Satellite Gravimetry: A Review of Its Realization

Abstract

Since Kepler, Newton and Huygens in the seventeenth century, geodesy has been concerned with determining the figure, orientation and gravitational field of the Earth. With the beginning of the space age in 1957, a new branch of geodesy was created, satellite geodesy. Only with satellites did geodesy become truly global. Oceans were no longer obstacles and the Earth as a whole could be observed and measured in consistent series of measurements. Of particular interest is the determination of the spatial structures and finally the temporal changes of the Earth's gravitational field. The knowledge of the gravitational field represents the natural bridge to the study of the physics of the Earth's interior, the circulation of our oceans and, more recently, the climate. Today, key findings on climate change are derived from the temporal changes in the gravitational field: on ice mass loss in Greenland and Antarctica, sea level rise and generally on changes in the global water cycle. This has only become possible with dedicated gravity satellite missions opening a method known as satellite gravimetry. In the first forty years of space age, satellite gravimetry was based on the analysis of the orbital motion of satellites. Due to the uneven distribution of observatories over the globe, the initially inaccurate measuring methods and the inadequacies of the evaluation models, the reconstruction of global models of the Earth's gravitational field was a great challenge. The transition from passive satellites for gravity field determination to satellites equipped with special sensor technology, which was initiated in the last decade of the twentieth century, brought decisive progress. In the chronological sequence of the launch of such new satellites, the history, mission objectives and measuring principles of the missions CHAMP, GRACE and GOCE flown since 2000 are outlined and essential scientific results of the individual missions are highlighted. The special features of the GRACE Follow-On Mission, which was launched in 2018, and the plans for a next generation of gravity field missions are also discussed.

Earth's core variability from the magnetic and gravity field observations

“…Several centers have computed Earth's time variable gravity models based on the GRACE data: the Center for Space Research (CSR, USA), the Jet Propulsion Laboratory (JPL, USA), the GeoForschungsZentrum (GFZ, De), the Groupe de Recherche en Géodésie (GRGS, France), the Goddard Space Flight Center (GSFC, USA), the University of Technology Gratz (TU Gratz, Au) (Flechtner et al, 2021;Landerer and Swenson, 2012;Tapley et al, 2005;Dahle et al, 2019;Kvas et al, 2019).…”

Geological Mapping Optimisation Using Satellite Gravity, Satellite Imagery, and Seismic Shear Velocity (Vs30) to Monitor Lithological Condition in Geothermal Area of Mount Salak, West Java

“…Satellite gravity is implementing gravity anomaly distribution measurement to calculate the rock density [20,21]. Simply, satellite gravity was worked similar with terrestrial gravimeter, but for this one was attached in satellite vehicle [22,23]. Reciprocally with satellite imagery that was utilised satellite vehicle as carrier to orbit the earth [24,25].…”

Using Satellite-Based Terrestrial Water Storage Data: A Review

“…Those techniques have since then made enormous progress, and GRACE-based TWS observations have reached a level of maturity enabling them to be used in a wide variety of applications, such as monitoring of freshwater resources and assimilation into numerical hydrological models (Tapley et al 2019 ; Rodell et al 2018 ). Following the success of the pioneering GRACE mission, gravimetric TWS remote sensing has entered a new phase where several successor missions are being proposed and implemented (Wiese et al 2011 ; Elsaka et al 2013 ; Pail et al 2015 ; Haagmans et al 2020 ; Flechtner et al 2021 ). The objective is to both extend the existing data record and improve the spatiotemporal resolution of the final data products.…”