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

Analysis of 25.3 years of global GNSS timing data (165.2 million station pairs) documents persistent velocity-dependent correlations in atomic clock networks. Critically, we propose that standard GNSS processing algorithms, designed to remove energetic (common-mode) errors via datum constraints, inadvertently preserve the subtle, geometry-dependent (differential) correlations that are the focus of this work. Building on the multi-centre study's validation (R²=0.92-0.97 between CODE, IGS, ESA), the extended temporal baseline confirms decadal stability and enables investigation of long-period geophysical phenomena inaccessible in shorter baselines. Seven independent signatures are identified: (1) Spatial anisotropy persists with EW>NS (global ratio=2.16, strength=1.981, p 30), velocity-dependent anisotropy (r=-0.888), and geometric alignment (EW/NS=2.16). The absence of GM/r² scaling is physically consistent with the hypothesis that energetic couplings are filtered by processing while geometric information is transmitted; raw carrier-phase analysis will test this transmission mechanism. Raw data validation and multi-constellation replication represent critical next steps.