Cobar P5009 EXT 2 reduced to pole grid

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 0.00039074 degrees (approximately 40m).The data are in nanoTesla (or nT). The data used to produce this grid was acquired in 2021 by the NSW Government, and consisted of 53617 line-kilometres of data at 200m 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）数据用于表征地壳内造岩矿物成分差异所引起的地球磁场强度变化。依据岩石磁化率的不同，磁异常可分为正异常（磁场强度高于正常背景值）与负异常（磁场强度低于正常背景值）两类。本数据集已通过标准处理流程进行校正，确保记录的响应仅来自地下岩石。经处理后生成的数据集可通过解译揭示地下地质构造。GA地球物理学家已对处理后的数据开展质量核查，确保GA发布的最终数据满足使用需求。该地磁网格的单元尺寸为0.00039074度（约40米），数据单位为纳特（nanoTesla, nT）。本网格所用数据由新南威尔士州政府于2021年采集，总测线长度达53617测线公里，测线间距为200米，观测离地高度为60米。数据已应用可变极化归算（Variable Reduction to the Pole, VRTP），使磁异常中心与磁化体中心对齐。该VRTP处理流程采用差分极化归算方法，计算最高阶数为5阶多项式。磁倾角与磁偏角基于IGRF-11地磁参考模型，结合调查代表性日期与观测高程数据计算得到。