GSNSW Grafton Tenterfield TMI 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 GSNSW Grafton Tenterfield TMI Grid Geodetic has a cell size of 0.0005 degrees (approximately 52m). The units are in nanoTesla (or nT). The data used to produce this grid was acquired in 2011 by the NSW Government, and consisted of 100488 line-kilometres of data at 250m line spacing and 60m terrain clearance.总磁场强度（Total Magnetic Intensity, TMI）数据用于衡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。本数据集采用标准流程进行处理，以确保所记录的响应仅源自地下岩石。经处理后得到的数据集可通过解译揭示地下地质构造。经处理的数据会由GA地球物理学家开展质量核查，以确保GA发布的最终数据符合使用要求。本GSNSW格拉夫顿-滕特菲尔德TMI大地测量网格的单元格大小为0.0005度（约52米），数据单位为纳特斯拉（nanoTesla, nT）。用于生成该网格的数据由新南威尔士州政府于2011年采集，包含100488线公里的观测数据，测线间距为250米，地形离地高度为60米。