National Gravity Compilation 2019 CSCBA 1VD image

Gravity data measure small changes in gravity due to changes in the density of rocks beneath the Earth's surface. The data collected 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 National Gravity Compilation 2019 CSCBA 1VD image is an image derived from the complete spherical cap Bouguer anomaly grid for the 2019 Australian National Gravity Grids A series. These gravity data were acquired under the project No. 202008. The grid used to create this image has a cell size of 0.00417 degrees (approximately 435m). This gravity anomaly grid is derived from ground observations stored in the Australian National Gravity Database (ANGD) as at September 2019, supplemented with offshore data sourced from v28.1 of the Global Gravity grid developed using data from the Scripps Institution of Oceanography, the National Oceanic and Atmospheric Administration (NOAA), and National Geospatial-Intelligence Agency (NGA) at Scripps Institution of Oceanography, University of California San Diego. Out of the approximately 1.8 million gravity observations, nearly 1.4 million gravity stations in the ANGD, and marine data were used to generate this grid. The ground gravity data used in the national gravity grids has been acquired by the Commonwealth, State and Territory Governments, the mining and exploration industry, universities and research organisations from the 1940's to the present day. Station spacing varies from approximately 11 km down to less than 1 km, with major parts of the continent having station spacing between 2.5 and 7 km. Terrain corrections to gravity were calculated using both offshore bathymetry and onshore topography data. The image shows the first vertical derivative of the complete Bouguer anomalies over Australia and its continental margins. A first vertical derivative was calculated by applying a fast Fourier transform (FFT) process to the complete spherical cap Bouguer anomaly grid of the 2019 Australian National Gravity Grids A series.重力数据用于监测因地球表层下方岩石密度变化引发的微小重力场变化。所采集的数据将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的影响。处理后得到的数据集可通过解译，揭示地下地质构造特征。经处理的数据将由GA地球物理学家开展质量核查，以确保GA发布的最终数据符合使用要求。本次发布的《2019年国家重力编图CSCBA 1VD影像》，源自2019年澳大利亚国家重力网格A系列的完整球冠布格异常网格。该重力数据采集自项目编号202008的相关工作。生成该影像所用的网格单元尺寸为0.00417度（约435米）。该重力异常网格的数据来源为截至2019年9月存储于澳大利亚国家重力数据库（ANGD）的地面观测数据，并补充了源自全球重力网格v28.1的海洋数据；全球重力网格v28.1的构建使用了斯克里普斯海洋研究所、美国国家海洋和大气管理局（NOAA）以及美国国家地理空间情报局（NGA）的相关数据，相关数据由加利福尼亚大学圣迭戈分校斯克里普斯海洋研究所提供。在总计约180万条重力观测数据中，本次网格构建使用了ANGD中近140万个重力测点数据与海洋观测数据。本次国家重力网格所使用的地面重力数据，采集时段跨越1940年代至今，数据来源包括联邦、州及领地政府、矿业与勘探行业、高校及科研机构。测点间距范围约11公里至不足1公里，澳大利亚大陆大部分区域的测点间距介于2.5公里至7公里之间。重力地形校正计算结合了海洋水深数据与陆域地形数据。该影像展示了澳大利亚及其大陆边缘区域完整布格异常的一阶垂直导数结果。一阶垂直导数的计算通过对2019年澳大利亚国家重力网格A系列的完整球冠布格异常网格应用快速傅里叶变换（FFT）流程实现。