GRACE terrestrial water storage (TWS) using improved point-mass (IPM) solution

The data sets contain the GRACE monthly terrestrial water storage anomaly (TWSA) grids based on the improved point-mass (IPM) solution at Hohai University (HHU). The HHU-IPM-GRACE records for monthly TWSA values are in mm of equivalent water height for the reference period April 2002 to May 2022 in the form of a NetCDF file. 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.) The variables within the file ‘HHU_IPM_GRACE_TWS_200204_202205_v03.nc’ are ‘lat’ (latitude), ‘lon’ (longitude), ‘tws’ (terrestrial water storage), and ‘time’. Latitudes and longitudes are respectively 720-by-1 and 1440-by-1 vectors in arc-degrees (decimal) north and east, respectively, and the values refer to the cells' center. The TWS is a 720-by-1440-by-209 matrix, where the rows refer to the latitudes, the columns refer to longitudes, and the pages refer to the epochs (209 monthly solutions). Time is a 209-by-1 vector containing the number of days since January 1, 2002. A MATLAB code ‘read_hhu_ipm_tws.m’ is available for extracting the results and plotting the first month. Alternatively, the variables can be extracted and or displayed in Panoply Data Viewer available at https://www.giss.nasa.gov/tools/panoply/.