Comparison of the influences of initial error and model parameter error on the predictability of numerical forecast
初始误差和参数误差对混沌系统可预报性影响的比较

Based on the nonlinear error growth dynamics introduced by the authors recently,the influences of initial error and model parameter error on the Lorenz system's predictability are studied.The major results are summarized as follows:(i)When there is initial error only or model parameter error only in the Lorenz system,the error growth and predictability limit are comparable between two kinds of error problems.This result holds basically for the wide range of parameter space of Lorenz system.(ii)When initial error and model parameter error coexist in the Lorenz system,the influences of initial error and model parameter error on the predictability of Lorenz system depend on their relative sizes.When the size of initial error is far greater than that of model parameter error,the predictability limit of Lorenz system is mainly determined by initial error.On the contrary,when the size of model parameter error is far greater than that of initial error,the predictability limit of Lorenz system is mainly determined by model parameter error.When the size of initial error is close to that of model parameter error,they both contribute to the predictability limit of Lorenz system.These results indicate that when numerical weather forecast is made,we should pay great attention to the determination of model parameter, not just the determination of initial condition.