给出基于Ls+AR模型的日长变化(LOD)预报方法,探讨周期项对LOD预报精度的影响,对LOD中不同周期项组合的预报精度进行分析。计算结果表明,在LOD的预报中,除周年、半周年项外,18.6年和9.3年长期周期项、三分之一周年短周期项对预报精度的影响亦较大,顾及这几项的误差影响,可大大提高预报精度。
After reviewing the prediction of LOD based on the LS + AR model, the influence of different cycle term on prediction accuracy is analyzed by using different combination of the main cycle terms. The results showthat long-term cycles of 18.6-year and 9.3-year, the short-term cycle of one-third year have great impact on LOD prediction accuracy. Therefore, it is recommended that the above three cycle terms should be taken into account in high-accuracy LOD prediction except for annual and semi-annual cycle terms.