The animation was generated from the monthly ocean mass grids, which contain ocean water mass given as equivalent water thickness derived from GRACE ocean bottom pressure processed by GFZ. Equivalent water thickness is used to represent the water mass so it can be comparable to sea level anomalies due to water mass changes. The time coverage for the monthly grids are determined by GRACE months. For the list of GRACE month dates visit http://grace.jpl.nasa.gov/data/grace-months/. For more information please visit http://grace.jpl.nasa.gov/data/get-data/monthly-mass-grids-ocean/.