Using InterComm Enhanced ESMF To Couple TIME-GCM and CAM

1. IN21B-1062 • CAM: • NCAR Community Atmosphere Model • CAM 3.0 is the fifth generation of the NCAR atmospheric GCM • Cleanly separates the parameterization suite from the dynamical core • Includes packages for the treatment of clouds, ice, and aerosols Introduction: This project uses ESMF and InterComm to produce a multi-executable coupled model. The model consists of CAM and TIME-GCM running separately side by side. ESMF is used to wrap CAM data and to interpolate data from the CAM grid to the TIME-GCM grid. A contributed InterComm interface to ESMF allows data to be sent from CAM to TIME-GCM, where it is used to provide lower boundary forcing. This forcing is useful because it should allow TIME-GCM to incorporate the complex, changing view of the lower atmosphere provided by CAM and to thereby produce a more nuanced model of the ionosphere-thermosphere system. CAM TIME-GCM Cam Setup TIME-GCM Setup Initialize InterComm Create Block Regions Initialize InterComm Create Block Regions Register Regions Commit Regions Initialize ESMF Create Data objects Translate to InterComm Setup Regridding • ESMF: • Earth System Modeling Framework • Provides standard interface for models to facilitate inclusion in a coupled system • Allows models to exchange data via a flexible, but standardized data structure • Provides a wide range of utilities to ease model coupling • For example: • Data regridding • Data redistribution • Time management • Error handling • May be found at www.esmf.ucar.edu Regrid Temperature Regrid Geopotential Send Temperature Send Geopotential Receive Temperature Receive Geopotential InterComm CAM Calcs TIME-GCM Calcs • Next Steps: • Fix periodic region problem • Scientific investigation of the completed coupled system Initial Results • InterComm: • Allows data to be transmitted between separate executables • Allows coupling with truly minimal code modification • Coupling info not hard-coded, but separated into job description file • Contributed interfaces facilitate moving data in/out of ESMF components • May be found at www.cs.umd.edu/projects/hpsi/chaos/ResearchAreas/ic Conclusions: Although the coupled system is still a work in progress, our experience during this project has shown that the combination of ESMF and InterComm provides an effective synergy for creating multi-executable coupled systems. ESMF provides the ability to wrap model data and then easily regrid it to a desination grid. InterComm then allows the data to be efficiently passed to the destination application where it can be incorporated into calculations. Neutral Temp. Start Neutral Temp. After 1 Hour Using InterComm Enhanced ESMF To Couple TIME-GCM and CAM Robert Oehmke1, Michael Wiltberger1, Alan Sussman2, Wenbin Wang1, and Norman Lo2 The Coupled System • TIME-GCM: • Thermosphere-Ionosphere-Mesosphere-Electrodynamics General Circulation Model • Simulates the circulation, thermal and compositional structures from 30-500km • Gravity waves parameterized based on linear saturation theory • Continuous efforts to compare model results with ground and satellite observations • Grid contains periodic region in addition to ghostcells • CAM to TIME-GCM Coupling: • Takes place at the 10mb pressure level • Transfers temperature from CAM to TIME-GCM • Transfers geopotential from CAM to TIME-GCM • Quantities are regridded via bilinear interpolation • Extra communication to fill periodic region • Current Status: • The coupled system runs • The data is transferred correctly from CAM to TIME-GCM • Initial results from the coupled system are reasonable in most areas • The one problem area appears to result from an incorrectly set periodic region National Center for Atmospheric Research University of Maryland