利用GRACE时变重力数据推算日长变化

VARIATIONS OF LOD INFERRED FROM TEMPORAL GRACE GRAVITY DATA

讨论了月时变二阶位系数对地球主惯性矩、主惯性轴以及日长变化的影响,利用小波分析方法处理了GRACE月平均重力场的二阶位系数,消除了数据中的突跳和噪声。对比了基于处理前和处理后的二阶系数所得到的地球主惯性矩和主惯性轴,且基于处理后的数据给出了日长变化。计算结果表明,与月时变地球主惯性矩和主惯性轴相关的地球系统的质量迁移使得日长在近6年内有所缩短。

The impacts of the temporal second-order potential coefficients on the Earth＇ s principal axes and moments of inertia as well as variations of length of day （LOD） are studied. By using the wavelet analysis and adoption the monthly-averaged GRACE gravity model, the second-order potential coefficients were processed and the jumps and noises presented in these data were removed. After comparing the Earth＇ s principal axes and moments of inertia obtained from the processed with those from the non-processed coefficients, the associated variations of LOD were obtained based on the processed data. Numerical calculation results show that the mass redistribution related to the monthly temporal principal axes and moments of inertia could lead to a decreasing tendency of LOD during the recent 6 years.