GSNSW Exploration NSW Area K Peel magnetic rtp grid geodetic

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 0.00048 degrees (approximately 50m).The data are in nanoTesla (or nT). The data used to produce this grid was acquired in 1998 by the NSW Government, and consisted of 61165 line-kilometres of data at 250m line spacing and 60m terrain clearance. 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-11 geomagnetic reference model using a data representative date and elevation representative of the survey.

总磁强度（Total Magnetic Intensity, TMI）数据用于测量地壳中造岩矿物含量差异所引起的地球磁场强度变化。磁异常可根据岩石磁化率分为正异常（磁场强于正常值）或负异常（磁场弱于正常值）。数据通过标准方法处理，以确保记录的响应仅来源于地下岩石。处理结果生成的数据集可通过解译揭示地下地质结构。GA的地球物理学家会对处理后的数据进行质量检查，确保GA发布的最终数据满足使用需求。

该磁网格的单元格大小为0.00048度（约50米），数据单位为纳特斯拉（nT）。生成此网格所用的数据由新南威尔士州政府（NSW Government）于1998年采集，包含61165测线公里，测线间距250米，飞行高度60米。数据已采用可变化极（Variable Reduction to the Pole, VRTP）处理，使磁异常中心与磁化体重合。VRTP处理遵循高达5阶多项式的差分化极计算方法。磁倾角和磁偏角是利用该调查的典型日期和高程数据，从国际地磁参考场11代模型（International Geomagnetic Reference Field, IGRF-11）中推导得出的。