Triangular truncation scheme; Fourier transforms; single program multiple data architecture; wallclock time; speedup and efficiency
A spectral General Circulation Model at horizontal resolutmns T21 and T42 has been integ-
rated upto 30 d on 16 and 32 processors of Meiko T800. The model at resoluuon T21 is also implemented on 16 processors (T800) of a parallel computer (CHIPPS) built m India. The wallclock timings of model mtegration for 1, 10 and 30 d are noted and the speedup and efficiency of 16 and 32 processors have been computed. Results show that a T42 parallel model with nine levels in the vertical takes less than 36 elapsed
minutes on 32 processors for 1 d mtegration. In case ofT21 model integration, the maximum speedup and efficiency achieved on 16 processors are about 10 and 63%, respectively. When the horizontal resolution of the model is doubled to T42, the maximum speedup and efficiency obtained on 32 processors are about 9 and 29%, respectively. It is also found that when the physical parametrisatmn schemes are mcluded In the
model and thereby the number of arithmetic operations are increased, the speedup and efficiency of 16 as well as 32 processors increase compared to the case voth no physics m the model.