCi,rxn = αi,rxnIRRrxn
  3. ΔCi,chem = Σrxn ∈ rxnsΔCi,rxn

Development Status - What features are available?

Integrated Process Rates

Process rates are fully functional, but will be extended in the future.

  1. Transport
  2. Convective Mixing
  3. Wet deposition
  4. Emissions*
  5. Dry deposition*
  6. Heterogeneous Chemistry
  7. Gas-phase Chemistry

*Gas-phase emissions and dry deposition are solved either in the chemical solver or in asymmetric convection routines. Separation within convection has not yet been implemented.

Integrated Reaction Rates

Integrated Reaction Rates are fully functional with two solver options.

  1. Sparse Matrix Vector Gear: available
  2. Kinetic Pre-Processor
    1. Rosenbrock (coming soon)
    2. LSODES (available upon request)

To do:

  1. Confirm that inexact SMV results for $lt; 1% of results are the result of tracer lumping rather than SMVGEAR species specific error correction
  2. Incorporate error correction if necessary
  3. Complete KPP Rosenbrock solver implementation


Installation and Application - How can I use it?

The code is available in a github repository that is currently available upon request from Barron Henderson at the University of Florida.