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CTM - IFS interfaces GEMS- GRG

CTM - IFS interfaces GEMS- GRG. Review of meeting in January and more recent thoughts Johannes Flemming. Background. Assimilating remotely sensed observation about atmospheric composition GEMS production is hosted at ECMWF Integrated Forecast System ( IFS ) provides background

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CTM - IFS interfaces GEMS- GRG

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  1. CTM - IFS interfacesGEMS- GRG Review of meeting in January and more recent thoughts Johannes Flemming GEMS Kick- off MPI -Hamburg 4.-5.7. 2005

  2. Background • Assimilating remotely sensed observation about atmospheric composition • GEMS production is hosted at ECMWF • Integrated Forecast System (IFS) provides background • Transport, emissions, deposition and chemical conversion • GRG-specific problem: • Chemical mechanism with > 40 species can hardly be incorporated in IFS GEMS Kick- off MPI -Hamburg 4.-5.7. 2005

  3. GRG - approach • Include observable species in IFS (transport and assimilation) • O3, NO2, SO2, CO and HCHO can be observed from space (?) • Assimilate species in IFS with ECMWF 4D-VAR • Simulated source and sinks by coupling Chemical Transport Models (CTM) • CTM: MOZART (MPI-H), TM5 (KNMI), Mocage (meteo-france) GEMS Kick- off MPI -Hamburg 4.-5.7. 2005

  4. What do we have to consider? • Fields to be exchanged • Choice of coupling method • Choice of model grid • Frequency and timing of exchange in forecast and assimilation runs • Common computing environment for IFS and CTMs • Harmonised interfaces GEMS Kick- off MPI -Hamburg 4.-5.7. 2005

  5. Coupling method • Coupler OASIS4 • Is being developed in PRISM (work in progress) • Can exchange 3D fields between different grids • Mass conservation atmospheric balances (?) • Support of reduced Gaussian grid (?) • Spectral and grid point presentation • Coupling on the level of the MPI processes • CTM should be MPI parallel • File output possible • Coding interfaces and control by XML scripts • GEMS needs will be considered in development GEMS Kick- off MPI -Hamburg 4.-5.7. 2005

  6. CTM & IFS • Horizontal resolution • IFS: reduced Gaussian grid, T159 • CTM: Regular or Gaussian grid, T63/ T42 • Vertical resolution • IFS: L90 Levels in sigma hybrid coordinate • CTM: L20-30 Levels in sigma hybrid coordinate (same coefficients) • Orography & surface pressure • CTMs should use an orography consistent with the spectral truncation of the IFS output • Advection scheme, chemical mechanism • MPI parallelisation (?) GEMS Kick- off MPI -Hamburg 4.-5.7. 2005

  7. IFS fields to CTM • Wind components – mass fluxes • Temperature • Humidity • Clouds • Convective mass fluxes • Profiles of precipitation • Vertical diffusion coefficient • IFS concentrations (data assimilation mode) • Surface pressure • ………? GEMS Kick- off MPI -Hamburg 4.-5.7. 2005

  8. CTM fields to IFS • Production P • Loss rate L • LC and PC due to chemistry (3D) • PE due to emissions (2D) • LD due to deposition (2D/3D cloud) • Not standard output • LC , PC ,LDand PE are not independent • Totals only (?) • Concentrations (Initial conditions) (?) GEMS Kick- off MPI -Hamburg 4.-5.7. 2005

  9. “Dislocation” problem GEMS Kick- off MPI -Hamburg 4.-5.7. 2005

  10. “Dislocation” problem • IFS concentration fields differ from CTM fields because of different transport and data assimilation • CTMs P&L is not consistent with IFS concentration fields • IFS chemical analysis is not chemically consistent with CTM fields (difficult to merge) • Is this an issue ? GEMS Kick- off MPI -Hamburg 4.-5.7. 2005

  11. Forecast mode • 2-way coupling requires synchronous run • Exchanged met-data and P&L have to be assumed constant till next coupling • P&L IC required • How to consistently merge IFS chemical analysis in CTM IC • 1-way coupling (CTM gets met-data) • would allow lagged coupling (temporal interpolation of met-data) GEMS Kick- off MPI -Hamburg 4.-5.7. 2005

  12. Coupling in Forecast mode GEMS Kick- off MPI -Hamburg 4.-5.7. 2005

  13. ECMWF 4D-VAR Data assimilation T,u,v,q,O3 O3 transport + “chemistry” O3 advection only O3 transport + “chemistry” GEMS Kick- off MPI -Hamburg 4.-5.7. 2005

  14. Coupling in Data assimilation mode • Tangent linear and adjoint of coupled system (IFS-OASIS4-CTM) would be needed (not feasible) • Problems: • Including “P&L chemistry” in inner loops (Do we need it? What are the consequences?) • How to consistently transfer assimilated concentration to CTM IC • Impact of analysed met data on CTM (P&L) • 1. Option: • No chemistry in 4D-VAR inner loops (as currently for Ozone) • 2. Option: • Fixed L and P terms from CTM forecast • no impact on CTM except for met data in out loop • Does coupler work in 4DVAR (?) GEMS Kick- off MPI -Hamburg 4.-5.7. 2005

  15. CTM-implementation • GEMS partners access to ECMWF HPCF • Member state or special project access • Source code management for CTM and Coupler • Perforce projects for CTMS and OASIS (license?) • Build and scheduling system for CTMs and Coupler • ECMWF build-system for the CTMs • Code sharing CTM and IFS • no restriction to the CTM code (?) • CTM parallelisation • The CTMs need to be MPI-parallel for efficient coupling • OASIS MPI1 mode only on IBM • Model have to run with communicator provided by coupler • Seems to be no problem GEMS Kick- off MPI -Hamburg 4.-5.7. 2005

  16. Status and (short-term) Plansat ECMWF • IFS code • CY29r2 based version with 5 GRG prognostic and Aerosol • Identify best position for OASIS4 interfaces (met and chemistry) • Routine for global budget calculation • OASIS4 coupler • Playing with code and toy models (local linux environment) • No support of reduced Gaussian grid • MPI2 mode (spawning) not possible • Graphical Interface ready for editing of XML configuration files • Build CTM toy model and couple it to IFS • CTM – Implementation • Meeting on technical issues • TM5 and Mozart run at ECMWF HPCF in special project status • Implement CTMs in GEMS environment as soon as code is available GEMS Kick- off MPI -Hamburg 4.-5.7. 2005

  17. Issues CTM-IFS coupling I • Technical implementation of coupler • How long will it take to get OASIS4 running with IFS and CTM • CTM efficiency, MPI communication, Coupler efficiency • Data to be exchanged • List complete • Grids support (vertical and horizontally) • Spectral or Grid point • Different resolution and orography • Mass conservative interpolation • Coupling frequency • High temporal coupling frequency reduces problems (requires efficient coupler) GEMS Kick- off MPI -Hamburg 4.-5.7. 2005

  18. Issues CTM-IFS coupling II • “Constant L&P and met-data” assumption • Careful analysis of temporal scales of P and L • Coupling in data assimilation mode • “chemistry” modelling in inner loops • Analysed met-data for CTM • Different resolution and orography • Different concentration patterns in CTM and IFS (“Dislocation problem”) • P&L fields dislocated • Chemically consistent CTM analysis • More “chemistry” in IFS (?) • Using more “balanced” tracers (NOx, Ox) in IFS GEMS Kick- off MPI -Hamburg 4.-5.7. 2005

  19. END Thank You! GEMS Kick- off MPI -Hamburg 4.-5.7. 2005

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