Resolving the "Dark Uncertainty" in Optical Clocks: A Bicomponent Phenomenological Model for Secular Drift and Orbital Modulation

Recent high-precision comparisons between Yb+ and Sr optical clocks have revealed a long-term systematic variance, currently classified as an unresolved "dark uncertainty." We demonstrate that this variance is not stochastic noise, but the vectorial superposition of two distinct deterministic phenomena. By applying a strict, zero-free-parameter phenomenological model, we decompose the signal into an isotope-dependent secular drift - scaling with the nuclear spin difference (∆I) - and a macroscopic periodic modulation rigidly locked to Earth's orbital ephemerides. When both the secular quantum aging and the Keplerian metric modulation are accounted for, the residual variance drops to the intrinsic operational limits of the hardware, yielding a reduced chi-square (χ2v) of 1.06 over the mature measurement baseline. This resolves the dark uncertainty anomaly and suggests that modern optical clocks act as geometric-topological sensors, actively registering their internal entropic degradation and exact orbital kinematics.