The WHU_RL01 GRACE monthly gravity field solutions are produced with the classical dynamic approach at the GNSS Research Center of Wuhan University. Three sets of monthly solutions complete to d/o 60, 90 and 120 are produced without any regularization for the time period from 2002-04 to 2016-07.

K-Band range rates with a sampling of 5 seconds and reduced-dynamic orbits with a sampling of 5 minutes are used as observations. To account for the colored noise in the K-Band range-rate measurements, the frequency-dependent data weighting scheme proposed by Ditmar et al. (2007) is adopted. Additionally, a unified weight for the reduced-dynamic orbits is applied based on its a priori precision of 2 cm for each component.

The strategy adopted for producing the WHU_RL01 GRACE monthly gravity field models is summarized in Table 1 (please find it in the attached explanatory file). It should be noted that relatively short arcs (6 hours per arc) are used to reduce the resonance effects caused by inaccuracies in initial state vectors and background force models (Colombo, 1984). The reduced-dynamic orbits are also used as observations in our data processing. Although a reduced-dynamic orbit contain certain a priori gravity field information, the resulting bias in the gravity field solutions have been proved to be limited when inverted together with the K-band measurements (Chen et al., 2014; Liu et al., 2010).