Oceanic Tide Model FES2014b: Comparison with Gravity Measurements

The oceanic gravimetric effect is calculated by expanding the cotidal maps of the FES2014 oceanic tide model into spherical functions with the use of load Love numbers from the work (Spiridonov and Vinogradova, 2017). The calculation results for the amplitudes and phases of the oceanic gravimetric effect for eight main tidal waves (Q1, O1, P1, K1, N2, M2, S2, and K2) at nine European gravity observation stations of the Global Geodynamic Project (GGP) network are presented. The amplitude delta factors and phase shifts of these tidal waves for the Earth with the ocean are predicted and compared with observations. The difference vectors (prediction minus observations) are analyzed in detail with the use of both different theoretical tide models and oceanic-effect calculation versions. The FES2014 model is included in the ATLANTIDA3.1 tidal prediction software. The results of the work show, first, that the FES2014 is one of the best oceanic models today. The amplitude delta factors and phase shifts of tidal waves calculated with its help for the Earth with the ocean are generally in better agreement with observations when analyzed separately than the FES2012 model results. This is especially evident at Strasbourg and Vienna sites. The analysis of difference vectors implies that FES2014 is slightly inferior to FES2012 in terms of proximity to observations. This fact still requires an explanation. However, the amplitudes of the difference vectors calculated with the FES2012 and FES2014 models usually differ by no more than a few hundredths of a percent of the tidal wave amplitudes. Such small differences can be due to a number of factors unrelated to the oceanic effect.