地球及其形状非对称性的重力学研究  

Asymmetry of the Earth and Its Shape by Gravity Method

作　　者：方剑[1] 马宗晋[2] 

机构地区：[1]中国科学院测量与地球物理研究所 [2]中国地震局地质研究所,北京市祁家豁子100029

出　　处：《武汉大学学报（信息科学版）》2005年第8期748-751,共4页Geomatics and Information Science of Wuhan University

基　　金：国家自然科学基金资助项目(49834002);地球空间环境与大地测量教育部重点实验室基金资助项目。

摘　　要：依据卫星重力、大地水准面观测结果,对表示地球形状的大地水准面异常进行了不同阶次的球谐函数计算和分析,发现2～6阶大地水准面异常表现出了地球双重非对称的基本形状,而高于6阶的大地水准面异常只表示了地球形态的局部变化特征.另外,采用阻尼最小二乘方法,利用全球地震层析成像资料和大地水准面异常资料联合反演了三维全球地幔密度异常.结果显示了地幔密度异常不仅在横向上,而且在纵向上也存在着明显的不均匀性.对比分析低阶大地水准面异常和地幔密度异常结果表明,地球形状非对称性主要是由下地幔的物质密度不均匀引起的.Based on satellite gravity and geoid observation results, we calculated and analyzed different order and degree of harmonic function ofgeoid, which can express earth shape. It is found that 2-6 degree geoid anomaly shows the fundamental shape of earth shape asymmetry, and geoid anomaly of more than 6 degree only shows the local undulation character of the earth shape. Moreover, The authors inverted three dimensional global mantle density anomaly combining geoid data and seismic tomography data by means of damping least square method. The density anomaly result shows that mantle density is obviously inhomogeneity not only in horizontal direction, but also in radial direction. Comparing low degree geoid anomaly with mantle density anomaly, The authors think the earth shape asymmetry is mainly caused by lower mantle density inhomogeneity.

关 键 词：大地水准面 地震层析成像 地幔密度异常 地球形状 非对称性 

分 类 号：P227[天文地球—大地测量学与测量工程] P223[天文地球—测绘科学与技术]