球冠谐分析法与直接解拉普拉斯方程法重力异常转换效果对比

Comparison of gravity transformation methods through spherical cap harmonic analysis and solving-Laplace’s-equation-directly

在重力异常转换计算过程中,当观测区域面积巨大时,须考虑地球曲率的影响.本文作者以球冠谐分析法和直接解拉普拉斯方程法为例,通过模型试验和实测数据处理详细对比了球面位场转换和平面位场转换的效果,并取得以下认识:(1)对于简单模型,球冠谐分析法的转换结果优于直接解拉普拉斯方程法,而后者具有明显的边界效应;(2)对于稍复杂的模型,球冠谐分析法会表现出显著的峰值衰减和幅度很小的周期性震荡;(3)应用于实测数据时,两种方法均表现出严重的分辨率损失,尽管球冠谐分析法的分辨率要高一些.

In the process of gravity anomaly transformation, the influence of earth curvature should be considered when the observation area is very large. Taking spherical cap harmonic analysis method and solving-Laplace’s-equation-directly method as examples, the authors compared in details, through model tests and real data processing, the performances of spherical and plane field transformations, and attained the following conclusions:(1)For very simple model, spherical cap harmonic analysis method is superior to solving-Laplace’s-equation-directly method, while the latter presents heavy boundary effect;(2)When applied to a more complex model, the results by spherical cap harmonic analysis method present notable peak attenuations and oscillations of very low amplitude;(3)Both methods present serious resolution losses when applied to real data, even if the spherical cap analysis method has higher resolution.