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.重力数据可用于探测地球表层下方岩石密度变化所引发的微小重力场扰动。所采集的重力数据需通过标准化流程开展处理，以确保记录到的响应仅由地下岩石的密度变化引起。经处理得到的数据集可用于解译，以揭示地下地质构造。经处理的数据将由GA的地球物理学家进行质量校验，确保GA发布的最终数据满足使用需求。本《2019年国家重力汇编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。该批重力数据采集自项目编号为202008的科研项目。用于生成该影像的网格单元尺寸为0.00417度（约合435米）。该重力异常网格的数据源为截至2019年9月存储于澳大利亚国家重力数据库（Australian National Gravity Database, ANGD）的地面观测数据，并补充了全球重力网格v28.1提供的近海数据；该全球重力网格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（National Oceanic and Atmospheric Administration, NOAA）以及美国国家地理空间情报局（National Geospatial-Intelligence Agency, NGA）的数据，相关数据由加州大学圣迭戈分校斯克里普斯海洋研究所提供。本次网格生成共使用了约180万条重力观测数据，其中包括ANGD数据库内近140万个重力测点数据以及海洋观测数据。用于构建本次国家重力网格的地面重力数据，采集自1940年代至今的澳大利亚联邦、州和领地政府、矿业与勘探行业、高校及科研机构。测点间距范围约为11千米至不足1千米，澳大利亚大陆大部分区域的测点间距介于2.5千米至7千米之间。重力地形校正通过联合近海水深数据与陆上地形数据计算得到。本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分布。一阶垂直导数通过对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执行快速傅里叶变换（fast Fourier transform, FFT）流程计算得到。