GSQ Southern Bowen Basin Qld magnetic rtp vd1 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 GSQ Southern Bowen Basin Qld magnetic rtp vd1 grid geodetic is the first vertical derivative of the TMI RTP grid of the Southern Bowen Basin, Qld, 2004 survey.This grid has a cell size of 0.001 degrees (approximately 106m) , and given in units of nT per metre (nT/m). The data used to produce the TMI grid was acquired in 2004 by the QLD Government, and consisted of 74554 line-kilometres of data at 400m line spacing and 80m 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. A first vertical derivative was calculated by applying a fast Fourier transform (FFT) process to the TMI RTP grid of the Southern Bowen Basin, Qld, 2004 survey to produce this grid. This grid was calculated using an algorithm from the INTREPID Geophysics software package. This grid shows the magnetic response of subsurface features with contrasting magnetic susceptibilities. The grid can also be used to locate structural features such as dykes.

总磁场强度（Total Magnetic Intensity, TMI）数据可用于表征由地壳中成岩矿物成分差异所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），具体取决于岩石的磁化率。该数据集通过标准流程进行处理，以确保记录的响应仅源自地下岩石。处理后得到的数据集可通过解译揭示地下地质结构。由GA地球物理学家对处理后的数据开展质量检查，以确保GA发布的最终数据符合使用要求。本次的GSQ昆士兰州南部博文盆地磁法化极一阶垂直导数大地测量网格（GSQ Southern Bowen Basin Qld magnetic rtp vd1 grid geodetic），是2004年针对昆士兰州南部博文盆地采集的TMI化极（Reduction to Pole, RTP）网格的一阶垂直导数数据。该网格的单元格大小为0.001度（约合106米），单位为纳特每米（nT/m）。用于生成TMI网格的原始数据由QLD政府于2004年采集，总测线长度达74554线千米，测线间距为400米，地形离地高度为80米。该数据已完成可变化极（Variable Reduction to Pole, VRTP）处理，使磁异常中心位于磁化体上方。VRTP处理采用了最高至5阶多项式的差分化极计算方法。磁倾角与磁偏角源自IGRF-11地磁参考模型，其参数选取匹配本次测量的代表性日期与高程。本网格通过对2004年昆士兰州南部博文盆地TMI RTP网格应用快速傅里叶变换（Fast Fourier Transform, FFT）算法计算得到一阶垂直导数。本次网格计算采用了INTREPID Geophysics地球物理软件包中的算法。该网格可表征具有不同磁化率的地下地质体的磁响应特征。此外，该网格还可用于识别岩脉等构造特征。