1980～2013年二阶重力场球谐系数变化研究

Second-Degree Spherical Harmonic Gravity Changes from 1980 to 2013

基于重力场系数与极移和日长变化（LOD）之间的相互关系,计算1980～2013年二阶重力场系数变化（ΔC21、ΔS21）,并将其与人卫激光测距（SLR）的结果进行比较分析。结果表明,两者的变化趋势一致。SLR解算的ΔC20存在6a变化的周期信号,但其振幅只是LOD中6a信号的1/10,表明LOD中的6a信号不是由大气、海洋、陆地水等地球动力学过程所激发的,现在还无法确定其激发机制。

Based on the function relationship between gravity coefficient and the Earth orientation parameters（EOP）,we estimate second-degree spherical harmonic gravity changesΔC21andΔS21from1980to 2013.Comparison of theΔC21andΔS21 provided by SLR,shows that they agree well with each other.Moreover,we find a 6-year periodicity exists inΔC20provided by SLR.Otherwise the amplitude is just 1/10,as compared with the 6-year signal of LOD.This indicates that the 6-year periodicity of LOD is not excited by the atmospheric and oceanic hydrologic motion and the Earth＇s body,although the exact mechanisms are still not understood.