GSNSW Exploration NSW Area M Kayrunnera 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 0.00048 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 55448 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）数据用于表征由地壳中成岩矿物组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），其分类取决于岩石的磁化率。本数据集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。经处理后得到的数据集可用于解译，以揭示地下地质构造。经处理后的数据会由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。该磁场网格的单元尺寸为0.00048度（约50米），数据单位为纳特斯拉（nanoTesla, nT）。用于构建该网格的数据由新南威尔士州（New South Wales, NSW）政府于1999年采集，总测线长度达55448千米，测线间距为250米，地形离地高度为60米。已对该数据施加可变极化归（Variable Reduction to the Pole, VRTP）处理，使磁异常中心对准磁化体上方。该VRTP处理采用差分极化归算方法，最高可至5阶多项式拟合。磁场倾角与偏角源自IGRF-11国际地磁参考场（International Geomagnetic Reference Field-11, IGRF-11），其参数选取与本次测量的代表性日期及高程相匹配。