National Gravity Compilation 2019 includes airborne tilt 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 includes airborne tilt image is derived from the 2019 Australian National Gravity Grids B series. These gravity data were acquired under the project No. 202008. The national grid 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. Airborne gravity and gravity gradiometry data were also included to provide better resolution to areas where ground gravity data was not of a suitable quality. Out of the approximately 1.8 million gravity observations, nearly 1.4 million gravity stations in the ANGD together with Airborne Gravity surveys totaling 345,000 line km and 106,000 line km of Airborne Gravity Gradiometry were used to generate this grid. The ground gravity data used in this grid 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. Airborne surveys have a line spacing ranging from 0.5 km to 2.5 km. Terrain corrections to gravity were calculated using both offshore bathymetry and onshore topography data. The image shows the tilt filter of the complete Bouguer anomalies (B series) over Australia and its continental margins.

重力数据用于测量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流程处理，以确保记录的重力响应仅由地下岩石引起。处理后得到的数据集可通过解译揭示地下地质构造。经GA地球物理学家开展质量核查，确保GA发布的最终数据符合使用要求。
本次2019年国家重力汇编所包含的航空倾斜图像，源自2019年澳大利亚国家重力网格B系列。该批重力数据依托项目编号202008采集获取。该国家网格的单元尺寸为0.00417度（约合435米）。该重力异常网格源自截至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，并辅以全球重力网格v28.1的近海数据；全球重力网格v28.1的构建使用了来自斯克里普斯海洋研究所（Scripps Institution of Oceanography）、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。此外还纳入航空重力与重力梯度数据，以提升地面重力数据质量欠佳区域的解译分辨率。本次网格构建共使用约180万条重力观测数据，其中包括ANGD内近140万个重力测点，以及总长34.5万千米的航空重力测量数据与10.6万千米的航空重力梯度测量数据。本网格所用的地面重力数据，采集自20世纪40年代至今的联邦、州和领地政府、矿业与勘探行业、高校及科研机构。测点间距介于约11千米至不足1千米之间，澳大利亚大陆大部分区域的测点间距处于2.5至7千米范围内。航空测量的测线间距介于0.5至2.5千米之间。重力地形校正计算同时采用了近海水深数据与陆上地形数据。本图像展示了澳大利亚及其大陆边缘完整布格异常（B系列）的倾斜滤波结果。