Gravity Dips Caused by Loss of Ice in Antarctica
Loss of ice in Antarctica has been discussed extensively due to its implications for rising sea levels and the changing landscape of the continent, but it turns out that there is another unexpected effect: gravity dips.
The ESA’s Gravity Field and Steady-State Ocean Circulation Explorer (GOCE) satellite obtained high-resolution measurements of Antarctica’s gravitational field between November 2009 and June 2012. Recent analysis led by Johannes Bouman of the German Geodetic Research Institute found that where the ice has been receding, so has the gravity field. The paper has been published in the journal Geophysical Research Letters.
In order to monitor the melting, draining, and regrowth of Antarctica’s ice more precisely, it has been divided up into catchment basins. GOCE is the first instrument sensitive enough to detect local changes in gravity specific to each individual basin. Additionally, GOCE’s data provides geologists with insights into earthquakes and volcanic activity.
GOCE’s measurements were combined with data from NASA’s Gravity Recovery and Climate Experiment (GRACE), an older satellite whose readings are more coarse. Together, they were able to generate an extremely accurate and detailed model of Earth’s gravity field, even exploring the differences between the upper mantle and crust of the planet, as well as determining the upper atmosphere’s density.