They are anomalies regarding the period from January 2004 to December 2009. The data sets are provided at a spatial partitioning of 0.25-by-0.25 arc-degrees. (The resolution is still GRACE’s native resolution which is 300-400 km.)
https://www.selectdataset.com/dataset/99d8b48d9c7fa9b837819b0c7faaa9a3



