Three-Year Characterization of Boundary Layer Dynamics From GNSS Zenith Wet Delay Spectral Analysis

Abstract

Continuous monitoring of boundary layer turbulence remains a challenge due to sparse conventional instrumentation. Here we suggest that spectral analysis of Global Navigation Satellite System (GNSS) zenith wet delay (ZWD) fluctuations yields physically meaningful diagnostics of boundary layer state. From 3 years of co-located GNSS and Doppler lidar observations (January 2022–December 2024) at Payerne, Switzerland, we extract the variance σ², a measure of integrated water vapor turbulence intensity, and the cutoff frequency fc, which marks the spectral extent of turbulent mixing. Annual harmonic analysis reveals that σ² captures 54% of its variance through the seasonal cycle (R² = 0.54, peak in January), while fc peaks in August (R² = 0.49). The inverse σ²–fc coupling (r = -0.61) tightens to r = -0.77 under summer convective conditions, consistent with regime-dependent physical correspondence. Cross-instrument comparison with Doppler lidar turbulent kinetic energy (TKE) integrated over 100–550 m is compatible with the fundamental vertical sampling mismatch between troposphere-weighted GNSS and profile-limited lidar measurements. These results establish GNSS networks as a globally available sensing system for boundary layer turbulence monitoring.