Applications of the GRACE satellite missions
The satellites of the GRACE missions record mass changes in the Earth system. In this way, the effects of climate change, e.g. in the altered global water cycle, can be observed particularly well.
At regular intervals, so-called gravity field maps are produced on the basis of new data, showing trends for continental ice masses, sea level rise and terrestrial water storage including groundwater.
In the following, you will find an overview of the fields of application as well as the key statements on the most important scientific findings.
Terrestrial Water Storage
- Terrestrial water storage includes the water that is stored on and in all the land of the Earth, from storage in vegetation to ice and snow and down to the deepest aquifers.
- The amount of water stored is a state variable of the global hydrologic cycle and affects water availability and its changes over time.
- The GRACE and GRACE-FO satellite missions are capable of measuring temporal and spatial changes in total water storage.
- Terrestrial water storage is defined an essential climate variable by the World Meteorological Organization (WMO) which should have be observed with priority in order to document long-term climate changes.
To the focus page Terrestrial water storage
Groundwater
- Groundwater is a significant source of freshwater that is increasingly threatened by anthropogenic overuse and climate change.
- GRACE/GRACE-FO satellite observations can also be used to derive changes in groundwater storage from observations of total water storage (TWS).
- With the G3P project (Global Gravity-based Groundwater Product), GFZ and international partners have developed a service that offers data on global water storage in groundwater.
To the focus page Groundwater
Ice sheets
- In recent decades, the melting of ice sheets, ice caps and glaciers has increased worldwide due to the warming of the ocean and atmosphere. With the help of the gravity field missions GRACE/GRACE-FO, these changes in global ice masses can be precisely observed and quantified.
- The loss of ice mass in the Arctic and Antarctic depends on the amount of precipitation, as well as surrounding air and ocean temperatures. However, differences can be observed in annual balances and seasonal fluctuations.
- Small-scale mass changes, such as those of mountain glaciers outside Greenland and Antarctica, are also recorded by the GRACE/GRACE-FO satellites. The greatest mass losses are recorded in Alaska, followed by northern Canada and Svalbard (Norway) in the Arctic Ocean. The contribution of glacier melt to sea level rise can be estimated with GRACE at approximately 199 billion tons of ice per year (2002–2016).
To the focus page Ice
Sea level
- The steadily ongoing rise in mean sea level has various severe consequences for human societies in densely populated coastal regions.
- Increases in global mean sea level are caused by two main factors: the input of meltwater from continental ice sheets and glaciers, and the thermal expansion of the water due to global warming caused by higher greenhouse gas concentrations.
- Meltwater and thermal expansion each contribute about 50% to the current increase in mean sea level of in total 3.4 mm per year.
- While the capacity of ocean water to absorb additional heat is limited at some point, further melting of the Earth's large ice sheets could cause global sea level to rise by dozens of meters.
To the focus page Sea level changes
Solid Earth
- Various movements of the seemingly solid and rigid surface of the Earth can be observed with the satellites of the GRACE and GRACE-FO missions. These movements are associated with changes in the gravitational field and occur on different time scales.
- The two main types of movements that can be detected are the following:
- the extremely slow but steady post-glacial movements in the Earth's mantle and lithosphere, which continue until today and
- postseismic movements after earthquakes due to sudden shifts between crustal blocks.
To the focus page Solid Earth