Distributed Global Climate Model via Advanced Communications Technology Satellite

Ray Sears, Pat Gary, and Lee Foster with the ACTS High Data Rate Terminal.

Objective

Explore methodologies and performance issues for decomposing a coupled atmosphere-ocean Global Climate Model (GCM) to run concurrently on the CRAY J932 at GSFC and the CRAY YMP-232/T3D at JPL interconnected via the Advanced Communications Technology Satellite (ACTS).

Approach

Dr. R. Mechoso (UCLA) and Drs. M. Suarez and P. Schopf (GSFC) will define coupled but distributed GCMs (DGCMs) from among the main modules: UCLA atmospheric GCM (AGCM), NOAA/GFDL oceanic GCM (OGCM), NASA/GSFC Aries AGCM, and NASA/GSFC Poseidon OGCM. Communications interface is to consist of Cray high-speed channel attached to a special HIPPI/ATM adapter, which is interfaced to an ATM switch that connects to either a 155 Mbps or a 622 Mbps SONET port on the ACTS High Data Rate Terminal (HDRT).

Accomplishments

Prepared site and set up the HDRT at GSFC. Achieved ACTS-based communications from computers at GSFC to computers both at JPL and Kansas City which are sites of other ACTS HDRT's. In memory-to-memory ttcp tests between the CRAY J932 at GSFC and the CRAY Y-MP/T3D at JPL, with the maximum TCP window size set to 4 Mbytes, we recorded ttcp throughputs of approximately 56 Mbps through ACTS. This rate compares favorably with the throughput of approximately 66 Mbps we recorded in similar tests between these same two computers over the terrestrial NREN. We also supported live demonstrations/exhibits of ACTS' high data rate performance at the Armed Forces Communications and Electronic Association '96, SuperComm '96, and Advanced Digital Libraries '96 conferences.

Significance

Uses ACTS to form a meta-supercomputer that will accelerate the speed of GCMs.

Status/Plans

• FY97: Complete 155 Mbps network operational readiness tests and initiate routing DGCM testing between GSFC's CRAY J932 and JPL's CRAY Y-MP/T3D. Also prepare infrastructure and conduct separate ACTS-related 622 Mbps tests.
• FY98: Serve as part of a joint government-industry-academic hybrid Satellite/Terrestrial Interoperability Testbed investigating and evaluating new tools and protocols for enabling the next generation of seamless hybrid networking.

Point of Contact

Pat Gary
Goddard Space Flight Center
pat.gary@gsfc.nasa.gov
301-286-9539

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