The graphic above shows the average precipitable water in the atmosphere for January as calculated by the Parallel Community Climate Model (PCCM2). The calculation requires a 153 day simulation of the earth's weather and was performed on an Intel Paragon (XPS35) at Oak Ridge National Laboratory. The validation of this simulation by comparison with the NCAR CCM2 model output and with observations, have demonstrated the feasibility of use of massively parallel computers for climate modeling.
The objectives of our research are
Semi-Lagrangian Community Climate Model A significant advance was made on the use of the Semi-Lagrangian Transport method for climate modeling. An experimental model based on the CCM2 and a fully semi-Lagrangian treatment of advective terms was developed and a study of the climate and resolution properties of the new model completed. This yielded the exciting result that double the spatial resolution for the dynamics is possible with no extra computational cost. This in conjunction with the long (stable) timesteps of the SLT method make this method a strong candidate for inclusion in the next generation, advanced climate model.
High Resolution Climate Simulation In the development of the next climate model and in understanding the results of the present PCCM2, it is important to know whether the model has converged with respect to the horizontal grid resolution. What difference would a finer, more resolved grid have on the simulated climate? A series of T170 high resolution runs have been made using the PCCM2 at ORNL and LANL. These runs indicate an improvement in the representation of certain regional scale features of the atmospheric circulation patterns.
PCCM2.1 Performance Implementations of PCCM2 are now available on the Intel Paragon, the IBM SP2, the CRAY T3D and the CRAY C90. The performance of of the code on these platforms gives an indication of relative machine performance and indicates the usefullness of the MPP platforms for climate research. Two horizontal resolutions are compared The performance is given in the number of seconds it takes to simulate one day on the computer. Two resolutions are shown. The T42 resolution corresponds to a 2.8 degree grid while T170 is a 0.7 degree grid. The higher resolution represents the what might be required for regional scale modeling of climate impacts.