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Weather Forecast

Global climate numerical simulation consists of atmosphere mode, ocean mode, land mode and sea ice mode. Atmospheric model accounts for the main computation time. The shallow water wave equations are partial differential equations of hyperbolic conservation and it is the most basic atmospheric dynamics equations. The scalable algorithm research is very important.

NSCC-TJ cooperated with the Institute of Software to test the self-developed program on TH-1A named the fully implicit numerical simulation program. Through using as many CPU cores as possible (up to 82,944 cores), we carried out the strong/weak scalability test and try a scale of tens of billions of grid. The test uses isolated mountain example from Williamson standard test set. Computing grid retain unchanged in the strong scalability test and more CPU cores, less computational consumption. A strong scalability test results are shown in Figure 1, the program increased from the 4608 cores to 82944 cores and the parallel efficiency is about 60%. In the Weak scalability test, we fixed on each CPU computing grid size and time step: if we adopt an explicit algorithm and the stability conditions restricts, the total grid size will increase in response to the CPU cores increase and result in the computational consumption increase at last. A fully implicit method, with the CPU core number from 36 to 57 600 (1600 times), calculate steps will not be changed and the computation time rise in slowly because of the complexity of the algorithm (about 6.3-fold), shown in Figure 2.

Fig.1 Strong scalability test results
Fig.2 Weak scalability test results

Isolated mountain selected from Williamson standard test set, Figure 3 shows the simulation results on the 15th days of pressure distribution.

Fig.3 Isolated mountain test example

 

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