EIGEN-GL04S is a strictly static gravity field model, up to degree and order 150 from GRACE and LAGEOS data only. It is given in normalized spherical harmonic (SH) coefficients in ITRF2000, and uses exactly 2 years of GRACE + LAGEOS data (73 10-day periods between 2003/02/24 and 2005/02/23). Its reference date is 2004.0. This field does not include time-variable terms (see EIGEN-GL04S-ANNUAL below).
EIGEN-GL04C is a strictly static gravity field model, up to degree and order 360, from GRACE and LAGEOS data,plus surface data (Earth altimetric and gravimetric data). Its reference date is 2004.0.
EIGEN-GL04S-ANNUAL is based on EIGEN-GL04S, this field includes time-variable components: drift, annual and semi-annual sine and cosine.Drift terms however should be taken with some care since they were determined over only two years.