Estimation method for field source location in the presence of strong remanent magnetization in low-latitude regions

Abstract

Normalized source strength (NSS) is often applied to interpret magnetic anomalies due to its low sensitivity to magnetization direction. However, when calculating NSS, it is usually necessary to calculate the magnetic potential based on the direction of the geomagnetic field. Similar to the reduction-to-the-pole method routinely computed in the wavenumber domain, NSS is unstable at low latitudes. Therefore, we proposed a new method called the low-latitude normalized source strength (LLNSS); with this approach, the NSS is calculated using the magnetic anomaly instead of the magnetic potential. This approach expands the range of application of the NSS method. The proposed method does not depend on the direction of the geomagnetic field, making it suitable for processing and interpreting magnetic data in the presence of strong residual magnetization, particularly in low-latitude areas. This method was tested on both synthetic and field datasets. Comparative model test results showed that our algorithm had better calculation stability, lower magnetization direction sensitivity, and stronger field-source positioning ability. Real data processing results further validated the effectiveness and practicality of our method.