地形—均衡补偿重力、大地水准面异常频谱分析

Frequency analyze of topography-isostasy compensative gravity and geoid anomaly

将地形高、地球内部质量异常以及重力、大地水准面展开成球谐级数,依据岩石圈弹性挠曲均衡补偿理论建立地形—均衡补偿重力、大地水准面异常的球谐级数表达式.由此可以研究地形—均衡补偿重力、大地水准面异常与球谐级数阶次的关系,以及不同波长地形荷载与岩石圈挠曲补偿的关系,探讨地形—均衡补偿重力、大地水准面的频谱特性.从观测大地水准面异常和自由空气重力异常扣除地形—均衡补偿大地水准面、重力异常,可以得到均衡大地水准面异常和均衡重力异常.均衡大地水准面异常已经消除了浅层物质不均匀的影响,反映的是地球深部物质密度不均匀分布.均衡重力异常显示出中短波长特性,反映的是地壳上地幔物质分布的失衡和物质调整的动力学特征.

Expending geography, earth interior mass, gravity and geoid into sphere harmonic series, we establish topography-isostasy compensation gravity and geoid sphere harmonic series expression according to isostatic compensation theory of lithospheric flexibility. Thus, we can the relation between topography-isostasy compensative gravity, geoid and order and degree of sphere harmonic series and topography wavelength. Deducted topography-isostasy compensation gravity, geoid anomalies from observed free air gravity and geoid anomalies, isostatic gravity anomaly and isostatic geoid anomaly could be obtained. Isostatic geoid anomaly eliminates the gravity effect of shallow mass. Isostatic geoid anomaly reflects inhomogenity of earth deep mass distribution. Isostatic gravity anomaly shows middleshort wavelength character, reflects mass distribution imbalance and mass adjust dynamical character in crust and upper-mantle.