Magnetic Anomaly Map of Australia, Seventh Edition, 2020 - Enhanced Products Package - upward continued grid UC12km16kmRes (UC12km16kmRes)

Total magnetic intensity (TMI) data measures variations in the intensity of the Earth's 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 data are processed via standard methods to ensure the response recorded is that due only to the rocks in the ground. The results produce datasets that can be interpreted to reveal the geological structure of the sub-surface. The processed data is checked for quality by GA geophysicists to ensure that the final data released by GA are fit-for-purpose.This magnetic grid has a cell size of 0.00083 degrees (approximately 88m).The data are in nanoTesla (or nT). It is estimated that 33 500 000 line-kilometres of survey data collected by State and Territory geological surveys and Geoscience Australia were acquired to produce the 2019 national magnetic grid. The data has had a variable reduction to the pole applied to centre the magnetic anomaly over the magnetised body. The VRTP processing followed a differential reduction to pole calculation up to 5th order polynomial. Magnetic inclination and declination were derived from the IGRF-15 geomagnetic reference model using a data representative date and elevation representative of the survey. The upward continuation manipulates the magnetic data to enhance the large deep source anomalies and minimises shallow anomalies. To constrain long wavelengths in the grid, an independent data set, the Australia-wide Airborne Geophysical Survey (AWAGS) airborne magnetic data, was used to control the base levels of the survey grid. This survey grid is essentially levelled to AWAGS.

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发的地球磁场强度变化。磁异常可分为正异常（磁场强度高于正常水平）与负异常（磁场强度低于正常水平），其类型取决于岩石的磁化率。该数据通过标准方法开展处理，以确保所记录的响应仅源于地下岩石。经处理后得到的数据集可通过解译揭示地下地质构造。经过处理的数据会由（Geoscience Australia, GA）地球物理学家进行质量核查，以确保GA发布的最终数据符合使用要求。该磁网格的单元尺寸为0.00083度（约88米），数据单位为纳特斯拉（nanoTesla, nT）。据估算，为构建2019年国家磁网格，共采集了由各州及领地地质调查机构与澳大利亚地质科学局收集的3350万测线公里的调查数据。该数据已施加变向化极（Variable Reduction to the Pole, VRTP）处理，以使磁异常中心位于磁化体上方。此次VRTP处理采用了最高至5阶多项式的微分化极计算方法。磁倾角与磁偏角由IGRF-15地磁参考模型推导得出，所用数据的代表年份与高程均匹配该调查项目的实际情况。向上延拓处理可对磁数据进行操作，以增强深部大型源磁异常并削弱浅部异常。为约束网格中的长波长分量，我们采用独立数据集——全澳航空地球物理调查（Australia-wide Airborne Geophysical Survey, AWAGS）航空磁数据——来控制测网的基准面。该测网基本已依据AWAGS数据完成平差处理。