Yearly data of the length of day ( ALOD ) from 1800 were analysed by means of a narrow band filter , and the time-varying components with various frequencies were obtained .
本文用窄带滤波器处理了1800年以来的日长变化（△LOD）的年均值序列，得到在十年尺度上的各频率分量的时变过程。
alod