A TIMEGCM CAM Multiexecutable Coupled Model Using ESMF
A TIME-GCM CAM Multi-executable Coupled Model Using ESMF and Inter. Comm Robert Oehmke, Michael Wiltberger, Alan Sussman, Wenbin Wang, and Norman Lo
Introduction • • TIME-GCM is a model of the upper atmosphere CAM is a model of the lower atmosphere This project coupled TIME-GCM and CAM is lower boundary forcing for TIME-GCM Models run side by side as separate executables ESMF in CAM interpolates between grids Inter. Comm sends data between executables
Motivation • Scientific: – Current TIME-GCM model does not capture observed hemispheric asymmetries – Including more complex lower boundary forcing from the lower atmosphere model should help this • Technical: – Demonstrate efficacy of ESMF Inter. Comm combination – Use of these tools makes coupling models easier
ESMF • Earth System Modeling Framework • Provides standard interfaces for models • Provides standard structure for transferring data between models • Provides a range of utilities to ease coupling – Data regridding – Data redistribution – Time management – Error handling
Inter. Comm • Library developed at the U. of Maryland by Alan Sussman and colleagues • Allows data to be transferred between separate executables • Allows communication between parallel codes for any data distribution or number of processors • Allows coupling with minimal code modification • Contributed interfaces facilitate moving data in/out of ESMF components
CAM • • • NCAR Community Atmosphere Model CAM 3. 0 is the latest generation of the NCAR AGCM Includes packages for clouds, ice, and aerosols MPI based parallel code Using Eulerian spectral dynamics option Using 128 x 64 Gaussian Grid
TIME-GCM • Thermosphere-Ionosphere-Mesosphere-Electrodynamics General Circulation Model • Developed at HAO by Ray Roble and colleagues • Simulates circulation, thermal, and compositional structures from 30 -500 km • Continuous efforts to compare model results with ground and satellite observations • MPI based parallel code • Using 72 x 36 regular latitude longitude grid
CAM to TIME-GCM Coupling • • Takes place at the 10 mb pressure level Transfers temperature from CAM to TIME-GCM Transfers geopotential from CAM to TIME-GCM Quantities are regridded via bilinear interpolation Models each executing in parallel during coupling Models running as separate executables while coupling Coupling occurs every timestep
Coupled System CAM TIME-GCM Cam Setup TIME-GCM Setup Initialize Inter. Comm Create Block Regions Register Regions Commit Regions Initialize ESMF Create Data objects Translate to Inter. Comm Setup Regridding CAM Calcs Regrid Temperature Regrid Geopotential Send Temperature Send Geopotential Inter. Comm Receive Temperature Receive Geopotential TIME-GCM Calcs
Current Status • We have the coupled system running • Data flows correctly between models • We have some preliminary output • Next Steps: – Scientific investigation of coupled system – Improvement of coupling: • Other interpolation methods? • More data flowing between models?
Coupling Interface at 30 km Plots of Neutral Temperature Stand Alone TIME-GCM Coupled TIME-GCM
Upper Stratosphere Plots of Neutral Temperature Stand Alone TIME-GCM Coupled TIME-GCM
Mesosphere Plots of Neutral Temperature Stand Alone TIME-GCM Coupled TIME-GCM
Thermosphere Plots of Neutral Temperature Stand Alone TIME-GCM Coupled TIME-GCM
Conclusions • Inter. Comm and ESMF form an effective combination for creating multi-executable coupled models • Using these tools allowed coupling with minimal code modification • There are difference in the preliminary output between stand alone and coupled, but analysis is still needed
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