Global Time Echoes: 25-Year Temporal Evolution of Distance-Structured Correlations in GNSS Clocks

This study extends the Global Time Echoes program to 25.3 years of GNSS timing data, analyzing 30-second clock products from the CODE analysis center (2000–2025; 474 unique receivers; 165.2 million station pairs). Distance-structured correlations previously identified across independent analysis centers remain stable over decadal timescales, with persistent east–west > north–south anisotropy (ratio=2.16, strength=1.981±0.23, p<10⁻¹⁵).

This analysis builds on the initial multi-center study (Global Time Echoes: Distance-Structured Correlations in GNSS Clocks, https://doi.org/10.5281/zenodo.17127229) and follows the theoretical framework introduced in the Temporal Equivalence Principle (https://doi.org/10.5281/zenodo.16921911).

Six independent signatures converge on systematic gravitational coupling: (1) Spatial anisotropy persists with EW>NS (ratio=2.16, strength=1.981±0.23, p<10⁻¹⁵), (2) anisotropy ratio correlates strongly with orbital velocity (r=-0.864, p<10⁻¹¹, 6.6σ) across 25 solar orbits, (3) 47% of planetary events survive ultra-conservative Bonferroni correction (34/156), (4) coupling to 18.6-year lunar nutation (R²=0.640, p<10⁻⁸) and semiannual nutation (R²=0.904), (5) network synchronization (score=0.582) replicates multi-center range (0.579-0.624), (6) null results for solar rotation (27-day) and lunar standstill demonstrate selectivity for orbital-gravitational phenomena over surface features.

Observed patterns confirm key a priori TEP predictions: correlation length λ=1,000-10,000 km (observed: 4,201±1,967 km), exponential decay preferred over power-law (ΔAIC=12.8), velocity-dependent anisotropy (r=-0.864), and geometric alignment (EW/NS=2.16). 

Prior work demonstrated cross-center consistency over 2.5 years (CODE/IGS/ESA, R²=0.92-0.97). This extended dataset enables decadal-scale tests and provides the first long-term validation of distance-structured correlations in GNSS timing networks.