高空正常地磁场在航磁编图中的应用

在研究磁异常时,习惯将正常地磁场从测得的地磁场值中消除,以便突出上地幔和地壳内的各种磁异常。正常地磁场的选择正确与否,直接影响到人们对磁异常的认识及地质现象的研究。对于大面积的航空磁测编图,正常地磁场的选择尤为重要。

THE APPLICATION OF THE HIGH-ALTITUDENORMAL GEOMAGNETIC FIELD TO AEROMAGNETICMAP COMPILATION

This paper presents the encouraging result obtained in the first application of the high-altitude normal geomagnetic field calculated from aeromagnetic data to aeromagnetic map compilation for the alpine region. The test by available data has demonstrated that the high-altitude normal geomagnetic field calculated from aeromagnetic data has precision higher than that of the surface normal geomagnetic field. In compiling ATanomalous maps, the utilization of high-altitude normal geomagnetic field correction remarkably improves the variation of the regional magnetic fields and the manifestation of the local magnetic anomalies.Based on a comparison between the high-altitude and the surface normal geomagnetic fields, the author argues that annual variation and difference in height between calculation sites are major factors responsible for the differences between two sorts of normal geomagnetic fields. He also summarizes the means as well as some experience gained for applying normal geomagnetic fields of diverse ages in extensive aeromagnetic map compilation, and proposes a scheme for establishing the nationwide normal geomagnetic field by means of surveyed aeromagnetic values.