The Earth’s gravity field changes with time due to various geodynamical processes.
The motions are secular and periodic. The largest secular changes are caused by
mantle convection, mass transportation (e.g. glacier melting and sea level rise) and glacial isostatic adjustment, as well as plate and intraplate motions. Notable periodic variations are due to Earth’s rotation (e.g. the pole tide of period 14 months), seasonal variations caused by variations in atmospheric and hydrologic conditions and tidal variations of various different periods. Today, most successful data for studying the temporal changes of the gravity field is dedicated satellite-gravity mission GRACE. The monthly GRACE data can be used for different applications such as: