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) to estimate a dimensionless coherence-based correlation metric between 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), treating the long-span GNSS dataset as a targeted empirical test of TEP predictions.

Six independent signatures converge on a systematic, decadal-stable correlation pattern in the GNSS timing coherence field that is empirically consistent with gravitational/kinematic 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=-0.888, p<2×10⁻⁷, 5.1σ; 5 M surrogates) across 25 solar orbits, (3) 43% of planetary events survive ultra-conservative Bonferroni correction (38/67 significant detections; 49 BY-FDR), (4) coupling to 18.6-year lunar nutation (R²=0.641, p<10⁻⁸) and semiannual nutation (R²=0.904, p<10⁻²⁰), (5) network synchronization (score=0.554) 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 match key a priori TEP predictions in their spatial and temporal structure: correlation length λ=1,000-10,000 km (observed: 4,201±1,967 km), exponential decay preferred over power-law (Gaussian/squared-exponential ΔAIC≈0 vs power-law ΔAIC>30), velocity-dependent anisotropy (r=-0.888), and geometric alignment (EW/NS=2.16). The underlying physical mechanism and amplitude scaling, including the absence of clear GM/r² mass scaling in planetary responses, remain open questions that require raw carrier-phase analysis and independent replication.

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.