摘要
将起伏地形上的测点垂直投影至水平面上,并将地形上的位场u放在水平面的对应点上,这样就有一个平面上的假想位场u。用快速傅立叶变换（FFT）计算平面位场的垂向导数 u/ n,将这个垂向导数移至地形的对应点上,近似作为地形上的位的垂向导数 u/ n。根据Green公式,从地形上的位u和位的法向导数 u/ n,用积分的方法可计算地形上部任一点的位。在计算出地形上部一个平面上的位后,可用FFI迅速计算其它平面的位,包括与地形相交的平面上的位。在通常的位场延拓方法中,如用等效源法解一个线形代数方程组要需用很大内存量,要耗去大量计算时间。本方法的主要特点是省略了解线形代数方程组的步骤,从而大大节约计算时间。模型计算表明,本方法的计算精度是令人满意的。用本方法对航磁实际资料进行延拓,取得较好的效果。
Vertically projecting the observation point at a undulate terrain onto a horizontal plane and copying the potential u at the terrain to the corresponding point at the horizontal plane, we get a fictitious potential field on a horizontal plane. An FFT is then can applied to calculate the outward normal derivativ u/ n of the potential u on the horizontal plane. The calculated derivativeis u/ n is used approximately as the outward normal derivativeof u/ n of the potential u on the terrain. Based on the potential u and the normal derivativeon the terrain, Green's formula is used to calculate the potential u at an arbitrary point above the terrain. When the potential u at a level above the terrain is obtained, an FFT is used again to calculate the potential u at other level above the sources of the potential. The other method of continuation of potential field, e.g., the equivalent source method, requires solving a large set of linear algebraic equations that take a hefty amount of computer memory and expends considerably the computation time. This method does not require solving algebraic equations and is of a high computation speed. The model tests demonstrated that the accuracy of this method is satisfactory. Using this method to continue the practical aeromagnetic anomaly shows a good result.
出处
《高校地质学报》
CAS
CSCD
2002年第3期241-247,共7页
Geological Journal of China Universities
关键词
位场
曲面延拓
地形
重力场
磁场
快速傅立叶变换
等效源法
potential field
continuation between general surfaces
terrain correction for magnetic data
