重磁位场的正则化向下延拓

A NEW NORMALIZED METHOD OF DOWNWARD EXTRAPOLATION FOR POTENTIAL FIELD

传统的位场向下延拓方法，在下延至场源体顶面深度附近区域，位场将发生强烈的振荡效应，无法继续向下延拓，难以用空间位场特征确定场源体的深度等特征，当然更无法划分出垂向迭加体。本文讨论了一种新的正则化方法：利用引入位场频率，埋深与正则化因子等有关的校正函数。使得向下延拓过场源体时，场值不奇异。因此，可以达到场源体以下任意需要的深度。理论场和实测资料的正则化向下延拓成果表明，本方法能有效地反映出场源体的深度等特征，也能较准确地划分出具有垂向与水平迭加的单个场源体。

By using the traditional method of downward extrapolation, the potential field would be amplified in an oscillatory style at the top of the source body and the calulation process would present a kind of divergence. So the extrapolated field can not represent the real field distribution, especially under the condition of vertical superposition of many source bodies. In the new normalization algorithm, a correction function has been introduced into the normalized factor which is related to the depths of source bodies and frequency characteristics of the potential field. When an extrapolation level reaches the top of the source body, the singularity of the calculated field does not appear and the extrapolation process can be proceeded in the whole half space under the observable surface. Some tests for the oretical field data sets and observed field data sets indicate that the new normalized method will lead to a real representation of the potential field in the whole half space under the observable surface and can be used in determining the vertical distribution of source bodies.