This image is from data taken by NASA's Gravity Recovery and Climate Experiment showing the Amazon basin in South America. The amount of water stored in the Amazon basin varies from month to month.
Animations are available at the Photojournal.
NASA's GRACE mission has become a key source of knowledge about global ice mass changes. Studies of Greenland using GRACE and other data indicate that between 2000 and 2008 the Greenland ice sheet lost as much as 1,500 gigatons of mass.