GSNSW Exploration NSW Area J Cobar Nymagee magnetic first vd 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 Exploration NSW Area J Cobar Nymagee magnetic first vd grid geodetic is a first vertical derivative of the Total Magnetic Intensity grid for the GSNSW Exploration NSW Area J, Cobar-Nymagee merge, 1999.This grid has a cell size of 0.00049 degrees (approximately 50m). The grid has units of nanoTesla per km (or nT/km). The data used to produce the TMI grid was acquired in 1998 by the NSW Government, and consisted of 70181 line-kilometres of data at 250m line spacing and 60m terrain clearance. A Fast Fourier Transform (FFT) process was applied to the original grid to calculate the first vertical derivative grid.总磁场强度（Total Magnetic Intensity, TMI）数据用于表征地壳内造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）两类，具体取决于岩石的磁化率。该数据通过标准化流程进行处理，以确保记录的响应仅源于地下岩石。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验，以确保GA发布的最终数据符合使用要求。本次提供的GSNSW勘探新南威尔士州J区块科巴-尼马吉（Cobar-Nymagee）合并区地磁一阶垂直导数网格数据（1999年版），为1999年GSNSW勘探新南威尔士州J区块科巴-尼马吉合并区总磁场强度网格的一阶垂直导数结果。该网格的单元尺寸为0.00049度（约合50米），单位为纳特斯拉每千米（nT/km）。用于生成该总磁场强度网格的数据由新南威尔士州政府于1998年采集，共计70181测线千米，测线间距为250米，地形离地高度为60米。研究人员通过快速傅里叶变换（Fast Fourier Transform, FFT）算法对原始网格进行处理，以计算得到该一阶垂直导数网格。