Atmospheric Corrections for Superconducting Gravimeters Using Operational Weather Models

Abstract Inversion of internal structure of the Earth using surface waves and free oscillations is a hot topic in seismological research nowadays. With the ambient noise data on seismically quiet days sourced from the gravity tidal observations of seven global distributed superconducting gravimeters (SGs) and the seismic observations for validation from three collocated STS-1 seismometers, long-period surface waves and background free oscillations are successfully extracted by the phase autocorrelation (PAC) method, respectively. Group-velocity dispersion curves at the frequency band of 2–7.5 mHz are extracted and compared with the theoretical values calculated with the preliminary reference Earth model. The comparison shows that the best observed values differ about ±2% from the corresponding theoretical results, and the extracted group velocities of the best SG are consistent with the result of the collocated STS-1 seismometer. The results indicate that reliable group-velocity dispersion curves can be measured with the ambient noise data from SGs. Furthermore, the fundamental frequency spherical free oscillations of 2–7 mHz are also clearly extracted using the same ambient noise data. The results in this study show that the SG, besides the seismometer, is proved to be another kind of instrument that can be used to observe long-period surface waves and free oscillations on seismically quiet days with a high degree of precision using the PAC method. It is worth mentioning that the PAC method is first and successfully introduced to analyze SG observations in our study.

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Adaptive parallelization techniques in global weather models

Parallel Computing ◽

10.1016/s0167-8191(98)00051-9 ◽

1998 ◽

Vol 24 (8) ◽

pp. 1167-1175 ◽

Cited By ~ 4

Author(s):

Bouchaib Radi ◽

Jean-Francois Estrade

Keyword(s):

Weather Models

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Benchmark campaign and case study episode in Central Europe for development and assessment of advanced GNSS tropospheric models and products

10.5194/amt-2015-395 ◽

2016 ◽

Author(s):

J. Douša ◽

G. Dick ◽

M. Kačmařík ◽

R. Brožková ◽

F. Zus ◽

...

Keyword(s):

Central Europe ◽

Functional Model ◽

Heavy Precipitation ◽

Severe Weather ◽

Path Delay ◽

Numerical Weather ◽

Horizontal Gradients ◽

Numerical Weather Models ◽

Zenith Path Delay ◽

Weather Models

Abstract. Initial objectives and design of the Benchmark campaign organized within the European COST Action ES1206 (2013-2017) are described in the paper. This campaign has aimed at supporting the development and validation of advanced GNSS tropospheric products, in particular high-resolution and ultra-fast zenith total delays (ZTD) and tropospheric gradients derived from a dense permanent network. A complex dataset was collected for the 8-week period when several extreme heavy precipitation episodes occurred in central Europe which caused severe river floods in this area. An initial processing of data sets from Global Navigation Satellite System (GNSS) and numerical weather models (NWM) provided independently estimated reference parameters – zenith tropospheric delays and tropospheric horizontal gradients. Their provision gave an overview about the product similarities and complementarities and thus a potential for improving a synergy in their optimal exploitations in future. Reference GNSS and NWM results were inter-compared and visually analysed using animated maps. ZTDs from two reference GNSS solutions compared to global ERA-Interim re-analysis resulted in the accuracy at the 10-millimeter level in terms of RMS (with a negligible overall bias), comparisons to global GFS forecast showed accuracy at the 12-millimeter level with the overall bias of -5 mm and, finally, comparisons to mesoscale ALADIN-CZ forecast resulted in the accuracy at the 8-milllimetre level with a negligible total bias. The comparison of horizontal tropospheric gradients from GNSS and NWM data demonstrated a very good agreement among independent solutions with negligible biases and the accuracy of about 0.5 mm. Visual comparisons of maps of zenith wet delays and tropospheric horizontal gradients showed very promising results for future exploitations of advanced GNSS tropospheric products in meteorological applications such as severe weather event monitoring and weather nowcasting. The GNSS products revealed a capability of providing more detailed structures in atmosphere than the state-of-the-art numerical weather models are able to capture. Initial study on contribution of hydrometeors (e.g. cloud water, ice or snow) to GNSS signal delays during severe weather reached up to 17 mm in zenith path delay and suggested to carefully account them within the functional model. The reference products will be further exploited in various specific studies using the Benchmark dataset. It is thus going to play a key role in these highly inter-disciplinary developments towards better mutual benefits from advanced GNSS and meteorological products.

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The Contribution of GGP Superconducting Gravimeters to GGOS

International Association of Geodesy Symposia - Observing our Changing Earth ◽

10.1007/978-3-540-85426-5_97 ◽

2008 ◽

pp. 841-852 ◽

Cited By ~ 4

Author(s):

David Crossley ◽

Jacques Hinderer

Keyword(s):

Superconducting Gravimeters

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Estimation of free core resonance parameters based on long-term strain observations in the diurnal frequency band

Физика земли ◽

10.31857/s0002-33372019341-50 ◽

2019 ◽

pp. 41-50

Author(s):

V. K. Milyukov ◽

A. Amoruso ◽

L. Crescentini ◽

A. P. Mironov ◽

A. V. Myasnikov ◽

...

Keyword(s):

Laser Interferometer ◽

Liquid Core ◽

Resonant Mode ◽

Parameter Estimates ◽

Retrograde Motion ◽

Tidal Waves ◽

Superconducting Gravimeters ◽

Fixed Reference ◽

Free Core Resonance

The free core nutation (FCN) is one of the Earth’s rotational eigenmodes, which is caused by the retrograde motion of the liquid core relative to the mantle. The FCN period and Q-factor are determined by the elastic properties of the core/mantle boundary (CMB) and their electromagnetic interaction. In the celestial coordinate system, the FCN period is about 430 days; in the Earth-fixed reference frame this effect manifests itself in the form of the free core resonance (FCR) whose frequency falls in the diurnal tidal band. FCR observation requires highly accurate measurement of the amplitudes and phases of the near-diurnal tidal waves. In particular, the parameter estimates for minor waves K1, P1, Ψ1, and Φ1 are critically important for evaluating the FCR effect, i.e., the period and decay of this resonant mode. The progress in the experimental study of FCR is mainly due to the accumulation of the data from superconducting gravimeters and VLBI; at the same time, also the data of the precision laser strainmeters were used. In this work, the FCR effect is studied based on the long-term strain precision records by two European stations: Baksan, Russia (laser interferometer–strainmeter with a measuring armlength of 75 m [Milyukov et al., 2005; 2007] and Gran Sasso, Italy (two perpendicular laser interferometer–strainmeters, BA and BC, each with a measuring armlength of 90 m [Amoruso and Crescentini, 2009]).

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