LOADING PREDICTION FILES README

The loading prediction files are available for most stations in the NGL database.  
Each file has a header line plus additional rows for each epoch for which a loading displacement estimte is provided.  
The times are those for which the station has position solutions up until the time of the last loading model update.
These files are typically updated every few months.

The predictions are from ESMGFZ (http://rz-vm115.gfz-potsdam.de:8080/repository, Dill and Dobslaw, JGR, 2013; Dill, 2008)
Their hydrological model is from from 24-hourly terrestrial water storage global hydrological model LSDM forced by ECMWF operational atmospheric data
produced by IERS Associated Product Centre Deutsches GeoForschungsZentrum (GFZ) Potsdam. LSDM masses are given on a regular 0.5x0.5 degrees.
http://rz-vm115.gfz-potsdam.de:8080/repository/entry/show?entryid=dadb0121-32f0-4eaa-a3ec-b5f37860e4d1

We get the NTAL, NTOL, HYDL measurements at each GPS station by fitting a spline to GFZ's lat, lon grids using their program "extractlatlon_bicubintp".

The header line has format:
station  latitude longitude type notes_on_source_and_latency

The subsequent rows have a six-column format:
  station JPL_date decimal_year east_displacement north_displacement up_displacement 
with displacement estimates in units of meters.

The "CM:CF Translation" file supplies for the specific station the geocenter motion in east, north, up coordinates. 
This translates between the CM and CF versions of the loading prediction files. 

NGL time series are in CM (IGS20).  To see the time series in CF you should subtract the values in this file.
which are based on the Altamimi et al. 2023 J. Geodesy, Table 3 geocenter motion.