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<p>Geodetic very long baseline interferometry (VLBI) is affected by stochastic fluctuations in atmospheric water vapor, which degrade delay measurements and limit the precision of derived geodetic parameters. The high quality and data rate of modern VLBI observations allow us to analyze high-rate residuals on two baselines (ONSA13NE–WETTZ13S, 920 km; MACGO12M–WESTFORD, 3138 km) to quantify turbulence-induced variations. Using power spectral density analysis and debiased Whittle maximum likelihood estimation, we estimate two turbulence parameters from 31 VGOS sessions: the cutoff frequency <InlineEquation ID="IEq1"><EquationSource Format="TEX">\(\lambda\)</EquationSource><EquationSource Format="MATHML"><math><mi>λ</mi></math></EquationSource></InlineEquation> (linked to the outer scale of turbulence) and the variance <InlineEquation ID="IEq2"><EquationSource Format="TEX">\(\sigma ^2\)</EquationSource><EquationSource Format="MATHML"><math><msup><mi>σ</mi><mn>2</mn></msup></math></EquationSource></InlineEquation> (reflecting turbulence intensity). Both parameters exhibit clear seasonal patterns consistent with atmospheric dynamics: higher <InlineEquation ID="IEq3"><EquationSource Format="TEX">\(\lambda\)</EquationSource><EquationSource Format="MATHML"><math><mi>λ</mi></math></EquationSource></InlineEquation> in winter indicates stable stratification with smaller eddies, while lower <InlineEquation ID="IEq4"><EquationSource Format="TEX">\(\lambda\)</EquationSource><EquationSource Format="MATHML"><math><mi>λ</mi></math></EquationSource></InlineEquation> in summer reflects buoyancy-driven convection with larger turbulent structures. Cross-validation using co-located Onsala telescopes yields correlations exceeding 0.82 for <InlineEquation ID="IEq5"><EquationSource Format="TEX">\(\sigma ^2\)</EquationSource><EquationSource Format="MATHML"><math><msup><mi>σ</mi><mn>2</mn></msup></math></EquationSource></InlineEquation> and 0.62 for <InlineEquation ID="IEq6"><EquationSource Format="TEX">\(\lambda\)</EquationSource><EquationSource Format="MATHML"><math><mi>λ</mi></math></EquationSource></InlineEquation>. These results provide a first step toward refining stochastic VLBI models and open perspectives for climatological applications through comparisons with satellite-derived atmospheric data.</p> Graphical abstract <p></p>

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Probing atmospheric turbulence with VLBI residuals: when theory meets observations

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  • 发表日期：

    2026年7月6日

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  • Gaël Kermarrec,
  • Matthias Schartner

摘要

Geodetic very long baseline interferometry (VLBI) is affected by stochastic fluctuations in atmospheric water vapor, which degrade delay measurements and limit the precision of derived geodetic parameters. The high quality and data rate of modern VLBI observations allow us to analyze high-rate residuals on two baselines (ONSA13NE–WETTZ13S, 920 km; MACGO12M–WESTFORD, 3138 km) to quantify turbulence-induced variations. Using power spectral density analysis and debiased Whittle maximum likelihood estimation, we estimate two turbulence parameters from 31 VGOS sessions: the cutoff frequency \(\lambda\)λ (linked to the outer scale of turbulence) and the variance \(\sigma ^2\)σ2 (reflecting turbulence intensity). Both parameters exhibit clear seasonal patterns consistent with atmospheric dynamics: higher \(\lambda\)λ in winter indicates stable stratification with smaller eddies, while lower \(\lambda\)λ in summer reflects buoyancy-driven convection with larger turbulent structures. Cross-validation using co-located Onsala telescopes yields correlations exceeding 0.82 for \(\sigma ^2\)σ2 and 0.62 for \(\lambda\)λ. These results provide a first step toward refining stochastic VLBI models and open perspectives for climatological applications through comparisons with satellite-derived atmospheric data.

Graphical abstract