Total Magnetic Intensity Grid of Australia 2019 - seventh edition - 80 m

Total magnetic intensity (TMI) data measures variations in the intensity of the Earth magnetic field caused by the contrasting content of rock-forming minerals in the Earth crust. Magnetic anomalies can be either positive (field stronger than normal) or negative (field weaker) depending on the susceptibility of the rock. The 2019 Total magnetic Intensity (TMI) grid of Australia has a grid cell size of ~3 seconds of arc (approximately 80 m). This grid only includes airborne-derived TMI data for onshore and near-offshore continental areas. Since the sixth edition was released in 2015, data from 234 new surveys have been added to the database, acquired mainly by the State and Territory Geological Surveys. The new grid was derived from a re-levelling of the national magnetic grid database. The survey grids were levelled to each other, and to the Australia Wide Airborne Geophysical Survey (AWAGS), which serves as a baseline to constrain long wavelengths in the final grid. It is estimated that 33 500 000 line-kilometres of survey data were acquired to produce the 2019 grid data, about 2 000 000 line-kilometres more than for the previous edition.

总磁场强度（Total Magnetic Intensity, TMI）数据用于测量由地壳内造岩矿物成分差异所引起的地球磁场强度变化。磁异常可分为正异常（磁场强度高于正常值）与负异常（磁场强度低于正常值），具体取决于岩石的磁化率。2019年澳大利亚总磁场强度网格的网格单元尺寸约为3角秒（约80米），该网格仅涵盖陆上及近岸大陆区域的航空测量总磁场强度数据。自2015年第六版发布以来，数据库已新增234项新勘测数据，这些数据主要由澳大利亚各州及领地地质调查局采集。新版网格是通过对国家磁场网格数据库进行重新平差得到的，各勘测网格之间以及与作为基线的全澳航空地球物理勘测（Australia Wide Airborne Geophysical Survey, AWAGS）完成了平差，以此约束最终网格中的长波长分量。据估算，为生成2019版网格数据，共采集了3350万测线公里的勘测数据，较前一版本增加约200万测线公里。