Data from the European Space Agency’s (ESA) Gravity Field and Steady-State Ocean Circulation Explorer (GOCE) satellite has shown that the ice lost from West Antarctica has caused changes in the Earth’s gravity field. The GOCE satellite measured the Earth’s gravity over the span of four years to better understand the strength of gravity at the Earth’s surface. This venture is the most accurate gravity model ever produced (1).
Gravity maps of Antarctica and surrounding ocean have been improved thanks to higher resolution satellite measurements.
The strength of gravity at Earth’s surface varies slightly from location to location due to factors such as the planet’s rotation and the position of mountains and trenches. Changes in the mass of large ice sheets can also cause small local differences in gravity. Recently, scientists from the German Geodetic Research Institute, Delft University of Technology, the Jet Propulsion Lab, and the Technical University of Munich analyzed the GOCE’s data of Antarctica from November 2009 to June 2012 and found that the decrease in the mass of ice during this period was mirrored in the GOCE’s measurements.
Using gravity data to assess changes in ice mass is not a new technique. A NASA and German Aerospace Center joint mission from 10 years ago, the GRACE satellites, also measure changes in gravity. However, measurements from the GRACE satellites are coarser than those from the GOCE, so they cannot be used to look at features such as Antarctica’s smaller watersheds.
By combining high-resolution measurements from the GOCE with data from GRACE, scientists found that a decrease in ice from West Antarctica from 2009 to 2012 caused a dip in the gravity field over the region (1).
In addition, scientists plan to use the GOCE data to validate satellite altitude measurements for an even clearer understanding of ice sheet and sea level change.
Sources:
1. Bouman, J, M Fuchs, E Ivins, W van der Wal, E Schrama, P Visser, and M Horwath. “Antarctic outlet glacier mass change resolved at basin scale from satellite gravity gradiometry.” Geophysical Research Letters 41.16 (2014): 5919. Wiley Online Library. Web. 5 Oct. 2014.