Satellite-altitude horizontal magnetic gradient anomalies used to define the Kursk Magnetic Anomaly

摘要

The Kursk Magnetic Anomaly (KMA), Russia, is one of the world's largest magnetic anomalies. We used satellite altitude horizontal gradient magnetic anomaly data to study this feature. There are two main objectives of our research; the first, to determine if the technique of the horizontal magnetic anomaly gradient analysis can be applied to CHAMP satellite altitude data to define the outline of the source of the Kursk Magnetic Anomaly(KMA). Another objective is to use the ten years of CHAMP data to reproduce the horizontal magnetic anomaly gradient data that will be measured by the two lower orbiting ESA/Swarm mission. We will be able to evaluate the application of these newer satellite altitude data for studying large areas with significant crustal magnetization. While we have acquired sufficient CHAMP orbital data to compute a horizontal gradient anomaly map from these ten years of data; the future ESA/Swarm missionwill, however, allowus to compute directly the horizontal magnetic anomaly without orbital altitude and/or magnetic secular variations; however the east-west gradient that the Swarm is measuring will minimize, but not eliminate, the difference in external fields between the two lower satellites. One will still need to use relatively quiet data (e.g., K_p<1) for crustal field mapping. Our results, developed frominterpreting the satellite horizontalmagnetic anomaly data, indicate that the source of the KMA is bowl shaped body open to the northwest covering an area of approximately 190,000 km~2.