中文摘要：

为了分析地王拉低阶重力场的时变规律，分刖利用GFZ和CSR处理的从2003年到2012年十年间的GRACE卫星数据，对其低阶位系数C20、C2、C22、C30、C40、S21和S22分别构造时间序列并进行时变分析。运用小波分析探测其时间序列的周期特征，发现C20、C21、C22和C40具有明显的周年和半年周期，C30、S21和S22也具有明显的周年周期和不明显的半年周期，GFZ和CSR两者的结果基本一致。利用交叉小波和小波相干谱分析得到GFZ和CSR处理的结果在周年周期内具有很强的相关性，在半年周期内相关性降低。

英文摘要：

In order to analyze changes of the Earth＇s low degree gravity field, we utilize GRACE data from January 2003 to December 2012 obtained from GFZ and CSR respectively to form the independent time series of variations C20、 C21、 C22、 C30、C40、S21 and S22. The Morlet wavelet analysis is used to determine the periods of time series and the results show that the significant semi annual and annual cycles of C20, C21, C22 and C40, and the semi-annual and significant annual cycles of C30,S21 and S22. The GFZ and CSR products have consistent results. We find that the low-degree spherical harmonic coefficients exist the strong correlation in the armual cycle and the decreasing correlation in the semi-annual cycle between GFZ and CSR products by the cross wavelet transform and wavelet coherence.