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Design and Development of MAQM, an Air Quality Model Architecture with Process-Level Modularity

Design and Development of MAQM, an Air Quality Model Architecture with Process-Level Modularity. Weimin Jiang, Helmut Roth, Qiangliang Li, Steven C. Smyth, Fuquan Yang. Outline. Why is process-level (PL) modularity crucial for AQ models ?

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Design and Development of MAQM, an Air Quality Model Architecture with Process-Level Modularity

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  1. Design and Development of MAQM, an Air Quality Model Architecturewith Process-Level Modularity Weimin Jiang, Helmut Roth, Qiangliang Li, Steven C. Smyth, Fuquan Yang

  2. Outline • Why is process-level (PL) modularity crucial for AQ models ? • What did we do in initiating a new generation of AQ model with PL modularity? • The conceptual MAQM architecture and its implementation in FORTRAN • The MAQM/CMAQ model • Possible future work • Acknowledgements CMAS Conference, Chapel Hill

  3. Why PL modularity ? Complicated atmos. processes & rapidly evolving AQ science Air quality model with process-level modularity Simple & transparent structure; Transferable code; Well structured model science & algorithms; Localised errors & bugs; Flexible process analysis capability. Broad community participation in model development and improvement Complete and robust model science CMAS Conference, Chapel Hill

  4. What did we do ? • MAQM: a new software architecture for air quality models • MAQM = Modular Air Quality Model; • Treats processes as individual blocks; • Blocks can be added, removed, replaced, modified, reorganized. • MAQM/CMAQ: a 3-D air quality model based on the MAQM architecture and mostly on the CMAQ science • Developed new pre-processors, MAQM data modules, the MAQM driver, and some MAQM process modules; • Extracted CMAQ algorithms/code and converted them into MAQM process modules; • Integrated all the pre-processors, MAQM data modules and MAQM process modules into a complete model. CMAS Conference, Chapel Hill

  5. The conceptual MAQM architecture

  6. MAQM components & design principles • 2 types of structural components: • Status; • Process. • 6 design principals: • Uniqueness of shared status information: global status data repository; • Self-contained process modules; • Structural separation of process modules; • Structural separation and linkages of status and processes; • Simple MAQM driver and its interface with process modules; • Minimized usage of hardcoding and repetitive code. CMAS Conference, Chapel Hill

  7. MAQM implementation in FORTRAN • MAQM global status data repository a set of FORTRAN data modules • MAQM process modules FORTRAN modules, sets of self-contained FORTRAN subroutines and/or functions • Process modules access data module components via the USE statements and the ONLY option at any levels • Simple MAQM driver calls to process modules: one way passing of time stamp and time step only • Example: software structure of MAQM/CMAQ  next slide CMAS Conference, Chapel Hill

  8. ... ... ...

  9. Emission Meteorology Gas_chem Advection ...... ... ... ... ...

  10. Emission Meteorology Gas_chem Advection ...... ... ... ... ...

  11. MAQM/CMAQ: details (1) • saprc99_ae4_aq_SVOC mechanism: • Modified from saprac99_ae4_aq; • Processed through PROCCHEM chemical mechanism processor. • Generalized CMAQ modal PM approach; • 5 global data modules: grid, gas, aero, met, const • 20 process modules: optional and replaceable • grid init_met int_gas init_aero • BConc_gas BConc_aero emission gas_chem • nucleation condensation inor_aero SOA • coagulation advection diffusion cloud • ddep_gas ddep_part meteorology output

  12. MAQM/CMAQ: details (2) • Inputs: optional depending on the process modules used. • IC and BC: ASCII files allowing different concentrations in different grid cells; • Meteorology, emissions, photolysis: same as CMAQ. • Outputs: • Three output files in I/O API format for each day: • GasConc_[yyyyddd]: gas concentrations; • Aero_Conc_[yyyyddd]: modal aero quantities (conc, Dg, sg) • PMx_[yyyyddd]: total and speciated PM0.01, PM0.1, PM1, PM2.5, PM5, PM10; • size cut-offs can be changed by users. • Conventional or SI units: user selected.

  13. Possible future work • Almost endless possibilities by the community, e.g. • New/restructured models using the MAQM architecture • Module-by-module science investigation and improvement • New and alternative process modules • Revised meteorology and emission modules to use input files from alternative sources • On-line meteorology and/or emission modules: • Possibilities: air quality meteorology • emission • Time- and location-varying boundary conditions • Process impact/sensitivity analysis

  14. Acknowledgements • US EPA: • The CMAQ model; • Early ideas of AQM modularity; • Community modelling concept. • All the organizations that contributed to the CMAQ code that we adapted/adopted. • CMAS: • Distributing and supporting CMAQ and other relevant modelling tools; • Organizing and facilitating community-wide discussions. • Dr. Jack Chen of our group: comments and suggestions. CMAS Conference, Chapel Hill

  15. CMAS Conference, Chapel Hill

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