大地水准面起伏对地球内部密度结构反演的影响

EFFECT OF GEOID UNDULATION ON INVERSION OF DENSITY STRUCTURES OF THE EARTH

计算了中国大陆地区大地水准面起伏引起的重力效应,得到了改正后的布格重力异常。讨论了在不同地形情况下大地水准面起伏重力效应及其与布格重力异常之间的相对比值,发现两者与地形具有明显的相关性,前者在盆地地区最大,后者在我国地形第三阶梯最大,盆地地区次之。建议在利用布格重力异常反演和解释地球内部密度结构时,要考虑大地水准面起伏引起的重力效应,尤其是在我国地形第三阶梯和盆地地区。

Difference between geoid and reference ellipsoid called geoid undulation. Bouguer gravity anomalies are widely used in density inversion,however,the effects of geoid undulation on gravity were not considered in traditional gravity corrections during the calculation of bouguer gravity. Effects of geoid undulation on gravity were calculated,and bouguer gravity anomalies under consideration of the effects were obtained,as well as,the gravity effects and its relative ratios to bouguer anomalies were analyzed. The results indicate that both of them is coherent with terrain distributions,the largest effects of geoid undulation on gravity locate in basins while the largest relative ratios locate in the third terrain ladder of China mainland. It is suggested that the gravity effects of geoid undulation should be considered when bouguer gravity anomalies were used to invert and interpret density structures,especially in the third terrain ladder of China mainland and basin areas.