The generation of a high-quality monthly gravity field solutions and mass change grids requires accumulation of satellite-to-satellite tracking data for about 30 days. However, within some months, a few days of data may not be used due to instrument issues, calibration campaigns etc.; the table provided below lists the actual gravity-month dates (start, end, and missing) over which data were collected and used in the estimation of gravity fields. The 'Common' missing days are missing in SDS solutions from JPL, CSR, and GFZ; the last 3 columns indicate additional days missing from individual center solutions. Please note that there are several missing consecutive weeks due to 'GRACE battery management' starting in 2011, occurring approximately every 6 months.
When comparing 'monthly mean' data sets - either from observations or simulations - to GRACE / GRACE-FO fields, we recommend that users carefully assess whether the underlying sub-monthly sampling needs to be matched between the data sets (i.e., forming monthly averages from daily data using only those days that were used in GRACE or GRACE-FO).