Author: Akira Kageyama, Title: "Dynamo Simulation by Earth Simulator" IUGG2003, Sapporo, Japan, (2003, June) --------------------- key words: geodynamo, MHD, self-organization ---------------- ---------------- abstract ---------------- DYNAMO SIMULATION BY EARTH SIMULATOR Akira KAGEYAMA (Earth Simulator Center, Japan Marine Science and Technology) From 1990's, we have been performed a series of computer simulations of MHD dynamo in rotating spherical shells. Since our initial motivation was to see the geomagnetic field as one of the self-organization phenomena in nature, we approached to the geodynamo as a fundamental problem of MHD physics. So, we tried to keep our dynamo model as simple as possible, in order to extract essential physics of the MHD dynamo process. Another obvious reason of such a simplifed model (and with non-realistic parameters) was the limitation of the available computer power. In 2002, the author moved to the Earth Simulator Center, Japan, which has the world's fastest computer, called the Earth Simulator (ES). The ES is a vector-parallel type supercomputer that has 640 processor nodes, each consisting of 8 vector processors. The peek speed of ES is 40TFlops and the momory size is 10TB. This tremendous power of ES enables us to attack the geodynamo probelm with more realistic simulation model as well as much more higer (or lower) nondimensional parameters. We have been endeavored to convert and improve our dynamo simulation model (and the code) to be highly optimized to the vector-parallel architecture of ES. In this paper, we will report our new simulation results obtained by ES.