Analysis on the Time-lag Correlation for the Changes of the Length of the Day and Geomagnetic Field

Two data sets including the historical geomagnetic field model and the length of the day are used to analyze the correlation characteristics of the geomagnetic field variation and the changes in the length of the day from 1840~2000.The results show that a lag correlation is available in the changes of geomagnetic field and the length of the day.The geomagnetic intensity parameter is approximately exceeding LOD by 7.5~10a (year).However the geomagnetic western drift parameters lag behind LOD variation, the western drift components ??? and ??? lag behind LOD by 7.5a, the average drifting speed and the latitudinal drifting components of the geomagnetic field lag behind LOD by 20~22.5a.