Affiliations: Department of Earth, Atmospheric and Planetary
Sciences, Massachusetts Institute of Technology, Room 54-1515, 77 Massachusetts
Avenue, Cambridge, MA 02139, USA | Jet Propulsion Lab, California Institute of
Technology, CA, USA | NASA Advanced Supercomputing, Ames Research Center,
CA, USA
Abstract: Up to 1920 processors of a cluster of distributed shared memory
machines at the NASA Ames Research Center are being used to simulate ocean
circulation globally at horizontal resolutions of 1/4, 1/8, and 1/16-degree
with the Massachusetts Institute of Technology General Circulation Model, a
finite volume code that can scale to large numbers of processors. The study
aims to understand physical processes responsible for skill improvements as
resolution is increased and to gain insight into what resolution is sufficient
for particular purposes. This paper focuses on the computational aspects of
reaching the technical objective of efficiently performing these global
eddy-resolving ocean simulations. At 1/16-degree resolution the model grid
contains 1.2 billion cells. At this resolution it is possible to simulate
approximately one month of ocean dynamics in about 17 hours of wallclock time
with a model timestep of two minutes on a cluster of four 512-way NUMA Altix
systems. The Altix systems' large main memory and I/O subsystems allow
computation and disk storage of rich sets of diagnostics during each
integration, supporting the scientific objective to develop a better
understanding of global ocean circulation model solution convergence as model
resolution is increased.
