TY - JOUR

T1 - On the determination of the atmospheric outer scale length of turbulence using GPS phase difference observations: the Seewinkel network

AU - Kermarrec, Gaël

AU - Schön, Steffen

N1 - Funding Information: Open Access funding enabled and organized by Projekt DEAL. This study is supported by the Deutsche Forschungsgemeinschaft under the project KE2453/2-1, as a pre-step to the analysis of atmospheric noise from a terrestrial laser scanner. The Seewinkel network was initially analysed during a Feodor-Lynen fellowship (A.v. Humboldt foundation) of the second author at TU Graz with Fritz K. Brunner as his host.

PY - 2020/12/4

Y1 - 2020/12/4

N2 - Microwave electromagnetic signals from the Global Navigation Satellite System (GNSS) are affected by their travel through the atmosphere: the troposphere, a non-dispersive medium, has an especial impact on the measurements. The long-term variations of the tropospheric refractive index delay the signals, whereas its random variations correlate with the phase measurements. The correlation structure of residuals from GNSS relative position estimation provides a unique opportunity to study specific properties of the turbulent atmosphere. Prior to such a study, the residuals have to be filtered from unwanted additional effects, such as multipath. In this contribution, we propose to investigate the property of the atmospheric noise by using a new methodology combining the empirical mode decomposition with the Hilbert–Huang transform. The chirurgical “designalling of the noise” aims to filter both the white noise and low-frequency noise to extract only the noise coming from tropospheric turbulence. Further analysis of the power spectrum of phase difference can be performed, including the study of the cut-off frequencies and the two slopes of the power spectrum of phase differences. The obtained values can be compared with theoretical expectations. In this contribution, we use Global Positioning System (GPS) phase observations from the Seewinkel network, specially designed to study the impact of atmospheric turbulence on GPS phase observations. We show that (i) a two-slope power spectrum can be found in the residuals and (ii) that the outer scale length can be taken to a constant value, close to the physically expected one and in relation with the size of the eddies at tropospheric height.[Figure not available: see fulltext.]

AB - Microwave electromagnetic signals from the Global Navigation Satellite System (GNSS) are affected by their travel through the atmosphere: the troposphere, a non-dispersive medium, has an especial impact on the measurements. The long-term variations of the tropospheric refractive index delay the signals, whereas its random variations correlate with the phase measurements. The correlation structure of residuals from GNSS relative position estimation provides a unique opportunity to study specific properties of the turbulent atmosphere. Prior to such a study, the residuals have to be filtered from unwanted additional effects, such as multipath. In this contribution, we propose to investigate the property of the atmospheric noise by using a new methodology combining the empirical mode decomposition with the Hilbert–Huang transform. The chirurgical “designalling of the noise” aims to filter both the white noise and low-frequency noise to extract only the noise coming from tropospheric turbulence. Further analysis of the power spectrum of phase difference can be performed, including the study of the cut-off frequencies and the two slopes of the power spectrum of phase differences. The obtained values can be compared with theoretical expectations. In this contribution, we use Global Positioning System (GPS) phase observations from the Seewinkel network, specially designed to study the impact of atmospheric turbulence on GPS phase observations. We show that (i) a two-slope power spectrum can be found in the residuals and (ii) that the outer scale length can be taken to a constant value, close to the physically expected one and in relation with the size of the eddies at tropospheric height.[Figure not available: see fulltext.]

KW - Double difference residuals

KW - GPS phase observations

KW - Kolmogorov spectrum

KW - Matérn model

KW - Outer scale length of turbulence

UR - http://www.scopus.com/inward/record.url?scp=85097189241&partnerID=8YFLogxK

U2 - 10.1186/s40623-020-01308-w

DO - 10.1186/s40623-020-01308-w

M3 - Article

VL - 72

JO - Earth, planets and space

JF - Earth, planets and space

SN - 1343-8832

M1 - 184

ER -