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GEOS- Chem Chemical Transport Model: Current Status and Future Plans. Daniel J. Jacob, GEOS- Chem Model Scientist Harvard University. Science Team Meeting at Caltech, 1998. Chemistry, Aerosols, and Climate: Tropospheric Unified Simulation (CACTUS). Input data
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GEOS-Chem Chemical Transport Model:Current Status and Future Plans Daniel J. Jacob, GEOS-Chem Model Scientist Harvard University
Science Team Meeting at Caltech, 1998 Chemistry, Aerosols, and Climate: Tropospheric Unified Simulation (CACTUS)
Input data • NASA GEOS meteorological fields • other GEOS-Chem Chemical Transport Model (CTM) Solve 3-D chemical continuity equations on global Eulerian grid Nested model • Modules • emissions • transport • chemistry • aerosols • deposition • sub-surface • Applications • chemical processes, transport, budgets • inverse analyses • radiativeforcing • air quality • biogeochemistry • … Model adjoint Capabilities of present standard model: • Ozone-OH-NOx-aerosolchemistry, aerosol microphysics, carbon gases, mercury, … • 1980-present GEOS meteorological data, future and paleoclimates (GISS GCM) • Horizontal resolution: 1/4ox5/16o (native), 1/2ox2/3o (native), 1ox1o, 2ox2.5o, 4ox5o • Adjoint model for inverse/sensitivity analyses • Nested model for continental-scale simulations
GEOS-Chem GEOS-Chemcontributes to broader Earth science activities • Aircraft and satellite missions • forecasting and data analysis • a priori infomation • Chemistry-climate interactions • Two-way interface with GCMs • Earth system models • Atmospheric chemistry module • Data assimilation systems • Chemical data assimilation • Local air quality models • outer nest • Collaboration with other CTMs • module exchanges • intercomparisons
The GEOS-Chemuser community: 72 institutions, 18 countries • The model is managed by a GEOS-Chem Support Team based at Harvard (Bob Yantosca, Mike Long, Melissa Payer), Dalhousie University in Canada (Sajeev Philip) and University of Colorado (Nicolas Bousserez, adjoint model) • Scientific oversight is by a 22-member Steering Committee including Hong Liao (Co-Chair, Chemistry-Climate Working Group) and Yuxuan Wang (Co-Chair, Nested Model Working Group) • Developments by user community are rapidly integrated into standard version • Strong model integrity is maintained by version control and benchmarking, • Extensive networking between users, GEOS-Chem meetings every two years
China’s presence in the GEOS-Chem user community is rapidly growing Chinese scientists are important contributors to GEOS-Chem
Functioning of the GEOS-Chem community • GEOS-Chem is a grass-roots community model • Code is open-access, extensively documented and supported • All model development is initiated by users to serve their research needs • New developments are promptly implemented in the standard model • Young scientists have opportunity to get involved in model development • Strong model management maintains model unity, traceability, state of science • GEOS-Chem Support Team maintains standard model: new developments, benchmarking, version control, user support • Support Team is funded by NASA (1 FTE) and NSERC (0.5 FTE); strong leverage from community volunteerism is essential • GEOS-Chem Steering Committee monitors model development, promotes good practices and communication, leads Working Groups • The model is owned by its users, and with ownership comes responsibilities: • Keep up with the model (newsletters, wiki, working groups, IGC meetings) • Contribute to the community: help with requests, report bugs… • Share mature developments for incorporation into standard model • Update regularly to latest standard version of model • Be generous in credit to developers The success of GEOS-Chem relies on the spirit of its user community!
Development of grid-independent GEOS-Chem model Grid-independent GEOS-Chem Transport (GCM or other) • Grid-independent model computes chemical updates on any grid to pass on to a GCM • Allows flexible coupling to different dynamical cores for data assimilation, climate modeling • Presently developed for coupling with NASA GEOS data assimilation system using ESMF interface • Facilitates massively parallel implementation through MPI • Has been developed as part of the standard GEOS-Chem model; will eventually replace standard model in a way transparent to users
Future directions for GEOS-Chem Continued improvement of core model Organic gas+aerosol chemistry, aerosol microphysics, … Software improvements Grid-independent model to enable MPI parallelization New chemical solvers to speed up code Expansion of model capabilities Stratospheric chemistry, radiative forcing, two-way nesting, biogeochemical cycling Coupling with meteorological models Chemistry-climate interactions, chemical data assimilation Operational applications Carbon monitoring system (model adjoint), air quality forecasting…