To represent both the basin-scale circulation in the ocean and the local small-scale variations at the same time, a high resolution global ocean general circulation model (OGCM) is essential. Recent progress in parallel computing techniques together with the high ability of computer itself makes it possible to use such a high resolution OGCM for climate variability issues. We have developed and are using a global OGCM based on the Princeton Ocean Model, with 1/6 degrees horizontal grid resolutions. This model has been running on the Numerical Wind Tunnel at National Aerospace Laboratory in Japan, using 64 PEs with 256 MB memory for each PE, and is successful in reproducing very realistic variations of the currents and tracer fields. In the present study, details of the model and some examples of those variations from 16-year calculation with climatological forcing fields are introduced.

A portable QCD simulation program running on NWT with 128 PE's shows the performance 0.032 micro sec/link update, which is about 189 times faster than a highly optimized code on CRAY X-MP/48 with four processors. The performance corresponds to 178 GFLOPS sustained speed.

NAL Numerical Wind Tunnel (NWT) is a distributed memory parallel computer developed through joint research and development of NAL and Fujitsu. It is based on the analysis of CFD codes developed in NAL. The target performance is more than 100 times faster than VP400. In this paper, the parallel computation model employed in the development of the NWT is described. The specification and feature of the NWT and the NWT Fortran are discussed. Finally, performance evaluations and some applications are presented. We find that the target performance is attained.>