SRTM2gravity: An Ultrahigh Resolution Global Model of Gravimetric Terrain Corrections

Abstract

We present a new global model of spherical gravimetric terrain corrections which take into account the gravitational attraction of Earth’s global topographic masses at 3” (~90 m) spatial resolution. The conversion of Shuttle Radar Topography Mission (SRTM)-based digital elevation data to implied gravity effects relies on the global evaluation of Newton’s law of gravitation, which represents a computational challenge for 3” global topography data. We tackled this task by combining spatial and spectral gravity forward modelling techniques at the 0.2 mGal accuracy level and used advanced computational resources in parallel to complete the 1 million CPU-hour-long computation within ~2 months. Key outcome is a 3” map of topographic gravity effects reflecting the total gravitational attraction of Earth’s global topography at ~28 billion computation points. The data, freely available for use in science, teaching and industry, is immediately applicable as new in-situ terrain correction to reduce gravimetric surveys around the globe. Plain Language Summary Measurement and study of the gravitational force (the g-value) is essential for geoscientists concerned with, e.g., mineral prospection and investigation of Earth’s gravitational field. Most applications require the analyst to remove the gravitational signal caused by the surrounding and remote terrain (mountains, valleys) from the g-value at the location of the measurement. This task involves tedious numerical computations when high-resolution terrain data sets, e.g., from the Shuttle Radar Topography Mission (SRTM) are used. Utilizing improved computational methods and 1 million computation hours on a supercomputer, a globally 90 m-detailed map has been created that shows the subtle influence of the terrain on g-measurements at ~28 billion measurement sites around the globe. This first-of-its-kind map, released into the public domain, is expected to simplify the daily work of geoscientists in research and industry concerned with gravity interpretation and to clear the path for next-generation global gravity maps with extreme detail.