Figure 1
From: Parameters of the Earth’s Free Core Nutation from Diurnal Strain Tides
Ocean loading effects on strain tides. (a) Crustal thickness (interpolated from the 15′ × 15′ EuCRUST-07 model52) of Southern Europe (map generated using GMT v. 4.5.12, https://www.generic-mapping-tools.org/); locations (solid blue circles) of the LNGS (Laboratori Nazionali del Gran Sasso) and LSC (Laboratorio Subterráneo de Canfranc) laboratories and directions (solid green lines) of the two pairs of laser geodetic strainmeters (BA, BC and LAB780, GAL16) are also shown. (b) Phasor plot of solid tides (red arrows), load tides (green arrows) and total tides (blue arrows) computed along the interferometers. Amplitudes are normalized to the solid components. As for phasor directions, a horizontal rightward arrow would indicate 0° phase lag with respect to local potential; counterclockwise angles indicate positive phase lags. Solid tides are computed using Eqs. 4 and 5 and the reference IERS 20103 frequency-dependent Love and Shida numbers; load tides are computed using FES201434 ocean model and cPREM36 Earth model. Results are similar if the other ocean and Earth models are used (see Data and Methods). (c) Misfit distributions (arbitrary units) obtained when using different Earth and ocean models for computing ocean loading.
