数值模式预报时效对计算精度和时间步长的依赖关系

A Study on the Dependency of Maximum Prediction Time on Computation Precision and Time Step-size in Numerical Model

通过数值计算研究Lorenz非线性动力系统,探讨了非线性动力系统中初值问题的解对时间步长和计算精度的依赖关系,从新的角度研究动力系统的预报时效问题,讨论了评价舍入误差对预报时效影响程度的方法。实验结果表明:动力系统的预报时效不仅与初值误差有关,而且在一定条件下敏感地依赖于计算采用的时间步长和计算精度。

Some dependencies on machine precision and step-size in float calculation of nonlinear dynamical system initial value question with errors are studied by using of multiple precision method for the Lorenz nonlinear equations. When using certain float point precision in computation the intrinsic maximum effective computation time can be used to study the maximum prediction time in atmospheric science. A method based on multiple precision computing to evaluate and extend the nonlinear dynamic system＇s maximum prediction time is presented. From the result we found that the predictability time is not only depend on initial error but also sensitive to the precision and the time step-size used in the computation.