GSNSW Exploration NSW Area J Cobar Nymagee Part2 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 0.00049 degrees (approximately 50m).The data are in nanoTesla (or nT). The data used to produce this 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. 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.

总磁场强度（Total Magnetic Intensity, TMI）数据用于测量由地壳内造岩矿物成分差异引发的地球磁场强度变化。根据岩石的磁化率差异，磁异常可分为正异常（磁场强度高于正常水平）与负异常（磁场强度低于正常水平）两类。该数据通过标准处理流程开展预处理，确保所记录的响应仅由地下岩石引起。处理后得到的数据集可用于解译，以揭示地下地质结构。经处理的数据已由GA地球物理学家完成质量校验，以确保GA发布的最终数据符合应用要求。该磁网格的单元尺寸为0.00049度（约合50米），数据单位为纳特斯拉（nT）。用于生成该网格的数据由新南威尔士州政府于1999年采集，原始数据包含31212线公里的测量数据，线间距为250米，地形离地高度为60米。该数据已施加变极化归算（VRTP）处理，使磁异常中心位于磁化体的正上方。VRTP处理采用差分极化归算算法，最高可至五阶多项式拟合。磁倾角与磁偏角基于IGRF-11地磁参考模型计算得到，计算时采用了与本次调查匹配的代表性观测日期与海拔数据。