GSNSW Exploration NSW Area J Cobar Nymagee Part2 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 Part2 magnetic first vd grid geodetic is a first vertical derivative of the Total Magnetic Intensity grid for the Cobar-Nymagee Part 2, NSW, 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 1999 by the NSW Government, and consisted of 31212 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）数据可量化表征地壳中成岩矿物成分差异所引发的地球磁场强度变化。根据岩石磁化率的差异，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。该数据集通过标准流程开展预处理，以确保所记录的磁场响应仅源自地下岩石。经处理得到的数据集可通过解译揭示地下地质构造。预处理后的数据会由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。本次发布的GSNSW Exploration NSW Area J Cobar Nymagee Part2磁学一阶垂直导数大地测量网格，系1999年新南威尔士州Cobar-Nymagee第二分区总磁场强度网格的一阶垂直导数数据。该网格单元尺寸为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1999年采集，包含总长31212测线千米的实测数据，测线间距为250米，航空测量地形离地高度为60米。研究人员通过快速傅里叶变换（Fast Fourier Transform, FFT）对原始网格进行处理，以计算得到该一阶垂直导数网格。