GSWA P1177 Katanning 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 GSWA P1177 Katanning TMI grid geodetic has a cell size of 0.00083 degrees (approximately 85m). The units are in nanoTesla (or nT). The data used to produce this grid was acquired in 2008 by the WA Government, and consisted of 75805 line-kilometres of data at a line spacing between 100m and 400m, and 60m terrain clearance.总磁强度（Total Magnetic Intensity, TMI）数据用于量化地壳中成岩矿物成分差异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。该数据通过标准流程进行处理，以确保记录的磁场响应仅由地下岩石引起。处理后得到的数据集可通过解译揭示地下地质结构。经处理的数据会由GA地球物理学家开展质量校验，以确保GA发布的最终数据符合使用要求。本GSWA P1177 Katanning TMI大地测量栅格的单元尺寸为0.00083度（约85米），数据单位为纳特斯拉（nanoTesla，简称nT）。用于生成该网格的数据由西澳大利亚州政府于2008年采集，总测线长度达75805线公里，测线间距介于100米至400米之间，地形离地高度为60米。