Principal Investigator John A Taylor Project r60

Centre for Resource and Environmental Studies Machine VP

Co-Investigators Jay W Larson, David Hansen and Robert J Oglesby,

Centre for Resource and Environmental Studies and Purdue University, USA

Climate Studies with the CCM1 - Controls for the Present Day Climate

We have just completed the implementation of a widely used GCM, the NCAR CCM1, on the ANUSF VP2200. This model is available to the ANU (and Australian Universities at large) community for a wide variety of climate studies. A key need for these types of studies is the making and archival of well-documented and analysed control runs. Although the CCM1 has been successfully run on a variety of supercomputers (including control runs), experience has shown that the model yields slightly different results when run on different machines, due to differences in compilers, operating systems, and numerical libraries. Though small, these differences are sufficient to affect strongly the precise experiment-control statistical comparisons that are crucial to the assessment of the significance of experimental results. Thus we propose to make a series of CCM1 control runs for the version on the VP2200 that will be used for a variety of climate and climatic change studies.

What are the basic questions to be addressed?

Investigate the representation of present day climate using a global climate model.

What are the results to date and the future of the work?

Control runs with CCM1 have nearly been completed. The focus will now be on performing control runs with CCM2.

What computational techniques are used and why is a supercomputer required?

Three-dimensional computations of high resolution atmospheric transport and chemistry are extremely intensive. The models demand large amounts of memory and generate huge amounts of output. The model uses the spectral transform technique to solve the model equations.