Computational Design and Performance of the Fast Ocean Atmosphere Model.pdfVIP

Computational Design and Performance of the Fast Ocean Atmosphere Model, Version One Robert Jacob1, Chad Schafer2, Ian Foster1, Michael Tobis3, and John Anderson3 1 Argonne National Laboratory, Mathematics and Computer Science Division 9700 S. Cass Ave., Argonne, IL 60439, USA, jacob@mcs.anl.gov 2 University of California at Berkeley, Department of Statistics 367 Evans Hall, Berkeley, CA 94720, USA 3 University of Wisconsin–Madison, Space Science and Engineering Center 1225 W. Dayton St., Madison, WI 53706, USA Abstract. The Fast Ocean Atmosphere Model (FOAM) is a climate system model intended for application to climate science questions that require long simulations. FOAM is a distributed-memory parallel climate model consisting of parallel general circulation models of the atmosphere and ocean with complete physics paramaterizations as well as sea-ice, land surface, and river transport models. FOAM’s coupling strategy was chosen for high throughput (simulated years per day). A new coupler was written for FOAM and some modifications were required of the compo- nent models. Performance data for FOAM on the IBM SP3 and SGI Origin2000 demonstrates that it can simulate over thirty years per day on modest numbers of processors. 1 Introduction The Earth’s climate is the long-term average of the behavior of the ocean, land surface, and sea ice. These components exchange heat, momentum, and fresh water with each other through their common interfaces. The difference in heat storage times, fluid dynamic scales, and transport/storage of water results in complex interactions between the components. To study the Earth’s climate, researchers have developed coupled models, comprising an atmospheric general circulation model (GCM), a model of the ocean general circulation, a model of the dynamic and thermodynamic prop- erties of sea ice, and a model of the temperature and composition of the land surface. Typically, each component model is a separately developed program with its ow